Isolation of daucosterol from Polygonum capitatum and its antitumor activity against gastric cancer BGC-823 cells

Daucosterol, a phytosterol glycoside, can be extracted from various natural plants and exhibits a variety of pharmacological properties. However, there is a paucity of research regarding the inhibitory effects of daucosterol on gastric cancer cells and the mechanisms involved. The objective of this study was to isolate pure daucosterol from the whole plant of Polygonum capitatum and investigate its inhibitory effects on gastric cancer BGC-823 cells in vitro, as well as the underlying mechanisms. The findings indicate that daucosterol has been successfully isolated from the petroleum ether extract of P. capitatum using silica gel column chromatography, with its identity confirmed by MS and both ¹H and ¹³C NMR spectroscopy. Daucosterol significantly inhibited the growth and proliferation of BGC-823 cells in a dose-dependent manner within a specified concentration range. Additionally, treatment with daucosterol notably increased the apoptosis rate of BGC-823 cells. Moreover, the expression of caspase-3 and MICA/B in/on BGC-823 cells was significantly upregulated following daucosterol treatment, while the expression of the anti-apoptotic Bcl-2 protein was significantly downregulated. Consequently, these findings suggest that daucosterol not only inhibits the proliferation of BGC-823 cells and induces apoptosis by upregulating caspase-3 expression and downregulating Bcl-2 protein expression in vitro, but also enhances the sensitivity of BGC-823 cells to the cytotoxicity effects of immune effector cells by upregulating MICA/B expression.