Novel cytotoxic constituents of Orthosiphon diffusus

Abstract

Chemical investigation on Orthosiphon diffusus resulted in the isolation of four relatively rare, novel polychiral furanopyrans, orthodiffenes A-D (1-4) which were characterized from detailed studies of their 1D and 2D NMR spectra. The X-ray crystallographic analysis of orthodiffene A (1) was accomplished. The in vitro cytotoxic activity of orthodiffenes A-C (1-3) was tested against Jurkat and HL-60 cells using camptothecin as a positive control. Orthodiffenes A (1) and B (2) showed comparable activity to camptothecin against HL-60 and Jurkat cells, respectively.