alkylresorcinol

{{Short description|Class of chemical compounds}}

File:Alkylresorcinol structure.svgs|alt=Chemistry diagram of general structure of those found in cereals]]

File:Bilobol.svg (5-[(Z)-pentadec-8-enylo]resorcinol)]]

Alkylresorcinols (ARs), also known as resorcinolic lipids, are amphiphilic phenolic lipids characterised by a non-polar odd-numbered alkyl side chain with up to 27 carbon atoms attached to a polar resorcinol (1,3-dihydroxybenzene) ring.{{Cite journal | last1 = Baerson | first1 = S. R. | last2 = Schröder | first2 = J. | last3 = Cook | first3 = D. | last4 = Rimando | first4 = A. M. | last5 = Pan | first5 = Z. | last6 = Dayan | first6 = F. E. | last7 = Noonan | first7 = B. P. | last8 = Duke | first8 = S. O. | doi = 10.4161/psb.5.10.13062 | title = Alkylresorcinol biosynthesis in plants: New insights from an ancient enzyme family? | journal = Plant Signaling & Behavior | volume = 5 | issue = 10 | pages = 1286–1289 | year = 2010 | pmid = 20861691| pmc = 3115369}}{{Cite journal |last1=Kozubek |first1=Arkadiusz |last2=Tyman |first2=John H. P. |date=1999-01-13 |title=Resorcinolic Lipids, the Natural Non-isoprenoid Phenolic Amphiphiles and Their Biological Activity |url=https://pubs.acs.org/doi/10.1021/cr970464o |journal=Chemical Reviews |language=en |volume=99 |issue=1 |pages=1–26 |doi=10.1021/cr970464o |pmid=11848979 |issn=0009-2665}}{{Cite journal |last1=Ross |first1=Alastair B. |last2=Shepherd |first2=Martin J. |last3=Schüpphaus |first3=Meike |last4=Sinclair |first4=Vicky |last5=Alfaro |first5=Begoña |last6=Kamal-Eldin |first6=Afaf |last7=Åman |first7=Per |date=2003-07-01 |title=Alkylresorcinols in Cereals and Cereal Products |url=https://pubs.acs.org/doi/10.1021/jf0340456 |journal=Journal of Agricultural and Food Chemistry |language=en |volume=51 |issue=14 |pages=4111–4118 |doi=10.1021/jf0340456 |pmid=12822955 |issn=0021-8561}}

Natural sources of alkylresorcinols

Alkylresorcinols are relatively rare in nature and are reported to be found in fungi, bacteria, and some lower and higher plants. DB-2073 is an antibiotic isolated from the broth culture of Pseudomonas sp.{{Cite journal |last1=Kanda |first1=N. |last2=Ishizaki |first2=N. |last3=Inoue |first3=N. |last4=Oshima |first4=M. |last5=Handa |first5=A. |year=1975 |title=DB-2073, a new alkylresorcinol antibiotic. I. Taxonomy, isolation and characterization |journal=The Journal of Antibiotics|volume=28 |issue=12 |pages=935–942 |doi=10.7164/antibiotics.28.935 |pmid=1206006 |doi-access=free}} They are also the main constituents of the outer shell of the cyst of Azotobacter.{{Cite journal |last1=Funa |first1=N. |last2=Ozawa |first2=H. |last3=Hirata |first3=A. |last4=Horinouchi |first4=S. |year=2006 |title=Phenolic lipid synthesis by type III polyketide synthases is essential for cyst formation in Azotobacter vinelandii |journal=Proceedings of the National Academy of Sciences|volume=103 |issue=16 |pages=6356–6361 |bibcode=2006PNAS..103.6356F |doi=10.1073/pnas.0511227103 |pmc=1458882 |pmid=16597676 |doi-access=free}}

