Bioactive Secondary Metabolites From Two Marine Microorganisms Strains

Marine environment encompassing a prodigious club of microorganism's especially marine actinobacteria and fungi were proven with the ability to produce structurally unique secondary metabolites.In this study we chose two strains Streptomyces sp.actinobacteria isolated from marine sediment South East China Sea and XZ-1 fungal strain collected from Kueishantao hydrothermal vent Taiwan.They were cultured in normal and metal-stress condition.The ethyl acetate extracts of their fermented medium were studied and purified by different spectroscopic techniques including TLC,Column Chromatography and Preparative HPLC.The structure of pure compounds were identified by HPLC,U.V and NMR.Their potential as a biomolecules was studied in vitro against Staphylococcus aureus,Bacillus subtilis and E.coli.Treatments such as the use of biotic and abiotic elicitors were reported by several studies to enhance the production of secondary metabolites from marine microorganism.Elicitation by chemical means including heavy metals is one of a new technique for drug discovery.In this study the strain H-1003 Streptomyces sp.was cultured with metal stress.The results revealed that the metabolic patterns of the actinobacteria changed with different kind of metals including Co2+,Cr2+ and mix metals(Co2++ Cd)stimulation and produced 4 new metabolites.The new secondary metabolites were isolated by prepartive HPLC and identified by HPLC-MS and NMR.Their structures were determined to be four known compounds enterocin(1),anhydromevaLonolactone(2),cyclo-trans-4-OH-(D)-Pro-(D)-Phe(3)and L,L-cyclo(phenylalanyl-tryptophyl)(4).Compound 1 because of its unique carbon skeleton containing mono substituted benzene ring and a methoxy-substituted a-pyrone ring and strong antibacterial activity it was a total different compound from other products.The compound 1 enterocin production was further enhanced by using response surface methodology.The optimum metal stress conditions consisted of culturing marine actinobacteria H-1003 with addition of Cobalt 2mM ions in optimized Gause's medium having Starch 20mg for 10 days at 180 revolution/min.Under this condition,enterocin production was enhanced with a value of 5.33mg/L,which was totally absent at H-1003 control and much higher than competitive conditions.Because of its unique living environment and challenging habitat condition the hydrothermal vent microorganisms become the hotspot of marine natural products research.In this study marine fungi strain XZ-1 was cultured in a normal PDA medium.The ethyl acetate culture extract of fermented fungi was isolated and purified by TLC,column chromatography and Preparative HPLC and identified by HPLC-MS,U.V and NMR.A total number of 6 compounds were isolated.All the compounds were identified as known compounds including ergosterol(5),Homodimeric WIN 64821(6),Hydroxysydonic acid(7),Diorcinol(8)and Cordyol C(9)respectively.Because of a huge amount of interesting compounds from marine environment it is still an untapped drug treasure house which should be explored for future interesting drugs.