Study On Natural Products From Marine Sponge And Associated Actinomycetes, As Well As Bioactivity Induction Of These Actinomycetes

Marine sponges are the richest source of marine natural products, which harbor large amounts of diverse microbes accounting for nearly 40% of the total sponge biomass. It is evident that sponge associated microbes are involved in the biosynthesis of some sponge derived natural products, and sometimes are the true producers.In the first part of this thesis, Axinella sp., a marine sponge collected from the South China Sea, was investigated for its chemical constituents. Two bioactive compounds- Debromohymenialdisine and Hymenialdisine were isolated from the alcohol extract by extraction, portition, and ODS chromatography. Their structures were elucidated by employing modern spectrometric analysis techniques such as EI/MS, ESI/MS, 1H-NMR and 13C-NMR. Both compounds are aldisine alkaloids and MAPK pathway inhibitors with potent bioactivity that deserve further pharmacological studies.The second part of this thesis focused on screening antibacterial active compounds from the 41 commercial-important actinomycete strains isolated from five different mairne sponges Hymeniacidon perleve, et al.. These strains were cultured in three different fermentation media. After the organic solvent extraction, a bioactive strain 124 was identified by TLC and bioassays. The fermentation was then scaled-up with 30L broth harvested. The broth was extracted using acetic ether.Further purification using column chromatography, Sephadex-LH, and TLC combined HPLC. Finally the purified compounds 124-11 and 124-13 were obtained, and were identified as Genistein and Daidzein. They possess a range of bioactivities, but perhaps were isolated from the fermentation media as soybeanextract is one of the media components.In order to increase the production of bioactive compounds from sponge associated microbes,the co-culture of different actinomycete strains isolated from sponges were tested for the potential induction ability. The preliminary results indicated that both actinomycete co-culture and induction by respective fermentation broth are effective atrategies for production of new metabolites that are not produced by monoculture. The change in metabolic profiles can be explained by synergism, antagonism and competition by different actinomycetes in co-cultures.