| Mangrove located in tropical and subtropical regions around the world is an unique intertidal ecosystem.It provides a large number of habitats for aquatic and terrestrial organisms.In the word,there are nearly 60-70%tropical and subtropical coastlines covered by mangroves,meanwhile the ecosystems of mangrove have a great value in ecology.The special habitat like periodic tidal,low latitudes,strong ultraviolet radiation,estuary coast of muddy soil,causes the changing of all kinds mangrove ecosystem factors,such as salinity,temperature,nutrient change constantly,which makes the ecosystem of microbial communities adapts to the special environment to create unique metabolic products.These metabolites are usually novel in structure and have significant biological activity.Therefore,it is an important source of new drug lead compounds,and it is of great significance for us to study the secondary metabolites of microorganisms from mangroves and to screen the lead compounds for new drugs.In this study,28 fungal strains were isolated from rhizosphere soil samples of mangroves in the South China Sea.Screening under the guidance of human pathogenic bacteria(MRSA)activity test and anti plant pathogenic fungi activity test,two strains including Penicillium janthinellum HK1-6 and Penicillium javanicum HK1-23 were choosed to study on antimicrobial secondary metabolites.Secondary metabolites were separated by using combining silica gel chromatography,gel chromatography and semi-preparative reversed phase liquid chromatography and identified by using MS,NMR,CD,UV and other modern spectroscopy techniques.As a result,eight compounds were found,including four new compounds,combined with two new derivatives.There are three types of compounds,including six azaphilones compounds,three butenolide compounds and a macrolide compound.In order to to activate the silent gene cluster of fungus P.janthinellum HK1-6 to produce new metabolites,we tried to add the amino acid to the culture medium or co-culture with other strians to regulate the metabolism of this fungus.The results indicate that the secondary metabolites of the fungus changedThe obtained compounds were evaluated their antibacterial or antifungal activity by using the MIC method,the filter paper method or the toxic medium method.The results showed that the azaphilones compound 2-4 had strong activities against two methicillin-resistant Staphylococcus aureus 43300 and S.aureus ATCC 33591 with the MIC values ranged from 3.13 to 5.25?g·mL-1(vancomycin,MIC=0.39-0.78?g·mL-1).Penicillic(7)displayed significant antibacterial activity against S.aureus ATCC 25923(the inhibition zone is 28 mm and 23 mm,respectively at the concentrations of 10 and 25?g·mL-1)and against S.aureus ATCC 43300(the inhibition zone is 15 mm and 11 mm,respectively at the concentrations of 10 and 25?g·mL-1).The inhibition zone of vancomycin was 10 mm at the concentrations of 2?g·mL-1.Penicillic acid(7)and brefldin A(10)showed significant antifungal activities against Rhizoctonia solani and R cerealis.The EC50 values of penicillic acid(7)and breflain A(10)against R.solani were 151.9 and 14.5 ?g·mL-1,respectively(carbendazim EC50=1.71?g·mL-1).The EC50 values of penicillic acid(7)and brefldin A(10)against R.cerealis were 44.83 and 24.06?g·mL-1,respectively(carbendazim EC50=2.05?g·mL-1).So it is improtant of researching these anti-microtnal compounds in further study.In this research,under the guidance of testing biological activity with human pathogenic bacteria and plant pathogenic fungi,the antimicrobial natural products from fungi in the South China Sea were traced and isolated.It is provide a basis for further study of human new antibacterial drugs and agricultural antibiotics. |
PDF Full Text Request