A pair of new oxindole alkaloids, named macrophyllines C (1) and D (2), together with two known oxindole alkaloids isorhynchophylline (3) and corynoxine (4) were isolated from Uncaria macrophylla. Their structures were elucidated based on detailed spectroscopic analysis and by comparison with literature data. In addition, all the isolates were tested for their anti-HIV activities and cytotoxicities in C8166 cells and compounds 2-4 showed weak anti-HIV activities with EC50 values of 11.31 ± 3.29 μM, 18.77 ± 6.14 μM and 30.02 ± 3.73 μM, respectively.
Keywords: Oxindole alkaloid; Uncaria macrophylla; anti-HIV activity; macrophylline.