||Marine actinobacteria was considered as potential sources of bioactive compounds. Many natural products research pioneers found lots of bioactive secondary metabolites with novel skeletons from Streptomyces spp., some of which have been developed as new drugs. In our researches on marine microbial natural products, we found two marine-derived bacterial strains LQ-II and GT, which were isolated from the deep-sea sediments in the offshore of Siao-liou-ciou. Both strains showed apparently inhibitory effect against Candida albicans. By the 16S rRNA sequence analysis, the strains LQ-II and GT were identified as S. albogriseolus and S. gougerotii, respectively|
Literature surveys indicated that different organisms can produce more or less similar compounds. It will confuse scientists to make reduplicative works on the isolation of known compounds. To avoid the reduplicative isolation, we plan to develop a new research strategy by the modern analytic equipment, LC-MS/MS, and the state-of-art computation, molecular modeling, to target the isolation of new compounds. Till now, we isolated 12 compounds from the ethyl acetate extract of S. albogriseolus LQ-II, including six diketopiperazines (L1~L6), one valinomycin (L7), one homononactinic acid derivative (L8), one steroid (L9), one N-acetyl-β-oxotryptamine (L10), one terephthalate (L11), one nucleoside (L12) and 14 compounds from the ethyl acetate extract of S. gougerotii GT, including eight diketopiperazines (G1~G8) , one 9-fluorenone (G13), one β-oxo tryptamine derivative (G14), and four γ-butyrolactone (G9~G12). Among them, one γ-butyrolactone is new compound (G9). The bioactivities of these isolates are under investigation.