Quassinoids from Eurycoma longifolia Jack roots and their potential inhibitory activity against human benign prostatic hyperplasia cells (BPH-1) and testosterone-induced BPH rat model

Benign prostate hyperplasia (BPH) is an enlargement of the prostate gland, because of hormonal changes in aging males which contribute significantly to excessive proliferation over apoptosis of prostatic cells. The anti-proliferative and induced apoptotic activities of Eurycoma longifolia quassinoids on cancer cell lines could be promising therapeutic targets on BPH. Hitherto, no report of the quassinoids against BPH problem was available. In this study, a systematic phytochemical fractionation of the root extract, TAF2 was performed, which led to the discovery of nine previously described C20 quassinoids (1-9). Two undescribed C20 (10 and 12) and one undescribed (11) C19 quassinoids were identified by detailed NMR and HR-ESI-MS data analysis. Their absolute configurations were assigned by ECD spectral analysis. The quassinoids (1-12) were tested for inhibitory activity against the proliferation of human BPH-1 and human skin Hs27 fibroblast cells cultured in vitro. 1, 2 and 3 at 10 μM significantly reduced BPH-1 cell viability and were cytotoxic to Hs27 fibroblast cells. 2 was selected for further study of anti-BPH activity against testosterone induced BPH rats. At 5 mg/kg, 2 reduced the rat prostatic weight and prostatic index, consistent with the decrease in papillary acini number and epithelial thickness of the prostate tissues. These quassinoids may be potential anti-BPH compounds that require further studies.