Evaluation of Antiaris africana methanol extract and compounds for antioxidant and antitumor activities

Abstract

A methanol extract from the stem bark of Antiaris africana Engler (Moraceae), as well as compounds isolated and identified as betulinic acid (1), 3β-acetoxy-1β,11α-dihydroxy-olean-12-ene (2), ursolic acid (3), oleanolic acid (4), strophanthidol (5), periplogenin (6), convallatoxin (7), strophanthidinic acid (8), methyl strophanthinate (9), and 3,3′-dimethoxy- 4′-O-β-d-xylopyronosylellagic acid (10), were tested for their antioxidant and anticancer activities. The DPPH radical scavenging assay was used for the antioxidant test while the potato disk tumor induction and XTT assays were used to detect antitumor activities. The antioxidant test showed that the methanol extract and compounds 1, 9, and 10, as well as vitamin C, used as reference antioxidant drug, were able to interact with more than 50% DPPH. The results of the potato disk tumor induction assay also indicated a pronounced tumor reducing activity of the methanol extract (83.12%) and compound 10 (96.64%). Samples showing more than 20% inhibition of Crown gall tumors were then tested against human DU-145 and hepatocarcinoma Hep G2 cells. The results showed inhibitory activities of 64.12% and 73.62%, respectively, on DU-145 and Hep G2 cells for the methanol extract. Compound 10 showed the highest inhibition potency on both cell lines with more than 70% inhibition at 50μg/mL. The methanol extract showed an IC50 value lower than this at 30μg/mL, a threshold value for potential antineoplastic extracts. The results of the present study provide supportive data for the traditional anticancer use of A. africana and indicate that the methanol extract as well as compound 10 represent a potential source of medicine for the treatment of cancer, having also interesting antioxidant properties. © 2009 Informa UK Ltd.