Sorghum bran in the diet dose dependently increased the excretion of catechins and microbial-derived phenolic acids in female rats.
Sorghum bran is concentrated with procyanidins (predominately polymers), which may be beneficial for health in humans; however, the bioavailability of procyanidins is not well-understood. Female Sprague-Dawley rats were fed an AIN93G diet containing 0, 5, 10, 20, or 40% Hi-tannin sorghum bran (n = 5-7 for each group) for 50 days. Sorghum bran contained 23.3 mg/g of procyanidins. The urinary excretions of catechin, epicatechin, methylated catechins, and phenolic acids were analyzed using liquid chromatography-tandem mass spectrometry. Sorghum bran dose dependently increased the urinary excretion of catechin (0-2.2 nmol/day) and 3'-O-methylcatechin (0-9.5 nmol/day). Their serum concentrations also increased with dose (range of 0-14 nM for 3'-O-methylcatechin). Among the 14 phenolic acids analyzed, 3,4-dihydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, and 4-hydroxyphenylacetic acid dominated in the serum (1.8-8 micromol/L). In the urine, 3-methoxy-4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, and 3-hydroxyphenylpropionic acid dominated and their excretion increased significantly with the level of sorghum bran in the diet. The summed phenolic acid excretion was 0.8 micromol/day in the control group and increased to 23 micromol/day for 40% sorghum bran group. The hippuric acid excretion ranged from 2.2 to 16.2 micromol/day and peaked in the 10% sorghum bran group. On the basis of chromic oxide, a nonabsorbable marker, total procyanidins and polymers disappeared progressively, and significant degradation occurred in the cecum and colon. Catechins and procyanidins in sorghum were bioavailable; however, bacteria-derived phenolic acids were the predominant metabolites of procyanidins. Procyanidins degraded in the gastrointestinal tract. Depolymerization was not observed.
Gu
Liwei
L
Arkansas Children's Nutrition Center, Agricultural Research Service, U.S. Department of Agriculture, 1212 Marshall Street, Little Rock, Arkansas 72202, USA.
House
Suzanne E
SE
Rooney
Lloyd
L
Prior
Ronald L
RL
D000818:Animals; D001419:Bacteria / Q000378:metabolism; D002392:Catechin / Q000652:urine*; D004043:Dietary Fiber / Q000008:administration & dosage* / Q000032:analysis*; D005260:Female; D062385:Hydroxybenzoates / Q000378:metabolism / Q000652:urine*; D044945:Proanthocyanidins / Q000008:administration & dosage / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D045868:Sorghum
D004043:Dietary Fiber; D062385:Hydroxybenzoates; D044945:Proanthocyanidins; D002392:Catechin; C017616:phenolic acid