Abstract
Protocatechuic acid exerts multiple health‐promoting effects such as anticancer, anti‐atherosclerosis, and neuroprotection in animal models. While protocatechuic acid produced in the lower gastrointestinal tract by microbial catabolism of several flavonoids is bioavailable, the pharmacokinetics of protocatechuic acid has not been evaluated so far in humans following its oral consumption. In this open‐label and single‐dose pharmacokinetic trial, 16 healthy adults followed a low‐phytochemical diet for three days. Next, after overnight fasting, participants consumed 150 g of chicory containing 248 μmol of protocatechuic acid. Blood, urine, and fecal samples were collected before and up to 24 hr after chicory consumption. Protocatechuic acid in the free and glucuronide/sulfate‐conjugated forms was almost undetectable in serum, urine, and fecal samples before chicory consumption. Chicory consumption increased the levels of protocatechuic acid and its glucuronide/sulfate conjugates in biological samples. The maximum serum concentrations of protocatechuic acid in the free‐, glucuronide‐, and sulfate‐conjugated forms were 3,273, 519, and 340 nmol/L, respectively. The recovery of total protocatechuic acid in blood circulation, urine, and feces was 23.79%, 12.17%, and 12.79% of the ingested dose, respectively. Moreover, glucuronide and sulfate conjugates of protocatechuic acid made up 34.79%, 60.15%, and 72.70% of its total recovery in blood circulation, urine, and feces, respectively. Collectively, protocatechuic acid from chicory is bioavailable and undergoes partial glucuronidation and sulfation in human adults, and its regular consumption may exert health‐promoting effects.
Highlights
Protocatechuic acid in the free and glucuronide/sulfate‐conjugated forms was almost undetectable in serum, urine, and fecal samples before chicory consumption
Chicory consumption increased the levels of protocatechuic acid and its glucuronide/sulfate conjugates in biological samples
To test whether human gut microbiota metabolism of their compounds contributes to the pool of protocatechuic acid in the subjects after chicory consumption, we incubated gallic, caffeic, 5‐caffeoylquinic, caftaric, or chicoric acid with fresh human feces of healthy adults that have not consumed fruits, vegetables, and plant‐based beverages/wine for 48 hr
Summary
Protocatechuic, gallic, caffeic, 5‐caffeoylquinic, and chicoric acid were purchased from Chengdu Must Bio‐Technology Co., Ltd. ‐glucuronidase (EC 3.2.1.31, type IX A from E. coli), sulfatase (type H‐1 from helix pomatia, containing ‐glucuronidase), d‐saccharic acid 1,4‐lactone (a glucuronidase inhibitor), mycophenolic acid, and brain–heart infusion were purchased from Sigma. None of the women participants were pregnant They were healthy as judged by a medical questionnaire, with normal blood values for blood pressure, aspartate aminotransferase, and alanine aminotransferase. All participants were informed about the purpose of the study and gave written informed consent before their inclusion in the trial. This trial was approved by the Ethics Committee of the School of Public Health at Sun Yat‐sen. University [2017 No 009] and registered at ClinicalTrials.gov as ChiCTR1800014393 This trial was conducted in accordance with the Declaration of Helsinki of 1975 as revised in 2008
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