Identification and mechanism of hepatoprotective saponins and endogenous metabolites in the sweet variant of Gynostemma pentaphyllum

Gynostemma pentaphyllum (Thunb.) Makino has been traditionally utilized as medicinal herb and function food in traditional Chinese medicine for treating chronic hepatic disorders. Sweet variants of G. pentaphyllum collected from different regions of China are cultivated as the primary resources for the preparation of curative products. We and other groups identified a series of dammarane-type triterpenoids enriched in the plant, such as gypenosides LVI and XLVI, as the bioactive components responsible for the hepatoprotective effect. However, their therapeutic potential may be constrained by low oral bioavailability and complex metabolic pathways. This study applied an in vitro analysis of gut microbiome-based metabolism to determine the major pathway of the gypenosides. Structure-activity relationships, pharmacokinetic studies, and pharmacodynamic results revealed that the removal of the C-3 saccharide chain is not only the main metabolic pathway in the intestinal tract but also generates the active hepatoprotective ingredient with higher bioavailability and potency than the proteotype. Notably, the investigation of underlying the mechanism demonstrated that the compounds inhibited the activation of hepatic stellate cells via the AMPK/P300/Smad3 signaling pathway. Collectively, these findings demonstrate that in vivo metabolism is critical for unlocking the therapeutic potential of orally administered sweet variant G. pentaphyllum, as this metabolic process releases active ingredients that overcome the bioavailability limitations of the parent gypenoside.