Crystal violet

{{Short description|Triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria}}

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 476997552

| ImageFile = Kristallviolett.svg

| ImageSize = 230

| ImageAlt = Kekulé, skeletal formula of a crystal violet minor tautomer

| ImageFile1 = Methyl violet 10B 3D ball.png

| ImageAlt1 = Ball-and-stick model of crystal violet as a chloride salt

| PIN = 4-{Bis[4-(dimethylamino)phenyl]methylidene}-N,N-dimethylcyclohexa-2,5-dien-1-iminium chloride

| OtherNames = {{unbulletedlist|Aniline violet|Basic violet 3|Baszol violet 57L|Brilliant violet 58|Hexamethyl-p-rosaniline chloride|Methylrosanilide chloride|Methyl Violet 10B|Methyl violet 10BNS|Pyoctanin}}

|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 548-62-9

| CASNo1_Ref = {{cascite|correct|CAS}}

| CASNo1 = 1733-13-7

| CASNo1_Comment = (base)

| PubChem = 11057

| PubChemOther = {{PubChemCID|68050}} (base)

| ChemSpiderID = 10588

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = J4Z741D6O5

| UNII1_Ref = {{fdacite|correct|FDA}}

| UNII1 = B4JIJ2C6AT

| UNII1_Comment = (base)

| EINECS = 208-953-6

| UNNumber = 3077

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 41688

| DrugBank_Ref = {{drugbankcite|changed|drugbank}}

| DrugBank = DB00406

| KEGG = D01046

| KEGG_Ref = {{keggcite|correct|kegg}}

| MeSHName = Gentian+violet

| ChEMBL = 64894

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| RTECS = BO9000000

| Beilstein = 3580948

| SMILES = [Cl-].CN(C)c1ccc(cc1)[C+](c1ccc(cc1)N(C)C)c1ccc(cc1)N(C)C

| SMILES1 = [Cl-].CN(C)C1=CC=C(C=C1)[C+](C1=CC=C(C=C1)N(C)C)C1=CC=C(C=C1)N(C)C

| StdInChI = 1S/C25H30N3.ClH/c1-26(2)22-13-7-19(8-14-22)25(20-9-15-23(16-10-20)27(3)4)21-11-17-24(18-12-21)28(5)6;/h7-18H,1-6H3;1H/q+1;/p-1

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| InChI = 1/C25H30N3.ClH/c1-26(2)22-13-7-19(8-14-22)25(20-9-15-23(16-10-20)27(3)4)21-11-17-24(18-12-21)28(5)6;/h7-18H,1-6H3;1H/q+1;/p-1

| StdInChIKey = ZXJXZNDDNMQXFV-UHFFFAOYSA-M

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| InChIKey = ZXJXZNDDNMQXFV-REWHXWOFAV

}}

|Section2={{Chembox Properties

| C=25|H=30|N=3|Cl=1

| Solubility = 4 g/L at 25 °C{{Cite book |last=Green|first=Floyd J.|pages=239–240|url=https://books.google.com/books?id=D0OTFN7coVIC|title=The Sigma-Aldrich Handbook of Stains, Dyes, and Indicators |date=1990 |publisher=Sigma-Aldrich Corp.|isbn=978-0-941633-22-2|location=Milwaukee, Wisconsin|oclc=911335305}}

| MeltingPtC = 205

}}

|Section6={{Chembox Pharmacology

| ATCCode_prefix = D01

| ATCCode_suffix = AE02

| ATC_Supplemental = {{ATC|G01|AX09}}

}}

|Section7={{Chembox Hazards

| GHSPictograms = {{GHS corrosion}} {{GHS exclamation mark}} {{GHS health hazard}} {{GHS environment}}

| GHSSignalWord = DANGER

| HPhrases = {{H-phrases|302|318|351|410}}

| PPhrases = {{P-phrases|273|280|305+351+338|501}}

| LD50 = 1.2 g/kg (oral, mice)

1.0 g/kg (oral, rats){{Cite journal |last1=Hodge |first1=H. C. |last2=Indra |first2=J. |last3=Drobeck |first3=H. P. |last4=Duprey |first4=L. P. |last5=Tainter |first5=M. L. |year=1972 |title=Acute oral toxicity of methylrosaniline chloride |journal=Toxicology and Applied Pharmacology |volume=22 |issue=1 |pages=1–5 |doi=10.1016/0041-008X(72)90219-0 |pmid=5034986|bibcode=1972ToxAP..22....1H }}

}}

Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic (vermicide) properties and was formerly important as a topical antiseptic. The medical use of the dye has been largely superseded by more modern drugs, although it is still listed by the World Health Organization.

