Six new compounds, irciformonins E~J (1~6), were isolated from CH2Cl2/MeOH extract of the sponge Ircinia formosana collected in Taiwan, toghther with two known compounds, irciformonins A and B. These compounds possess a linear C-22-sesterterpenoids type skeleton. The structures of all compounds were elucidated by spectroscopic analysis including 1D and 2D-NMR, optical rotation, IR, UV and high resolution mass spectra, as well as comparison with those in references. The stereochemistry of these compounds were determined by NOESY experiments, MM2 minimized energy, as well as comparison with those in references. The structures of all compounds possess a furan ring, a five membered lactone ring , and three methyl groups. Compounds 1 and 2 are geometric isomers. The differences between them are the substituents of the methoxyl group and the double bond. Compounds 1 and 2 possess substituents of the methoxyl group at C-10 and C-12 and have the double bond at C-11/C-12 and C-10/C-11. The differences between compounds 3 and 6 are the functional groups of the acetyl moeity and the double bond. Compound 3 has an acetyl group at C-12. Compounds 3 and 6 contain two double bonds at C-10/C-11 and C-11/C-12. Compound 4 has a cyclopentane between C-12~C-15 and a ketone group at C-10 while compound 5 possesses two acetyl groups at C-10 and C-15 positions.

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.

Magister Pharmaceuticae - Mpharm / Cancer is a major health problem worldwide and killing millions of people each year. The use of natural products as chemotherapeutic agents is well established, however, many of the currently available drugs are associated with undesirable side effects and high toxicity. Furthermore, the development of drug resistant cancers makes the search for anticancer lead compounds a priority. In this study a library of prefractionated marine sponge extracts was established and used to prioritise samples for isolation of bioactive metabolites. From the generated library, two of the sponges of genera Ircinia sp. and Latrunculid sp. resulted in isolation of furanosesterterpenes (7E,12Z,20Z,18S-variabilin) and pyrroloiminoquinone (tsitsikammamine A and tsitsikammamine N-18 oxime) alkaloids respectively. The structures of these compounds were elucidated by analysis of 1D and 2D NMR data. These compounds displayed moderate to potent cytotoxicity against MCF-7, PC-3, U-87 and HEK-293 cells lines through apoptosis, with lack of selectivity for cancer cell lines.