Abstract:
Plants offer unlimited compounds that can be developed into anticancer agents. In this study, compounds isolated from Croton sylvaticus Hochst were evaluated for their cytotoxicity against human drug sensitive (CCRF-CEM) and drug resistant (CEM/ADR5000) leukemia cell lines. The isolation was carried out using column chromatography (CC) and their structure elucidation was determined by use of 1D and 2D NMR spectroscopy in comparison with literature. The cytotoxicity of the compounds was evaluated using resazurin reduction bioassay. Approximately 200g crude extract from the stem bark extract (1:1 methanol in dichloromethane and 0.95:0.05 methanol to water) of Croton sylvaticus Hochst yielded three labdane diterpenoids namely austroinulin (57, 34 mg), labd-13(E)-ene-8α, 15-diol(74, 43 mg) and 18-nor-labd-13(E)-ene-8α,15-diol (109, 82 mg). The crude extract (1:1MeOH in CH2Cl2) was found to be active at the tested concentration of 10 g/ml exhibiting cell inhibition of 86 %compared to the positive control, doxorubicin which showed cell inhibition of 97.36 % against the drug sensitive leukemia cells, CCRF-CEM. All the three isolated labdanediterpenoids57, 74 and 109 showed lower activity against the cell resistant and cell sensitive leukemia cells, with cell viabilities of44.89±2.31, 91.88±4.27 and 51.40±4.08 %, respectively against the drug sensitive CCRF-CEM cells and 53.97±0.70, 79.74±1.77 and 66.17±4.79 %, respectively against the drug resistant CEM-ADR5000 cells. While the positive control, doxorubicin had cell viability of 2.64 %and 78.97 % for CCRF-CEM and CEM-ADR500, respectively. Seemingly, the pure compounds lost their synergistic effect during isolation that is why their cytotoxicity against the cancer cells is low as compared to the extract.
