Diterpenes and disulfides from the marine mangrove plant Bruguiera sexangula var. rhynchopetala

Phytochemical investigation of the stems of Bruguiera sexangula var. rhynchopetala resulted in the isolation and characterization of four new and seven known secondary metabolites. The new compounds were spectroscopically identified as 17-hydroxy-16-oxobeyer-9(11)-en-19-al (1), 16,17-dihydroxy-19-nor-ent-kaur-9(11)-en-3-one (2), (16R)-13,17-epoxy-16-hydroxy-ent-kaur-9(11)-en-19-al (3). and (-)-3.4-dihydro-3-hydroxy-7-methoxy-2H-1,5-benzodithiepine-6,9-dione (10). The configurations of the known compounds brugierol (11) and isobrugierol (12) were re-investigated. Compounds 11 and 12, together with 2,6-dimethoxy-1,4-benzoquinone (13), are proposed to be degradation products of the novel, unusual disulfide 10 (Scheme).