The name gentian violet was originally used for a mixture of methyl pararosaniline dyes (methyl violet), but is now often considered a synonym for crystal violet. The name refers to its colour, being like that of the petals of certain gentian flowers; it is not made from gentians or violets.

Production

A number of possible routes can be used to prepare crystal violet.{{Citation |title=Colour Index 3rd Edition Volume 4 |url=https://www.colour-index.org/help/3121_Triarylmethane.pdf |page=4391 |year=1971 |archive-url=https://web.archive.org/web/20110719160728/https://www.colour-index.org/help/3121_Triarylmethane.pdf |place=Bradford |publisher=Society of Dyers and Colourists |archive-date=2011-07-19 |url-status=dead}}{{Citation |last1=Gessner |first1=T. |title=Ullmann's Encyclopedia of Industrial Chemistry |edition=6th |year=2002 |contribution=Triarylmethane and Diarylmethane Dyes |place=Weinheim |publisher=Wiley-VCH |doi=10.1002/14356007.a27_179 |last2=Mayer |first2=U.|isbn=978-3-527-30385-4 }} The original procedure developed by the German chemists Kern and Caro involved the reaction of dimethylaniline with phosgene to give 4,4′-bis(dimethylamino)benzophenone (Michler's ketone) as an intermediate. This was then reacted with additional dimethylaniline in the presence of phosphorus oxychloride and hydrochloric acid.

The dye can also be prepared by the condensation of formaldehyde and dimethylaniline to give a leuco dye:{{Citation |last=Thetner |first=D. |title=Kirk-Othmer Encyclopedia of Chemical Technology |url=https://mrw.interscience.wiley.com/emrw/9780471238966/kirk/article/tripthet.a01/current/pdf |archive-url=https://archive.today/20130105105555/http://mrw.interscience.wiley.com/emrw/9780471238966/kirk/article/tripthet.a01/current/pdf |url-status=dead |archive-date=January 5, 2013 |year=2000 |contribution=Triphenylmethane and related dyes |publisher=Wiley |doi=10.1002/0471238961 |isbn=978-0-471-48494-3 |url-access=subscription }}. Also available from [https://www.scribd.com/doc/30109454/Triphenylmethane-and-Related-Dyes Scribd] {{Webarchive|url=https://web.archive.org/web/20121104145950/https://www.scribd.com/doc/30109454/Triphenylmethane-and-Related-Dyes |date=2012-11-04 }}.

:CH₂O + 3 C₆H₅N(CH₃)₂ → CH(C₆H₄N(CH₃)₂)₃ + H₂O

Second, this colourless compound is oxidized to the coloured cationic form (hereafter with oxygen, but a typical oxidizing agent is manganese dioxide, MnO₂):

:CH(C₆H₄N(CH₃)₂)₃ + HCl + {{1/2}} O₂ → [C(C₆H₄N(CH₃)₂)₃]Cl + H₂O

Dye colour

{{pH indicator|indicator_name=Crystal violet|low_pH=−1.0|high_pH=2.0|low_pH_color=yellow|high_pH_color=#8800FF|high_pH_text=white}}

{{Multiple image

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| image1 = Sample of Crystal Violet.jpg

| alt1 = Black lumps in a glass beaker

| caption1 = Solid crystal violet

| image2 = Crystal Violet in aqueous solution.jpg

| alt2 = Purple liquid in a test tube

| caption2 = Crystal violet in aqueous solution

}}

When dissolved in water, the dye has a blue-violet colour with an absorbance maximum at 590 nm and an extinction coefficient of 87,000 M⁻¹ cm⁻¹.{{Cite journal |last1=Adams |first1=E. Q. |last2=Rosenstein |first2=L. |year=1914 |title=The color and ionization of crystal-violet |journal=J. Am. Chem. Soc. |volume=36 |issue=7 |pages=1452–1473 |doi=10.1021/ja02184a014 |hdl-access=free |hdl=2027/uc1.b3762873}} The colour of the dye depends on the acidity of the solution. At a pH of +1.0, the dye is green with absorption maxima at 420 nm and 620 nm, while in a strongly acidic solution (pH −1.0), the dye is yellow with an absorption maximum at 420 nm.{{citation needed|date=December 2022}}

The different colours are a result of the different charged states of the dye molecule. In the yellow form, all three nitrogen atoms carry a positive charge, of which two are protonated, while the green colour corresponds to a form of the dye with two of the nitrogen atoms positively charged. At neutral pH, both extra protons are lost to the solution, leaving only one of the nitrogen atoms positive charged. The pK_a for the loss of the two protons are approximately 1.15 and 1.8.

