Testing the Pharmacokinetic Interactions of 24 Colonic Flavonoid Metabolites with Human Serum Albumin and Cytochrome P450 Enzymes

Abstract

Flavonoids are abundant polyphenols in nature. They are extensively biotransformed in enterocytes and hepatocytes, where conjugated (methyl, sulfate, and glucuronide) metabolites are formed. However, bacterial microflora in the human intestines also metabolize flavonoids, resulting in the production of smaller phenolic fragments (e.g., hydroxybenzoic, hydroxyacetic and hydroxycinnamic acids, and hydroxybenzenes). Despite the fact that several colonic metabolites appear in the circulation at high concentrations, we have only limited information regarding their pharmacodynamic effects and pharmacokinetic interactions. Therefore, in this in vitro study, we investigated the interactions of 24 microbial flavonoid metabolites with human serum albumin and cytochrome P450 (CYP2C9, 2C19, and 3A4) enzymes. Our results demonstrated that some metabolites (e.g., 2,4-dihydroxyacetophenone, pyrogallol, O-desmethylangolensin, and 2-hydroxy-4-methoxybenzoic acid) form stable complexes with albumin. However, the compounds tested did not considerably displace Site I and II marker drugs from albumin. All CYP isoforms examined were significantly inhibited by O-desmethylangolensin; nevertheless, only its effect on CYP2C9 seems to be relevant. Furthermore, resorcinol and phloroglucinol showed strong inhibitory effects on CYP3A4. Our results demonstrate that, besides flavonoid aglycones and their conjugated derivatives, some colonic metabolites are also able to interact with proteins involved in the pharmacokinetics of drugs.

Effects of Chrysin and Its Major Conjugated Metabolites Chrysin-7-Sulfate and Chrysin-7-Glucuronide on Cytochrome P450 Enzymes and on OATP, P-gp, BCRP, and MRP2 Transporters

“…Inhibitory effects of chrysin, C7S, and C7G on CYP2C9 (Mohos et al, 2020), CYP2C19 (Fliszár-Nyúl et al, 2019), and CYP3A4 (Mohos et al, 2018b) enzymes were investigated as has been reported, without modifications. Inhibition of CYP2D6 enzyme by chrysin and its conjugates was examined based on their effects on CYP2D6-catalyzed O-demethylation of dextromethorphan.…”

Interactions of Mycotoxin Alternariol with Cytochrome P450 Enzymes and OATP Transporters

“…The potential inhibitory effects of AOH on CYP2C9, 2C19, 2D6, and 3A4 enzymes were tested in vitro employing CypExpress human kits, using the substrates recommended by the U.S. Food and Drug Administration (FDA; ; accessed on 19 December 2022) (diclofenac, S -mephenytoin, dextromethorphan, and testosterone, respectively). The impacts of increasing concentrations of AOH (0.00, 0.05, 0.50, 2.0, 5.0, 10, 25, 30, and 50 μM) were examined on diclofenac 4′-hydroxylation (CYP2C9) [ 25 ], S -mephenytoin 4-hydroxylation (CYP2C19) [ 26 ], dextromethorphan demethylation (CYP2D6) [ 20 ], and testosterone 6β-hydroxylation (CYP3A4) [ 27 ] as described previously, without modifications. In these assays, the substrates and products were quantified by HPLC-UV [ 28 ].…”

Contribution of the Gut Microbiome to Drug Disposition, Pharmacokinetic and Pharmacodynamic Variability

“…To illustrate, phenolic fragments (e.g., hydroxybenzoic, hydroxyacetic and hydroxycinnamic acids, and hydroxybenzenes) are produced from flavonoids by bacterial microflora. Some of these metabolites form stable complexes with albumin in vitro [41] though appear to have limited potential to displace drugs from binding sites. Finally, several "uremic toxins" that are dependent on the presence of gut microflora, such as indoxyl sulfate, hippuric acid, and phenylacetic acid, are also highly bound in plasma to albumin [42,43].…”