Bruguiesulfurol, a new sulfur compound from Bruguiera gymnorrhiza.

A new cyclic 4-hydroxy-dithiosulfonate, bruguiesulfurol (1), as well as two known 4-hydroxydithiolane 1-oxides, brugierol (2) and isobrugierol (3) were isolated from the flowers of Bruguiera gymnorrhiza. With stably-transfected HepG2 cells, the three isolates activated antioxidant response element (ARE) luciferase activation with (EC(50)) values of 56.7, 3.7 and 1.8 microM, respectively. Compounds 2 and 3 also inhibited phorbol ester-induced NF-kappaB (nuclear factor-kappaB) luciferase activity with IC (50) values of 85.0 and 14.5 microM, respectively. In addition, compound 2 inhibited enzyme cyclooxygenase-2 (COX-2) activity with an IC(50) value of 6.1 microM. The structures of these isolates were determined by spectral data, and that of compound 1 was confirmed by X-ray crystallographic analysis.