In alkaline solutions, nucleophilic hydroxyl ions attack the electrophilic central carbon to produce the colourless triphenylmethanol or carbinol form of the dye.{{Citation needed|date = March 2015}} Some triphenylmethanol is also formed under very acidic conditions when the positive charges on the nitrogen atoms lead to an enhancement of the electrophilic character of the central carbon, which allows the nucleophilic attack by water molecules. This effect produces a slight fading of the yellow colour.{{citation needed|date=December 2022}}

Applications

=Industry=

File:Ditto machine copies of tests.jpg duplicated tests papers, inked with crystal violet. ]]

Crystal violet is used as a textile and paper dye, and is a component of navy blue and black inks for printing, ball-point pens, and inkjet printers. Historically, it was the most common dye used in early duplication machines, such as the mimeograph and the ditto machine.{{Cite patent|number=US2838994A|title=Elements for use in practice of spirit duplication process|gdate=1958-06-17|invent1=Lebl|invent2=Joseph|invent3=Florence|inventor1-first=Richard C.|inventor2-first=Savit|inventor3-first=Robert T.|url=https://patents.google.com/patent/US2838994A/en}} It is sometimes used to colourize diverse products such as fertilizer, antifreeze, detergent, and leather.{{citation needed|date=December 2022}} Marking blue, used to mark out pieces in metalworking, is composed of methylated spirits, shellac, and gentian violet.{{Citation |last1=Brink |first1=C. |title=Engineering Fabrication & Boilermaking |page=44 |year=2008 |url=https://books.google.com/books?id=coOZXYLqqPoC&pg=PA44 |access-date=2021-07-14 |archive-url=https://web.archive.org/web/20210714054223/https://books.google.com/books?id=coOZXYLqqPoC&lpg=PA44 |archive-date=2021-07-14 |url-status=live |publisher=Pearson South Africa |isbn=978-1-77025-374-2 |last2=McNamara |first2=B.}}.

= Science =

File:Bacteria photomicrograph.jpg stained with crystal violet]]

When conducting DNA gel electrophoresis, crystal violet can be used as a nontoxic DNA stain as an alternative to fluorescent, intercalating dyes such as ethidium bromide. Used in this manner, it may be either incorporated into the agarose gel or applied after the electrophoresis process is finished. Used at a 10 ppm concentration and allowed to stain a gel after electrophoresis for 30 minutes, it can detect as little as 16 ng of DNA. Through use of a methyl orange counterstain and a more complex staining method, sensitivity can be improved further to 8 ng of DNA.{{cite journal|last1=Yang |first1=Y. |title=Counterion-dye staining method for DNA in agarose gels using crystal violet and methyl orange |journal=Electrophoresis |volume=22 |issue=5 |pages=855–859 |year=2001 |doi=10.1002/1522-2683()22:5<855::AID-ELPS855>3.0.CO;2-Y |pmid=11332752 |last2=Jung |first2=D. W. |last3=Bai |first3=D. G. |last4=Yoo |first4=G. S. |last5=Choi |first5=J. K.|s2cid=28700868 }} When crystal violet is used as an alternative to fluorescent stains, it is not necessary to use ultraviolet illumination; this has made crystal violet popular as a means of avoiding UV-induced DNA destruction when performing DNA cloning in vitro.{{citation needed|date=December 2022}}

Crystal violet can be used as an alternative to Coomassie brilliant blue (CBB) in staining of proteins separated by SDS-PAGE, reportedly showing a 5x improved sensitivity vs CBB.{{cite journal |last1=Krause |first1=Robert G. E. |last2=Goldring |first2=J. P. Dean |year=2019 |title=Crystal violet stains proteins in SDS-PAGE gels and zymograms |journal=Analytical Biochemistry |publisher=Elsevier BV |volume=566 |pages=107–115 |doi=10.1016/j.ab.2018.11.015 |issn=0003-2697 |pmid=30458124 |s2cid=53944873}}

