Aqueous, dichloromethane and methanol extracts of Vernonia guineensis Benth. tubers were tested for activity against three prostate cancer cell lines (PC-3, DU-145 and AT3B-1). The dichloromethane extract was subjected to bioactivity guided fractionation. Anti-proliferation, clonogenic and antiangiogenic activity of the crude extracts and isolated compound were tested. The WST-1 assay was used for the anti-proliferation activity meanwhile the standard clonogenic test and the rat ring aorta assay were carried out to determine the clonogenic and antiangiogenic activity of tested products respectively.
The aqueous and methanol extracts of Vernonia guineensis Benth. demonstrated weak activity against prostate cancer cell lines in vitro with IC50 > 100 渭g/mL. The dichloromethane extract was more potent with IC50 of 56.233 卤 3.630 渭g/ml and 67.316 卤 2.452 渭g/ml against the DU-145 and PC-3 cell lines respectively. Activity guided fractionation of this extract yielded a Pentaisovalerylsucrose (1) isolated for the first time from a natural source to the best of our knowledge. Compound 1 demonstrated in vitro activity against the human prostate cancer cell lines PC-3 and DU-145 with IC50 of 5.701 卤 0.142 渭M and 4.275 卤 0.710 渭M, respectively. The IC50 of the compound was 5.763 卤 0.425 渭M against AT3B-1, a rat prostate cancer cell line expressing P-glycoprotein which is linked to drug resistance in most metastatic cancers. Compared to compound 1, Paclitaxel and Docetaxel were active against AT3B-1 at 2.641 卤 1.253 渭M and 0.613 卤 0.251 渭M. Paclitaxel showed IC50 values of 0.004 卤 0.002 渭M and 0.003 卤 0.001 渭M against DU-145 and PC-3 prostate cancer cell lines respectively. Docetaxel showed IC50 values of 0.002 卤 0.001 渭M and 0.004 卤 0.001 渭M against DU-145 and PC-3 prostate cancer cell lines respectively.
The in vitro anti-prostate cancer and the antiangiogenic activity of Vernonia guineensis Benth. extracts and isolated compound support the use of the tubers of this plant for the treatment of prostate cancer.