Studies On The Secondary Metobolites From Aspergillus Sp.SCSIOW20 And Myceliophthora Thermophila

To date, only 5 % of the total numbers of fungal species have been described in nature. In marine and some other extreme environments, the difficulty of sampling even hindered the exploitation of these microbial resources. Microorganisms from extreme living conditions often have unique metabolic pathways which are different from ordinary terrestrial microbes, sometimes leading to the production of novel secondary metabolites with unique bioactivities, provides new opportunities for natural products and drug development research.Based on our group’s early study on 20 fungal strains from deep marine sediment, collected from South China Sea, W-20, which showed a certain anti-Aβ peptide aggregation activity, was chosen for further study. W-20 was then identified as Aspergillus sp. based on ITS r DNA sequencing analysis. 6 compounds were isolated from the fermentation broth of Aspergillus sp. SCSIOW20, by using normal and reverse phase silica gel, Sephadex LH-20, and HPLC. The structures were identified by spectroscopic analysis as diorcinol(1), sydowic acid(2), monodictyphenone(3), ergosterol(4), syodonic acid(5) and C15/C15’-epi-WIN 64821(6). It is the first report for isolation of compound 6 from nature. All compounds were tested for anti-A 6 exhibited comparable activity(relative inhibitory rate: 42.9 士 5.9 %) with positive control, EGCG. This is the first report for diketopiperazines type compounds showing anti-Aβ peptide aggregation activity. To increase the diversity of secondary metabolites, suberic bishydroxamate(SBHA), one of the histone deacetylase inhibitors, was used to induce W-20 secondary metabolites production. As a result, another metabolite: sydonol(7) was obtained.The biodiversity study using thermophilic fungi stimulated with chemical modifiers has also been carried out. Myceliophthora thermophila(ATCC 42464) was cultivated by adding 5-azacytidine(5-AC), significant differences in the chemical profiles, both n-butyl alcohol extracts of fermentation broth and the acetone extracts of mycelium, were found compared with ordinary fermentation, and different concentrations of inducers resulted in different effects.