Chem. Pharm. Bull. 55(6) 890—893 (2007)

and steroids. As part of our search for bioactive substances from marine organisms, the Formosan soft coral Nephthea elongata KÜKENTHAL (Nephtheidae) was studied because the CH2Cl2 extracts showed significant cytotoxicity to P-388 (mouse lymphocytic leukemia) cell culture as determined by standard procedures. Bioassay-guided fractionation resulted in the isolation and chraracterization of seven new prenylbicyclogermacrane diterpenoids, pacificins K—Q (1—7). Pacificin K (1) proved to have molecular formula C22H36O3 from its HR-FAB-MS, C-NMR, and DEPT spectroscopic data. C-NMR and DEPT spectrum of 1 exhibited the presence of six methyls, six sp methylenes, three sp methines, two sp methine, two sp quaternary carbon and one sp quaternary carbon. The presence of two trisubstituted olefins in 1 was shown by the NMR data (dH 5.09 d, 5.25 d; dC 131.2 qC, 125.2 CH, 140.0 qC, 125.2 CH) (Tables 1, 2). The NMR data (dH 0.26 m, 0.40 m, 0.55 m, 0.98 m; dC 4.5 CH2, 27.4 CH, 30.3 CH) (Tables 1, 2) pointed to a 1,2-disubstituted cyclopropane ring in 1. The H-NMR also spectrum contained signals for six tertiary methyl groups, (dH 0.60, 0.81, 1.61, 1.69, 1.86, 2.03). The presence of an ambiguous carbon bearing an oxygen (dC 71.6 qC) was shown in the C-NMR spectrum. The spectral data of 1 exhibited some similarity to those of a prenylbicyclogermacrane diterpenoid, palmatol (8), isolated from Alcyonium palmatum, except for the presence of an acetoxyl at C-11. COSY correlations from H-11 to H-10/H-12 and HMBC correlations (Fig. 1) from H-11 to C-12/C-10/OCOCH3 confirmed the position of the acetoxyl at C-11. The relative stereochemistry of 1 was deduced from a 2D NOESY experiment (Fig. 2), which indicated that Me-19, Me-20, H-11, and H-16 were on one side of the molecule, while Me-18, H-10, and H-14 were on the opposite side of the molecule. From these data, pacificin K can be formulated as 1. Pacificin L (2) was shown to have a molecular formula of C20H34O3 by its HR-FAB-MS, C-NMR, and DEPT spectroscopic data. The Hand C-NMR spectral data of 2 exhibited some similarity to those of a prenylbicyclogermacrane diterpenoid, pacifin A (9), isolated from Nephthea pacifica, except for the replacement of the olefin at C-2/C-3 by an 890 Vol. 55, No. 6