Characterization of the antiproliferative activity of Xylopia aethiopica

We report that X. aethiopica extract prepared with 70% ethanol has antiproliferative activity against a panel of cancer cell lines. The IC50 was estimated at 12 μg/ml against HCT116 colon cancer cells, 7.5 μg/ml and > 25 μg/ml against U937 and KG1a leukemia cells, respectively. Upon fractionation of the extract by HPLC, the active fraction induced DNA damage, cell cycle arrest in G1 phase and apoptotic cell death. By using NMR and mass spectrometry, we determined the structure of the active natural product in the HPLC fraction as ent-15-oxokaur-16-en-19-oic acid.The main cytotoxic and DNA-damaging compound in ethanolic extracts of Xylopia aethiopica is ent-15-oxokaur-16-en-19-oic acid.Natural compounds have attracted considerable attention as preventive and therapeutic agents against cancer [1]. Indeed, 74% of anticancer compounds are natural products or their derivatives. According to the World Health Organization (WHO), 80% of the population in Africa and in some Asian countries still use plant preparations to treat their illnesses, including cancer. The cloves of the plant Xylopia aethiopica, a member of the custard apple family, Annonaceae, are used as a spice in various traditional dishes of Western and Central Africa. The plant is also used in decoction to treat dysentery, bronchitis, ulceration, skin infection and female sterility. Several studies have shown that X. aethiopica extracts possess antibacterial [2-5], antifungal [6] and anti-plasmodial [7] activities. X. aethiopica extract contains an antioxidant activity [8]; it also increases antioxidant defense and protects rats from the adverse effects of irradiation [9,10].Although some extracts of this plant have antioxidant properties, others have cytotoxic effects on a wide range of cancer cell lines [11]. A recent study of various Cameroonian spices [12] found that extract of X. aethiopica had cytotoxic activity against pancreatic and leukemia cells sufficient for the plant to be considered a potential s