Alkylresorcinol

Bilobol (5-[(Z)-pentadec-8-enylo]resorcinol)

Alkylresorcinols, also known as resorcinolic lipids, are phenolic lipids composed of long aliphatic chains and resorcinol-type phenolic rings.[1]

Natural sources of alkylresorcinols

Alkylresorcinols are relatively rare in nature, with the main known sources being wheat, rye, barley, triticale (cereal grasses), the fruit of Gingko biloba Bilobol, a mollusc and some species of bacteria.

DB-2073 (2-n-hexyl-5-n-propylresorcinol)

DB-2073 is an antibiotic isolated from the broth culture of Pseudomonas sp.[2] They are also the main constituents of the outer shell of the cyst of Azotobacter.[3]

Occurrence in cereals

Alkylresorcinols are present in high amounts in the bran layer (e.g. pericarp, testa and aleurone layers) of wheat and rye[4] (0.1-0.3 % of dry weight). 5-Alkylresorcinols can also be found in rice, though not in the edible parts of the rice plant.[5]

They are only present in very low amounts in the endosperm (the part of cereal grain that is used to make white flour), which 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.[6]

Alkylresorcinols 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.[6]

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.[7][8] Alkylresorcinol metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3,5-dihydroxyphenylpropionoic acid (DHPPA) were first identified in urine[9] and can be quantified in urine[10] and plasma,[11] and may be an alternative, equivalent biomarker of whole grain wheat intake.[12]

The average intake of alkylresorcinols in the UK is around 11 mg/person/day, and in Sweden is around 20 mg/person/day.[13] 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).

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.[6] Alkylresorcinols also increase gamma-tocopherol levels in rats when fed in high amounts (0.2% of total diet and above.[14]

The alkylresorcinols in Grevillea banksii and Grevillea 'Robyn Gordon' are responsible for contact dermatitis.[15]

Trivial names of some resorcinolic lipids

Derivatives

Sorgoleone is a hydrophobic root exudate of Sorghum bicolor.[17]