The dye is used as a histological stain, particularly in Gram staining for classifying bacteria.{{cite journal |last1=G |first1=Barbolini |last2=AC |first2=Pessina |date=1977 |title=Non-specificity of crystal violet staining for renin granules |journal=Acta Histochemica |publisher=Acta Histochem |volume=58 |issue=2 |pages=191–193 |doi=10.1016/S0065-1281(77)80127-X |issn=0065-1281 |pmid=70939}}

In biomedical research, crystal violet can be used to stain the nuclei of adherent cells.{{Cite journal |last1=Klingenberg |first1=Marcel |last2=Becker |first2=Jürgen |last3=Eberth |first3=Sonja |last4=Kube |first4=Dieter |last5=Wilting |first5=Jörg |date=2014-04-06 |title=The NADPH Oxidase Inhibitor Imipramine-Blue in the Treatment of Burkitt Lymphoma |journal=Molecular Cancer Therapeutics |volume=13 |issue=4 |pages=833–841 |doi=10.1158/1535-7163.mct-13-0688 |pmid=24482381 |doi-access=free}} In this application, crystal violet works as an intercalating dye and allows the quantification of DNA which is proportional to the number of cells.{{citation needed|date=December 2022}}

Crystal violet is also used as a tissue stain in the preparation of light microscopy sections.{{Cite journal |last1=Henneman |first1=Sheila A. |last2=Kohn |first2=Frank S. |date=June 1975 |title=Methylene blue staining of tissue culture monolayers |journal=Tissue Culture Association Manual |language=en |volume=1 |issue=2 |pages=103–104 |doi=10.1007/BF01352624 |issn=0361-0268 |series=Methods in Cell Science}} In laboratory, solutions containing crystal violet and formalin are often used to simultaneously fix and stain cells grown in tissue culture to preserve them and make them easily visible, since most cells are colourless.

It is also sometimes used as a cheap way to put identification markings on laboratory mice; since many strains of lab mice are albino, the purple colour stays on their fur for several weeks.{{cite journal|first=A. N. |last=Assal |title=Review on the Identification Methods of Laboratory Mice, Rats, Rabbits, and Guinea pigs |journal=Scandinavian Journal of Laboratory Animal Sciences |volume=15 |issue=1 |date=2019 |pages=19–31 |doi=10.23675/SJLAS.V15I1.697}}

In forensics, crystal violet was used to develop fingerprints. It is able to develop fingerprint marks from live human skin.{{Cite journal |last1=Feldman |first1=M. A. |last2=Meloan |first2=C. E. |last3=Lambert |first3=J. L. |date=1982-10-27 |title=A new method for recovering latent fingerprints from skin |url=https://pubmed.ncbi.nlm.nih.gov/7175462/ |journal=Journal of Forensic Sciences |volume=27 |issue=4 |pages=806–811 |doi=10.1520/JFS12196J |issn=0022-1198 |pmid=7175462}}

=Medical=

Gentian violet has antibacterial, antifungal, antihelminthic, antitrypanosomal, antiangiogenic, and antitumor properties.{{Citation |last1=Docampo |first1=R. |title=The metabolism and mode of action of gentian violet |work=Drug Metab. Rev. |volume=22 |issue=2–3 |pages=161–178 |year=1990 |doi=10.3109/03602539009041083 |pmid=2272286 |last2=Moreno |first2=S. N.}}{{Cite journal |last1=Maley |first1=Alexander M. |last2=Arbiser |first2=Jack L. |date=Dec 2013 |title=Gentian Violet: a 19th century drug re-emerges in the 21st century |journal=Experimental Dermatology |volume=22 |issue=12 |pages=775–780 |doi=10.1111/exd.12257 |pmc=4396813 |pmid=24118276}} It is used medically for these properties, in particular for dentistry, and is also known as "pyoctanin" (or "pyoctanine").{{Citation |last=Gorgas |first=Ferdinand J. S. |title=Pyoctanin – Methyl-Violet – Pyoctanine |url=https://chestofbooks.com/health/materia-medica-drugs/Manual-Of-Dental-Materia-Medica-And-Therapeutics/Pyoctanin-Methyl-Violet-Pyoctanine.html |work=Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics, 7th edition |year=1901 |postscript=. |archive-url=https://web.archive.org/web/20110708143253/http://chestofbooks.com/health/materia-medica-drugs/Manual-Of-Dental-Materia-Medica-And-Therapeutics/Pyoctanin-Methyl-Violet-Pyoctanine.html |publisher=chestofbooks.com |access-date=2011-03-15 |archive-date=2011-07-08 |url-status=live}} It is commonly used for:

Marking the skin for surgery preparation and allergy testing;
Treating Candida albicans and related fungal infections, such as thrush, yeast infections, various types of tinea (ringworm, athlete's foot, jock itch);
Treating impetigo; it was used primarily before the advent of antibiotics, but still useful to persons who may be allergic to penicillin.

