The present study was undertaken to determine the effects of varying light intensities on the morphology and physiology of the soft coral Pachyclavularia violacea. The soft corals P. violacea were treated by LED light and the illumination ranged from 50 to 200 £gmol photon m-2 s-1, i.e. high light (200 £gmol photon m-2 s-1), medium light (140 £gmol photon m-2 s-1), medium-low light (100 £gmol photon m-2 s-1 and low light (50 £gmol photon m-2 s-1). The theca length, the density of zooxanthellae and the concentrations of chlorophyll a and proteins were measured to evaluate the response of P. violacea to different light intensities. A significant longer theca length was found in the group of medium-low light (5¡V 9mm) than the groups of high and low light intensities (1-2mm) (p<0.001). And, the theca length in the groups of medium and medium-low was more close to their source population. Over the 6-month experimental periods, the densities of zooxanthellae in the groups of medium and medium-low were in the range of 1.5 ~3.8 x 105 (N/mg) which were significantly higher than other groups (p<0.01). The concentrations of chlorophyll a in the low light group were 0.5~ 2.0 (ng/mg) during the experimental periods which were significantly higher than other groups (p<0.05). In the fifth and sixth months, the concentrations of chlorophyll a per zooxanthellae in the group of medium-low were in the range of 0.4~5.8 Chl. a ¡Ñ 10-5 (ng/zoox.) which were significantly higher than other groups (p<0.01). The protein content in the group of low light was significantly lower than other groups in the fifth month. And, the protein contents were decreased significantly in all groups in the sixth month. Based on the results, it is concluded that theca length and the density of zooxanthellae were sensitive responses to light adaptation. The light intensity about 100 £gmol photon m-2 s-1 might be an appropriate range to culture the soft coral P. violacea because the theca length in the group was close to its source population.

The organic extracts of two marine soft corals Pachyclavularia violacea and Subergorgia suberosa, collected along the coast of Kenting, Taiwan, were found to exhibit significant cytotoxicities toward several cancer cell lines (Table 1). In order to discover bioactive compounds, we have investigated the chemical constituents of these two marine organisms. Investigation on P. violacea has led to the isolation of twenty-five compounds, including twenty-one new compounds, pachyclavulariolide G (1), pachyclavulariolide H (3), pachyclavulariolide I (4), pachyclavulariolides J¡VS (6¡V15), pachyclavulariaenones A¡VG (16¡V22), secopachyclavulariaenone A (23), and four known compounds pachyclavulariolide (2), pachyclavulariolide E (5), pachyclavulariolide A (24) and pachyclavulariolide B (25). Also, we have investigated the chemical constituents of S. suberosa. This study led to the isolation of fifteen compounds, including six new compounds, 2b-acetoxysubergorgic acid (27), subergorgiol (31), suberosols A¡VD (34¡V37), and nine known compounds, subergorgic acid (26), 2b-hydroxysubergorgic acid (28), methyl ester of subergorgic acid (29), 2b-acetoxy methyl ester of subergorgic acid (30), buddledin D (32), buddledin C (33), 5b-pregnan-3,20-dione (38), £G1- 5b-pregnen-3,20-dione (39) and 3a-acetoxy -5b-pregnan-20-one (40). Compounds 39, 40 were isolated from natural sources for the first time. Structures of these compounds were determined on the basis of chemical method and spectroscopic evidences. Cytotoxicities of these compounds against P-388, KB, A-549 and HT-29 cancer cell lines also were described. Compound, 7, 32, 33, 36, 37 have been found to show moderate activity toward the above cancer cell lines.