Investigation On Novel Bioactive Metabolites Produced By Four Symbionts

Symbionts are microorganisms living inside hosts during a variable period of their life. During the long-time co-evolution with their hosts, symbionts have many chances to acquire unique traits in their physiology and biochemistry and produce secondary metabolites which have novel structures and special bioactivity.In this dissertation, four symbiots were isolated from the root of Vatica mangachapol, the leaves of Phragmites australis, the gut of Penaeus orientalis Kishi-nouye and the leaves of Cynodon dactylon. The structure and bioactivity of the secondary metabolites from the four symbionts were investigated.51 compounds were isolated and elucidated on the basis of spectral experiments such as UV, IR, MS, NMR and CD, of which 6 were new compounds. Furthermore, neuraminidase inhibitory activity of these compounds were tested. The specific were described as follows:1. Myrothecium sp. Km-R-1 was an endophytic fungus isolated from the root of Vatica mangachapol. From the liquid fermentation,15 compounds were isolated.13 known compounds and two newα,β-unsaturatedγ-lactone compounds were elucidated. Compound 1 and 2 showed moderate neuraminidase inhibitory activity.2. Alternaria alternate 002-B-1b was an endophytic fungus isolated from the leaves of Phragmites australis. From the liquid fermentation,19 compounds were isolated.17 known compounds and one new tricycloditerpene compound were elucidated. Compound 16,23,24 and 25 showed moderate neuraminidase inhibitory activity. 3. Streptomyces seoulensis IFB-A01 was a marine-derived actinomycete isolated from the gut of Penaeus orientalis Kishi-nouye. From the solid fermentation,8 compounds were isolated.3 known compounds and one new benzodiazepine compound with one new nortriterpenoid compound were elucidated. Compound 35 and 37 showed moderate neuraminidase inhibitory activity.4. Chaetomium globosum 007-iL-3b was an endophytic fungus isolated from the leaves of Cynodon dactylon. From the solid fermentation,9 compounds were isolated. 6 known compounds and one new polyketone compound was elucidated. Compound 44 and 46 showed moderate neuraminidase inhibitory activity.Furthermore, natural bioactive products from endophytic fungus were reviewed briefly.