Neuroactive gypenosides from Yunnan Gynostemma pentaphyllum: Nrf2-mediated cytoprotection and cholinesterase inhibition.

Abstract

Gynostemma, commonly known as "Jiaogulan," is a medicinal and edible plant genus native to Asia, with Yunnan Province recognized as a primary center of biodiversity and distribution. Despite its widespread use, the neuroactive constituents and their geographical variation remain insufficiently investigated. In this study, we compared the AChE and BuChE inhibitory activities of five Yunnan-collected samples and their neuroprotective effects against 6-OHDA-induced oxidative injury in SH-SY5Y cells. Among them, G. pentaphyllum from Zhaotong City (ZTB) displayed the most potent bioactivity. Bioactivity-guided fractionation of ZTB afforded 11 compounds, including two previously undescribed gypenosides (1 and 2). Mechanistic investigations revealed that compounds 1-4 significantly reduced reactive oxygen species and malondialdehyde levels, restored superoxide dismutase activity, and improved neuronal cell survival by activating the Nrf2/HO-1/NQO1 antioxidant pathway, as confirmed by western blot analysis. Additionally, the isolated flavonoids-kaempferol, quercetin, and ombuoside-exhibited strong AChE inhibitory effects. Collectively, these findings demonstrate clear regional differences in pharmacological efficacy among the five samples, identify new gypenosides from ZTB with both cholinesterase-inhibitory and cytoprotective activities in vitro, and provide preliminary scientific validation for the ethnopharmacological application of ZTB in the context of neurodegenerative disorders. These results suggest that this species could be considered a potential candidate plant for functional foods.