Medicinal plants

File:Arabic herbal medicine guidebook.jpeg's 1st century {{lang|la|De materia medica}}, seen here in a {{circa|1334}} copy in Arabic, describes some 1000 drug recipes based on over 600 plants.]]

{{further|History of herbalism|History of pharmacy}}

Plants, including many now used as culinary herbs and spices, have been used as medicines, not necessarily effectively, from prehistoric times. Spices have been used partly to counter food spoilage bacteria, especially in hot climates,{{cite journal |last1=Billing |first1=Jennifer |last2=Sherman |first2=P. W. |title=Antimicrobial functions of spices: why some like it hot |journal=Quarterly Review of Biology |volume=73 |issue=1 |pages=3–49 |date=March 1998 |doi=10.1086/420058 |pmid=9586227 |s2cid=22420170 }} and especially in meat dishes that spoil more readily.{{cite journal |last1=Sherman |first1=P. W. |last2=Hash |first2=G. A. |title=Why vegetable recipes are not very spicy |journal=Evolution and Human Behavior |volume=22 |issue=3 |pages=147–163 |date=May 2001 |doi=10.1016/S1090-5138(00)00068-4 |pmid=11384883 }} Angiosperms (flowering plants) were the original source of most plant medicines.{{cite encyclopedia |title=Angiosperms: Division Magnoliophyta: General Features |encyclopedia=Encyclopædia Britannica (volume 13, 15th edition) |year=1993 |page=609 }} Human settlements are often surrounded by weeds used as herbal medicines, such as nettle, dandelion and chickweed.{{cite journal |last=Stepp |first=John R. |title=The role of weeds as sources of pharmaceuticals |journal=Journal of Ethnopharmacology |volume=92 |issue=2–3 |pages=163–166 |date=June 2004 |doi=10.1016/j.jep.2004.03.002 |pmid=15137997}}{{cite journal|last1=Stepp |first1=John R. |last2=Moerman |first2=Daniel E. |title=The importance of weeds in ethnopharmacology |journal=Journal of Ethnopharmacology |volume=75 |issue=1 |pages=19–23 |date=April 2001 |doi=10.1016/S0378-8741(00)00385-8 |pmid=11282438}} Humans were not alone in using herbs: some animals, such as non-human primates, monarch butterflies and sheep ingest plants when they are ill.{{cite book |author=Sumner, Judith |title=The Natural History of Medicinal Plants |publisher=Timber Press |year=2000 |isbn=978-0-88192-483-1 |page=16}}

Samples from prehistoric burial sites indicate that Paleolithic peoples consumed plants. For instance, a 60,000-year-old Neanderthal burial site, "Shanidar IV", in northern Iraq yielded pollen from eight plant species.{{cite journal |last=Solecki |first=Ralph S. |title=Shanidar IV, a Neanderthal Flower Burial in Northern Iraq |journal=Science |volume=190 |issue=4217 |date=November 1975 |pages=880–881 |doi=10.1126/science.190.4217.880 |bibcode=1975Sci...190..880S |s2cid=71625677 }} At Taforalt cave, Morocco, 15,000-year-old remains of ephedra were found inside a tomb, indicating its possible role in funeral rites.{{Cite journal |last1=Morales |first1=Jacob |last2=Carrión Marco |first2=Yolanda |last3=Cooper |first3=Joanne H. |last4=Turner |first4=Elaine |last5=Freyne |first5=Alison |last6=Hogue |first6=Joshua |last7=Ziani |first7=Ismail |last8=Barton |first8=R. Nicholas E. |last9=Bouzouggar |first9=Abdeljalil |last10=Humphrey |first10=Louise T. |display-authors=3|date=2024-11-02 |title=Late pleistocene exploitation of Ephedra in a funerary context in Morocco |journal=Scientific Reports |language=en |volume=14 |issue=1 |pages=26443 |doi=10.1038/s41598-024-77785-w |issn=2045-2322 |pmc=11531600 |pmid=39488593}} A mushroom found in the personal effects of Ötzi the Iceman, whose body was frozen in the Ötztal Alps for more than 5,000 years, may have been used against whipworm.{{cite journal |author=Capasso, L. |title=5300 years ago, the Ice Man used natural laxatives and antibiotics |journal=Lancet |volume=352 |issue=9143 |pages=1864 |date=December 1998 |pmid=9851424 |doi=10.1016/S0140-6736(05)79939-6 |s2cid=40027370 |doi-access=free }}

File:PEbers c41-bc.jpg ({{circa|1550 BC}}) from Ancient Egypt describes the use of hundreds of plant medicines.]]

In ancient Sumeria, hundreds of medicinal plants including myrrh and opium are listed on clay tablets from around 3000 BC. The ancient Egyptian Ebers Papyrus lists over 800 plant medicines such as aloe, cannabis, castor bean, garlic, juniper, and mandrake.{{cite book |last=Sumner |first=Judith |title=The Natural History of Medicinal Plants |publisher=Timber Press |year=2000 |isbn=978-0-88192-483-1|page=17}}{{sfn|Petrovska|2012|pp=1–5}}

In antiquity, various cultures across Europe, including the Romans, Celts, and Nordic peoples, also practiced herbal medicine as a significant component of their healing traditions.

The Romans had a rich tradition of herbal medicine, drawing upon knowledge inherited from the Greeks and expanding upon it. Notable works include those of Pedanius Dioscorides, whose "De Materia Medica" served as a comprehensive guide to medicinal plants and remained influential for centuries.Osbaldeston, Tess Anne. Dioscorides: De Materia Medica. Olms-Weidmann, 2000 Additionally, Pliny the Elder's "Naturalis Historia" contains valuable insights into Roman medical plant practices Pliny the Elder. Natural History. Harvard University Press, 1938-1963

Among the Celtic peoples of ancient Europe, herbalism played a vital role in both medicine and spirituality. Druids, the religious leaders of the Celts, were reputed to possess deep knowledge of plants and their medicinal properties. Although written records are scarce, archaeological evidence, such as the discovery of medicinal plants at Celtic sites, provides insight into their herbal practices Ross, Anne. Pagan Celtic Britain: Studies in Iconography and Tradition. Constable, 1967

In the Nordic regions, including Scandinavia and parts of Germany, herbal medicine was also prevalent in ancient times. The Norse sagas and Eddic poetry often mention the use of herbs for healing purposes. Additionally, archaeological findings, such as the remains of medicinal plants in Viking-age graves, attest to the importance of herbal remedies in Nordic culture Wills, Tarrin. "Herbal Medicine in the Viking Age." Viking Magazine, vol. 80, no. 3, 2017, pp. 22–27.

From ancient times to the present, Ayurvedic medicine as documented in the Atharva Veda, the Rig Veda and the Sushruta Samhita has used hundreds of herbs and spices, such as turmeric, which contains curcumin.{{cite book |last1=Dwivedi |first1=Girish |last2=Dwivedi |first2=Shridhar |year=2007 |title=History of Medicine: Sushruta – the Clinician – Teacher par Excellence |publisher=National Informatics Centre |url=http://medind.nic.in/iae/t07/i4/iaet07i4p243.pdf |access-date=8 October 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081010045900/http://medind.nic.in/iae/t07/i4/iaet07i4p243.pdf |archive-date=10 October 2008 }} The Chinese pharmacopoeia, the Shennong Ben Cao Jing records plant medicines such as chaulmoogra for leprosy, ephedra, and hemp.{{cite book |last=Sumner |first=Judith |title=The Natural History of Medicinal Plants |publisher=Timber Press |year=2000 |isbn=978-0-88192-483-1 |page=18}} This was expanded in the Tang dynasty Yaoxing Lun.{{cite book |last=Wu |first=Jing-Nuan |title=An Illustrated Chinese Materia Medica |publisher=Oxford University Press |year=2005 |isbn=978-0-19-514017-0 |page=6 |url=https://books.google.com/books?id=H9Q8agQrJR0C&pg=PA6}} In the fourth century BC, Aristotle's pupil Theophrastus wrote the first systematic botany text, Historia plantarum.{{cite book |last=Grene |first=Marjorie |title=The philosophy of biology: an episodic history |year=2004 |publisher=Cambridge University Press |isbn=978-0-521-64380-1 |url=https://books.google.com/books?id=TJSGJjh8Jo8C&pg=PA11 |page=11}} In around 60 AD, the Greek physician Pedanius Dioscorides, working for the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in {{lang|la|De materia medica}}. The book remained the authoritative reference on herbalism for over 1500 years, into the seventeenth century.{{cite book |last=Collins |first=Minta |title=Medieval Herbals: The Illustrative Traditions |publisher=University of Toronto Press |year=2000 |isbn=978-0-8020-8313-5 |page=32 |url=https://books.google.com/books?id=s7c2EaxDYjUC&pg=PA32}}

File:Physician talking to a female patient in a garden Wellcome L0073711.jpg's 1025 The Canon of Medicine, showing a physician talking to a female patient in a garden, while servants prepare medicines.]]

During the Middle Ages, herbalism continued to flourish across Europe, with distinct traditions emerging in various regions, often influenced by cultural, religious, indigenous, and geographical factors.

