Racemic xanthine and dihydroxydopamine conjugates from Cyclopelta parva and their COX-2 inhibitory activity

Abstract Seven new compounds including three pairs of enantiomeric xanthine analogues (1–3), a pair of enantiomeric hypoxanthine analogue (4), and three pairs of enantiomeric N-acetyldopamine dimers (6–8), together with a known one (5) (Fig. 1) were isolated from the insect Cyclopelta parva. Their structures including absolute configurations were assigned by using spectroscopic and computational methods. Chiral HPLC was used to separate racemic 1–8. Biological evaluation found that 6b and 7a are potent COX-2 inhibitory agents with IC50 values at 385.2 nM and 868.8 nM respectively.