Alkylresorcinol

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

Alkylresorcinols are phenolic lipids composed of long aliphatic chains and phenolic rings.

Natural occurrences

Bilobol is found in the fruit of Gingko biloba.

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

DB-2073 is an antibiotic isolated from the broth culture of Pseudomonas sp.^[1]

They are also the main constituents of the outer shell of the cyst of Azotobacter. Alkylresorcinols are also found in other bacteria, animals and plants.^[2]

Occurences in food

Alkylresorcinols are present in high amounts in the bran layer (e.g. pericarp, testa and aleurone layers) of wheat and rye^[3] (0.1-0.3 % of dry weight). 5-Alkylresorcinols can also be found in rice.^[4]

They are not present 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.^[5]

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.^[5]

Biomarkers of whole grain diet

Increasing evidence from human intervention trials suggests that they are the most promising biomarker of whole grain wheat and rye intake.^[6][7] Alkylresorcinol metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3,5-dihydroxyphenylpropionoic acid (DHPPA) were first identified in urine^[8] and can be quantified in urine^[9] and plasma,^[10] and may be an alternative, equivalent biomarker of whole grain wheat intake.^[11]

The average intake of alkylresorcinols in the UK is around 11 mg/person/day, and in Sweden is around 20 mg/person/day.^[12] 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).

Health effects

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.^[5] Alkylresorcinols also increase gamma-tocopherol levels in rats when fed in high amounts (0.2 % of total diet and above.^[13]

The alkyl resorcinols in Grevillea banksii and Grevillea 'Robyn Gordon' are responsible for contact dermatitis.^[14]

Sources