Studies On Bioactive Metabolites Produced By Three Symbionts

Insect endophytic microorganisms are a kind of important resources,which can produce various kinds of secondary metabolites with novel skeletons and biological activities.In the study,three symbionts including two fungi and one bacterium were isolated from Lytta vesicatoria and Munronia delavayi.The strains were classified by morphological characteristics and analysis of rDNA sequence.20 compounds were isolated using some chromatography techniques,including silica gel column chromatography column?CC?,reversed phase C₁₈ HPLC and sephadex LH-20 CC.The structures were elucidated by detailed spectral analysis of 1D-and 2D-NMR and ESI-MS experiments.In vitro cytotoxic activites of some compounds were evaluated using MTT method.The specific were detailed as follows.1.One endophytic fungus BM2 isolated from Lytta vesicatoria was determined as Fusarium oxysporum based on fungus's morphology and 18S rDNA sequence analyses.Six pure compounds were obtained from the ethyl acetate extract of BM2 fermentation and structureswereelucidatedasergosterol?1?,cyclo?phe-pro??2?,methyl?R?-2-hydroxy-3-phenyl-propionate?3?,4-oxopentanoicacid?4?,N-?4-oxopentyl?-acetamide?5?,and methyl?R?-2-hydroxy-3-?4'-hydroxyphenyl?propanoate?6?,respectively.In vitro cytotoxic activities of compounds 1-6 were evaluated using MTT method,and the results showed that compound 2 exhibited cytotoxic activity against HepG2and SMMC-7721 cell lines with IC₅₀ values of 44.1?g/mL and 47.6?g/mL.2.One endophytic bacteria BMX isolated from L.vesicatoria was determined as Bacillus cereus based on 16S rDNA sequence analyses.Five pure compounds were obtained from the ethyl acetate extract of BMX fermentation and structures were elucidated as2,4-Pyrimidinediol?7?,2,4-Dihydroxy-5-methylpyrimidine?8?,[1-??2R?-3,4-dihydroxy-5-?hydroxymethyl?-tetrahydrofuran-2-yl?pyrimidine-2,4?1H,3H?-dione]?9?,[3-?4-Hydroxy-phenyl?-propionicacid]?10?,and?4,7-Dihydroxy-3,9-dimethyl-oxonan-2-one??11?,respectively.3.One endophytic fungus ATT isolated from Munronia delavayi was determined as Fusarium oxysporum based on fungus's morphology and 18S rDNA sequence analyses.Nine pure compounds were obtained from the ethyl acetate extract of ATT fermentation and structures were elucidated as?4-amino-2-hydroxypyrimidine??12?,(1H-pyrazole-3-carboxylic acid methyl ester?13?,?4-hydroxy-7-?2-hydroxy-butyl?-3-methyl-oxepan-2-one??14?,?2-amino-3-methyl-pentanoicacid??15?,?2,5-diamino-pentanoicacid??16?,?2-amino-3-methyl-butyric acid??17?,4-hydroxy-benzoic acid?18?,dehydrofusaric acid?19?,and fusaric acid?20?,respectively.