Among the plant sources, the shell oil of cashew nut (Anacardium occidentale L.) has the highest amount of ARs, which consists of 20% phenolic lipids. Moreover, ARs were found in the peels and pulp of peas (Pisum sativum L.),{{Cite journal |last1=Zarnowski |first1=Robert |last2=Kozubek |first2=Arkadiusz |date=1999-02-01 |title=Alkylresorcinol Homologs in Pisum sativum L. Varieties |journal=Zeitschrift für Naturforschung C |volume=54 |issue=1–2 |pages=44–48 |doi=10.1515/znc-1999-1-208 |issn=1865-7125|doi-access=free }} pulp and leaves of ginkgo (Ginkgo biloba L.),{{Cite journal |last1=Żarnowska |first1=Ewa D. |last2=Żarnowski |first2=Robert |last3=Kozubek |first3=Arkadiusz |date=2000-12-01 |title=Alkylresorcinols in Fruit Pulp and Leaves of Ginkgo biloba L. |journal=Zeitschrift für Naturforschung C |volume=55 |issue=11–12 |pages=881–885 |doi=10.1515/znc-2000-11-1206 |pmid=11204190 |issn=1865-7125|doi-access=free }} pulp and peels of mango (Mangifera indica L.),{{Cite journal |last1=Knödler |first1=Matthias |last2=Reisenhauer |first2=Katharina |last3=Schieber |first3=Andreas |last4=Carle |first4=Reinhold |date=2009-05-13 |title=Quantitative Determination of Allergenic 5-Alk(en)ylresorcinols in Mango (Mangifera indica L.) Peel, Pulp, and Fruit Products by High-Performance Liquid Chromatography |url=https://pubs.acs.org/doi/10.1021/jf803934p |journal=Journal of Agricultural and Food Chemistry |language=en |volume=57 |issue=9 |pages=3639–3644 |doi=10.1021/jf803934p |pmid=19338352 |issn=0021-8561}} and in some cereals. In the case of cereals, the hyaline layer, inner pericarp, and testa showed the highest amounts of AR.{{Cite journal |last1=Landberg |first1=Rikard |last2=Kamal-Eldin |first2=Afaf |last3=Salmenkallio-Marttila |first3=Marjatta |last4=Rouau |first4=Xavier |last5=Åman |first5=Per |date=September 2008 |title=Localization of alkylresorcinols in wheat, rye and barley kernels|journal=Journal of Cereal Science|language=en |volume=48 |issue=2 |pages=401–406 |doi=10.1016/j.jcs.2007.09.013}}

File:DB-2073.svg (2-n-hexyl-5-n-propylresorcinol)]]