In the Early Middle Ages, Benedictine monasteries preserved medical knowledge in Europe, translating and copying classical texts and maintaining herb gardens.{{cite book |last=Arsdall |first=Anne V. |title=Medieval Herbal Remedies: The Old English Herbarium and Anglo-Saxon Medicine |publisher=Psychology Press |year=2002 |isbn=978-0-415-93849-5 |pages=70–71 |url=https://books.google.com/books?id=ITxsaqEmVHAC&pg=PA70}}{{cite book |last=Mills |first=Frank A. |chapter=Botany |editor=Johnston, William M. |title=Encyclopedia of Monasticism: M-Z |publisher=Taylor & Francis |year=2000 |isbn=978-1-57958-090-2 |page=179 |chapter-url=https://books.google.com/books?id=GfC0TDkJJNgC&pg=PA179}} Hildegard of Bingen wrote Causae et Curae ("Causes and Cures") on medicine.{{cite journal |author=Ramos-e-Silva Marcia |year=1999 |title=Saint Hildegard Von Bingen (1098–1179) "The Light Of Her People And Of Her Time" |journal=International Journal of Dermatology |volume=38 |issue=4 |pages=315–320 |doi=10.1046/j.1365-4362.1999.00617.x |pmid=10321953 |s2cid=13404562 }}

In France, herbalism thrived alongside the practice of medieval medicine, which combined elements of Ancient Greek and Roman traditions. Catholic monastic orders played a significant role in preserving and expanding herbal knowledge. Manuscripts like the "Tractatus de Herbis" from the 15th century depict French herbal remedies and their uses.Givens, Jean A. "The Tractatus de Herbis: A Thirteenth-Century Herbal." The British Library, 1982. Monasteries and convents served as centers of learning, where monks and nuns cultivated medicinal gardens. Likewise, in Italy, herbalism flourished with contribution Italian physicians like Matthaeus Platearius who compiled herbal manuscripts, such as the "Circa Instans," which served as practical guides for herbal remedies.Givens, Jean A. "The Tractatus de Herbis: A Thirteenth-Century Herbal." The British Library, 1982

In the Iberian Peninsula, the regions of the North remained independent during the period of Islamic occupation, and retained their traditional and indigenous medical practices. Galicia and Asturias, possessed a rich herbal heritage shaped by its Celtic and Roman influences. The Galician people were known for their strong connection to the land and nature and preserved botanical knowledge, with healers, known as "curandeiros" or "meigas," who relied on local plants for healing purposes Fernández, Marta. "The Herbalist in Galicia." Ethnobotany Research and Applications, vol. 8, 2010, pp. 263–277. The Asturian landscape, characterized by lush forests and mountainous terrain, provided a rich source of medicinal herbs used in traditional healing practices, with "yerbatos," who possessed extensive knowledge of local plants and their medicinal properties Díaz-Puente, José Manuel, et al. "Traditional Medicine in Asturias (Northern Spain)." Journal of Ethnopharmacology, vol. 45, no. 2, 1995, pp. 67–74. Barcelona, located in the Catalonia region of northeastern Spain, was a hub of cultural exchange during the Middle Ages, fostering the preservation and dissemination of medical knowledge. Catalan herbalists, known as "herbolarios," compiled manuscripts detailing the properties and uses of medicinal plants found in the region. The University of Barcelona, founded in 1450, played a pivotal role in advancing herbal medicine through its botanical gardens and academic pursuits.Vallès, Joan. "Botany and Medicine in Medieval Barcelona." Dynamis, vol. 19, 1999, pp. 349–377.

In Scotland and England, herbalism was deeply rooted in folk traditions and influenced by Celtic, Anglo-Saxon, and Norse practices. Herbal knowledge was passed down through generations, often by wise women known as "cunning folk." The "Physicians of Myddfai," a Welsh herbal manuscript from the 13th century, reflects the blending of Celtic and Christian beliefs in herbal medicine.Lloyd, Robert, editor. "The Physicians of Myddfai." The Welsh MSS. Society, 1861.

In the Islamic Golden Age, scholars translated many classical Greek texts including Dioscorides into Arabic, adding their own commentaries.{{cite book |title=The New Healing Herbs |last=Castleman |first=Michael |publisher=Rodale |year=2001 |page=[https://archive.org/details/newhealingherbs00mich/page/15 15] |isbn=978-1-57954-304-4 |url=https://archive.org/details/newhealingherbs00mich/page/15 }}; {{cite book |last=Collins |first=Minta |title=Medieval Herbals: The Illustrative Traditions |publisher=University of Toronto Press |year=2000 |isbn=978-0-8020-8313-5 |page=115 |url=https://books.google.com/books?id=s7c2EaxDYjUC&pg=PA115 }}; {{cite web |url=https://www.nlm.nih.gov/exhibition/islamic_medical/islamic_11.html |title=Pharmaceutics and Alchemy |publisher=US National Library of Medicine |access-date=26 January 2017 |archive-date=5 January 2017 |archive-url=https://web.archive.org/web/20170105140717/https://www.nlm.nih.gov/exhibition/islamic_medical/islamic_11.html |url-status=live }}; {{cite book |last=Fahd |first=Toufic |title=Botany and agriculture |page=815}}, in {{cite book |last1=Rashed |first1=Roshdi |last2=Morelon |first2=Régis |title=Encyclopedia of the History of Arabic Science: Astronomy-Theoretical and applied, v.2 Mathematics and the physical sciences; v.3 Technology, alchemy and life sciences |url=https://books.google.com/books?id=Fx7GtwAACAAJ |year=1996 |publisher=Routledge |isbn=978-0-415-02063-3 }}

Herbalism flourished in the Islamic world, particularly in Baghdad and in Al-Andalus. Among many works on medicinal plants, Abulcasis (936–1013) of Cordoba wrote The Book of Simples, and Ibn al-Baitar (1197–1248) recorded hundreds of medicinal herbs such as Aconitum, nux vomica, and tamarind in his Corpus of Simples.{{cite book |title=The New Healing Herbs |last=Castleman |first=Michael |publisher=Rodale |year=2001 |page=[https://archive.org/details/newhealingherbs00mich/page/15 15] |isbn=978-1-57954-304-4 |url=https://archive.org/details/newhealingherbs00mich/page/15 }} Avicenna included many plants in his 1025 The Canon of Medicine.{{cite journal |last=Jacquart |first=Danielle |journal=European Review |volume=16 |issue=2 |pages=219–227 [223] |year=2008 |title=Islamic Pharmacology in the Middle Ages: Theories and Substances |doi=10.1017/S1062798708000215 }} Abu-Rayhan Biruni,{{cite journal |author1=Kujundzić, E. |author2=Masić, I. |title=[Al-Biruni--a universal scientist]|journal=Med. Arh. |date=1999 |volume=53 |issue=2 |pages=117–120 |language=hr |pmid=10386051}} Ibn Zuhr,{{cite journal |doi=10.1086/372742 |last1=Krek |first1=M. |year=1979 |title=The Enigma of the First Arabic Book Printed from Movable Type |journal=Journal of Near Eastern Studies |volume=38 |issue=3|pages=203–212 |s2cid=162374182 }} Peter of Spain, and John of St Amand wrote further pharmacopoeias.{{cite journal |doi=10.1067/mcp.2000.106465 |author1=Brater, D. Craig |author2=Daly, Walter J. |year=2000 |title=Clinical pharmacology in the Middle Ages: Principles that presage the 21st century | journal=Clinical Pharmacology & Therapeutics |volume=67 |issue=5|pages=447–450 [448–449] |pmid=10824622|s2cid=45980791 }}

File:The Grete Herball, Title Page, 1526.jpg, 1526]]

The Early Modern period saw the flourishing of illustrated herbals across Europe, starting with the 1526 Grete Herball. John Gerard wrote his famous The Herball or General History of Plants in 1597, based on Rembert Dodoens, and Nicholas Culpeper published his The English Physician Enlarged.{{cite journal |author-link=Charles Singer |last=Singer |first=Charles |date=1923 |title=Herbals |journal=The Edinburgh Review |volume=237 |pages=95–112}}

Many new plant medicines arrived in Europe as products of Early Modern exploration and the resulting Columbian Exchange, in which livestock, crops and technologies were transferred between the Old World and the Americas in the 15th and 16th centuries. Medicinal herbs arriving in the Americas included garlic, ginger, and turmeric; coffee, tobacco and coca travelled in the other direction.{{cite journal |last1=Nunn |first1=Nathan |last2=Qian |first2=Nancy |year= 2010 |title=The Columbian Exchange: A History of Disease, Food, and Ideas |journal=Journal of Economic Perspectives |volume=24 |issue=2 |pages=163–188 |jstor=25703506 |doi=10.1257/jep.24.2.163 |citeseerx=10.1.1.232.9242 }}{{cite journal |last1=Heywood |first1=Vernon H. |title=The role of New World biodiversity in the transformation of Mediterranean landscapes and culture |url=http://147.163.105.223/bocconea/24-069.pdf |journal=Bocconea |volume=24 |pages=69–93 |date=2012 |access-date=2017-02-26 |archive-url=https://web.archive.org/web/20170227062205/http://147.163.105.223/bocconea/24-069.pdf |archive-date=2017-02-27 |url-status=dead }}

In Mexico, the sixteenth century Badianus Manuscript described medicinal plants available in Central America.{{cite journal |author=Gimmel Millie |year=2008 |title=Reading Medicine In The Codex De La Cruz Badiano |journal=Journal of the History of Ideas |volume=69 |issue=2|pages=169–192 |doi=10.1353/jhi.2008.0017|pmid=19127831 |s2cid=46457797 }}

