Bidirectional Interactions between Green Tea (GT) Polyphenols and Human Gut Bacteria.

Green tea (GT) polyphenols undergo extensive metabolism within gastrointestinal tract (GIT), where their derivatives compounds potentially modulate the gut microbiome. This biotransformation process involves a cascade of exclusive gut microbial enzymes which chemically modify the GT polyphenols influencing both their bioactivity and bioavailability in host. Herein, we examined the in vitro interactions between 37 different human gut microbiota and the GT polyphenols. UHPLC-LTQ-Orbitrap-MS/MS analysis of the culture broth extracts unravel that genera Adlercreutzia, Eggerthella and Lactiplantibacillus plantarum KACC11451 promoted C-ring opening reaction in GT catechins. In addition, L. plantarum also hydrolyzed catechin galloyl esters to produce gallic acid and pyrogallol, and also converted flavonoid glycosides to their aglycone derivatives. Biotransformation of GT polyphenols into derivative compounds enhanced their antioxidant bioactivities in culture broth extracts. Considering the effects of GT polyphenols on specific growth rates of gut bacteria, we noted that GT polyphenols and their derivate compounds inhibited most species in phylum Actinobacteria, Bacteroides, and Firmicutes except genus Lactobacillus. The present study delineates the likely mechanisms involved in the metabolism and bioavailability of GT polyphenols upon exposure to gut microbiota. Further, widening this workflow to understand the metabolism of various other dietary polyphenols can unravel their biotransformation mechanisms and associated functions in human GIT.

Oral Ingestion of AP Collagen Peptide Leads to Systemic Absorption of Gly-Pro-Hyp, Alleviating H2O2-Induced Dermal Fibroblast Aging.

Collagen-derived dipeptides and tripeptides have various physiological activities. In this study, we compared the plasma kinetics of free Hyp, peptide-derived Hyp, Pro-Hyp, cyclo(Pro-Hyp), Hyp-Gly, Gly-Pro-Hyp, and Gly-Pro-Ala after ingestion of four different collagen samples: AP collagen peptide (APCP), general collagen peptide, collagen, and APCP and γ-aminobutyric acid (GABA) combination. Each peptide was measured by high-performance liquid chromatography and triple quadrupole mass spectrometer. We found that, among all the peptides that were analyzed, only Gly-Pro-Hyp was significantly increased after ingestion of APCP compared with that of general collagen peptides and collagen. In addition, ingestion of the APCP and GABA combination improved the absorption efficiency of Gly-Pro-Ala. Finally, we reveal that Gly-Pro-Hyp was effective for preventing H2O2-induced reduction in extracellular matrix (ECM)-related genes, COL1A, elastin, and fibronectin, in dermal fibroblasts. Taken together, APCP significantly enhances the absorption of Gly-Pro-Hyp, which might act as an ECM-associated signaling factor in dermal fibroblasts, and the APCP and GABA combination promotes Gly-Pro-Ala absorption. Clinical Trial Registration number: UMIN000047972.