Study On The Secondary Metabolites From Actinomycetes YG-7 From Soil Collected From Yingge Ridge And Their Biological Activities

Actinomycetes,belonging to the special bacteria,which are widely distributed in the world,is considered as "biosynthetic machinery",because of their ability to produce plenty of new secondary metabolites with unique activity.Actinomycetes have presented their market values,and dominate in the field of agriculture,pharmaceuticals,and industry,closing related to human life,such as antibiotics produced by actinomycetes have been widely used.However,drug resistant have become important issue in the clinic recently,and the problem increase day by day,due to the abuse of antibiotics.Therefore,it is still significant to continue to search for new secondary metabolites from actinomycetes with novel structures and unique activities.The strains in this study were obtained from the soil of Yinggeling in Ledong County,Hainan Province.The actinomycete YG-7 was selected as the target strain by chemical and biological screening and identified as Streptomyces sp YG-7 by morphological characteristics,16S rDNA sequence determination and phylogenetic analysis.The fermentation conditions of actinomycete YG-7 was optimized through analysis of HPLC chromatogram of the secondary metabolites,as well as their biological activities,when cultivated in different culture media and different culture time periods.The stability of the crude extract was analyzed.The results showed that the anti-MRSA(methicillin-resistant Staphylococcus aureus,MRS A)active substance of actinomycete YG-7 was not high in heat resistance and stable at 20?40?,and the biological activity was decrease when the temperature over 40?;the active substance was unstable under strong acid and alkaline conditions;and it had good stability under ultraviolet light irradiation.The secondary metabolites of actinomycete YG-7 were isolated and purified by various column chromatography techniques,and the structure of the compounds was identified by spectral data analysis combined with physicochemical constants.Twenty-six compounds were isolated from the secondary metabolites of actinomycete YG-7.Their structures were determined as:(1R,5R,E)-3-(2-(2,6-dioxopiperidin-4-yl)ethylidene)-1,5-dimethyl-4-oxocyclohexyl acetate(1),(1S,5R,E)-3-(2-(2,6-dioxopiperidin-4-yi)ethylidene)-1,5-dimethyl-4-oxocyclohexyl acetate(2),4-((E)-2-((3R,5R)-3,5-dimethyl-2-oxocyclohexylidene)ethyl)piperidine-2,6-dione(3),4-((E)-2-((3R,5S)-3,5-dimethyl-2-oxocyclohexylidene)ethyl)piperidine-2,6-dione(4),iso-cycloheximide(5),cycloheximide(6),4-(2-(2-hydroxy-3,5-dimethylphenyl)-2-oxoethyl)piperidine-2.6-dione(7),3-[2-[2-hydroxy-3-(hydroxymethyl)-5-methylphenyl]-2-oxoethyl]glutarimide(8),acetoxycycloheximide(9),2-acetamido-5-chlorobenzamide(10),cyclo(L-Pro-L-Leu)(11),3,6-dibenzylidene-2,5-piperazinedione(12),albonoursin(13),(3Z,6S)-3-benzylidene-6-isobutylpiperazine-2,5-dione(14),(3S,6Z)-3-benzyl-6-benzylidene-2,5-dioxopiperazine(15),3-hydroxy-2-methyl-4-pyrone(Aldrich)(16),isophthalic acid(17),methyl 3-carbamoylbenzoate(18),2,3-dihydroxypropyl hexadecanoate(19),N-Phenylacetamide(20),4-methoxy-6-methyltetrahydro-2H-pyran-2,5-diol(21),Methyl-a-D-olivoside(22),4-hydroxy-3-methoxybenzoic acid(23),p-hydroxybenzoic acid(24),m-hydroxybenzoic acid(25),isophthalic acid(26).Among them,9 amide compounds(1?9),5 piperazines(11?15),2 glycoside compounds(21?22),4 benzoic acid compounds(23?26),1 Chlorinated compound(10),1 ester compound(19).compounds 1 and 2 are new compounds,and compounds 10,17 and 18 are new natural products.The antibacterial and a-glucosidase inhibitory activities of the compounds were tested by the filter paper diffusion method and the pNPG method.respectively.The results showed that compounds 10,12?15,17?18 presented a-glucosidase activity,and the inhibition rate ranges from 12.67%to 39.50%;Compounds 1?7 expressed fungi growth inhibitory activity against Candida albicans,Saccharomyces,Fusarium oxysporum f.sp.cubense racel,FOC1.Colletotrichum musae,Mango pestalotiopsis and Pyricularia oryzae,and the antibacterial effect range is 7.24?11.25 mm:Compounds 10?26 have bacteria growth inhibitory activity against Escherichia coli and Staphylococcus aureus,methicillin-resistant Staphylococcus aureus,and the antibacterial effect range is 7.11?10.51mm.