The Active Metabolites From The Co-culture Of Beauveria Bassiana And Nigrospora Oryzae In Dendrobium Candidum

In recent years,the research about secondary metabolites from single strain in natural has become increasingly mature.How to induce strain to generate new secondary metabolites by other means is the focus of current research.Based on the theory of co-culture,the two different strains from the same plant were co-culturedto find active secondary metabolites induced by the co-cultured fungus.The paper is divided into four chapters:The first chapter summarizes the azaphilones derived from different endophytic fungus and their biological activities for nearly two decades.In the second chapter,17 strains of fungus isolated from Dendrobium candidum were screened for chemical diversity.The single fungi with great chemical diversity was selected to mix with each other,in order to obtain rich metabolic types.Therefore,the two target strains of TPZ 26 and TPZ 10-1 were obtained by TLC screening.By measuring the ITS sequences of the two strains,it was determined that TPZ 26 is Beauveria bassiana and TPZ 10-1 is Nigrospora oryzae.In the third chapter,the compounds from co-cultured Nigrospora oryzae with Beauveria bassiana were studied.Six compounds were isolated from the co-cultured fungus,including five new compounds:nigbeauvin A(1),nigbeauvin B(2),nigbeauvin C(3),nigbeauvin D(4)and nigbeauvin E(5);and one known compound scytalone(6).Compound 2 had an unprecedented skeletonof azaphilones with a bicyclic oxygen bridge.Some of new compounds were tested for antibacterial,NO production inhibition,acetylcholinesterase inhibitory activity,cytotoxic activity,porcine pancreatic lipase inhibitory activity and tyrosinase inhibitory activity.In the antibacterial activity experiment,the metabolites produced by the co-cultured fungi showed a competitive interaction with Beauveria bassiana and Nigrospora oiyzae.Compound 1 showed weak antibacterial activity against Beauveria bassiana with MIC value 128?g/mL,and against Nigrospora oryzae with MIC value 512?g/mL.Compound 1 did not show antibacterial activity against common pathogens Bacillus subtilis and Candida albicans.Iin the NO production inhibition experiment,compounds 1 and 2 with 50?M showed significant nitric oxide(NO)inhibitory activity with ratios of 37%and 39%.Compounds 1 and 2 did not show activities in acetylcholinesterase AchE inhibitory activity,cytotoxic activity,PPL inhibitory activity and tyrosinase inhibitory activity.In the fourth chapter,themetabolites from co-cultured Nigro.spora oryzae with Beauveria bassiana in solid rice were studied.The two strains were co-cultLured with yam,taro,sweet potato,potato and rice respectively.It was found that the metabolitesfrom the culture medium of the yam,taro,sweet potato and potato was the same.The metabolitesfrom rice solid medium was different.And the different fermentation time conditions for the solid rice co-cultured was studied.The Beauveria bassiana was cultured for three days in potato and then the Nigrospora oryzae was added.They were co-cultured for seven days.Then the fermentation was expandedin the solid rice for 30 days.Five known compounds were isolated and identified from thefermentation:3,3'-methylenebis(4-hydroxy-6-methyl-2H-pyran-2-one)(1),sclerin(2),4,8-dihydroxy-1-tetralone(isosclerone)(3),murranoic acid A(4)and 5,8,12-trihydroxy-9-octadecenoic acid(5).Antibacterial activity experiments were carried out.Compounds 1 and 2 showed antibacterial activity against Beauveria bas.siana with MIC value 32 p,g/m L and 64 ?g/mL.Compound 4 showed antibacterial activity againstBeauveria bassiana with MIC value 128 ?g/mL;compound 5 showed strong inhibitory activity against Beauveria bassiana with MIC of 2 ?g/mL.