Plasma pharmacokinetics of (poly)phenol metabolites and catabolites after ingestion of orange juice by endurance trained men

The health benefits of orange juice (OJ) consumption are attributed in part to the circulating flavanone phase II metabolites and their microbial-derived ring fission phenolic catabolites. The present study investigated these compounds in the bloodstream after acute intake of 500 mL of OJ. Plasma samples obtained at 0, 1, 2, 3, 4, 5, 6, 7, 8 and 24 h after OJ intake were analysed by HPLC-HR-MS. Eleven flavanone metabolites and 36 phenolic catabolites were identified and quantified in plasma. The main metabolites were hesperetin-3'-sulfate with a peak plasma concentration (C_max) of 80 nmol/L, followed by hesperetin-7-glucuronide (C_max 24 nmol/L), hesperetin-3'-glucuronide (C_max 18 nmol/L) and naringenin-7-glucuronide (C_max 21 nmol/L). Among the main phenolic catabolites to increase in plasma after OJ consumption were 3'-methoxycinnamic acid-4'-sulfate (C_max 19 nmol/L), 3-hydroxy-3-(3'-hydroxy-4'-methoxyphenyl)propanoic acid (C_max 20 nmol/L), 3-(3'-hydroxy-4'-methoxyphenyl)propanoic acid (C_max 19 nmol/L), 3-(4'-hydroxyphenyl)propanoic acid (C_max 25 nmol/L), and 3-(phenyl)propanoic acid (C_max 19 nmol/L), as well as substantial amounts of phenylacetic and hippuric acids. The comprehensive plasma pharmacokinetic profiles that were obtained are of value to the design of future ex vivo cell studies, aimed at elucidating the mechanisms underlying the potential health benefits of OJ consumption. CLINICAL TRIAL REGISTRATION NUMBER: This trial was registered at clinicaltrials.gov as NCT02627547.

Mono-methylindoles induce CYP1A genes and inhibit CYP1A1 enzyme activity in human hepatocytes and HepaRG cells

Mono-methylindoles (MMI) were described as agonists and/or antagonists of the human aryl hydrocarbon receptor (AhR). Here, we investigated the effects of MMI on AhR-CYP1A pathway in human hepatocytes and HepaRG cells derived from human progenitor hepatic cells. All MMI, except of 2-methylindole, strongly induced CYP1A1 and CYP1A2 mRNAs in HepaRG cells. Induction of CYP1A genes was absent in AhR-knock-out HepaRG cells. Consistently, CYP1A1 and CYP1A2 mRNAs and proteins were induced by all MMIs (except 2-methylindole), in human hepatocytes. The enzyme activity of CYP1A1 was inhibited by MMIs in human hepatocytes and LS180 colon cancer cells in a concentration-dependent manner (IC₅₀ values from 1.2 μM to 23.8 μM and from 3.4 μM to 11.4 μM, respectively). Inhibition of CYP1A1 activity by MMI in human liver microsomes was much weaker as compared to that in intact cells. Incubation of parental MMI with human hepatocytes either diminished (4-methylindole, 6-methylindole) or enhanced (7-methylindole) their agonist effects on AhR in AZ-AHR reporter cells. In conclusion, overall effects of MMI on AhR-CYP1A pathway in human cells comprise the induction of CYP1A genes through AhR, the inhibition of CYP1A catalytic activity and possibly the metabolic transformation causing loss or gain of AhR agonist activity of parental compounds.