Studies On The Secondary Metabolites And Antibacterial Activities Of Five Soil-derived Actinomycetes

Objective:Five actinomycetes from rhizosphere soil of different plants were fermented,and secondary metabolites were extracted and purified from the culture.Their structures were identified and their antibacterial activities were preliminarily evaluated.Methods:Organic solvent extraction,silica gel column chromatography,gel column chromatography and high performance liquid chromatography were used for separation and purification.MS,IR,UV,NMR,X-ray single crystal diffraction and other spectroscopic methods were used to analyze the structure and antibacterial activity of monomer compounds.Results:Twenty nine compounds,including three new compounds,were isolated and identified from five actinomycetes strains.Seven compounds were isolated from ethyl acetate extract of fermentation broth of Streptomyces sp.3GCPA seperated from soybean rhizosphere soil and identified as resistomycin(1),tetracenomycin D(2),8-demethoxysteffimycin C(3),steffimycin(4),steffimycin D(5),tetrangomycin(6),ochromycinone(7).Three anthraquinones were isolated from the fermentation broth of Streptomyces sp.KIB-1955,it was found that the three compounds displayed significant inhibitory activity against Staphylococcus aureus,Escherichia coli and Bacillus subtilis.Compounds 8 and 10 also displayed weak inhibitory activity against Botrytis cinerea.From Streptomyces sp.KIB-DT18,five compounds were isolated and identified as 2-methylaminobenzoyl 6-deoxy-α-L-talopyranoside(11),naphthomycin E(12),methanethiol derivative of naphthomycin A(13),naphthoquinomycin B(14)and harziphilone(15);eleven known compounds were isolated from a rhizosphere soil-derived Streptomyces sp.KIB-1669,and namely lansai D(16),lancai C(17),albonoursin(18),(3Z,6E)-3-(4-hydroxybenzylidene)-1-methyl-6-(2-methylpropylidene)piperazine-2,5-dione(19),oxopropaline D(20),N-(2-hydroxyphenyl)-acetamide(21),carboximidamide(22),1,3-diphenethylurea(23),amethysamide(24),dimethyl-benadrostin(25)and 8-Hydroxyl-2,4-dioxoquinazoline(26).Three macrolides secondary products from a rizophere soil-derived Streptomyces sp.KIB-H1556 of Datura stramonium L.Their structures were identified as bafilomycin D(27),bafilomycin B1(28)and bafilomycin B2(29),and compounds 28 and 29 showed broad-spectrum inhibitory activity against plant pathogenic fungi.Conclusion:These compounds include polyketones,tetracyclines,anthraquinones,naphthoquinones,cyclic dipeptides and macrolides,et al.Compounds 8,9,10 were new compounds,The antifungal assays demonstrated that compounds 28 and 29 possessed broad-spectrum antifungal activity,especially for corn related pathogenic fungi.This information suggests that bafilomycins are potential biological control agent for corn pathogenic fungi diseases.