Abstract

Cola acuminate is one of the three edible forms of bizzy nut that has been used for medicinal and therapeutic purposes. However, the precise compound responsible for its biological effects has not been completely identified. Using sequential solid--liquid extraction of bizzy nut coupled with bioactive screening, ether extract was obtained (Biz-2) and it possesses tumor inhibitory activity specific for prostate cancer cells. Enrichment of this tumor inhibitory activity (Biz-2Fr.3) resulted in the elimination of caffeine and tannin, suggesting that Biz-2-Fr.3 activity is due to a unique set of compounds. Biz-2-Fr.3 contains three to four unique compounds with a molecular mass ranging from 120 to 440 amu as evident by high performance liquid chromatography (HPLC), UV-Vis spectroscopy and LC/MS. Biz-2-Fr.3 was found to exhibit growth inhibition and cytotoxicity against the hormone-independent (DU-145) and hormone-­â€dependent (LNCaP) prostate cancer cell lines via microculture tetrazolium (MTT) assay. In the DU145 cell, Biz-­â€2Fr.3 induces a growth-inhibition with a GI₅₀ of 120 ppm with no apparent toxicity in normal transformed prostate cells. The inhibition of DU145 cell proliferation by Biz-2Fr.3 was as a result of retardation of the cell cycle occurring mainly in the G1 phases of the cycle. This cell cycle arrest was associated with the decrease in cyclin D protein levels following Biz--2Fr.3 treatment. It was observed that Biz-2Fr.3 did not elicit any toxicity as evidenced by biochemical markers of liver injury which caused decrease in body weight or serum protein profiles. These results suggest that C. acuminate possesses an anti-­â€cancer activity that is distant from its previously reported biological effects.

Key words: Cola acuminate, bizzy nut, prostate, toxicity.