{{further|Pharmacognosy}}

The place of plants in medicine was radically altered in the 19th century by the application of chemical analysis. Alkaloids were isolated from a succession of medicinal plants, starting with morphine from the poppy in 1806, and soon followed by ipecacuanha and strychnos in 1817, quinine from the cinchona tree, and then many others. As chemistry progressed, additional classes of potentially active substances were discovered in plants. Commercial extraction of purified alkaloids including morphine began at Merck in 1826. Synthesis of a substance first discovered in a medicinal plant began with salicylic acid in 1853. Around the end of the 19th century, the mood of pharmacy turned against medicinal plants, as enzymes often modified the active ingredients when whole plants were dried, and alkaloids and glycosides purified from plant material started to be preferred. Drug discovery from plants continued to be important through the 20th century and into the 21st, with important anti-cancer drugs from yew and Madagascar periwinkle.{{cite journal |last=Petrovska |first=Biljana Bauer |title=Historical review of medicinal plants' usage |journal=Pharmacognosy Reviews |date=2012 |volume=6 |issue=11 |pages=1–5 |doi=10.4103/0973-7847.95849 |pmid=22654398 |pmc=3358962 |doi-access=free }}{{Citation | author1=Price, J. R. | author2=Lamberton, J. A. | author3=Culvenor, C.C.J | title=The Australian Phytochemical Survey: historical aspects of the CSIRO search for new drugs in Australian plants. Historical Records of Australian Science, 9(4), 335–356 | journal=Historical Records of Australian Science | year=1992 | volume=9 | issue=4 | publication-date=1992 | publisher=Australian Academy of Science | url=https://www.publish.csiro.au/HR/HR9930940335 | pages=335–356 | doi=10.1071/hr9930940335 | access-date=2022-04-02 | archive-date=2022-01-21 | archive-url=https://web.archive.org/web/20220121231103/https://www.publish.csiro.au/hr/HR9930940335 | url-status=live }}

Medicinal plants are used with the intention of maintaining health, to be administered for a specific condition, or both, whether in modern medicine or in traditional medicine.{{cite journal |author1=Smith-Hall, C. |author2=Larsen, H.O. |author3=Pouliot, M. |title=People, plants and health: a conceptual framework for assessing changes in medicinal plant consumption |journal=J Ethnobiol Ethnomed |volume=8 |pages=43 |year=2012 |pmid=23148504 |pmc=3549945 |doi=10.1186/1746-4269-8-43 |doi-access=free }} The Food and Agriculture Organization estimated in 2002 that over 50,000 medicinal plants are used across the world.{{cite web |last1=Schippmann |first1=Uwe |last2=Leaman |first2=Danna J. |last3=Cunningham |first3=A. B. |title=Impact of Cultivation and Gathering of Medicinal Plants on Biodiversity: Global Trends and Issues 2. Some Figures to start with ... |work=Biodiversity and the Ecosystem Approach in Agriculture, Forestry and Fisheries. Satellite event on the occasion of the Ninth Regular Session of the Commission on Genetic Resources for Food and Agriculture. Rome, 12–13 October 2002. Inter-Departmental Working Group on Biological Diversity for Food and Agriculture. Rome |url=http://www.fao.org/docrep/005/AA010E/AA010e02.htm |publisher=Food and Agriculture Organization |access-date=25 September 2017 |date=12 October 2002 |archive-date=24 July 2017 |archive-url=https://web.archive.org/web/20170724135111/http://www.fao.org/docrep/005/AA010E/AA010e02.htm |url-status=live }} The Royal Botanic Gardens, Kew more conservatively estimated in 2016 that 17,810 plant species have a medicinal use, out of some 30,000 plants for which a use of any kind is documented.{{cite web|title=State of the World's Plants Report - 2016|url=https://stateoftheworldsplants.com/2016/report/sotwp_2016.pdf|publisher=Royal Botanic Gardens, Kew|access-date=25 September 2017|date=2016|archive-date=19 September 2017|archive-url=https://web.archive.org/web/20170919052314/https://stateoftheworldsplants.com/2016/report/sotwp_2016.pdf|url-status=dead}}

In modern medicine, around a quarter{{efn|Farnsworth states that this figure was based on prescriptions from American community pharmacies between 1959 and 1980.}} of the drugs prescribed to patients are derived from medicinal plants, and they are rigorously tested. In other systems of medicine, medicinal plants may constitute the majority of what are often informal attempted treatments, not tested scientifically.{{cite journal |last1=Tilburt |first1=Jon C. |last2=Kaptchuk |first2=Ted J. |title=Herbal medicine research and global health: an ethical analysis |journal=Bulletin of the World Health Organization |date=August 2008 |volume=86 |issue=8 |pages=577–656 |doi=10.2471/BLT.07.042820 |pmid=18797616 |pmc=2649468 |url=https://www.who.int/bulletin/volumes/86/8/07-042820/en/ |archive-url=https://web.archive.org/web/20100124091134/http://www.who.int/bulletin/volumes/86/8/07-042820/en/ |url-status=dead |archive-date=January 24, 2010 |access-date=22 September 2017 }} The World Health Organization estimates, without reliable data, that some 80 percent of the world's population depends mainly on traditional medicine (including but not limited to plants); perhaps some two billion people are largely reliant on medicinal plants.{{cite journal |last1=Farnsworth |first1=Norman R. |last2=Akerele |first2=Olayiwola |last3=Bingel |first3=Audrey S. |last4=Soejarto |first4=Djada D. |last5=Guo |first5=Zhengang |title=Medicinal plants in therapy |journal=Bulletin of the World Health Organization |date=1985 |volume=63 |issue=6|pages=965–981|pmid=3879679 |pmc=2536466 }} The use of plant-based materials including herbal or natural health products with supposed health benefits, is increasing in developed countries.{{cite journal |last1=Ekor |first1=Martins |title=The growing use of herbal medicines: issues relating to adverse reactions and challenges in monitoring safety |journal=Frontiers in Pharmacology |date=2013 |volume=4 |issue=3 |pages=202–4|doi=10.3389/fphar.2013.00177 |pmid=24454289 |pmc=3887317|doi-access=free }} This brings attendant risks of toxicity and other effects on human health, despite the safe image of herbal remedies. Herbal medicines have been in use since long before modern medicine existed; there was and often still is little or no knowledge of the pharmacological basis of their actions, if any, or of their safety. The World Health Organization formulated a policy on traditional medicine in 1991, and since then has published guidelines for them, with a series of monographs on widely used herbal medicines.{{cite book |last=Singh |first=Amritpal |title=Regulatory and Pharmacological Basis of Ayurvedic Formulations |url=https://books.google.com/books?id=zgBPDAAAQBAJ&pg=PA4 |date=2016 |publisher=CRC Press |isbn=978-1-4987-5096-7 |pages=4–5}}

Medicinal plants may provide three main kinds of benefit: health benefits to the people who consume them as medicines; financial benefits to people who harvest, process, and distribute them for sale; and society-wide benefits, such as job opportunities, taxation income, and a healthier labour force. However, development of plants or extracts having potential medicinal uses is blunted by weak scientific evidence, poor practices in the process of drug development, and insufficient financing.{{cite journal | vauthors = Berida T, Adekunle Y, Dada-Adegbola H, Kdimy A, Roy S, Sarker S | title = Plant antibacterials: The challenges and opportunities | journal = Heliyon | volume = 10 | issue = 10 | page = e31145 | date = May 2024 | pmid = 38803958 | pmc = 11128932 | doi = 10.1016/j.heliyon.2024.e31145 | doi-access = free }}

{{further|Phytochemistry}}

All plants produce chemical compounds which give them an evolutionary advantage, such as defending against herbivores or, in the example of salicylic acid, as a hormone in plant defenses.{{cite book |title = Salicylic Acid – A Plant Hormone |author1 = Hayat, S. |author2 = Ahmad, A. |isbn = 978-1-4020-5183-8 |year = 2007 |publisher = Springer Science and Business Media |url-access = registration |url = https://archive.org/details/salicylicacidpla0000unse }} These phytochemicals have potential for use as drugs,{{citation|author=Kai Lamottke, Christophe Ripoll, Robert Walczak |date=2011 |pages=52-56 https://www.researchgate.net/publication/260943788_The_Roots_of_Innovation |periodical=European Biopharmaceutical Review |title=The roots of innovation |volume=15}} and the content and known pharmacological activity of these substances in medicinal plants is the scientific basis for their use in modern medicine, if scientifically confirmed. For instance, daffodils (Narcissus) contain nine groups of alkaloids including galantamine, licensed for use against Alzheimer's disease. The alkaloids are bitter-tasting and toxic, and concentrated in the parts of the plant such as the stem most likely to be eaten by herbivores; they may also protect against parasites.{{cite book |last1=Bastida |first1=Jaume |last2=Lavilla |first2=Rodolfo |last3=Viladomat |first3=Francesc Viladomat |editor1-last=Cordell |editor1-first=G. A. |chapter=Chemical and Biological Aspects of Narcissus Alkaloids |date=2006 |volume=63 |pages=87–179 |doi=10.1016/S1099-4831(06)63003-4 |pmid=17133715 |title=The Alkaloids: Chemistry and Biology |journal=The Alkaloids. Chemistry and Biology |pmc=7118783 |isbn=978-0-12-469563-4}}{{cite web |title=Galantamine |url=https://www.drugs.com/mtm/galantamine.html |publisher=Drugs.com |date=2017 |access-date=17 March 2018 |archive-date=14 October 2018 |archive-url=https://web.archive.org/web/20181014091614/https://www.drugs.com/mtm/galantamine.html |url-status=live }}{{cite journal |pmid=16437532 |year=2006 |last1=Birks |first1=J. |editor1-first=Jacqueline S |editor1-last=Birks |title=Cholinesterase inhibitors for Alzheimer's disease |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=1 |pages=CD005593 |doi=10.1002/14651858.CD005593|pmc=9006343 }}

