Phytochemical investigation and in vitro cytotoxic evaluation of alkaloids from Abuta rufescens.

A phytochemical investigation of Abuta rufescens was performed to authenticate plant material reported previously and to assess the cytotoxicity of the alkaloids obtained from the plant. Three alkaloids which have not previously been reported from this species, two phenolic (subsessiline, an oxoaporphine, and telitoxine, an azafluoranthene) and one non-phenolic (isoimerubrine, a tropoloisoquinoline), were isolated and identified. These alkaloids, along with others previously isolated from this and another Abuta species (grandirubrine, a tropoloisoquinoline), were evaluated for cytotoxic activity against several human cancer cell lines (HCT-116 colon adenocarcinoma, ACHN renal carcinoma, and A549 lung carcinoma). The tropoloisoquinoline alkaloids (grandirubrine, imerubrine, and isoimerubrine) exhibited the greatest cytotoxicity against the cell lines, especially ACHN and HCT-116 cells. The azafluoranthene alkaloid imeluteine exhibited lesser cytotoxicity, as did one of the oxoaporphine alkaloids.