In resource-limited settings, gentian violet is used to manage burn wounds,{{Cite journal |last1=Choudhary |first1=KN |last2=Soni |first2=PP |last3=Sao |first3=DK |last4=Murthy |first4=R |last5=Deshkar |first5=AM |last6=Nanda |first6=BR |date=April 2013 |title=Role of gentian violet paint in burn wound management: a prospective randomised control trial |journal=J Indian Med Assoc |volume=111 |issue=4 |pages=248–50 |pmid=24475556}} inflammation of the umbilical cord stump (omphalitis) in the neonatal period,{{Cite journal |last1=Qamar |first1=FN |last2=Tikmani |first2=SS |last3=Mir |first3=F |last4=Zaidi |first4=AK |date=Nov 2013 |title=Community-based management and outcome of omphalitis in newborns in Karachi, Pakistan. |journal=The Journal of the Pakistan Medical Association |volume=63 |issue=11 |pages=1364–9 |pmid=24392520}} oral candidiasis in HIV-infected patients{{Cite journal |last1=Jurevic |first1=RJ |last2=Traboulsi |first2=RS |last3=Mukherjee |first3=PK |last4=Salata |first4=RA |last5=Ghannoum |first5=MA |last6=Oral HIV/AIDS Research Alliance Mycology Focus |first6=group |date=May 2011 |title=Identification of gentian violet concentration that does not stain oral mucosa, possesses anti-candidal activity and is well tolerated. |journal=European Journal of Clinical Microbiology & Infectious Diseases |volume=30 |issue=5 |pages=629–33 |doi=10.1007/s10096-010-1131-8 |pmc=3076549 |pmid=21210170}} and mouth ulcers in children with measles.{{Cite book |last1=Berman |first1=Stephen |url=https://www.aap.org/en-us/advocacy-and-policy/aap-health-initiatives/children-and-disasters/Documents/MANUAL-05-internacional-2011.pdf |title=Module 5. Management of Prevalent Infections in Children Following a Disaster |last2=Nyquist |first2=Christine |last3=Lynch |first3=Julia A. |last4=Gentile |first4=Ángela |publisher=American Association of Pediatrics |page=22 |access-date=24 July 2014 |archive-date=8 August 2014 |archive-url=https://web.archive.org/web/20140808070820/https://www.aap.org/en-us/advocacy-and-policy/aap-health-initiatives/children-and-disasters/Documents/MANUAL-05-internacional-2011.pdf |url-status=live }}

In body piercing, gentian violet is commonly used to mark the location for placing piercings, including surface piercings.{{citation needed|date=December 2022}}

=Veterinary=

Because of its antimicrobial activity, it is used to treat ich in fish. However, it usually is illegal to use in fish intended for human consumption.{{Cite web |url=https://www.fao.org/fileadmin/user_upload/vetdrug/docs/15-2013-gentian-violet.pdf |title=5. Gentian violet – Food and Agriculture Organization |last1=Erdely |first1=Holly |last2=Sanders |first2=Pascal |website=Food and Agriculture Organization |access-date=2017-08-30 |quote=Residues in food and their evaluations – Conditions of use |archive-date=2017-08-30 |archive-url=https://web.archive.org/web/20170830132559/https://www.fao.org/fileadmin/user_upload/vetdrug/docs/15-2013-gentian-violet.pdf |url-status=live }}

History

File:Alfred Kern ca1890.jpg

=Synthesis=

Crystal violet is one of the components of methyl violet, a dye first synthesized by Charles Lauth in 1861.{{Citation |last=Lauth |first=C. |title=On the new aniline dye, 'Violet de Paris' |url=https://books.google.com/books?id=QlYEAAAAYAAJ&pg=PA138 |work=Laboratory |volume=1 |pages=138–139 |year=1867}} From 1866, methyl violet was manufactured by the Saint-Denis-based firm of Poirrier et Chappat and marketed under the name "Violet de Paris". It was a mixture of the tetra-, penta- and hexamethylated pararosanilines.{{Citation |title=The British coal-tar industry: its origin, development, and decline |url=https://archive.org/stream/britishcoaltarin00gardrich#page/172/mode/2up |page=173 |year=1915 |editor-last=Gardner |editor-first=W. M. |place=Philadelphia |publisher=Lippincott}}

