Cytotoxic activities of Hypoxis hemerocallidea, Helichrysum caespititium and Dicoma anomala extracts on DU145 prostate cancer cell line

Background: Cancer mortality rate is still increasing every year despite advanced treatment regimes. Medicinal plants are one of the most important sources of anticancer agents. Aim: This study was conducted to evaluate the cytotoxic effects of the aqueous and methanolic extracts of Hypoxis hemerocallidea, Helichrysum caespititium and Dicoma anomala on prostate cancer cell line (DU145) in vitro. Setting: This is an in vitro study conducted under controlled laboratory settings at the University of Johannesburg, Department of Biomedical Sciences, South Africa. Methods: Corms of the plants were collected and extracted with aqueous and methanolic solvents using the direct maceration method. DU145 cells were treated, respectively, with the aqueous and methanolic extracts of H. hemerocallidea, H. caespititium and D. anomala at various concentrations. Cell viability was quantified using the bisBenzimide H33342 trihydrochloride (Hoechst 33342) and propidium iodide (PI) dual-staining method assay after 48 h. Results: The aqueous extracts of H. hemerocallidea and H. caespititium did not result in significant inhibition of DU145 cell line. However, an antiproliferative effect on the DU145 cell line was seen with D. anomala aqueous extracts at the concentrations of 15 µg/mL and 62.5 µg/mL, respectively. Additionally, methanolic extracts from H. caespititium and D. anomala arrested DU145 cell line at 15 µg/mL and 31 µg/mL concentrations in comparison to the untreated cell line and melphalan treatment control. However, not much termination was noticeable from the methanolic extracts of H. hemerocallidea on the cell line at 48 h. Conclusion: These findings indicate that the methanolic extracts of D. anomala can act as a potential anticancer agent, with further analysis recommended to isolate the active compound and to understand its mechanism of action. Contribution: The potential for D. anomala to be an alternative is supported by these findings, provided that active anticancer constituents are successfully characterised.