Absorption of dietary alkylresorcinols in ileal-cannulated pigs and rats

Abstract

Alkylresorcinols (AR) are amphiphilic 1,3-dihydroxy-5-alkyl phenolic lipids. AR in food are only found in the outer layers of wheat and rye grains, and in whole grains are present at concentrations of 500-1000 mg/g. In wheat and rye, there are five main homologues, differing in the length of the odd-numbered alkyl chain (from seventeen to twenty-five C atoms long). Because AR may be bioactive, and might serve as biomarkers for these cereals, their absorption was investigated in model experiments with pigs and rats. Pigs with a cannula in the terminal ileum were fed four diets containing rye fractions with different levels of AR and the ileal effluents were analysed. The ileal recovery of AR was found to vary between 21 and 40 %, with no major difference between different chain-length homologues. The absorption of AR by rats was investigated by feeding 14 C-labelled heneicosylresorcinol (C 21 : 0 ). Of the total activity, about 34 % was recovered in the urine, showing that the labelled AR was absorbed and metabolised by rats. AR were mostly cleared from rats by 60 h. It is concluded that AR are absorbed in the small intestine of single-stomached animals and excreted in metabolised form in the urine, and might contribute to the nutritional qualities of wholegrain wheat and rye diets.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

“…Riboflavin (vitamin B 2 ): 95 % as oral supplement in human subjects (615) Niacin (vitamin B 3 ): low (19) Pantothenic acid (vitamin B 5 ): about 50 % in human subjects for average American diet (616) Pyridoxine (vitamin B 6 ): 71-79 % for an average American diet compared with free compound (616) a-Tocopherol: 70 % in human subjects fed free compound (617) Total ferulic acid: 3·2 -3·6 % urinary excretion in rats (152) Free/soluble-conjugated ferulic acid: at least that of wheat bran in rat small intestine (154) Bound ferulic acid: a small fraction released within small intestine by intestinal esterases (618) Alkylresorcinols: 60-79 % from ileal samples in pigs fed whole-grain rye bread (619) Phytosterols: weakly absorbed from the gut (620) Total free inositols (myo-and chiro-inositol):…”

Biological activity of phenolic lipids

“…The study of their micellization in solution is important because in many interfacial processes the performance of the surfactant depends on its concentration and orientation at the interface. On the other hand, it was demonstrated that alkylresorcinols present in daily diet are absorbed by rats, pigs [11], and humans [12,13], and their molecules can incorporate into erythrocyte membranes [14]. Resorcinolic lipids are the group of phenolic lipids with the most precisely defined amphiphilic properties.…”

“…Resorcinolic lipids show very low values for the critical micelle concentration (CMC). The CMCs determined for different homologues in neutral pH by solubilization of 1,6-diphenyl-1,3-5-hexatriene were in the range of 4.5-8.5 lM and depended on the length and saturation of the hydrocarbon chains (8), diolefinic (8,11), and tri-olefinic (8,11,14) Fig. 1 The representative structures of selected phenolic lipids.…”

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

“…Studies have reported that the differences in consumption of ARs are due to age but not to body mass index (BMI) because older people change their dietary habits, increasing the amount of whole grain cereal intake (8). It has been estimated that the average daily intake of ARs in free-living population is around 11 mg/day in UnitedKingdom and around 40 mg/day in Finland (9,10), and that 60% of this amount is absorbed (9).…”