The Research On Secondary Metabolites And Activities From The Cocultures Of Four Endophytic Fungi From Dendrobium

To date,endophytes can produce a variety of metabolites with complex structures(especially under complex and extreme conditions),including alkaloids,terpenes,polyketides,lipids,glycosides,isoprenoids and derivatives of these metabolites.The metabolites show a variety of biological activities,including antibacterial,anticancer,antioxidant and other biological activities.This paper focused on the secondary metabolites from the cocultures of endophytic fungi from Dendrobium.The paper was mainly divided into four chapters:The first chapter was summarized for the research progress of the secondary metabolites from Nigrospora,Epicoccum,Irpex and Beauveria in the past two decades.The second chapter focused on the isolation and activity of secondary metabolites from the cocultures of Epicoccum sorghinum and Nigrospora oryzae.The first section mainly focused on the screening of target strains.36 fungi were screened for chemical diversities from the tissues of Dendrobium purpurea collected in Wenshan,Yunnan province.The strain ZPJ 20 was obtained because of abundant and various metabolites.The fungi ZPJ 20 and TPT 10-1 were co-cultured.The secondary metabolites from the cocultures of ZPJ 20 and TPZ 10-1 detected by TLC were abundant.According to the ITS sequence,ZPJ 20 was identified as Epicoccum sorghinum and TPZ 10-1 was identified as Nigrospora oryzae.The second section focused on the isolation and activities of secondary metabolites from the coculture of Epicoccum sorghinum and Nigrospora oryzae.Eight known compounds were isolated from the cocultures of Epicoccum sorghinum and Nigrospora oryzae: 2-Hydroxy-6-methyl benzoic acid(1),3,4-Dihydroxybenzaldehyde(2),2-Methyl-1,4-benzenediol(3),m-Hydroxybenzyl alcohol(4),3-Hydroxy-5-methybenzoic acid(5),2-(Methoxymethyl)benzene-1,4-diol(6),3-Hydroxybenzoic acid(7),2-(Hydroxymethyl)benzene-1,4-diol(8).The 8compounds were tested for antimicrobial activity.Compounds 1-6 showed antimicrobial activity against Nigrospora oryzae TPZ10-1,with MICs of 8-64?g/mL;Compounds 3,4,6,and 7 showed antimicrobial activity against Epicoccum sorghinum,with MICs of2-128?g/mL.All compounds showed weak inhibitory activity on mixed-culture A and mixed-culture B.Compounds 2,4,5,7,and 8 showed antimicrobial activity against Colletotrichum gloeosporioides,with MICs of 8-128?g/mL;All compounds didn't show any antibacterial activity against the Fusarium oxysporum.The third chapter focused on the secondary metabolites from the coculture of Beauveria bassiana TPZ 26,Irpex lacteus TPZ-30 and Nigrospora oryzae TPZ 10-1.TPZ 26,TPZ-30,TPZ 10-1 were isolated from Dendrobium candidum seeds in Wenshan,Yunnan province.According to the ITS sequence,TPZ 26 was identified as Beauveria bassiana,TPZ-30 was identified as Irpex lacteus,and TPZ 10-1 was identified as Nigrospora oryzae.21 compounds were isolated from the cocultures,including 5 new compounds: nigpexin A(1),nigpexin B(2),nigpexin C(3),nigpexin D(4),and nigpexin E(5),and a new natural product: 3,4-Dihydroxypentanoic acid(6),which was obtained from natural materials for the first time,and 15 known compounds:(±)-?-Hydroxy-?-methyl-?-valerolactone(7),1,3-Diacetyl-2-oleoylglycerol(8),5-Hydroxy-3,7-dimethoxy-4-(methoxymethyl)-6-methylisobenzofuran-1(3H)-one(9),3,4,8-Trihydroxy-3,4-dihydronaphthalen-1(2H)-one(10),4-Hydroxybenzoic acid(11),Tyrosol(12),2-(2-Hydroxyphenyl)acetic acid(13),3-Indolecarboxylic acid(14),((5S,8S,8aS)-2,2,8-Trimethyl-1,2,3,5,6,7,8,8a-octahydroazulene-4,5-diyl)dimethanol(15),11-Aldehyde-5,6-seco-1,6(13)-tremuladien-5,12-olide(16),Conocenolide A(17),Conocenolide B(18),?-Sitosterol(19),3,4-Dihydro-3,6,8-trihydroxynaphthalen-l(2H)-one(Scytalone)(20),4,6,8-Trihydroxy-3,4-dihydronaphthalene-l(2H)-one(21).Based on the biogenesis of compounds,tremulane sesquiterpenes were produced by Irpex lacteus.Antifungal activity experiments of all compounds were finished.Compounds 4-13,15-21 showed antifungal activity against Nigrospora oryzae TPZ 10-1 with MICs in the range of 2-128 ?g/mL;Compounds 1-5,8,10-15,17-21 showed antifungal activity against Irpex lacteus TPZ-30,with MICs at 2-64?g/mL.The compounds 1-9,11-21 showed antimicrobial activity against Beauveria bassiana TPZ 26 with MICs at1-256?g/mL.Compounds 2-7,10-11,14,17-20 showed inhibitory activity against the Colletotrichum gloeosporioides ZPY-43 with MICs of 16-128?g/mL;All compoundshave almost no inhibitory activity against Fusarium oxysporum.The acetylcholinesterase(AChE)inhibitory activity of compounds 4,5,and 15 was tested.All compounds had no inhibitory activity on AChE.