In order to search for bioactive compounds from the organic extracts of a Formosan soft coral Lemnalia flava fourteen natural compounds, including seven new nardosinane sesquiterpenoids flavalin B-H (1-7), two new nornardosinane sesquiterpenoids flavalins I-J (8-9), along with five known compounds, 2-oxolemnacarnol (10), lemnacarnol (11), armatin F (12), (2R)-2-hydroxylemnal-1(10)-en-12-one (13) and laevinol B (14) were isolated from L. flava. The structures of these compounds were established by the detailed spectral analysis (IR, MS, 1D, 2D NMR) and by comparison of the spectral data with those of the related known compounds. The structure of 1 was unambiguously proven by X-ray diffraction analysis. The absolute configuration of 13 was further determined by a modified Mosher's method. The neuroprotective effect compounds of 1¡V3 against the damage of 6-hydroxydopamine (6-OHDA) toward SH-SY5Y cells was also measured. The cytotoxicity of 6-OHDA on SH-SY5Y cells was significantly reduced by pretreatment of 1 at various concentrations. The cytotoxicity of compounds 1¡V13 against human breast carcinoma (MCF-7), human colon carcinoma (WiDr), human laryngeal carcinoma (HEp 2), human medulloblastoma (Daoy) T-cell acute lymphoblastic leukemia(CCRF-CEM), colon adenocarcinoma (DLD-1), human promyelocytic leukemia (HL-60) and murine leukemia (P388D1) cell lines was studied. The ability of 1¡V13 to inhibit the up-regulation of pro-inflammatory iNOS (inducible nitric oxide synthase) and COX-2(cyclooxygenase-2) proteins in LPS (lipopolysaccharide)-stimulated RAW264.7 macrophage cells was examined, and it was shown that no cytotoxic and anti-inflammatory activity could be found for these compounds.

In our ongoing research for secondary metabolites from the Formosan soft corals, six sesquiterpenoids namely GN76-9-1 (1), GN76-10-3 (2), GN76-12-6-10-1 (3), GN76-25-1 (4), GN76-25-5 (5), and GN76-30-5 (6) were isolated from Lemnalia flava (GN76). Among these secondary metabolites, compound 1 possessing a ylangene-type skeleton is a new natural product. Chromatographic separation of the extracts of the Formosan soft coral Efflatounaria tottoni yielded one known compound, GN79-11-3 (7), having an alcyonolide-type structure. In addition, two known germacrane-type sesquiterpenoids, GN82-11-4-2-15 (8) and GN82-16-5-6-25 (9), were isolated from the extracts of the Formosan soft coral Klyxum simplex (GN82). The structures of compounds 1 possessing a ylangene-type skeleton is a new natural product. Chromatographic separation of the extracts of the Formosan soft coral Efflatounaria tottoni yielded one known compound, GN79-11-3 (7), having an alcyonolide-type structure. In addition, two known germacrane-type sesquiterpenoids, GN82-11-4-2-15 (8) and GN82-16-5-6-25 (9), were isolated from the extracts of the Formosan soft coral Klyxum simplex (GN82). The structures of compounds 1-9 were elucidated by extensive spectral analyses. The anti-inflammatory and neuro-protective activities of these compounds were measured in vitro. Compound 2 showed more specific inhibition against the increase of the pro-inflammatory iNOS and COX-2 proteins of LPS-stimulated RAW264.7 macrophage cells. Compound 8 also reveals more specific neuro protective activity to human neuroblastoma cells SH-SY5Y.

Marine invertebrates have been found to be a rich source of bioactive secondary metabolites. In order to search for bioactive compounds, we have studied the chemical constituents from the organic extracts of two Formosan soft corals, Sinularia Scabra and Lemnalia flava. This study had led to the isolation of eight natural compounds, including two new sesquiterpenoids, scabralin A (1) and scabralin B (2) along with two known compounds (3 and 4) from Sinularia scabra, and two new sesquiterpenoids, flavalin A (5) and flavalin B (6) along with three known compounds (4, 7 and 8) from Lemnalia flava. The structures of these compounds were established by the detailed spectral analysis (IR, MS, 1D, 2D NMR) and by comparison of the spectral data with the related known compounds. Lobohedleolide (9), with a great quantity in Lobophytum crassum, have also been modified to compounds 10−19 by chemical conversions with the corresponding reactants via EDC-coupling with an aid of HCl salt of DMAP to yield the related esters and amides.The cytotoxicity of compounds 1, 3−8 and 10¡V19 against the MCF-7 (human breast adenocarcinoma), WiDr (Human colon adenocarcinoma), Daoy (human medulloblastoma), Hep2 (human laryngeal carcinoma), Hep G2 (human liver carcinoma), CCRF-CEM (human T-cell acute lymphoblastic leukemia), and DLD-1 (human colon adenocarcinoma) tumor cell lines were determined. Compound 1 showed moderate activity against the growth of Daoy, Hep2, MCF-7, Hela and CCRF-CEM. Both 15 and 16 exhibited a moderate cytotoxicity against the growth of Hep G2, and compounds 10, 12¡V14, 17 and 18 showed a weak cytotoxicity of it. Compounds 10, 12 and 16¡V18 were found to exhibit moderate inhibition against the growth of CCRF-CEM. Compounds 10, 16 and 18 showed weak activity against the growth of DLD-1. Furthermore, compounds 10, 12 and 14-19 were found to show significant activity against the accumulation of the pro-inflammatory iNOS protein at 10 £gM.