Modern knowledge of medicinal plants is being systematised in the Medicinal Plant Transcriptomics Database, which by 2011 provided a sequence reference for the transcriptome of some thirty species.{{cite web |title=Transcriptome Characterization, Sequencing, And Assembly Of Medicinal Plants Relevant To Human Health |url=http://apps.pharmacy.uic.edu/depts/pcrps/MedTranscriptomePlants/ |publisher=University of Illinois at Chicago |last=Soejarto |first=D. D. |date=1 March 2011 |access-date=26 January 2017 |archive-date=20 April 2017 |archive-url=https://web.archive.org/web/20170420235537/http://apps.pharmacy.uic.edu/depts/pcrps/MedTranscriptomePlants/ |url-status=live }} Major classes of plant phytochemicals are described below, with examples of plants that contain them.{{cite book |author=Meskin, Mark S. |title=Phytochemicals in Nutrition and Health |publisher=CRC Press|year=2002 |isbn=978-1-58716-083-7 |page=123 |url=https://books.google.com/books?id=cJHsMALUDj0C&pg=PA123}}{{cite book |author1=Springbob, Karen |author2=Kutchan, Toni M. |chapter=Introduction to the different classes of natural products|editor=Lanzotti, Virginia |title=Plant-Derived Natural Products: Synthesis, Function, and Application |publisher=Springer |year=2009 |isbn=978-0-387-85497-7 |page=3 |chapter-url=https://books.google.com/books?id=Y8SpVXEng4QC&pg=PA3}}{{cite journal |last1=Elumalai |first1=A. |last2=Eswariah |first2=M. Chinna |title=Herbalism - A Review |journal=International Journal of Phytotherapy |date=2012 |volume=2 |issue=2 |pages=96–105 |url=http://www.phytotherapyjournal.com/File_Folder/96-105.pdf |access-date=2017-02-17 |archive-url=https://web.archive.org/web/20170217232814/http://www.phytotherapyjournal.com/File_Folder/96-105.pdf |archive-date=2017-02-17 |url-status=dead }}

{{further|Alkaloids}}

Alkaloids are bitter-tasting chemicals, very widespread in nature, and often toxic, found in many medicinal plants.{{cite book |author=Aniszewski, Tadeusz |title=Alkaloids – secrets of life|location=Amsterdam |publisher=Elsevier |year=2007|isbn=978-0-444-52736-3 |page=182}} There are several classes with different modes of action as drugs, both recreational and pharmaceutical. Medicines of different classes include atropine, scopolamine, and hyoscyamine (all from nightshade),{{cite web |title=Atropa Belladonna |url=http://www.ema.europa.eu/docs/en_GB/document_library/Maximum_Residue_Limits_-_Report/2009/11/WC500010731.pdf |publisher=The European Agency for the Evaluation of Medicinal Products |access-date=26 February 2017 |date=1998 |archive-date=17 April 2018 |archive-url=https://web.archive.org/web/20180417200131/http://www.ema.europa.eu/docs/en_GB/document_library/Maximum_Residue_Limits_-_Report/2009/11/WC500010731.pdf |url-status=live }} the traditional medicine berberine (from plants such as Berberis and Mahonia),{{efn|Berberine is the main active component of an ancient Chinese herb Coptis chinensis French, which has been administered for what Yin and colleagues state is "diabetes" for thousands of years, although with no sound evidence of efficacy.{{cite journal |last1=Yin |first1=Jun |last2=Xing |first2=Huili |last3=Ye |first3=Jianping |title=Efficacy of Berberine in Patients with Type 2 Diabetes |journal=Metabolism |date=May 2008 |volume=57 |issue=5 |pages=712–717 |pmid=18442638 |pmc=2410097 |doi=10.1016/j.metabol.2008.01.013}}}} caffeine (Coffea), cocaine (Coca), ephedrine (Ephedra), morphine (opium poppy), nicotine (tobacco),{{efn|Tobacco has "probably been responsible for more deaths than any other herb", but it was used as a medicine in the societies encountered by Columbus and was considered a panacea in Europe. It is no longer accepted as medicinal.{{cite journal |last1=Charlton |first1=Anne |title=Medicinal uses of tobacco in history |journal=Journal of the Royal Society of Medicine|date=June 2004 |volume=97 |issue=6 |pages=292–296 |pmid=15173337 |doi=10.1177/014107680409700614 |pmc=1079499}}}} reserpine (Rauvolfia serpentina), quinidine and quinine (Cinchona), vincamine (Vinca minor), and vincristine (Catharanthus roseus).{{cite journal |last1 =Gremigni|display-authors=etal|first1=P.|year=2003|title =The interaction of phosphorus and potassium with seed alkaloid concentrations, yield and mineral content in narrow-leafed lupin (Lupinus angustifolius L.) |journal=Plant and Soil |volume=253|issue=2 |pages =413–427 |jstor=24121197|doi=10.1023/A:1024828131581|s2cid=25434984}}

File:Opium poppy.jpg|The opium poppy Papaver somniferum is the source of the alkaloids morphine and codeine.

File:Nicotine.svg|The alkaloid nicotine from tobacco binds directly to the body's Nicotinic acetylcholine receptors, accounting for its pharmacological effects.{{cite web |title=Nicotinic acetylcholine receptors: Introduction |url=http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=76&familyType=IC |website=IUPHAR Database |publisher=International Union of Basic and Clinical Pharmacology |access-date=26 February 2017 |archive-date=29 June 2017 |archive-url=https://web.archive.org/web/20170629235725/http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=76&familyType=IC |url-status=live }}

File:Koeh-018.jpg|Deadly nightshade, Atropa belladonna, yields tropane alkaloids including atropine, scopolamine and hyoscyamine.

{{further|Glycosides}}

Anthraquinone glycosides are found in medicinal plants such as rhubarb, cascara, and Alexandrian senna.{{cite journal |author1=Wang, Zhe |author2=Ma, Pei |author3=He, Chunnian |author4=Peng, Yong |author5=Xiao, Peigen |title=Evaluation of the content variation of anthraquinone glycosides in rhubarb by UPLC-PDA |journal=Chemistry Central Journal |year=2013 |volume=7 |issue=1 |pages=43–56 |doi=10.1186/1752-153X-7-170 |pmid=24160332 |pmc=3854541 |doi-access=free }}{{cite book |doi=10.1016/S0378-6080(09)03148-1 |title=Treatments used in complementary and alternative medicine |volume=31 |pages=745–756 |series=Side Effects of Drugs Annual |year=2009 |last1=Chan |first1=K. |last2=Lin |first2=T.X. |isbn=978-0-444-53294-7 }} Plant-based laxatives made from such plants include senna,{{cite journal |author1=Hietala, P. |author2=Marvola, M. |author3=Parviainen, T. |author4=Lainonen, H. |title=Laxative potency and acute toxicity of some anthraquinone derivatives, senna extracts and fractions of senna extracts |volume=61 |issue=2 |pages=153–6 |journal=Pharmacology & Toxicology |pmid=3671329 |date=August 1987 |doi=10.1111/j.1600-0773.1987.tb01794.x }} rhubarb{{cite web |url=http://pharmaxchange.info/press/2012/12/pharmacognosy-of-rhubarb/ |title=Pharmacognosy of Rhubarb |author=Akolkar, Praful |work=PharmaXChange.info |date=2012-12-27 |access-date=2017-02-02 |archive-date=2015-06-26 |archive-url=https://web.archive.org/web/20150626142055/http://pharmaxchange.info/press/2012/12/pharmacognosy-of-rhubarb/ |url-status=live }} and Aloe.

The cardiac glycosides are powerful drugs from medicinal plants including foxglove and lily of the valley. They include digoxin and digitoxin which support the beating of the heart, and act as diuretics.{{cite web|title=Active Plant Ingredients Used for Medicinal Purposes|url=https://www.fs.fed.us/wildflowers/ethnobotany/medicinal/ingredients.shtml|publisher=United States Department of Agriculture|access-date=18 February 2017|quote=Below are several examples of active plant ingredients that provide medicinal plant uses for humans.|archive-date=12 July 2018|archive-url=https://web.archive.org/web/20180712052048/https://www.fs.fed.us/wildflowers/ethnobotany/medicinal/ingredients.shtml|url-status=live}}

File:Senna alexandrina Mill.-Cassia angustifolia L. (Senna Plant).jpg|Senna alexandrina, containing anthraquinone glycosides, has been used as a laxative for millennia.

