VOL. 3 No.2 JULY 2000 THE MANILA JOURNAL OF SCIENCE Diterpenes from the Soft Coral Clavularia inflata (Coelenterata, Octocorallia, Stolonifera) Glenn V. Alea Consolacion Y. Ragasa Chemistry Department, De La Salle University-Manila 2401 Taft Avenue, 1004, Manila, Philippines Keywords: Clavularia Inflata, diterpenes, (3S,4S)-clavulara-1(15), 17-diene-3,4-dio/, (4R)-clavulara-1(15), 17-diene- 4-0/, (1 R, 4R)-clauvulara-17 -ene-1, 4-diol Three diterpenes were isolated from the dichloromethane extract of the Stolonifer Clavularia inj/ata. The structure of(3S,4S)-clavulara-l (15), 17- diene-3,4-diol 1 was elucidated by 1D and 2D NMR spectroscopy while the structures of (4R)-c!avulara-l(l5),17-diene-4-o1 2 and (lR,4R)- clavulara-17-ene-l,4-dioI3 were determined by comparing their proton NMR spectra with those previously reported. INTRODUCTION Soft corals are a major source ofterpenoids. Studies conducted on these marine organisms led to the isolation of novel terpenoid metabolites of varying biological activities. The genus Clavularia, for example, gave a number of cytotoxic compounds exhibiting anti-tumor and anti-inflammatory activities"'. Five diterpenes have been isolated from Clavularia injlata. They are (3S,4S)-clavulara- 1 (15), 17-diene-3, 4-diol 1 4 • 5 , (4R)-clavulara- 1 (15), 1 7-diene-4-o1 2 4 . 5 , (1 R,4R)-clavulara-I7-ene- I,4-dioI3 4 ,5, (3E,5R,7E,11S,12S,14Z)-11-methyl- 15-nordolabella-3,7,14-trien-5-01 4 6 and (3Z,5E,9E, lR *, 12aR*)-1-isopropyl-6,1 0, 12a- trimethyl-l,2,4,7,8,11,12,12a- octahydrocyclopentacyc1oundecen-7-01, 57. The 25 stru( tures of3, 4, and 5 were determined by x-ray while the structures of 1 and 2 were determined by chemical intercorrelation with 3. Compounds 1, 2 and 3 were first reported as 1 (15),17 -diene, 4 hydroxyclavulara-l (15), 17-diene and 1 respectively4. However, the compounds were renamed after the absolute configurations of compounds 2 and 3 were determined by the modified Horeau method.' In this paper, we report the isolation and structure elucidation of the diterpenes 1,2, and 3 (Figure 1) from Clavulara injlata. This is the first report on the structure elucidation of 1 using I D and 2D NMR analysis.