Strain-specific metabolomic diversity of Lactiplantibacillus plantarum under aerobic and anaerobic conditions.

The chemotaxonomic diversity of 20 Lactiplantibacillus plantarum strains was investigated using non-targeted metabolite profiling under different culture conditions. Multivariate and metabolic pathway analyses based on GC-MS and LC-MS/MS datasets showed that amino acid metabolism, especially 2-hydroxy acids, was enriched under aerobic conditions (AE), whereas fatty acid & sugar metabolism was increased under anaerobic conditions (AN). Based on the metabolite profiles, L. plantarum strains were clustered into three main groups (A, B, and C). Overall, 79 and 83 significantly discriminant metabolites were characterized as chemical markers of AE and AN growth conditions, respectively. Notably, alcohols were more abundant in group A whereas amino acids, peptides, purines, and pyrimidines were significantly higher in group C. 2-hydroxy acids and oxylipins biosynthesized through amino acid and fatty acid metabolism, respectively, were more abundant in groups A and B. Furthermore, we observed a strong correlation between the chemical diversity of L. plantarum groups and their antioxidant activity from metabolite extracts. We propose a non-targeted metabolomic workflow to comprehensively characterize the chemodiversity of L. plantarum strain under different culture conditions, which may help reveal specific biomarkers of individual strains depending on the culture conditions.

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.

Cytotoxic phenolic compounds from Chionanthus retusus.

Cytotoxicity-guided fractionation and purification of MeOH extract from Chionanthus retusus Lindl. et Paxton resulted in the isolation of compounds. Fourteen phenolic compounds were isolated from the EtOAc soluble fraction, and their structures were determined by spectroscopic analysis. Isolated compounds were identified as phillygenin (1), scopoletin (2), pinoresinol (3), kaempferol (4), aromadendrin (5), 2-(4-hydroxyphenyl)ethanol (6), 3,3',5,5',7-pentahydroxyflavanone (7), luteolin (8), quercetin (9), apigenin (10), chrysoeriol (11), phillyrin (12), oleuropein (13), (7R,8R)-guaiacylglycerol (14). All compounds except for 12 and 13 were isolated for the first time from this plant and genus Chionanthus. Anti-proliferative effect of isolated compounds were evaluated by the sulforhodamin B assay against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 4 and 8-10 were significantly active with ED50 values of 1.84-6.35 microg/mL. Also, compounds 1, 3, 5 and 7 revealed cytotoxic effects at concentrations below 30 microg/mL.