Digitalis purpurea2.jpg|The foxglove, Digitalis purpurea, contains digoxin, a cardiac glycoside. The plant was used on heart conditions long before the glycoside was identified.{{cite web |title=Digitalis purpurea. Cardiac Glycoside |url=http://botany.csdl.tamu.edu/FLORA/Wilson/481/medbot/bot2.htm |publisher=Texas A&M University |access-date=26 February 2017 |quote=The man credited with the introduction of digitalis into the practice of medicine was William Withering. |archive-date=2 July 2018 |archive-url=https://web.archive.org/web/20180702064956/http://botany.csdl.tamu.edu/FLORA/Wilson/481/medbot/bot2.htm |url-status=live }}

File:Digoxin.svg|Digoxin is used to treat atrial fibrillation, atrial flutter and sometimes heart failure.

{{further|Polyphenol|Health effects of polyphenols}}

Polyphenols of several classes are widespread in plants, having diverse roles in defenses against plant diseases and predators. They include hormone-mimicking phytoestrogens and astringent tannins.{{cite journal |last1 =Da Silva|display-authors=etal|first1=Cecilia |year=2013|title =The High Polyphenol Content of Grapevine Cultivar Tannat Berries Is Conferred Primarily by Genes That Are Not Shared with the Reference Genome |journal=The Plant Cell |volume=25|issue=12 |pages=4777–4788 |jstor=43190600 |doi=10.1105/tpc.113.118810|pmid=24319081 |pmc=3903987}} Plants containing phytoestrogens have been administered for centuries for gynecological disorders, such as fertility, menstrual, and menopausal problems.{{cite book |last=Muller-Schwarze|first=Dietland |title=Chemical Ecology of Vertebrates |publisher=Cambridge University Press |year=2006|isbn=978-0-521-36377-8|page=287}} Among these plants are Pueraria mirifica,{{cite journal |author1=Lee, Y. S. |author2=Park J. S. |author3=Cho S. D. |author4=Son J. K. |author5=Cherdshewasart W. |author6=Kang K. S. |title=Requirement of metabolic activation for estrogenic activity of Pueraria mirifica |journal=Journal of Veterinary Science |volume=3 |issue=4 |pages=273–277 |date=Dec 2002 |pmid=12819377 |url=http://www.koreascience.or.kr/article/JAKO200210103477199.page |citeseerx=10.1.1.617.1507 |doi=10.4142/jvs.2002.3.4.273 |access-date=2019-04-19 |archive-date=2019-04-19 |archive-url=https://web.archive.org/web/20190419160011/http://www.koreascience.or.kr/article/JAKO200210103477199.page |url-status=live }} kudzu,{{cite journal |author1=Delmonte, P. |author2=Rader, J. I. |title=Analysis of isoflavones in foods and dietary supplements |journal=Journal of AOAC International |volume=89 |issue=4 |pages=1138–46 |year=2006 |pmid=16915857 |doi= 10.1093/jaoac/89.4.1138|doi-access=free }} angelica,{{cite book |first1=D.E. |last1=Brown|first2=N. J. |last2=Walton |title=Chemicals from Plants: Perspectives on Plant Secondary Products|publisher=World Scientific Publishing|year=1999|pages= 21, 141|isbn =978-981-02-2773-9}} fennel, and anise.{{cite journal |author=Albert-Puleo, M. |title=Fennel and anise as estrogenic agents |journal=Journal of Ethnopharmacology |volume=2 |issue=4 |pages=337–44 |date=Dec 1980 |pmid=6999244 |doi=10.1016/S0378-8741(80)81015-4 }}

Many polyphenolic extracts, such as from grape seeds, olives or maritime pine bark, are sold as dietary supplements and cosmetics without proof or legal health claims for medicinal effects.{{cite journal |author=European Food Safety Authority |title=Scientific Opinion on the substantiation of health claims related to various food(s)/food constituent(s) and protection of cells from premature aging, antioxidant activity, antioxidant content and antioxidant properties, and protection of DNA, proteins and lipids from oxidative damage pursuant to Article 13(1) of Regulation (EC) No 1924/20061 |journal=EFSA Journal |year=2010 |volume=8 |issue=2 |page=1489 |doi=10.2903/j.efsa.2010.1489|doi-access=free }} In Ayurveda, the astringent rind of the pomegranate, containing polyphenols called punicalagins, is used as a medicine, with no scientific proof of efficacy.{{cite book |title=Recent trends in horticulture in the Himalayas |author1=Jindal, K. K. |author2=Sharma, R. C. |year=2004 |isbn=978-81-7387-162-7 |publisher=Indus Publishing |url=https://books.google.com/books?id=LlogqveEFVgC}}

File:Angelica sylvestris 3.jpg|Angelica, containing phytoestrogens, has long been used for gynaecological disorders.

File:Phytoestrogens2.png|Polyphenols include phytoestrogens (top and middle), mimics of animal estrogen (bottom).{{cite journal |author1=Turner, J. V. |author2=Agatonovic-Kustrin, S. |author3=Glass, B. D. |title=Molecular aspects of phytoestrogen selective binding at estrogen receptors |journal=Journal of Pharmaceutical Sciences |volume=96 |issue=8 |pages=1879–85 |date=August 2007 |pmid=17518366 |doi=10.1002/jps.20987 }}

{{further|Terpenes}}

Terpenes and terpenoids of many kinds are found in a variety of medicinal plants,{{cite book |last1=Wiart |first1=Christopher |chapter=Terpenes |title=Lead Compounds from Medicinal Plants for the Treatment of Neurodegenerative Diseases|publisher=Elsevier Inc.|isbn= 978-0-12-398373-2|doi= 10.1016/C2011-0-09611-4|date=2014 |pages=189–284}} and in resinous plants such as the conifers. They are strongly aromatic and serve to repel herbivores. Their scent makes them useful in essential oils, whether for perfumes such as rose and lavender, or for aromatherapy.{{cite journal |last1=Tchen|first1=T. T.|year=1965|title=The Biosynthesis of Steroids, Terpenes and Acetogenins |journal=American Scientist |volume=53 |issue=4 |pages=499A–500A |jstor=27836252}}{{cite journal |last1=Singsaas|first1=Eric L.|year=2000 |title=Terpenes and the Thermotolerance of Photosynthesis |journal=New Phytologist |volume=146|issue=1 |pages=1–2 |jstor=2588737 |doi=10.1046/j.1469-8137.2000.00626.x|doi-access=free }} Some have medicinal uses: for example, thymol is an antiseptic and was once used as a vermifuge (anti-worm medicine).

File:Thymian.jpg|The essential oil of common thyme (Thymus vulgaris), contains the monoterpene thymol, an antiseptic and antifungal.{{cite web|title=Thymol (CID=6989)|url=https://pubchem.ncbi.nlm.nih.gov/compound/thymol|publisher=NIH|access-date=26 February 2017|quote=THYMOL is a phenol obtained from thyme oil or other volatile oils used as a stabilizer in pharmaceutical preparations, and as an antiseptic (antibacterial or antifungal) agent. It was formerly used as a vermifuge.|archive-date=12 July 2018|archive-url=https://web.archive.org/web/20180712052716/https://pubchem.ncbi.nlm.nih.gov/compound/thymol|url-status=live}}

File:Thymol2.svg|Thymol is one of many terpenes found in plants.

File:Papaver somniferum-Harford-02.JPG, Tasmania, 2010]]

{{main|Herbalism|List of plants used in herbalism}}

Medicinal plants demand intensive management. Different species each require their own distinct conditions of cultivation. The World Health Organization recommends the use of rotation to minimise problems with pests and plant diseases. Cultivation may be traditional or may make use of conservation agriculture practices to maintain organic matter in the soil and to conserve water, for example with no-till farming systems.{{cite web |title=WHO Guidelines on Good Agricultural and Collection Practices (GACP) for Medicinal Plants |url=http://apps.who.int/medicinedocs/en/d/Js4928e/4.3.html |archive-url=https://web.archive.org/web/20091020064719/http://apps.who.int/medicinedocs/en/d/Js4928e/4.3.html |url-status=dead |archive-date=October 20, 2009 |publisher=World Health Organization |access-date=26 February 2017 |date=2003}} In many medicinal and aromatic plants, plant characteristics vary widely with soil type and cropping strategy, so care is required to obtain satisfactory yields.{{cite journal |title=Scent of Mare Nostrum ― Medicinal and Aromatic Plants (MAPs) in Mediterranean soils |author1=Carrubba, A. |author2=Scalenghe, R. |year=2012 |volume=92 |issue=6 |pages=1150–1170 |doi=10.1002/jsfa.5630 |pmid=22419102 |journal=Journal of the Science of Food and Agriculture}}

File:Folio Materia Medica Dioscurides Met 13.152.6 (cropped).jpg

Medicinal plants are often tough and fibrous, requiring some form of preparation to make them convenient to administer. According to the Institute for Traditional Medicine, common methods for the preparation of herbal medicines include decoction, powdering, and extraction with alcohol, in each case yielding a mixture of substances. Decoction involves crushing and then boiling the plant material in water to produce a liquid extract that can be taken orally or applied topically.{{cite journal |last1=Yang |first1=Yifan |title=Theories and concepts in the composition of Chinese herbal formulas |url=https://www.sciencedirect.com/science/article/pii/B9780702031328000062 |publisher=Elsevier Ltd. |access-date=18 April 2020 |doi=10.1016/B978-0-7020-3132-8.00006-2 |year=2010 |journal=Chinese Herbal Formulas |pages=1–34|isbn=9780702031328 |doi-access=free }} Powdering involves drying the plant material and then crushing it to yield a powder that can be compressed into tablets. Alcohol extraction involves soaking the plant material in cold wine or distilled spirit to form a tincture.{{cite web |last1=Dharmananda |first1=Subhuti |title=The Methods of Preparation of Herb Formulas: Decoctions, Dried Decoctions, Powders, Pills, Tablets, and Tinctures |url=http://www.itmonline.org/arts/methprep.htm |publisher=Institute of Traditional Medicine, Portland, Oregon |date=May 1997 |access-date=2017-09-27 |archive-date=2017-10-04 |archive-url=https://web.archive.org/web/20171004042657/http://www.itmonline.org/arts/methprep.htm |url-status=live }}

