Anticancer activity of three African mistletoes
Three African mistletoes: Globimetula braunii, Tapinanthus bangwensis, and Tapinanthus globiferus used in the West African ethnomedicine for the management of diabetes, rheumatic pain, infections and tumours were investigated for anticancer activity against human prostate DU-145, breast JIMT- 1, and pancreatic MiaPaCa-2 / BxPC-3 cancer cell lines, with a view to establishing the most active plant extract and partition fraction. An 80 % ethanolic extract of each plant was tested against the cancer cell lines using methanethiosulfonate (MTS) assay. The results showed that the leaf extract of G. braunii (GL) demonstrated the best anticancer activity (CC50: 105.1±3.3 μg/mL) against breast cancer cells. GL was significantly better than Chlorambucil (CC50 ≥ 150.0 μg/mL), hence, necessitated its fractionation into n-hexane (G1), dichloromethane (G2), ethyl acetate (G3), n-butanol (G4) and aqueous fraction (G5). At 150.0 μg/mL, the ethyl acetate fraction (G3) demonstrated the best anticancer activity (70.4±2.4 % pancreatic cancer cell viability) among the fractions. The cytotoxic action of G3 (CC50: 322.5±27.2 μg/mL) and G2 (CC50: 307.8±5.4 μg/mL) against human prostate cancer DU-145 cell line were comparable. This suggested that the two fractions have constituents which could be responsible for the anticancer activity. The study validates the ethnomedicinal use of Globimetula braunii in the management of tumour.
Keywords: African mistletoes, anticancer, methanethiosulfonate assay, Globimetula braunii, Tapinanthus bangwensis, Tapinanthus globiferus