AUTHOR=Huang Guitao , Lai Mingwen , Xu Canhua , He Shan , Dong Lihong , Huang Fei , Zhang Ruifen , Young David James , Liu Hesheng , Su Dongxiao 

TITLE=Novel Catabolic Pathway of Quercetin-3-O-Rutinose-7-O-α-L-Rhamnoside by Lactobacillus plantarum GDMCC 1.140: The Direct Fission of C-Ring

JOURNAL=Frontiers in Nutrition

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.849439

DOI=10.3389/fnut.2022.849439

ISSN=2296-861X

ABSTRACT=<p>Lychee pulp phenolics (LPP) is mainly catabolized in the host colon, increasing the abundances of <italic>Bacteroides</italic> and <italic>Lactobacillus</italic>. Herein, five selected gut microbial strains (<italic>Bacteroides uniformis, B. thetaiotaomicron, Lactobacillus rhamnosus, L. plantarum</italic>, and <italic>L. acidophilus</italic>) were separately incubated with LPP to ascertain the specific strains participating in phenolic metabolism and the corresponding metabolites. The results indicated that <italic>B. uniformis, L. rhamnosus</italic>, and <italic>L. plantarum</italic> were involved in LPP utilization, contributing to 52.37, 28.33, and 45.11% of LPP degradation after 48 h fermentation, respectively. Unprecedentedly, the metabolic pathway of the major phenolic compound quercetin-3-<italic>O</italic>-rutinose-7-<italic>O</italic>-α-L-rhamnoside by <italic>L. plantarum</italic>, appeared to be the direct fission of C-ring at C2–O1 and C3–C4 bonds, which was proved from the occurrence of two substances with the deprotonated molecule [M–H]<sup>−</sup> ion at <italic>m/z</italic> 299 and 459, respectively. Meanwhile, it was fully confirmed that <italic>B. uniformis</italic> participated in the catabolism of isorhamnetin glycoside and procyanidin B2. In the <italic>B. uniformis</italic> culture, kaempferol was synthesized through dehydroxylation of quercetin which could be catabolized into alphitonin by <italic>L. rhamnosus</italic>. Furthermore, LPP metabolites exerted higher antioxidant activity than their precursors and gave clues to understand the interindividual differences for phenolic metabolism by gut microbiota.</p>