Traditional poultices were made by boiling medicinal plants, wrapping them in a cloth, and applying the resulting parcel externally to the affected part of the body.{{cite web |last1=Mount |first1=Toni |title=9 weird medieval medicines |url=http://www.historyextra.com/article/medieval/9-weird-medieval-medicines |publisher=British Broadcasting Corporation |date=20 April 2015 |access-date=27 September 2017 |archive-date=28 September 2017 |archive-url=https://web.archive.org/web/20170928005414/http://www.historyextra.com/article/medieval/9-weird-medieval-medicines |url-status=live }}

When modern medicine has identified a drug in a medicinal plant, commercial quantities of the drug may either be synthesised or extracted from plant material, yielding a pure chemical.{{cite journal|last1=Atanasov |first1=Atanas G. |last2=Waltenberger |first2=Birgit |last3=Pferschy-Wenzig |first3=Eva-Maria |last4=Linder |first4=Thomas |last5=Wawrosch |first5=Christoph |last6=Uhrin |first6=Pavel |last7=Temml |first7=Veronika |last8=Wang |first8=Limei |last9=Schwaiger |first9=Stefan |last10=Heiss |first10=Elke H. |last11=Rollinger |first11=Judith M. |last12=Schuster |first12=Daniela |last13=Breuss |first13=Johannes M. |last14=Bochkov |first14=Valery |last15=Mihovilovic |first15=Marko D. |last16=Kopp |first16=Brigitte |last17=Bauer |first17=Rudolf |last18=Dirsch |first18=Verena M. |last19=Stuppner |first19=Hermann |title=Discovery and resupply of pharmacologically active plant-derived natural products: A review |journal=Biotechnology Advances |date=December 2015 |volume=33 |issue=8 |pages=1582–1614 |doi=10.1016/j.biotechadv.2015.08.001 |pmid=26281720 |pmc=4748402 }} Extraction can be practical when the compound in question is complex.{{cite journal |last1=Pezzuto |first1=John M. |title=Plant-derived anticancer agents |journal=Biochemical Pharmacology |date=January 1997 |volume=53 |issue=2 |pages=121–133 |doi=10.1016/S0006-2952(96)00654-5 |pmid=9037244 }}

File:Marrakech 103.JPG's shop in the souk of Marrakesh, Morocco]]

{{further|Herbalism|Psychoactive drug|Drug discovery}}

Plant medicines are in wide use around the world.{{cite web|title=Traditional Medicine. Fact Sheet No. 134 |url=https://www.who.int/mediacentre/factsheets/fs134/en/ |archive-url=https://web.archive.org/web/20080727053337/http://www.who.int/mediacentre/factsheets/fs134/en/ |url-status=dead |archive-date=27 July 2008 |publisher=World Health Organization |access-date=26 February 2017 |date=May 2003 }} In most of the developing world, especially in rural areas, local traditional medicine, including herbalism, is the only source of health care for people, while in the developed world, alternative medicine including use of dietary supplements is marketed aggressively using the claims of traditional medicine. As of 2015, most products made from medicinal plants had not been tested for their safety and efficacy, and products that were marketed in developed economies and provided in the undeveloped world by traditional healers were of uneven quality, sometimes containing dangerous contaminants.{{cite web |last1=Chan |first1=Margaret |title=WHO Director-General addresses traditional medicine forum |url=https://www.who.int/dg/speeches/2015/traditional-medicine/en/ |archive-url=https://web.archive.org/web/20150822171551/http://www.who.int/dg/speeches/2015/traditional-medicine/en/ |url-status=dead |archive-date=August 22, 2015 |publisher=WHO |date=19 August 2015}} Traditional Chinese medicine makes use of a wide variety of plants, among other materials and techniques.{{cite web |title=Traditional Chinese Medicine: In Depth (D428) |url=https://nccih.nih.gov/health/whatiscam/chinesemed.htm |publisher=NIH |access-date=26 February 2017 |date=April 2009 |archive-date=4 April 2017 |archive-url=https://web.archive.org/web/20170404224358/https://nccih.nih.gov/health/whatiscam/chinesemed.htm |url-status=live }} Researchers from Kew Gardens found 104 species used for diabetes in Central America, of which seven had been identified in at least three separate studies.{{cite web |last1=Giovannini |first1=Peter |title=Managing diabetes with medicinal plants |url=https://www.kew.org/blogs/kew-science/managing-diabetes-medicinal-plants-0 |publisher=Kew Gardens |access-date=3 October 2017 |archive-date=3 October 2017 |archive-url=https://web.archive.org/web/20171003180423/https://www.kew.org/blogs/kew-science/managing-diabetes-medicinal-plants-0 |url-status=live }}{{cite journal |last1=Giovannini |first1=Peter |last2=Howes |first2=Melanie-Jayne R. |last3=Edwards |first3=Sarah E. |title=Medicinal plants used in the traditional management of diabetes and its sequelae in Central America: A review |journal=Journal of Ethnopharmacology |volume=184 |year=2016 |pages=58–71 |doi=10.1016/j.jep.2016.02.034 |pmid=26924564 |s2cid=22639191 |url=https://kclpure.kcl.ac.uk/portal/en/publications/medicinal-plants-used-in-the-traditional-management-of-diabetes-and-its-sequelae-in-central-america-a-review(69685ce6-6956-4937-bf12-ef28f0c3144c).html |access-date=2020-08-27 |archive-date=2022-06-07 |archive-url=https://web.archive.org/web/20220607162724/https://kclpure.kcl.ac.uk/portal/en/publications/medicinal-plants-used-in-the-traditional-management-of-diabetes-and-its-sequelae-in-central-america-a-review(69685ce6-6956-4937-bf12-ef28f0c3144c).html |url-status=live }} The Yanomami of the Brazilian Amazon, assisted by researchers, have described 101 plant species used for traditional medicines.{{cite web |last1=Milliken |first1=William |title=Medicinal knowledge in the Amazon |url=https://www.kew.org/blogs/kew-science/medicinal-knowledge-amazon |publisher=Kew Gardens |date=2015 |access-date=2017-10-03 |archive-date=2017-10-03 |archive-url=https://web.archive.org/web/20171003180313/https://www.kew.org/blogs/kew-science/medicinal-knowledge-amazon |url-status=live }}{{cite book |author1=Yanomami, M. I. |author2=Yanomami, E. |author3=Albert, B. |author4=Milliken, W |author5=Coelho, V. |title=Hwërɨ mamotima thëpë ã oni. Manual dos remedios tradicionais Yanomami |trans-title=Manual of Traditional Yanomami Medicines |date=2014 |publisher=Hutukara/Instituto Socioambiental |location=São Paulo}}

Drugs derived from plants including opiates, cocaine and cannabis have both medical and recreational uses. Different countries have at various times made use of illegal drugs, partly on the basis of the risks involved in taking psychoactive drugs.{{cite news |title=Scoring drugs. A new study suggests alcohol is more harmful than heroin or crack |newspaper=The Economist |url=https://www.economist.com/blogs/dailychart/2010/11/drugs_cause_most_harm |access-date=26 February 2017 |date=2 November 2010 |quote="Drug harms in the UK: a multi-criteria decision analysis", by David Nutt, Leslie King and Lawrence Phillips, on behalf of the Independent Scientific Committee on Drugs. The Lancet. |archive-date=28 January 2018 |archive-url=https://web.archive.org/web/20180128172545/https://www.economist.com/blogs/dailychart/2010/11/drugs_cause_most_harm |url-status=live }}{{-}}

File:Cinchona officinalis 001.JPG tree contains the alkaloid quinine, traditionally given for malaria.]]