Crystal violet itself was first synthesized in 1883 by {{Ill|Alfred Kern (chemist)|lt=Alfred Kern|de|Alfred Kern (Chemiker)}} (1850–1893) working in Basel at the firm of Bindschedler & Busch.{{cite patent | inventor1-last=Caro | inventor1-first=H. | inventor2-last=Kern | inventor2-first=A. | title=Manufacture of dye-stuff | issue-date=1883 | patent-number=290856 | country-code=US }}
{{cite patent | inventor1-last=Kern | inventor1-first=A. | title=Manufacture of dye-stuff or coloring-matter | issue-date=1883 | patent-number=290891 | country-code=US }}
{{cite patent | inventor1-last=Kern | inventor1-first=A. | title=Manufacture of purple dye-stuff | issue-date=1883 | patent-number=290892 | country-code=US }} To optimize the difficult synthesis which used the highly toxic phosgene, Kern entered into a collaboration with the German chemist Heinrich Caro at BASF.{{Citation |last1=Reinhardt |first1=C. |title=Heinrich Caro and the creation of modern chemical industry |url=https://books.google.com/books?id=TxEQ5iQmWIoC&q=Alfred%20Kern&pg=PA208 |pages=208–209 |year=2000 |place=Dordrecht, Netherlands |publisher=Kluwer Academic |isbn=0-7923-6602-6 |last2=Travis |first2=A.S. |access-date=2020-10-30 |archive-date=2022-02-28 |archive-url=https://web.archive.org/web/20220228104550/https://books.google.com/books?id=TxEQ5iQmWIoC&q=Alfred+Kern&pg=PA208 |url-status=live }} Kern also found that by starting with diethylaniline rather than dimethylaniline, he could synthesize the closely related violet dye now known as C.I. 42600 or C.I. Basic violet 4.{{cite patent | inventor1-last=Kern | inventor1-first=A. | title=Manufacture of dye-stuff or coloring-matter| issue-date=1883 | patent-number=290893 | country-code=US }}; Also available from [https://patents.google.com/patent/US290893 Google].

=Gentian violet=

The name "gentian violet" (or Gentianaviolett in German) is thought to have been introduced by the German pharmacist Georg Grübler, who in 1880 started a company in Leipzig that specialized in the sale of staining reagents for histology.{{Citation |last=Conn |first=H.J. |title=An investigation of American gentian violets: Report of Committee on Bacteriological Technic |url=https://jb.asm.org/cgi/reprint/7/5/529.pdf |work=J. Bacteriol. |volume=7 |issue=5 |pages=529–536 |year=1922 |doi=10.1128/JB.7.5.529-536.1922 |doi-access=free |access-date=2022-02-13 |archive-date=2022-02-28 |archive-url=https://web.archive.org/web/20220228104554/https://journals.asm.org/doi/pdf/10.1128/jb.7.5.529-536.1922 |url-status=live }}{{Citation |last=Titford |first=M. |title=George Grübler and Karl Hollborn: two founders of the biological stain industry |work=J. Histotechnol. |volume=16 |issue=2 |pages=155–158 |year=1993 |doi=10.1179/his.1993.16.2.155 |pmid=11615369}} The gentian violet stain marketed by Grübler probably contained a mixture of methylated pararosaniline dyes.{{Citation |last=Titford |first=M. |title=Comparison of historic Grübler dyes with modern counterparts using thin layer chromatography |work=Biotech. Histochem. |volume=82 |issue=4–5 |pages=227–234 |year=2007 |doi=10.1080/10520290701714005 |pmid=18074269|s2cid=29539186 }} The stain proved popular and in 1884 was used by Hans Christian Gram to stain bacteria. He credited Paul Ehrlich for the aniline-gentian violet mixture.{{Citation |last1=Clark |first1=G. |title=The history of staining |pages=95–97 |year=1983 |edition=3rd |place=Baltimore |publisher=Williams and Wilkins |isbn=0-683-01705-5 |last2=Kasten |first2=F.H.}} (Earlier editions were authored by H.J. Conn) Grübler's gentian violet was probably very similar, if not identical, to Lauth's methyl violet, which had been used as a stain by Victor André Cornil in 1875.{{Citation |last=Cornil |first=V. |title=Sur la dissociation du violet de méthylaniline et sa séparation en deux couleurs sous l'influence de certains tissus normaux et pathologiques, en particulier par les tissus en dégénérescence amyloïde |url=https://gallica.bnf.fr/ark:/12148/bpt6k3037k.image.langEN.f1358.pagination |work=Comptes Rendus de l'Académie des Sciences |volume=80 |pages=1288–1291 |year=1875 |language=fr |access-date=2022-02-13 |archive-date=2022-02-15 |archive-url=https://web.archive.org/web/20220215091918/https://gallica.bnf.fr/ark:/12148/bpt6k3037k.image.langEN.f1358.pagination |url-status=live }}

