Secondary Metabolites From Villosiclava Virens,Rhizopycnis Vagum And Trichothecium Roseum Along With Their Biological Activities

Fungi are a group of eukaryotic organisms widely distributing in the world.These organisms exist in the air,soil,freshwater,ocean,and live as the endophytes and epiphytes of plants and animals,and even grow in the hot springs,high altitude and low temperature areas with various stress conditions.A variety of bioactive compounds were found in the fungi,which can be applied widely in the fields of agriculture,medicine and food industry.In this study,two fungi Villosiclava virens UV-8b and Trichothecium roseum Liaoning-Rfsb033 from the rice false smut balls,and an endophytic fungus Rhizopycnis vagum Nitaf22 from Nicotiana tabacum L.were investigated for their secondary metabolites and biological activities including antibacterial activity,phytotoxicity and cytotoxicity.The main results are as follows.(1)Fifteen metabolites were first obtained from V.virens UV-8b.Among them,two alkaloids(V1 and V2)were new compounds,two metabolites(V3 and V12)were new natural products.Three steroids(V7-V9)showed antibacterial activity,compounds V3,V7,V8 and V10 displayed inhibitory activity on the radicle elongation of the seeds of two rice varieties(Lijiang,and Zhonghua 11).(2)Sixty-nine metabolites,including thirty-seven new compounds and one new natural product(R58),were first isolated from R.vagum Nitaf22.These new metabolites belonged to different structural types such as dibenzo-?-pyrones(R1-R12),sesquiterpenoids(eremophilane-type R25-R37,R43-R45 and R48,and cadinane-type R50?R55),anisic acid derivatives(R56 and R57).Among them,seventeen compounds exhibited antimicrobial activity against six pathogenic bacteria,twelve compounds showed phytotoxicity,five compounds displayed cytotoxicity.For the test compounds,steroid R64 showed the strongest antibacterial activity with IC50 vaule in the range 1.17-12.97 ?g/mL,eremophilane-type sesquiterpenoid R33 and R48 showed the highest inhibitory rates on the radicle elongation of rice seeds with the values of more than 80%at concentration of 0.40mg/mL,and dibenzo-?-pyrone R20 showed the best cytotoxicity with IC50 values in the range 3.2?7.8?M.(3)Nineteen metabolites were obtained from T.roseum Liaoning-Rfsb033.Among them,T1 was a new trichothecene mycotoxin,and T1,T5,and T13-T19 were found in Trichothecium sp.for the first time.Ten compounds showed inhibitory activity on the radicle elongation of the rice seeds,among them,T11,T12 and T18 were equal to positive control(Glyphosate),T1 and T2 were better than the positive control.In this study,the chemical investigation on the three fungi led to the isolation of one hundred and one compounds including forty new ones and three new natural products.Some metabolites exhibited strong antibacterial,phytotoxic and cytotoxic activities.The results will enrich structural diversity of the metabolites from the fungi V.virens,R.vagum,and T.roseum,and will provide a basis for studies of the physiological and ecological functions as well as the exploitation and application of the metabolites.In addition,the results will provide lead compounds for the innovation of new agrochemicals and pharmaceuticals.