References

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  1. ↑ Baerson, S. R.; Schröder, J.; Cook, D.; Rimando, A. M.; Pan, Z.; Dayan, F. E.; Noonan, B. P.; Duke, S. O. (2010). "Alkylresorcinol biosynthesis in plants: New insights from an ancient enzyme family?". Plant Signaling & Behavior 5 (10): 1286. doi:10.4161/psb.5.10.13062.
  2. ↑ Kanda, N.; Ishizaki, N.; Inoue, N.; Oshima, M.; Handa, A. (1975). "DB-2073, a new alkylresorcinol antibiotic. I. Taxonomy, isolation and characterization". The Journal of antibiotics 28 (12): 935–942. doi:10.7164/antibiotics.28.935. PMID 1206006.
  3. ↑ Funa, N.; Ozawa, H.; Hirata, A.; Horinouchi, S. (2006). "Phenolic lipid synthesis by type III polyketide synthases is essential for cyst formation in Azotobacter vinelandii". Proceedings of the National Academy of Sciences 103 (16): 6356–6361. doi:10.1073/pnas.0511227103. PMC 1458882. PMID 16597676.
  4. ↑ Suzuki, Y. (1999). "Structures of 5-alkylresorcinol-related analogues in rye". Phytochemistry 52 (2): 281–201. doi:10.1016/S0031-9422(99)00196-X.
  5. ↑ Suzuki, Y.; Kurano, M.; Esumi, Y.; Yamaguchi, I.; Doi, Y. (2003). "Biosynthesis of 5-alkylresorcinol in rice: Incorporation of a putative fatty acid unit in the 5-alkylresorcinol carbon chain". Bioorganic Chemistry 31 (6): 437–452. doi:10.1016/j.bioorg.2003.08.003. PMID 14613765.
  6. ↑ 6.0 6.1 6.2 Ross, A. B.; Kamal-Eldin, A.; Aman, P. (2004). "Dietary alkylresorcinols: Absorption, bioactivities, and possible use as biomarkers of whole-grain wheat- and rye-rich foods". Nutrition reviews 62 (3): 81–95. PMID 15098855.
  7. ↑ Landberg, R.; Kamal-Eldin, A.; Andersson, A.; Vessby, B.; Aman, P. (2008). "Alkylresorcinols as biomarkers of whole-grain wheat and rye intake: Plasma concentration and intake estimated from dietary records". The American journal of clinical nutrition 87 (4): 832–838. PMID 18400704.
  8. ↑ Landberg, R.; Kamal-Eldin, A.; Andersson, S. -O.; Johansson, J. -E.; Zhang, J. -X.; Hallmans, G.; Aman, P. (2009). "Reproducibility of Plasma Alkylresorcinols during a 6-Week Rye Intervention Study in Men with Prostate Cancer". Journal of Nutrition 139 (5): 975–980. doi:10.3945/jn.108.099952. PMID 19321581.
  9. ↑ Ross, A. B.; Åman, P.; Kamal-Eldin, A. (2004). "Identification of cereal alkylresorcinol metabolites in human urine—potential biomarkers of wholegrain wheat and rye intake". Journal of Chromatography B 809 (1): 125–130. doi:10.1016/j.jchromb.2004.06.015. PMID 15282102.
  10. ↑ Koskela, A.; Linko-Parvinen, A. -M.; Hiisivuori, P.; Samaletdin, A.; Kamal-Eldin, A.; Tikkanen, M. J.; Adlercreutz, H. (2007). "Quantification of Alkylresorcinol Metabolites in Urine by HPLC with Coulometric Electrode Array Detection". Clinical Chemistry 53 (7): 1380–1383. doi:10.1373/clinchem.2006.084764. PMID 17495018.
  11. ↑ Koskela, A.; Samaletdin, A.; Aubertin-Leheudre, M. N.; Adlercreutz, H. (2008). "Quantification of Alkylresorcinol Metabolites in Plasma by High-Performance Liquid Chromatography with Coulometric Electrode Array Detection". Journal of Agricultural and Food Chemistry 56 (17): 7678–7681. doi:10.1021/jf801252s. PMID 18690683.
  12. ↑ Aubertin-Leheudre, M.; Koskela, A.; Marjamaa, A.; Adlercreutz, H. (2008). "Plasma Alkylresorcinols and Urinary Alkylresorcinol Metabolites as Biomarkers of Cereal Fiber Intake in Finnish Women". Cancer Epidemiology Biomarkers & Prevention 17 (9): 2244–2248. doi:10.1158/1055-9965.EPI-08-0215. PMID 18768490.
  13. ↑ Ross, A. B.; Becker, W.; Chen, Y.; Kamal-Eldin, A.; Aman, P. (2005). "Intake of alkylresorcinols from wheat and rye in the United Kingdom and Sweden". The British journal of nutrition 94 (4): 496–499. doi:10.1079/bjn20051511. PMID 16197572.
  14. ↑ Ross, A. B.; Chen, Y.; Frank, J.; Swanson, J. E.; Parker, R. S.; Kozubek, A.; Lundh, T.; Vessby, B.; Aman, P.; Kamal-Eldin, A. (2004). "Cereal alkylresorcinols elevate gamma-tocopherol levels in rats and inhibit gamma-tocopherol metabolism in vitro". The Journal of nutrition 134 (3): 506–510. PMID 14988438.
  15. ↑ Menz, J.; Rossi, E. R.; Taylor, W. C.; Wall, L. (1986). "Contact dermatitis from Grevillea 'Robyn Gordon'". Contact dermatitis 15 (3): 126–131. doi:10.1111/j.1600-0536.1986.tb01311.x. PMID 2946534.
  16. ↑ Kozubek, A.; Tyman, J. H. P. (1999). "Resorcinolic Lipids, the Natural Non-isoprenoid Phenolic Amphiphiles and Their Biological Activity". Chemical Reviews 99 (1): 1–26. doi:10.1021/cr970464o. PMID 11848979.
  17. ↑ Dayan, F. E.; Rimando, A. M.; Pan, Z.; Baerson, S. R.; Gimsing, A. L.; Duke, S. O. (2010). "Sorgoleone". Phytochemistry 71 (10): 1032–1039. doi:10.1016/j.phytochem.2010.03.011. PMID 20385394.