Effects of polyphenolic-rich extracts from Citrus hystrix on proliferation and oxidative stress in breast and colorectal cancer

Abstract Objectives The anti-proliferative effects of Citrus hystrix have been reported. However, information on breast and colorectal cancer is limited especially the mechanistic aspects. In this study, the antioxidant activities of hexane, ethyl acetate, methanol and water extracts of C. hystrix leaves and their growth inhibitory effects on colorectal (HCT 116) and breast cancer (MCF 7, MDA-MB 231 and HCC 1937) cells were analysed. Methods Antioxidant and oxidative stress status were measured using non-cellular and cellular assays. Caspase and gene expression were utilized to determine anti-proliferative effects. Polyphenolic content was analysed using LC-IT-TOF/MS. Results The water extract showed the highest polyphenolic content and antioxidant activities (FRAP, DPPH, ABTS, superoxide anion radical scavenging, ferrous ion chelation, cellular antioxidant assay). The ethyl acetate extracts of C. hystrix (CH-EA) demonstrated the highest anti-proliferative activity against all cancer cell lines (IC50<100 μg/mL). Increase in ROS was observed in CH-EA-treated HCT 116, MDA-MB 231 and HCC 1937 cells (p<0.05). Increase in caspase activities and upregulation of Bax, Bcl-2, Cdk-1, TP53 and TNF-α expression in HCT 116 cells indicated activation of apoptosis by CH-EA. LC-IT-TOF/MS analysis indicated presence of quercetin and rutin in CH-EA. Conclusions CH-EA showed anti-proliferative effects, possibly through modulation of oxidative stress and apoptosis.