Plant medicines have often not been tested systematically, but have come into use informally over the centuries. By 2007, clinical trials had demonstrated potentially useful activity in nearly 16% of herbal extracts; there was limited in vitro or in vivo evidence for roughly half the extracts; there was only phytochemical evidence for around 20%; 0.5% were allergenic or toxic; and some 12% had basically never been studied scientifically.{{cite journal |last1=Cravotto |first1=G. |last2=Boffa |first2=L. |last3=Genzini |first3=L. |last4=Garella |first4=D. |title=Phytotherapeutics: an evaluation of the potential of 1000 plants |journal=Journal of Clinical Pharmacy and Therapeutics |date=February 2010 |volume=35 |issue=1 |pages=11–48 |pmid=20175810 |doi=10.1111/j.1365-2710.2009.01096.x |s2cid=29427595 |doi-access=free }} Cancer Research UK caution that there is no reliable evidence for the effectiveness of herbal remedies for cancer.{{cite web|url=https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/complementary-alternative-therapies/individual-therapies/herbal-medicine|title=Herbal medicine|publisher=Cancer Research UK|access-date=7 July 2019|quote=There is no reliable evidence from human studies that herbal remedies can treat, prevent or cure any type of cancer. Some clinical trials seem to show that certain Chinese herbs may help people to live longer, might reduce side effects, and help to prevent cancer from coming back. This is especially when combined with conventional treatment.|archive-date=29 May 2019|archive-url=https://web.archive.org/web/20190529165631/https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/complementary-alternative-therapies/individual-therapies/herbal-medicine|url-status=live}}

A 2012 phylogenetic study built a family tree down to genus level using 20,000 species to compare the medicinal plants of three regions, Nepal, New Zealand and the Cape of South Africa. It discovered that the species used traditionally to treat the same types of condition belonged to the same groups of plants in all three regions, giving a "strong phylogenetic signal". Since many plants that yield pharmaceutical drugs belong to just these groups, and the groups were independently used in three different world regions, the results were taken to mean 1) that these plant groups do have potential for medicinal efficacy, 2) that undefined pharmacological activity is associated with use in traditional medicine, and 3) that the use of a phylogenetic groups for possible plant medicines in one region may predict their use in the other regions.{{cite journal |last1=Saslis-Lagoudakis |first1=C. H. |last2=Savolainen |first2=V. |last3=Williamson |first3=E. M. |last4=Forest |first4=F. |last5=Wagstaff |first5=S. J. |last6=Baral |first6=S. R. |last7=Watson |first7=M. F. |last8=Pendry |first8=C. A. |last9=Hawkins |first9=J. A. |title=Phylogenies reveal predictive power of traditional medicine in bioprospecting |journal=Proceedings of the National Academy of Sciences |volume=109 |issue=39 |year=2012 |pages=15835–40 |doi=10.1073/pnas.1202242109 |bibcode=2012PNAS..10915835S |pmc=3465383 |pmid=22984175 |doi-access=free }}

File:An Ayurvedic Pharmacy, Rishikesh (1).jpg in India, such as the running of this Ayurvedic pharmacy in Rishikesh, is regulated by a government department, AYUSH.]]

The World Health Organization (WHO) has been coordinating a network called the International Regulatory Cooperation for Herbal Medicines to try to improve the quality of medical products made from medicinal plants and the claims made for them.{{cite web |title=International Regulatory Cooperation for Herbal Medicines (IRCH) |url=http://who.int/medicines/areas/traditional/irch/en/ |archive-url=https://web.archive.org/web/20130901005446/http://www.who.int/medicines/areas/traditional/irch/en/ |url-status=dead |archive-date=September 1, 2013 |publisher=World Health Organization |access-date=2 October 2017}} In 2015, only around 20% of countries had well-functioning regulatory agencies, while 30% had none, and around half had limited regulatory capacity. In India, where Ayurveda has been practised for centuries, herbal remedies are the responsibility of a government department, AYUSH, under the Ministry of Health & Family Welfare.{{cite journal |last1=Kala |first1=Chandra Prakash |last2=Sajwan |first2=Bikram Singh |title=Revitalizing Indian systems of herbal medicine by the National Medicinal Plants Board through institutional networking and capacity building |journal=Current Science |date=2007 |volume=93 |issue=6 |pages=797–806 |jstor=24099124 }}

WHO has set out a strategy for traditional medicines{{cite book |author=World Health Organization |title=WHO Traditional Medicine Strategy 2014-2023 |url=http://apps.who.int/iris/bitstream/10665/92455/1/9789241506090_eng.pdf?ua=1 |publisher=World Health Organization |isbn=978-92-4-150609-0 |year=2013 |access-date=2017-10-03 |archive-date=2017-11-18 |archive-url=https://web.archive.org/web/20171118192156/http://apps.who.int/iris/bitstream/10665/92455/1/9789241506090_eng.pdf?ua=1 |url-status=live }} with four objectives: to integrate them as policy into national healthcare systems; to provide knowledge and guidance on their safety, efficacy, and quality; to increase their availability and affordability; and to promote their rational, therapeutically sound usage. WHO notes in the strategy that countries are experiencing seven challenges to such implementation, namely in developing and enforcing policy; in integration; in safety and quality, especially in assessment of products and qualification of practitioners; in controlling advertising; in research and development; in education and training; and in the sharing of information.{{-}}

File:Taxus brevifolia Blue Mts WA.jpg was developed after screening of the Pacific yew, Taxus brevifolia (foliage and fruit shown) in 1971.]]

{{further|Drug discovery}}

The pharmaceutical industry has roots in the apothecary shops of Europe in the 1800s, where pharmacists provided local traditional medicines to customers, which included extracts like morphine, quinine, and strychnine.{{cite news |title=Emergence of Pharmaceutical Science and Industry: 1870-1930 |volume=83 |url=http://pubs.acs.org/cen/coverstory/83/8325/8325emergence.html |work=Chemical & Engineering News |issue=25 |date=20 June 2005 |access-date=2 October 2017 |archive-date=10 November 2018 |archive-url=https://web.archive.org/web/20181110234403/http://pubs.acs.org/cen/coverstory/83/8325/8325emergence.html |url-status=live }} Therapeutically important drugs like camptothecin (from Camptotheca acuminata, used in traditional Chinese medicine) and taxol (from the Pacific yew, Taxus brevifolia) were derived from medicinal plants.{{cite journal |last1=Heinrich |first1=M. |last2=Bremner |first2=P. |title=Ethnobotany and ethnopharmacy--their role for anti-cancer drug development |journal=Current Drug Targets |date=March 2006 |volume=7 |issue=3 |pages=239–245 |pmid=16515525 |doi=10.2174/138945006776054988}} The Vinca alkaloids vincristine and vinblastine, used as anti-cancer drugs, were discovered in the 1950s from the Madagascar periwinkle, Catharanthus roseus.{{cite journal |last1=Moudi |first1=Maryam |last2=Go |first2=Rusea |last3=Yien |first3=Christina Yong Seok |last4=Nazre |first4=Mohd. |title=Vinca Alkaloids |journal=International Journal of Preventive Medicine |date=November 2013 |volume=4 |issue=11 |pages=1231–1235 |pmid=24404355 |pmc=3883245}}

Hundreds of compounds have been identified using ethnobotany, investigating plants used by indigenous peoples for possible medical applications.{{cite journal |author1=Fabricant, D. S. |author2=Farnsworth, N. R. |title=The value of plants used in traditional medicine for drug discovery |journal=Environ. Health Perspect. |volume=109 |issue=Suppl 1 |pages=69–75 |date=March 2001 |pmid=11250806 |pmc=1240543 |doi=10.1289/ehp.01109s169 }} Some important phytochemicals, including curcumin, epigallocatechin gallate, genistein and resveratrol are pan-assay interference compounds, meaning that in vitro studies of their activity often provide unreliable data. As a result, phytochemicals have frequently proven unsuitable as the lead substances in drug discovery.{{cite journal |last1=Baell |first1=Jonathan |last2=Walters |first2=Michael A. |title=Chemistry: Chemical con artists foil drug discovery |journal=Nature |date=24 September 2014 |volume=513 |issue=7519 |pages=481–483 |doi=10.1038/513481a |pmid=25254460 |bibcode=2014Natur.513..481B |doi-access=free }}{{cite journal |last1=Dahlin |first1=Jayme L |last2=Walters |first2=Michael A |title=The essential roles of chemistry in high-throughput screening triage |journal=Future Medicinal Chemistry |date=July 2014 |volume=6 |issue=11 |pages=1265–90 |pmid=25163000 |pmc=4465542 |doi=10.4155/fmc.14.60 }} In the United States over the period 1999 to 2012, despite several hundred applications for new drug status, only two botanical drug candidates had sufficient evidence of medicinal value to be approved by the Food and Drug Administration.

The pharmaceutical industry has remained interested in mining traditional uses of medicinal plants in its drug discovery efforts. Of the 1073 small-molecule drugs approved in the period 1981 to 2010, over half were either directly derived from or inspired by natural substances.{{cite journal |last1=Newman |first1=David J. |last2=Cragg |first2=Gordon M. |title=Natural Products As Sources of New Drugs over the 30 Years from 1981 to 2010 |journal=Journal of Natural Products |date=8 February 2012 |volume=75 |issue=3 |pages=311–35 |doi=10.1021/np200906s |pmid=22316239 |pmc=3721181 }} Among cancer treatments, of 185 small-molecule drugs approved in the period from 1981 to 2019, 65% were derived from or inspired by natural substances.

