Induction of Apoptosis and Cell Cycle Arrest by Ethyl Acetate Extract of Salsola kali and Flavonoid Constituents Analysis

Abstract In our previous study on Salsola kali, the ethyl acetate extract revealed an in vitro cytotoxic effect against the tumor cell lines (MCF-7, HepG2, and A549). Therefore, this study was conducted to identify phenolic and flavonoid components in this extract by LC-ESI-TOF/MS technique and explore the mechanism of the cytotoxic effect on the progression of the cell cycle and the induction of apoptosis by flow cytometry. Further, protein markers were evaluated as cytotoxicity mechanisms to confirm apoptosis initiation. LC-ESI-TOF/MS analysis identified eleven phenolics and forty-five flavonoid compounds from the ethyl acetate extract. Ethyl acetate extract induced G1 cell population arrest in HepG2 cells after 24 hours of exposure. The flow cytometry data confirmed that ethyl acetate primarily initiates cell death by starting early and late apoptotic manners. Induction of apoptosis by ethyl acetate extract was proved by a significant increase in cytochrome C, caspase 3, and Bax levels, while the level of antiapoptotic BCl2 was significantly decreased. Moreover, the Bax/BCl2 ratio was increased after treatment in a dose-dependent manner of ethyl acetate extract compared to that of the untreated group. These findings suggest that ethyl acetate extract may have a remarkable anticancer effect in HepG2 cells through cell cycle regulation and apoptosis. GRAPHICAL ABSTRACT