= Occurrence in cereals =

The alkylresorcinols alkyl chain, present in cereals, ranges from 15 to 25 carbon atoms.{{Cite journal |last1=Ziegler |first1=Jochen U. |last2=Steingass |first2=Christof B. |last3=Longin |first3=Carl Friedrich H. |last4=Würschum |first4=Tobias |last5=Carle |first5=Reinhold |last6=Schweiggert |first6=Ralf Martin |date=September 2015 |title=Alkylresorcinol composition allows the differentiation of Triticum spp. having different degrees of ploidy|journal=Journal of Cereal Science|volume=65 |pages=244–251 |doi=10.1016/j.jcs.2015.07.013 |issn=0733-5210}} ARs have been reported to be present in high amounts in rye, wheat, and triticale, and in low concentrations in barley, maize, oat, and millet,{{Cite journal |last1=Chen |first1=Yan |last2=Ross |first2=Alastair B. |last3=Åman |first3=Per |last4=Kamal-Eldin |first4=Afaf |date=2004-12-01 |title=Alkylresorcinols as Markers of Whole Grain Wheat and Rye in Cereal Products|journal=Journal of Agricultural and Food Chemistry|language=en |volume=52 |issue=26 |pages=8242–8246 |doi=10.1021/jf049726v |pmid=15612824 |issn=0021-8561}}{{Cite journal |last1=Andersson |first1=Annica A. M. |last2=Lampi |first2=Anna-Maija |last3=Nyström |first3=Laura |last4=Piironen |first4=Vieno |last5=Li |first5=Li |last6=Ward |first6=Jane L. |last7=Gebruers |first7=Kurt |last8=Courtin |first8=Christophe M. |last9=Delcour |first9=Jan A. |last10=Boros |first10=Danuta |last11=Fraś |first11=Anna |last12=Dynkowska |first12=Wioletta |last13=Rakszegi |first13=Mariann |last14=Bedő |first14=Zoltan |last15=Shewry |first15=Peter R. |date=2008-11-12 |title=Phytochemical and Dietary Fiber Components in Barley Varieties in the HEALTHGRAIN Diversity Screen |url=https://pubs.acs.org/doi/10.1021/jf802037f |journal=Journal of Agricultural and Food Chemistry |language=en |volume=56 |issue=21 |pages=9767–9776 |doi=10.1021/jf802037f |pmid=18921979 |issn=0021-8561}} while no information is at present available for Khorasan wheat. They are most abundant in the bran fractions (2600-4100 μg/g; 0.1-0.3% of dry weight),{{Cite journal |last1=Suzuki |first1=Y. |year=1999 |title=Structures of 5-alkylresorcinol-related analogues in rye |journal=Phytochemistry|volume=52 |issue=2 |pages=281–289 |doi=10.1016/S0031-9422(99)00196-X}} whereas they are in trace amounts in strachy endosperm and germ. They can also be found in rice, though not in the edible parts of the rice plant.{{Cite journal |last1=Suzuki |first1=Y. |last2=Kurano |first2=M. |last3=Esumi |first3=Y. |last4=Yamaguchi |first4=I. |last5=Doi |first5=Y. |year=2003 |title=Biosynthesis of 5-alkylresorcinol in rice: Incorporation of a putative fatty acid unit in the 5-alkylresorcinol carbon chain |journal=Bioorganic Chemistry |volume=31 |issue=6 |pages=437–452 |doi=10.1016/j.bioorg.2003.08.003 |pmid=14613765}}

Their presence in the endosperm (the part of cereal grain that is used to make white flour), means that alkylresorcinols can be used as 'biomarkers' for people who eat foods containing wholegrain wheat and rye, rather than cereal products based on white flour.{{Cite journal

| last1 = Ross | first1 = A. B.

| last2 = Kamal-Eldin | first2 = A.

| last3 = Aman | first3 = P.

| title = Dietary alkylresorcinols: Absorption, bioactivities, and possible use as biomarkers of whole-grain wheat- and rye-rich foods

| journal = Nutrition Reviews

| volume = 62

| issue = 3

| pages = 81–95

| year = 2004

| pmid = 15098855

| doi=10.1301/nr.2004.mar.81-95

| doi-access = free

}} Moreover, they were thought to have anti-nutritive properties (e.g. decreasing growth of pigs and chickens fed rye), but this theory has been discredited, and a number of animal studies have demonstrated that they have no obvious negative effect on animals or humans.

== Biomarkers of a whole grain diet ==

Increasing evidence from human intervention trials suggests that they are the most promising biomarker of whole grain wheat and rye intake.{{Cite journal

| last1 = Landberg | first1 = R.

| last2 = Kamal-Eldin | first2 = A.

| last3 = Andersson | first3 = A.

| last4 = Vessby | first4 = B.

| last5 = Aman | first5 = P.

| title = Alkylresorcinols as biomarkers of whole-grain wheat and rye intake: Plasma concentration and intake estimated from dietary records

| journal = The American Journal of Clinical Nutrition

| volume = 87

| issue = 4

| pages = 832–838

| year = 2008

| pmid = 18400704

| doi = 10.1093/ajcn/87.4.832

| doi-access = free

}}{{Cite journal

| last1 = Landberg | first1 = R.

| last2 = Kamal-Eldin | first2 = A.

| last3 = Andersson | first3 = S. -O.

| last4 = Johansson | first4 = J. -E.

| last5 = Zhang | first5 = J. -X.

| last6 = Hallmans | first6 = G.

| last7 = Aman | first7 = P.