Although the name gentian violet continued to be used for the histological stain, the name was not used in the dye and textile industries.{{Citation |last=Conn |first=H.J. |title=Biological stains: a handbook on the nature and uses of the dyes employed in the biological laboratory |url=https://archive.org/stream/biologicalstains00conn#page/68/mode/2up |pages=68–69 |year=1925 |place=Geneva, NY |publisher=Commission on Standardization of Biological Stains}} The composition of the stain was not defined and different suppliers used different mixtures. In 1922, the Biological Stain Commission appointed a committee chaired by Harold Conn to look into the suitability of the different commercial products. In his book Biological Stains, Conn describes gentian violet as a "poorly defined mixture of violet rosanilins".

The German ophthalmologist Jakob Stilling is credited with discovering the antiseptic properties of gentian violet.{{Citation |last=Council on Pharmacy and Chemistry |title=New and Nonofficial Remedies |url=https://archive.org/stream/newnonofficialre37coun#page/210/mode/2up |pages=210–211 |year=1937 |place=Chicago |publisher=American Medical Association}} He published a monograph in 1890 on the bactericidal effects of a solution that he christened "pyoctanin", which was probably a mixture of aniline dyes similar to gentian violet.{{Citation |last=Stilling |first=J. |title=Anilin Farbstoffe als Antiseptica und ihre Anwendung in der Praxis |url=https://digital.ub.uni-duesseldorf.de/vester/content/titleinfo/1334819 |year=1890 |place=Strasbourg |publisher=Mittheilung |language=de |access-date=2022-02-13 |archive-date=2022-02-13 |archive-url=https://web.archive.org/web/20220213171319/https://digital.ub.uni-duesseldorf.de/vester/content/titleinfo/1334819 |url-status=live }} He set up a collaboration with E. Merck & Co. to market "Pyoktanin caeruleum" as an antiseptic.{{cite journal|first1=R. L. |last1=Berrios |first2=J. L. |last2=Arbiser |title=Novel antiangiogenic agents in dermatology |journal=Archives of Biochemistry and Biophysics |volume=508 |issue=2 |date=2011 |pages=222–226 |doi=10.1016/j.abb.2010.12.016|pmc=3060964 }}

In 1902, Drigalski and Conradi found that although crystal violet inhibited the growth of many bacteria, it has little effect on Bacillus coli (Escherichia coli) and Bacillus typhi (Salmonella typhi), which are both gram-negative bacteria.{{Citation |last1=Drigalski |first1=V. |title=Ueber ein Verfahren zum Nachweis der Typhusbacillen |work=Zeitschrift für Hygiene |volume=39 |issue=1 |pages=283–300 |year=1902 |doi=10.1007/BF02140310 |last2=Conradi |first2=H.|s2cid=22908909 }} A much more detailed study of the effects of Grübler's gentian violet on different strains of bacteria was published by John Churchman in 1912.{{Citation |last=Churchman |first=J.W. |title=The selective bactericidal action of gentian violet |journal=Journal of Experimental Medicine |volume=16 |issue=2 |pages=221–247, plates 21–31 |year=1912 |doi=10.1084/jem.16.2.221 |pmc=2125249 |pmid=19867569}} He found that most gram-positive bacteria (tainted) were sensitive to the dye, while most gram-negative bacteria (not tainted) were not, and observed that the dye tended to act as a bacteriostatic agent rather than a bactericide.{{citation needed|date=December 2022}}

