Isolation And Identification Of Secondary Metabolites Produced By Streptomyces Ahygroscopicus Var.Gongzhulingensis

The fermentation product of Streptomyces ahygroscopicus var.gongzhulingensis has been confirmed during field application to be an ecofriendly natural biological pesticide mainly used for control of crop fungal diseases.Recently,the extract of the fermentation product was proved possessing an potent inhibitory effect against the infection and multiplication of Tobacco mosaic virus(TMV)in its host tobacco plant,which indicated a potential and promising prospect of S.ahygroscopicus var.gongzhulingensis fermentation product applied for control of plant virus diseases.An antiviral bioassay-guiding isolation of the secondary metabolites from the fermentation product of S.ahygroscopicus var.gongzhulingensis was conducted.It was determined that both of the dichloromethane and ethyl acetate extracts exhibited potent anti-TMV activity at a concentration 200 ?g/m L with an inhibitory rate of 87.2% and 93.4%,respectively.A total of 11 compounds were isolated and identified based on the analysis of their NMR spectrum from the extracts,including norcardamine(1),3-[2-(3,5-dimethyl-2-hydroxyl-1-cyclohexenyl)-2-oxo-ethyl]glutarimide(2),actiphenol(3),3-[2-(3-methyl-5-hydroxymethyl-2-oxo-cyclohexyl)-2-hydroxyl-ethyl]glutarimide(4),3,4-dimethyl-2-(1-aminoethyl)-pentano-4-lactone(5),3,4-dimethyl-2-(1-aminoethyl)-pentano-4-lactone(6),(±)-(3S,4R,5R)-3,5-dihydroxyhexano-4-lactone(7),benzeneacetic acid(8),2-methoxy-benzeneacetic acid(9),9,12,13-trihydroxyoctadec-10(E)-enoic acid(10),and 8,9,10-trihydroxyoctadeca-6(Z)-enoic acid(11).The above compounds include one siderophore(1),three glutarimide antibiotics(2,3,and 4),three compounds containing five-membered lactone rings(5,6,and 7),two phenols(8 and 9)and two unsaturated longchain fatty acids(10,11).Among them,5 and 6 are two isomers,10 and 11 are two isomers,and 4,5 and 6 are new compounds discovered.The results show that the chemical structure of the secondary metabolites of S.ahygroscopicus var.gongzhulingensis has certain uniqueness and diversity,which lays a preliminary research foundation for further research on the anti-TMV activity and its antiviral mechanism of secondary metabolites of the strain.