Study On The Secondary Metabolites Of Two Antibacterial Fungi And Their Biological Activities

Screening drug lead compounds from natural products is still an important way for new drug development.Microbial metabolites,as important source of natural products,are characteristic in structure abundant and biological activity diversity.In addition,species is the magic key for microorganisms to become natural resource bank of medicinal chemical ingredients.Through Thin-Layer Chromatography(TLC),High Performance Liquid Chromatography(HPLC)and antibacterial activity screening,the target fungus HK-08 was isolated from the leaves of Nerium indicum,and identified as Colletotrichum sp.HK-08,while the strain Dq-25 was isolated from barnacle,and identified as Aspergillus sp.Dq-25.Their secondary metabolites were separated and purified by various column chromatography techniques after solid fermentation on rice.And their structures were identified according to a serial of spectra.Twenty compounds(1?20)were isolated and purified from Colletotrichum sp.HK-08,identified as: 2-(2-oxoindolin-3-yl)ethyl 2-(4-hydroxyphenyl)acetate(1),2-(2-oxoindolin-3-yl)ethyl 2-(2-hydroxyphenyl)acetate(2),2-(1H-indol-3-yl)ethyl 2-(4-hydroxyphenyl)acetate(3),phenethyl 2-phenylacetate(4),4-hydroxyphenethyl 2-phenylacetate(5),phenethyl 2-(4-hydroxyphenyl)acetate(6),4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate(7),4-hydroxyphenethyl 2-(2-hydroxyphenyl)acetate(8),2-(1Hindol-3-yl)ethyl 2-phenylacetate(9),1H-indole-3-carbaldehyde(10),tryptophol 2-(3-indolyl)ethanol(11),3-indole ethylacetate(12),3a-hydroxyindoline(13),butyl 2-(4-hydroxyphenyl)acetate(14),4-hydroxyphenethylacetate(15),2-hydroxyphenylethanol(16),p-hydroxyacetophenone(17),p-hydroxybenzoic acid(18),p-hydroxybenzaldehyde(19),methyl(9Z,12 Z,15Z)-octadeca-9,12,15-trienoate(20).Twelve compounds(21?32)were isolated and purified from Aspergillus sp.Dq-25,identified as: fortisterol(21),22 E,24R-3P,5a-dihydroxyerogosta-7,22-diene-6-one(22),(22E,24R)-ergosterol-7,22-diene-3?,5?,9?-triol-6-one(23),methyl 2-(4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)phenyl)acetate(24),3,4-dihydro-9,10-dihydroxy-7-methoxy-3-methyl-1H-naphtho[2,3c)pyran-1-one(25),(3R,4S)-(2)-4-hydroxymellein(26),(3R,4S)-3,4-dihydro-4,5,8-trihydroxy-3-methylisocoumarin(27),(R)-7-hydroxymellein(28),(R)-(-)-3-hydroxymellein(29),3-methyl-8-hydroxyisocoumarin(30),penicillic acid(31),dihydropenicillic acid(32).Among them,compounds 1,2 and 3 were new compounds,and compounds 6,8 and 13 were new natural products.The bioactivities of some compounds were evaluated.Compound 25 showed antimicroorganisms activities against Staphylococcus aureus and Fusarium oxysporum f.sp.cubense race1,FOC1.,and compound 31 showed antibacterial activity against S.aureus and Escherichia coli..Compound 9 showed a certain acetylcholinesterase inhibitory activity with an IC50 value of 69.30 ± 6.27 ?M.Compounds 6,7,12,and 31 showed cytotoxic activities with a varying degrees.Compounds 21,24,25,and 30 showed nematicidal activity against Panagrellus redivivus,and the lethal rate was between 9.97 ± 0.30% and 32.11 ± 0.21%.