| doi = 10.3945/jn.108.099952

| title = Reproducibility of Plasma Alkylresorcinols during a 6-Week Rye Intervention Study in Men with Prostate Cancer

| journal = Journal of Nutrition

| volume = 139

| issue = 5

| pages = 975–980

| year = 2009

| pmid = 19321581

| doi-access = free

}} Alkylresorcinol metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3,5-dihydroxyphenylpropionoic acid (DHPPA) were first identified in urine{{Cite journal

| last1 = Ross | first1 = A. B.

| last2 = Åman | first2 = P.

| last3 = Kamal-Eldin | first3 = A.

| doi = 10.1016/j.jchromb.2004.06.015

| title = Identification of cereal alkylresorcinol metabolites in human urine—potential biomarkers of wholegrain wheat and rye intake

| journal = Journal of Chromatography B

| volume = 809

| issue = 1

| pages = 125–130

| year = 2004

| pmid = 15282102

}} and can be quantified in urine{{Cite journal

| last1 = Koskela | first1 = A.

| last2 = Linko-Parvinen | first2 = A. -M.

| last3 = Hiisivuori | first3 = P.

| last4 = Samaletdin | first4 = A.

| last5 = Kamal-Eldin | first5 = A.

| last6 = Tikkanen | first6 = M. J.

| last7 = Adlercreutz | first7 = H.

| doi = 10.1373/clinchem.2006.084764

| title = Quantification of Alkylresorcinol Metabolites in Urine by HPLC with Coulometric Electrode Array Detection

| journal = Clinical Chemistry

| volume = 53

| issue = 7

| pages = 1380–1383

| year = 2007

| pmid = 17495018

| doi-access = free

}} and plasma,{{Cite journal

| last1 = Koskela | first1 = A.

| last2 = Samaletdin | first2 = A.

| last3 = Aubertin-Leheudre | first3 = M. N.

| last4 = Adlercreutz | first4 = H.

| title = Quantification of Alkylresorcinol Metabolites in Plasma by High-Performance Liquid Chromatography with Coulometric Electrode Array Detection

| doi = 10.1021/jf801252s

| journal = Journal of Agricultural and Food Chemistry

| volume = 56

| issue = 17

| pages = 7678–7681

| year = 2008

| pmid = 18690683

| citeseerx = 10.1.1.533.1473

}} and may be an alternative, equivalent biomarker of whole grain wheat intake.{{Cite journal

| last1 = Aubertin-Leheudre | first1 = M.

| last2 = Koskela | first2 = A.

| last3 = Marjamaa | first3 = A.

| last4 = Adlercreutz | first4 = H.

| title = Plasma Alkylresorcinols and Urinary Alkylresorcinol Metabolites as Biomarkers of Cereal Fiber Intake in Finnish Women

| doi = 10.1158/1055-9965.EPI-08-0215

| journal = Cancer Epidemiology, Biomarkers & Prevention

| volume = 17

| issue = 9

| pages = 2244–2248

| year = 2008

| pmid = 18768490

| doi-access =

}}

The average intake of alkylresorcinols in the UK is around 11 mg/person/day, and in Sweden is around 20 mg/person/day.{{Cite journal

| last1 = Ross | first1 = A. B.

| last2 = Becker | first2 = W.

| last3 = Chen | first3 = Y.

| last4 = Kamal-Eldin | first4 = A.

| last5 = Aman | first5 = P.

| title = Intake of alkylresorcinols from wheat and rye in the United Kingdom and Sweden

| journal = The British Journal of Nutrition

| volume = 94

| issue = 4

| pages = 496–499

| year = 2005

| pmid = 16197572 | doi=10.1079/bjn20051511

| doi-access = free

}} This varies widely depending on whether people normally consume wholegrain/wholemeal/brown bread, which is high in alkylresorcinols (300-1000 μg/g), or white wheat bread, which has very low concentrations of alkylresorcinols (<50 μg/g).