File:Datura stramonium - Köhler–s Medizinal-Pflanzen-051.jpg has been used for asthma, because it contains the alkaloid atropine, but it is also a powerful and potentially fatal hallucinogen.{{cite book |last1=Freye |first1=Enno |title=Pharmacology and Abuse of Cocaine, Amphetamines, Ecstasy and Related Designer Drugs |publisher=Springer |date=2010 |pages=217–218 |isbn=978-90-481-2447-3|doi=10.1007/978-90-481-2448-0_34 |chapter=Toxicity of Datura Stramonium }}]]

{{further|List of herbs with known adverse effects}}

Plant medicines can cause adverse effects and even death, whether by side-effects of their active substances, by adulteration or contamination, by overdose, or by inappropriate prescription. Many such effects are known, while others remain to be explored scientifically. There is no reason to presume that because a product comes from nature it must be safe: the existence of powerful natural poisons like atropine and nicotine shows this to be untrue. Further, the high standards applied to conventional medicines do not always apply to plant medicines, and dose can vary widely depending on the growth conditions of plants: older plants may be much more toxic than young ones, for instance.{{cite journal |last1=Ernst |first1=E. |title=Harmless Herbs? A Review of the Recent Literature |url=http://toxicology.usu.edu/endnote/Harmless-Herbs.pdf |journal=The American Journal of Medicine |volume=104 |issue=2 |pages=170–178 |year=1998 |pmid=9528737 |doi=10.1016/S0002-9343(97)00397-5 |access-date=2013-11-28 |archive-date=2019-11-05 |archive-url=https://web.archive.org/web/20191105150424/http://toxicology.usu.edu/endnote/Harmless-Herbs.pdf |url-status=dead }}{{cite journal |last1=Talalay |first1=P. |title=The importance of using scientific principles in the development of medicinal agents from plants |journal=Academic Medicine |volume=76 |issue=3 |pages=238–47 |year=2001 |pmid=11242573 |doi=10.1097/00001888-200103000-00010 |doi-access=free }}{{cite journal |doi=10.1016/S0378-8741(00)00394-9 |last1=Elvin-Lewis |first1=M. |year=2001 |title=Should we be concerned about herbal remedies |journal=Journal of Ethnopharmacology |volume=75 |issue=2–3|pages=141–164 |pmid=11297844}}{{cite journal |author=Vickers, A. J. |title=Which botanicals or other unconventional anticancer agents should we take to clinical trial? |journal=J Soc Integr Oncol |volume=5 |issue=3 |pages=125–9 |year=2007 |pmid=17761132 |doi= |pmc=2590766}}{{cite book |author=Ernst, E. |title=Dietary Supplements and Health |chapter=Herbal medicines: balancing benefits and risks |publisher=Novartis Foundation Symposium |volume=282 |pages=154–67; discussion 167–72, 212–8 |year=2007 |pmid=17913230 |doi=10.1002/9780470319444.ch11 |series=Novartis Foundation Symposia |isbn=978-0-470-31944-4}}{{cite journal |title=Adverse effects associated with herbal medicine |last1=Pinn |first1=G. |journal=Aust Fam Physician |volume=30 |issue=11 |pages=1070–5 |date=November 2001 |pmid=11759460}}

Plant extracts may interact with conventional drugs, both because they may provide an increased dose of similar compounds, and because some phytochemicals interfere with the body's systems that metabolise drugs in the liver including the cytochrome P450 system, making the drugs last longer in the body and have a cumulative effect.{{cite journal |title=Interactions of food and dietary supplements with drug metabolising cytochrome P450 enzymes |journal=Ceska Slov Farm |volume=56 |issue=4 |pages=165–73 |date=July 2007 |pmid=17969314 |last1=Nekvindová |first1=J. |last2=Anzenbacher |first2=P.}} Plant medicines can be dangerous during pregnancy.{{cite journal |title=Herb use in pregnancy: what nurses should know |journal=MCN Am J Matern Child Nurs |volume=30 |issue=3 |pages=201–6 |date=May 2005 |pmid=15867682 |last1=Born |first1=D. |last2=Barron |first2=ML |doi=10.1097/00005721-200505000-00009|s2cid=35882289 }} Since plants may contain many different substances, plant extracts may have complex effects on the human body.{{cite journal |author1=Tapsell, L. C. |author2=Hemphill, I. |author3=Cobiac, L. |display-authors=etal |title=Health benefits of herbs and spices: the past, the present, the future |journal=Med. J. Aust. |volume=185 |issue=4 Suppl |pages=S4–24 |date=August 2006 |pmid=17022438 |doi=10.5694/j.1326-5377.2006.tb00548.x |s2cid=9769230 |url=https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2450&context=hbspapers |access-date=2020-08-27 |archive-date=2020-10-31 |archive-url=https://web.archive.org/web/20201031172039/https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2450&context=hbspapers |url-status=live |hdl=2440/22802 |hdl-access=free }}

Herbal medicine and dietary supplement products have been criticized as not having sufficient standards or scientific evidence to confirm their contents, safety, and presumed efficacy.{{cite web |url=https://www.quackwatch.com/01QuackeryRelatedTopics/herbs.html |title=The herbal minefield |author=Barrett, Stephen |publisher=Quackwatch |date=23 November 2013 |access-date=17 November 2017 |archive-date=18 August 2018 |archive-url=https://web.archive.org/web/20180818071259/http://quackwatch.com/01QuackeryRelatedTopics/herbs.html |url-status=dead }}{{cite journal |pmid=22305255 |year=2012 |last1=Zhang |first1=J. |title=Quality of herbal medicines: Challenges and solutions |journal=Complementary Therapies in Medicine |volume=20 |issue=1–2 |pages=100–106 |last2=Wider |first2=B. |last3=Shang |first3=H. |last4=Li |first4=X. |last5=Ernst |first5=E. |doi=10.1016/j.ctim.2011.09.004}}{{cite journal |pmid=13129992 |year=2003 |last1=Morris |first1=C. A. |title=Internet marketing of herbal products |journal=JAMA |volume=290 |issue=11 |pages=1505–9 |last2=Avorn |first2=J. |doi=10.1001/jama.290.11.1505 }}{{cite journal |pmc=3325194 |year=2012 |last1=Coghlan |first1=M. L. |title=Deep Sequencing of Plant and Animal DNA Contained within Traditional Chinese Medicines Reveals Legality Issues and Health Safety Concerns |journal=PLOS Genetics |volume=8 |issue=4 |pages=e1002657 |last2=Haile |first2=J. |last3=Houston |first3=J. |last4=Murray |first4=D. C. |last5=White |first5=N. E. |last6=Moolhuijzen |first6=P |last7=Bellgard |first7=M. I. |last8=Bunce |first8=M |doi=10.1371/journal.pgen.1002657 |pmid=22511890 |doi-access=free }} Companies often make false claims about their herbal products promising health benefits that aren't backed by evidence to generate more sales. The market for dietary supplements and nutraceuticals grew by 5% during the COVID-19 pandemic, which led to the United States taking action to stop the deceptive marketing of herbal products to combat the virus.{{cite journal |last1=Lordan |first1=Ronan |title=Dietary supplements and nutraceuticals market growth during the coronavirus pandemic - implications for consumers and regulatory oversight |journal=Pharmanutrition |year=2021 |volume=18 |page=100282 |publisher=Elsevier Public Health Emergency Collection |doi=10.1016/j.phanu.2021.100282 |pmid=34513589 |pmc=8416287 }}{{cite web |title=United States Files Enforcement Action to Stop Deceptive Marketing of Herbal Tea Product Advertised as Covid-19 Treatment |url=https://www.justice.gov/usao-edny/pr/united-states-files-enforcement-action-stop-deceptive-marketing-herbal-tea-product |website=United States Department of Justice |date=3 March 2022 |publisher=Department of Justice |access-date=3 October 2022 |archive-date=3 October 2022 |archive-url=https://web.archive.org/web/20221003185407/https://www.justice.gov/usao-edny/pr/united-states-files-enforcement-action-stop-deceptive-marketing-herbal-tea-product |url-status=live }}

Where medicinal plants are harvested from the wild rather than cultivated, they are subject to both general and specific threats. General threats include climate change and habitat loss to development and agriculture. A specific threat is over-collection to meet rising demand for medicines. A case in point was the pressure on wild populations of the Pacific yew soon after news of taxol's effectiveness became public. The threat from over-collection could be addressed by cultivation of some medicinal plants, or by a system of certification to make wild harvesting sustainable.{{cite journal |last1=Kling |first1=Jim |title=Protecting medicine's wild pharmacy |journal=Nature Plants |date=2016 |volume=2 |issue=5 |page=16064 |doi=10.1038/nplants.2016.64|pmid=27243657 |s2cid=7246069 }} A report in 2020 by the Royal Botanic Gardens, Kew identifies 723 medicinal plants as being at risk of extinction, caused partly by over-collection.{{cite news |last1=Briggs |first1=Helen |title=Two-fifths of plants at risk of extinction, says report |url=https://www.bbc.co.uk/news/science-environment-54344309 |work=BBC |date=30 September 2020 |access-date=30 September 2020 |archive-date=29 September 2020 |archive-url=https://web.archive.org/web/20200929235402/https://www.bbc.co.uk/news/science-environment-54344309 |url-status=live }}{{cite web |title=State of the World's Plants and Fungi 2020 |url=https://www.kew.org/sites/default/files/2020-09/Kew%20State%20of%20the%20Worlds%20Plants%20and%20Fungi.pdf |publisher=Royal Botanic Gardens, Kew |access-date=30 September 2020 |date=2020 |archive-date=5 October 2020 |archive-url=https://web.archive.org/web/20201005025107/https://www.kew.org/sites/default/files/2020-09/Kew%20State%20of%20the%20Worlds%20Plants%20and%20Fungi.pdf |url-status=live }}

• Australian Phytochemical Survey
• Ethnomedicine
• European Directive on Traditional Herbal Medicinal Products
• Plant Resources of Tropical Africa

{{notelist}}

{{reflist|30em}}

{{Medicinal herbs & fungi}}

{{Authority control}}

Category:Plants and humans