Alkaloids from Alphonsea Elliptica Barks and Their Biological Activities

Abstract

This study was carried out to investigate the phytochemicals from the barks of Alphonsea elliptica. The barks  were harvested from Hutan Simpan Sembarong, Kluang, Johor; and extracted using dichloromethane (DCM), hexane and methanol successively. Isolation of dichloromethane crude extract was then performed using silica gel column chromatography and preparative thin layer chromatography (PTLC)techniques. Structural identification were carried out via 1D and 2D NMR, UV, IR, MS and comparison with reported data. Phytochemical study of the barks led tothe isolation of five alkaloid in which two were oxoaporphines; atherospermidine (1) and liriodenine (2),two were dioxoaporphines;cepharadione A (3) and N- methylouregidione (4), and an azafluorenone alkaloid;kinabaline (5). The hexane, DCM, and methanol crude extracts, together with five isolated alkaloids, were tested for theirradical scavenging activity,inhibition of xanthine oxidase activities and cytotoxicity. Atherospermidine and liriodenine possessed antioxidative activities with IC₅₀ value of 20.17 and 10.73, respectively. Atherospermidine, liriodenine, N-methylouregidione and kinabaline showed xanthine oxidase inhibitiory activityof 46.29, 7.66, 42.10 and 50.72 μM,respectively. Meanwhile, atherospermidine, liriodenine, cepharadione A and kinabaline showed cytotoxicity  against breast cancer cell line with IC₅₀ 89, 86, 79.85 and 62 µg/mL respectively.  All the alkaloids tested in this study were isolated for the first time from this species while Cepharadione A is reported for the first time in a species belongs to Alphonsea genus.

Keywords: Alphonsea ellipticaHk. f. et Th., Alkaloids, Radical scavenging activity, Xanthine oxidase, Cytotoxicity.