New abietane diterpenoids from the mangrove Avicennia marina.

Phytochemical investigations of the twigs of Avicennia marina yielded three new abietane diterpenoids 11-hydroxy-8,11,13-abietatriene 12- O-beta-xylopyranoside ( 1), and a pair of inseparable epimers 6 Halpha-11,12,16-trihydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial 11,6-hemiacetal ( 2) and 6 Hbeta-11,12,16-trihydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial 11,6-hemiacetal ( 3), as well as the new lignan (7' S,8' R)-4,4',9'-trihydroxy-3,3',5,5'-tetramethoxy-7,8-dehydro-9-al-2,7'-cyclolignan ( 5), together with 6,11,12,16-tetrahydroxy-5,8,11,13-abitetetraen-7-one ( 4), lyoniresinol ( 6), lyoniresinol 9'- O-beta- D-glucopyranoside ( 7), and diacetylmartynoside ( 8). Structure elucidation of the new compounds was accomplished by analysis of their spectroscopic data. Compounds 2 - 4 showed moderate cytotoxic and antimicrobial activities.