Studies On The Secondary Metabolites From Four Symbionts

Symbionts are microorganisms that reside in the internal of living hosts during a variable period of their life, without causing any immediate overt negative effects. Compare with pathogenic bacterium, Symbiotic microorganisms are more subtle, rarely causing problems, coexisting with their hosts under most circumstances. Because of the long time coevolution with their hosts, Symbionts acquire some unique traits, including distinctive physiological and biochemical characteristics, which can produce secondary metabolites with novel structures and special bioactivity.Symbiotic microorganism represent a dependable source of specific secondary metabolites, and an alternative source of compounds which originally isolated from hosts, it can be manipulated physicochemically and genetically, so it is probably to increase yields of desired metabolites and to produce novel analogues of active metabolites.This dissertation reports four symbionts from Trachelospermum jasminoides, Cynodon dactylon, Oxya chinensis and Chrysanthemum coronarium. we investigated the structure and bioactivity of the secondary metabolites from the four symbionts. A total of29compounds were isolated by a combination of chromatographies over Silica gel, TLC, and ODS reverse column, gel filtration over Sephadex LH-20, and semipreparative HPLC.22compounds were elucidated on the basis of spectral Experiments(UV、1H-NMR.13C-NMR、1H-1H COSY、HMBC、ROESY、HRESIMS、 EIMS、CD). The cytotoxic activities of individual compounds were screened. The specific were described as follows: 1. Myrothecium roridum (IFB-E009) was isolated from T.jasminoides, from the liquid fermentation,11compounds were obtained.9compounds were elucidated. compounds1-4were trichothecenes, compound6was plasticizer compound,5and7-9were alkaloids or dipeptides.compounds1-3showed moderate activities to the human hepatoma cells Hep-G2.2. An unknown fungi were isolated from C. coronarium in XiSha isoland, hainan province.11compouds were obtained from the liquid fermentation, and10of them were identified. compound12was enniatin, compounds13-15were dipeptides contain sulphur atoms, compounds16-17were dipeptides contain benzene ring.3. IFB-E039was isolated from C. dactylon.7compouds were obtained from the liquid fermentation, and4of them were identified. compounds20-23were Benzene derivatives.4. Amycolatopsis sp. HCal were isolated from O. chinensis.3compounds were obtained from the liquid fermentation, and2of them were identified. Compounds27,28were glycolipid compounds, compound28displayed modest immune suppressive activity and a better SI (in vitro cytotoxicity/immune-suppressive activity).Furthermore, natural bioactive products from the endophyte were reviewed briefly.