Research On Anti-staphylococcus Aureus Compounds Of Mangrove Rhizosphere Fungi In Sanya

Mangrove forest,which are located in tropical or subtropical intertidal zones.Biodiversity,high production capacity and species genes are all the characteristics of it.Because of rich soluble nutrients,the classes of microorganisms,metabolic pathways and natural products from it are different from those of common environment.44 fungal strains were isolated from 7 mud samples collected from Sanya mangrove forest.All the strains were subjected to small-scale fermentation.Then,the crude extracts were tested for their bioactiviry against Candida albicans and a panel of bacteria,like Staphylococcus aureus and Escherichia coli.Crude extracts of 29 strains displayed antibacterial activity against Staphylococcus aureus.Crude extracts of 7 strains exhibited antifungal activity against Candida albicans and crude extracts of 3 strains showed antibacterial activity against Escherichia coli.There were 7 strains showed activity against both Staphylococcus aureus and Candida albicans,2 strains showed activity against both Staphylococcus aureus and Escherichia coli,and 1 strain exhabited activity against Staphylococcus aureus,Candida albicans and Escherichia coli at the same time.Combining the activity results and the chemical diversity results of high performance liquid chromatography analysis,it was determined that MF190004,MF190008,and MF190035were selected as potential strains to carry out further large-scale fermentation and chemical investigations.The fungi were identified based on the DNA sequences of ITS DNA genes.Strain MF190008was identified as Penicillium chrysogenum.Strain MF190004 was identified as Aspergillus luchuensis.MF190035 was identified as Aspergillus costaricensis.These fungi were fermented in rice solid media,then the mycelia and culture media were extracted by the mixed solvent of ethyl acetate and methanol.The crude extracts ware fractionated into some fractions on reduced-pressure normal phase silica gel column chromatography,then these fractions were subjected to Sephadex LH-20 chromatography column and HPLC chromatography to yield compounds.¹H NMR,¹³C NMR,COSY,HMBC,HSQC,ROESY,mass spectrometry(MS),ultraviolet spectroscopy(UV)and specific rotation(OR)were used to characterized the structures of the compounds.11 compounds were identified,namely,3-hydroxy-2,2-dimethylchromane-6-carbaldehyde(1),(+)-asperteretone B(2),terretonin A(3),terretonin(4),4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde(5),asperlide B(6),aspernolide A(7),methyl-2-benzyl-4-hydroxyphenyl-2-(4-hydroxyphenylmethyl)-5-oxo-2H-furan-2-carboxylate(8),butyrolactone I(9),versicolactone B(10),1H-indole-3-carboxaldehyde(11).Compounds 1,2 are identified as new structural compounds.According to the bioactivity test,compounds 2,5,7,8,9,10 showed antibacterial activity against Staphylococcus aureus with the minimum inhibitory concentration(MIC)values of 12.5?g/m L,100?g/m L,100?g/m L,200?g/m L,50?g/m L,25?g/m L,respectively.Compound 5 showed antifungal activity against Candida albicans with MIC value of 100?g/m L.