== Biomarkers of cereal presence in archaeological pottery ==

Recently, alkylresorcinols have been widely recognised as a biomarker for the presence of cereals in archaeological pottery. They were previously found in a well-preserved Bronze Age wooden container from Switzerland,{{Cite journal |last1=Colonese |first1=Andre Carlo |last2=Hendy |first2=Jessica |last3=Lucquin |first3=Alexandre |last4=Speller |first4=Camilla F. |last5=Collins |first5=Matthew J. |last6=Carrer |first6=Francesco |last7=Gubler |first7=Regula |last8=Kühn |first8=Marlu |last9=Fischer |first9=Roman |last10=Craig |first10=Oliver E. |date=2017-07-26 |title=New criteria for the molecular identification of cereal grains associated with archaeological artefacts |journal=Scientific Reports |language=en |volume=7 |issue=1 |pages=6633 |doi=10.1038/s41598-017-06390-x |issn=2045-2322 |pmc=5529501 |pmid=28747692}} and coarse ware vessels from a Roman cavalry barrack at Vindolanda.{{Cite journal |last1=Hammann |first1=Simon |last2=Cramp |first2=Lucy J.E. |date=May 2018 |title=Towards the detection of dietary cereal processing through absorbed lipid biomarkers in archaeological pottery |journal=Journal of Archaeological Science |volume=93 |pages=74–81 |doi=10.1016/j.jas.2018.02.017 |issn=0305-4403|doi-access=free |hdl=1983/b7951ec2-3400-474c-ab5e-e0a173bf6ca0 |hdl-access=free }} A study demonstrated that the survival of ARs is highly dependent on the cooking procedures and burial conditions. However, if recoverable, analysis of these phenolic lipids in archaeological contexts is valuable as it can help explain the uptake and spread of cereal processing of past communities in particular regions.{{Cite journal |last1=Roffet-Salque |first1=Mélanie |last2=Dunne |first2=Julie |last3=Altoft |first3=David T. |last4=Casanova |first4=Emmanuelle |last5=Cramp |first5=Lucy J.E. |last6=Smyth |first6=Jessica |last7=Whelton |first7=Helen L. |last8=Evershed |first8=Richard P. |date=December 2017 |title=From the inside out: Upscaling organic residue analyses of archaeological ceramics |journal=Journal of Archaeological Science: Reports |volume=16 |pages=627–640 |doi=10.1016/j.jasrep.2016.04.005 |issn=2352-409X|doi-access=free |hdl=1983/a7881ecd-60f1-4f39-b90c-7c5d8bc17946 |hdl-access=free }}

Possible biological activities

In vitro studies have shown that alkylresorcinols may prevent cells turning cancerous, but that they do not have any effect on cells that are already cancerous. Alkylresorcinols also increase gamma-tocopherol levels in rats when fed in high amounts (0.2% of total diet and above).

The alkylresorcinols in Grevillea banksii and Grevillea 'Robyn Gordon' are responsible for contact dermatitis.{{Cite journal

| doi = 10.1111/j.1600-0536.1986.tb01311.x

| last1 = Menz | first1 = J.

| last2 = Rossi | first2 = E. R.

| last3 = Taylor | first3 = W. C.

| last4 = Wall | first4 = L.

| title = Contact dermatitis from Grevillea 'Robyn Gordon'

| journal = Contact Dermatitis

| volume = 15

| issue = 3

| pages = 126–131

| year = 1986

| pmid = 2946534

| s2cid = 2846186 }}

Trivial names of some resorcinolic lipids

Derivatives

Sorgoleone is a hydrophobic root exudate of Sorghum bicolor.{{Cite journal | last1 = Dayan | first1 = F. E. | last2 = Rimando | first2 = A. M. | last3 = Pan | first3 = Z. | last4 = Baerson | first4 = S. R. | last5 = Gimsing | first5 = A. L. | last6 = Duke | first6 = S. O. | doi = 10.1016/j.phytochem.2010.03.011 | title = Sorgoleone | journal = Phytochemistry | volume = 71 | issue = 10 | pages = 1032–1039 | year = 2010 | pmid = 20385394}}

References

{{Commons category|Alkylresorcinols}}

{{Reflist}}