Seven new steroids, GN70-153E (1), GN70-153F (2), GN70-153I (3), GN70-272F (4), GN70-272I (5), GN70-272L (6), and GN70-272L (7), were isolated from the Formosan soft coral Clavularia viridis by chromatographic separation of the EtOAc layer which was obstained from crude extraction in hexane¡ÐAcetone, 100% Acetone, Acetone¡ÐMeOH and 100% MeOH then partitioned between EtOAc and H2O. Their structures were determined based on the results of several kinds of spectroscopic analyses and HRESI-MS. Compounds 1-7 exhibited cyctotoxicity against HT-29 and P-388 cell lines in vitro.

In order to search for bioactive substances from marine organisms,the Taiwanese soft coral Clavularia inflata,collected along the coast of Green Island,Taiwan,was studied because of its significant cytotoxicity against NUGC-3 and HONE-1 cancer cell lines in EtOAc extract. Bioassay-guided fractionation resulted in the isolation of five diterpenoids,including four known compounds, ( 1R*, 12R* ) - dolabella- 4 (16), 7, 10- triene- 3, 13- dione (1),stolonidiol monoacetate (2), stolonidiol (3),clavutriolin (5),and one new compound,2- acetoxy- stolonidiol (4). Structures of these compounds were determined on the basis of spectroscopic evidence and chemical derivatization. The application of NMR techniques included 1D- and 2D- NMR,such as COSY, HMQC,HMBC and NOESY,etc. Compounds 1-5 are bicyclic dolabellane skeleton diterpenes. Compound 1 has two ketone groups at C-3 and C-13 positions,an exocyclic methylene at C-4 and two double bonds at C-7 and C-10 positions. Compounds 2-4 possess two epoxides at C-7,C-8,C-10,and C-11. Among them,compound 2 has an acetoxyl group at C-17,and a hydroxyl group at C-18. Compound 3 has two hydroxyl groups at C-17 and C-18 positions. Compound 4 has two hydroxyl groups at C-17 and C-18,and an acetoxyl group at C-2. Compound 5 contains three hydroxyl groups at C-8,C-17,and C-18,and a chlorine atom at C-7, and a epoxy moiety at C-10 and C-11 positions. The ctytotoxicity of these compounds and their derivatives against KB¡]human oral epidermoid carcinoma¡^,Hepa¡]human liver carcinoma¡^and Hela¡]human cervix epitheloid carcinoma¡^cancer cell lines were also measured. Compounds 1-3 and 5 exhibited significant cytotoxicity against KB cancer cell lines with ED50 values of 0.87,3.07, 1.35 and 0.36 mg/ml,respectively,meanwhile, compound 4 exhibited cytotoxicity against Hepa cancer cells with ED50 value of 1.20 mg/ml. However,the acetylated derivatives 6 and 7 were inactive against these cell lines.

Chromatographic separation of acetone/methylene chloride extracts of Formosan soft coral Capnella imbricata (GN75) led to the isolations of six new capnellenes, 8b,10a-diacetoxy-D9(12)-capnellene (1), D9(12)-capnellene-5b,8b,10a-triol (3), D9(12)-capnellene-8b,10a,13b-triol (4), 8b-acetoxy-D9(12) -capnellene (7), D9(12)-capnellene-8b,14b-diol (8), D9(10)-capnellene-12-ol-8-one (9), and three known compounds, D9(12)-capnellene-8b,10a-diol (2), D9(12)-capnellene-10a-ol-8-one (5), D9(12)-capnellene-8b-ol (6), one new calamenene, (+)-15-hydroxy-calamenene (10). One new prostanoid, GN61-97-11-8 (11) and five new steroids, GN61-91-141-14 (12), GN61-91-141-12 (13), GN61-77-6-I (14), GN61-77-6-E (15) and GN61-97-9-6 (16) were isolated from the methylene chloride extracts of the Formosan soft coral Clavularia viridis (GN61). All of these compounds were established on the basis of extensive spectral analysis and chemical reactions. The absolute structure of 2 was determined by MTPA esterifications. Compounds 1-3¡B5 and 12-16 showed more specific inhibition against the up-regulation of the pro-inflammatory iNOS and COX-2 proteins of LPS-stimulated RAW264.7 macrophage cells.

This dissertation mainly investigates the constituents of one species of sponge (Ircinia formosana) and three species of soft corals¡]Sinularia flexibilis¡BCespitularia hypotentaculata and Clavularia viridis¡^. These organisms were extracted with EtOAc and analyzed them with chemical methods. Twenty three new natural products were isolated and the cytotoxicity of these copounds was tested and evaluated. Four new C22-sesterterpenoids were isolated from the sponge Ircinia formosana, and designated as irciformonins A-D (1-4). In the investigation of the soft coral Sinularia flexibilis, nine new cembranes were purified, and they were called sinuladiterpenes A-I (5-13). Six new diterpenes, cespihypotins Q-V (14-19) were obtained from the soft coral Cespitularia hypotentaculata. In addition, the soft coral Clavularia viridis afforded four new prostanoids, designated claviridic esters A-D (20-23). The structures of these metabolites including their stereochemistries have been established by detailed spectroscopic analyses, particularly 2D NMR (1H¡V1H COSY, HMQC, HMBC, and NOESY) spectroscopy and mass and by comparison with the related physical and spectral data of known compounds. Cytotoxicity of the isolated compounds was measured by Dr. Kuo Yao-Haur, Institute of Chinese Medicine. Irciformonins C (3) and D (4) from sponge Ircinia formosana showed the cytotoxicity against WiDr (Human colon adenocarcinoma) with ED50 at 6.7 and 4.9 £gg/mL, respectively. Cespihypotin T (17) was found to exhibit the inhibition against Daoy (Human medulloblastoma) and WiDr (Human colon adenocarcinoma) at ED50 9.3 and 7.5 £gg/mL. Claviridic esters A (20) and B (21) exhibited significant cytotoxicity against the growth of Hep2 (Human hepatoma) at ED50 0.19 nad 0.16 £gg/mL, respectively. Claviridic ester B (21) also showed significant cytotoxicity against Daoy (Human medulloblastoma) tumor cells at ED50 0.18 £gg/mL.

The methylene chloride and acetone extracts of Formosan soft coral Clavularia violacea (Collected at Green Island) were found to exhibit significant cytotoxicity against P-388, A-549 and HT-29 cancer cell lines. Chromatographic separation let to the isolation of one prostanoid, 1, two cembranoid deterpenes, 2 and 3, one aromadedrane-type sesquiterpene, 4, one neodollabellane diterpene, 5, (+)-curcuphenol, 6 and two sesquiterpene lactones, 7 and 8. Compounds 1, 2, 4, and were new compounds. Compounds 1-5 exhibited significant cytotoxicity against P-388, HT-29 and A-549 cancer cell.