Evaluation of in Vitro Antioxidative, Cytotoxic and Apoptotic Activities of Rheum ribes Ethyl Acetate Extracts

Abstract

Rheum species are medicinally important plants due to the presence of anthracene derivatives. This study was designed to determine the antioxidative, cytotoxic and apoptotic properties of Rheum ribes shoot and root ethyl acetate extracts using human promyelocytic leukemia (HL-60) cell line as a model system. R. ribes shoot and root dry powder samples were prepared and extracted with ethyl acetate. The extracts were revealed to be a potential scavenger of DPPH radicals (IC50 value of 206.28 μg/ml for shoot and 10.92 μg/ml for root) and the chemical composition of the extracts was quantified by colorimetric determination of total phenol (GAE) and flavonoid (CAE) contents. HL–60 cells were cultured in the presence of various concentrations of extracts up to 72 h. R. ribes inhibited the survival of HL-60 cells in a concentration- and time-dependent manner, shown by XTT assay. R. ribes caused HL-60 cells apoptosis via formation of phosphatidylserine externalization, as evidenced by flow cytometry. Exposure of HL-60 cells to higher concentrations of extracts for 72 h resulted in a shift of 87% of the cell population from normal to the early/late apoptotic stage. These findings suggest that Rheum ribes ethyl acetate root extracts exhibits potential antioxidant and cytotoxic properties against HL-60 cells better than shoot extracts and exert their toxicity via induction of apoptosis.