Bioactive dammarane triterpenes from the mangrove plant Bruguiera gymnorrhiza

Three new dammarane triterpenes, bruguierins A-C (1-3), were isolated from a petroleum ether extract of the flowers of Bruguiera gymnorrhiza. Their structures were determined on the basis of physical and spectroscopic data interpretation. With stably transfected HepG2 cells, the three isolates activated antioxidant response element (ARE luciferase activation) with EC50 values of 7.8, 9.4, and 15.7 mu M, respectively. Bruguierin A (1) also inhibited phorbol ester-induced NF kappa B (nuclear factor-kappa B) luciferase activation with an IC50 value of 1.4 mu M and selectively inhibited cyclooxygenase-2 (COX2) activity with an IC50 value of 0.37 mu M. Compounds 2 and 3 were not active in these bioassays.