==Precautions==

One study in mice demonstrated dose-related carcinogenic potential at several different organ sites.{{Citation |last1=Littlefield |first1=N.A. |title=Chronic toxicity and carcinogenicity studies of gentian violet in mice |url=https://zenodo.org/record/1258433 |work=Fundam. Appl. Toxicol. |volume=5 |issue=5 |pages=902–912 |year=1985 |doi=10.1016/0272-0590(85)90172-1 |pmid=4065463 |last2=Blackwell |first2=B.N. |last3=Hewitt |first3=C.C. |last4=Gaylor |first4=D.W. |access-date=2019-06-30 |archive-date=2022-02-28 |archive-url=https://web.archive.org/web/20220228104555/https://zenodo.org/record/1258433 |url-status=live }}{{Cite web |url=https://cpdb.thomas-slone.org/chempages/GENTIAN%20VIOLET.html |title=Carcinogenic Potency Database (CPDB) |access-date=2022-02-13 |archive-date=2020-06-08 |archive-url=https://web.archive.org/web/20200608032100/https://cpdb.thomas-slone.org/chempages/GENTIAN%20VIOLET.html |url-status=live }}

The Food and Drug Administration in the US (FDA) has determined that gentian violet has not been shown by adequate scientific data to be safe for use in animal feed. Use of gentian violet in animal feed causes the feed to be adulterated and is a violation of the Federal Food, Drug, and Cosmetic Act in the US. On June 28, 2007, the FDA issued an "import alert" on farm-raised seafood from China because unapproved antimicrobials, including gentian violet, had been consistently found in the products. The FDA report states:

Like MG (malachite green), CV (crystal violet) is readily absorbed into fish tissue from water exposure and is reduced metabolically by fish to the leuco moiety, leucocrystal violet (LCV). Several studies by the National Toxicology Program reported the carcinogenic and mutagenic effects of crystal violet in rodents. The leuco form induces renal, hepatic and lung tumor in mice."{{Citation |title=Questions and Answers on FDA's Import Alert on Farm-Raised Seafood From China: What evidence is there that malachite green, gentian violet and nitrofuran cause cancer? |url=https://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/ucm119105.htm#q12 |year=2009 |publisher=US Food and Drug Administration |access-date=2010-08-18 |archive-date=2010-05-28 |archive-url=https://web.archive.org/web/20100528105154/https://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/ucm119105.htm#q12 |url-status=dead }}{{Citation |title=How FDA Regulates Seafood |url=https://www.fda.gov/downloads/ForConsumers/ConsumerUpdates/ucm106813.pdf |year=2007 |publisher=US Food and Drug Administration |access-date=2014-10-27 |archive-date=2015-09-24 |archive-url=https://web.archive.org/web/20150924163359/https://www.fda.gov/downloads/ForConsumers/ConsumerUpdates/ucm106813.pdf |url-status=dead }}

In 2019, Health Canada (HC) completed safety reviews on gentian violet and found it to be carcinogenic when in direct contact with the body. As a result, HC has worked with human and animal drug makers to discontinue and recall all drugs containing gentian violet, and recommended customers stop using and safely discard any remaining drug products that contain gentian violet. HC found the all medical devices containing gentian violet on the Canadian market to be safe over the short term, as these polyurethane foam dressings are very unlikely to cause contact with skin. HC recommends most people to limit the use of these dressings to 6 months, and pregnant and nursing people to avoid using it altogether, as there's not enough evidence to prove that prolonged use or use by pregnant/nursing people is safe.{{Cite web |url=https://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2019/70179a-eng.php |title=Health Canada warns Canadians of potential cancer risk associated with gentian violet |date=2019-06-11 |publisher=Government of Canada |access-date=12 July 2019 |archive-date=2019-07-13 |archive-url=https://web.archive.org/web/20190713032841/https://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2019/70179a-eng.php |url-status=live }} This caused Canadian engineering schools to revisit the usage of this dye during orientation, in which students "purple" themselves by dunking into a tub containing a dilute solution of the dye.{{Cite news |last=Szklarski |first=Cassandra |url=https://toronto.citynews.ca/2019/07/10/popular-campus-purpling-practice-under-review-in-wake-of-health-canada-warning/ |title=Popular campus 'purpling' practice under review in wake of Health Canada warning |date=10 July 2019 |work=CityNews |access-date=12 July 2019 |agency=Canadian Press |archive-date=11 July 2019 |archive-url=https://web.archive.org/web/20190711152600/https://toronto.citynews.ca/2019/07/10/popular-campus-purpling-practice-under-review-in-wake-of-health-canada-warning/ |url-status=live }}