Phytochemical Fingerprinting and Activity of Extracts from the Leaves of Dolichos kilimandscharicus (Fabaceae) on Jurkat-T Cells

Plants are a source of over a quarter of the prescription drugs currently in use worldwide. Zimbabwe has a rich plant biodiversity with only a limited number reported for the treatment of cancer. The leaf extracts of Dolichos kilimandscharicus were selected for the screening of their antiproliferative efficacy and cytotoxicity effects. This plant has increasingly been used by local folk as a treatment for cancer or cancer-related symptoms though its bioactivity has not been scientifically determined. This investigation also sought to identify constituent compounds in the crude extract preparations responsible for their antiproliferative efficacy. The antiproliferative effects of six-leaf extracts on Jurkat-T in vitro were investigated using the Trypan blue exclusion assay. The extracts were tested with increasing concentration, using chlorambucil as a standard anticancer drug. Cytotoxicity of extracts was determined against RAW 264.7 cells using a colorimetric tetrazolium-based assay. In additionthe ability of the extracts to induce apoptosis was determined for the most potent leaf extracts. The order of potency of the leaf extracts of D. kilimandscharicus against Jurkat-T cell line was found to be MeOH < Ethyl Acetate < DCM: MeOH < EtOH with IC₅₀s of 33.56, 30.44, 22.93, and 21.59 μg/mL, respectively. Furthermore, the most potent extracts exhibited very low cytotoxicity against all the tested cells. D. kilimandscharicus leaf extracts induced apoptosis in the Jurkat-T cells as was shown by DNA fragmentation. UPLC-MS analysis of crude extracts led to the identification of 23 compounds from the ethanol extract and these may be responsible for the observed antiproliferative effects. Rutin, quercetin, luteolin, apigenin, hispidulin, kaempferol derivatives, as well as caffeoylquinic acid are some of the compounds identified in the extracts. The results of this study showed that the ethanol and ethyl acetate leaf extracts of D. kilimandscharicus have antiproliferative activity against Jurkat-T cells and may act by inducing apoptosis.. The current findings offer supporting evidence for the use of these plant species in the treatment of cancer in ethnomedicinal practices.