| Marine invertebrates as rich sources of novel bioactive metabolites have attracted more and more attention. In the processes of searching for bioactive compounds, we have chemically investigated the sea cucumber Apostichopus (=Stichopus) japonicus SELENKA and the soft coral Sarcophyton sp.The cold water sea cucumber Apostichopus (=Stichopus) japonicus SELENKA (family) belongs to class Holothuroidea, order Aspidochiroia and family Stichopodidae. The great interest has developed in studying triterpene glycosides from this sea cucumber since Elyakov et aL reported the isolation of three glycosides from this species in 1968. Later Kitagawa et aL clarified the structures of two main glycosides named holotoxin A and B. The structure of the minor glycoside holotoxin C, suggested to be the similar type as holotoxin A and B, remained unclear. Maltsev et al reported the isolation and structure elucidation of another two triterpene glycosides, holotoxin Ai and Bi from S. japonicus. No more new triterpene glycoside from this sea cucumber was reported in the following years.As a continuation of our searching for new bioactive compounds from echinoderms, we have investigated this specie collected from Bohai Sea of China, off Dalian coast. The crude extracts were separated employing solvent partitioning followed by various chromatographic methods to afford 13 triterpene glycosides (AJ-1~AJ-13), the structures of which were elucidated on the basis of extensive spectroscopic analysis, with seven new compounds. All of these triterpene glycosides except AJ-9 and AJ-10 were isolated from this species for the first time, seven of which were new.The structures of the new triterpene glycosides were identified as: 3β-O-{2-O-[3-O-methyl-β-D-glucopyranosyl-(13)-β-D-xylopyranosyl-(1-4)-β-D-gl ucopyranosyl]-4-O-[3-O-methyl-β-D-glucopyranosyl-(1-3)-β-D-glucopyranosyl]-β-D -xylopranosyl}-holosta-9(11),25(26)-dien-16-one (AJ-1); 3β-0-{2-O-[3-β-methyl-β-D-glucopyranosyl-(l-3-)-β-D-xylopyranosyl-(l-4)-β-D-quinovopyranosyl]-4-O-[β-D -glucopyrano-(l-3)-β-D-glucopyranosyl]-β-D-xylopranosyl}-holosta-7(8),25(26)-die n-16-one(AJ-2); 3β-O-{2-O-[3-0-methyl-β-D-glucopyranosyl(1-3)-β-D-xylopyran osyl( 1 -4)-β-D-gluco-pyranosyl]-4-O-[β-D-glucopyranosyl( 1-3)-β-D-glucopyranos yl]-β-D-xylopranosyl}-holosta-9(l l),25-dien-16-one (AJ-3); 3-0-{2-0-[3-0-methyl-β-D-glucopyranosyl(1-3)-β-D-xylopyranosyl(1-4)-β-D-quinovopyranosyl]-4-0-[3-O-methyl-β-D-glucopyranosyl(l -3)-β-D-glucopyranosyl]-β-D-xylopranosyl}-holost a-9(l l)-en-3β,25,26-triol-16-one (AJ-4); 3β-O-{2-O-[3-O-methyl-β-D-glucopyrano syl(l-3)-β-D-xylopyranosyl(l-4)-β-D-quinovopyranosyl]-4-O-[3-O-methyl-β-D-gl ucopyranosyl( 1-3 )-β-D-glucopyranosyl]-β-D-xylopranosyl }-dehoIosta-9( 11 )-en-16, 25-dione (5); 3β-0-{2-0-[β-D-glucopyranosyl-(l-3)-β-D-xylopyranosyl-(1-4)-β-D -quinovopyranosyl]-4-0-[β-D-glucopyranosyl]-β-D-xylopranosyl}-lanosta-7(8),25(26) -dien-16-one(6); 3β-0-{2-0-[3-0-methyl-β-D-glucopyranosyl-(l-3)-β-D-xylopyran osyl-(l-4)-β-D-quinovopyranosyl]-4-O-[β-D-glucopyranosyl]-β-D-xylopranosyl}-lan osta-7(8),25(26)-dien-16-one(7). The known compounds were cladolosides B (AJ-8), holotoxin A1 (AJ-9), holotoxin B (AJ-10), bivittoside D (AJ-11), stichlorosides C1 (AJ-12) and holothurin A (AJ-13).Soft corals are thought to contain various bioactive constituents that chemically defend against attack. The soft coral Sarcophyton sp. belonging to order Alcyonacea and family Alcyoniidae is one of the common species found in the South China Sea. We have isolated a series of sterols with 3β, 5a, 6β-hydroxy skeleton from this specie, and the structures of 14 compounds were identified, including 7 new compounds. The new corals are: 24 (25)-ene-cholesta-3β, 5a, 6β-triol (SA-1), 11a-acetoxy-24-methylcholesta-22 (23), 25 (27)-diene-3β, 5α, 6β-triol (SA-2), lla-acetoxy-24 (25)-ene-cholesta-3β, 5α, 6β-triol (SA-3), lla- acetoxy-gorgostane-3β, 5a, 6β, 12a-tetrol (SA-4), 24 (S)-24- methylcholesta-la, 3β, 5α, 6β, lla-pentol (SA-5), 23, 24-dimethylcholesta-22 (23)-ene-3β, 5α, 6β, lla-tetrol (SA-6), lla-acetoxy-gorgostane-3β, 5α, 6β-triol (SA-7). The known sterols are: gorgostane-la, 3β, 5a, 6β, lla-pentol (SA-8), gorgostane-3β, 5α, 6β, 11a-tetrol (SA-9), 24 (S)-24-methylcholesta-3β, 5α, 6β, 11a-tetrol (SA-10), 11a-acetoxy-24 (S)-24- methylcholesta-3β, 5a, 6β-triol (SA-11), 24 (S)-24-methylcholesta-7 (8)-ene-3β, 5α, 6β-triol (SA-12), 23, 24-dimethylcholesta-16 (17)-ene-3β, 5α, 6β20 (S)-tetrol (SA-13), 24(S)-24- methylcholesta-3β, 5α, 6β (SA-14).The antifungal active assay of these saponins indicated that glycosides AJ-1, AJ-2, AJ-6, AJ-7, AJ-9, AJ-10 and AJ-12 exhibit significant antifungal activities against Cryptococcus neoformans; glycosides AJ-1, AJ-2, AJ-7, AJ-8 and AJ-12 exhibit significant antifungal activities against Candida albicans; glycosides AJ-1, AJ-2, AJ-8 and AJ-9 exhibit significant antifungal activities against Candida tropicalis, MIC80<8μg/ml.Our studies focused on chemical constituents of A. japonicus and Sarcophyton sp. and their bioactivities have established a foundation for further research and development of these two marine organisms with abundant resources in China, and provided important leading compounds for the development of new antifungal drugs.
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