The Secondary Metabolites From Two Endophytic Fungi Of Papayaand Their Antibacterial Activity

Plant endophytes can produce secondary metabolites with rich structural types and have good biological activity,and can be used as a rich source of novel struc tural and highly active compounds.Papaya is a characteristic fruit tree widely planted in tropical and subtropical regions.It can not only be used as a fresh fruit,but also has certain medicinal value.So far,there are very few studies on the secondary metabolites of endophytic fungi in papaya.In this study,two endophytic fungi with rich structural types were selected from the papaya endophytic fungi using chemical screening methods.One was identified as P.rolfsii Y17 and the other was P.sumatraense Y20.In this experiment,the secondary metabolites of these two endophytic fungi were separated and identified,and their antibacterial biological activities were evaluated,which provided a theoretical basis for revealing the metabolic properties of papaya endophytic fungi and discovering antibacterial active molecules.Comprehensive use of semi-preparative high performance liquid chromatography,sephadex LH-20 column chromatography,reversed phase ODS column,thin layer chromatography and other separation techniques.The structure of the compound was determined by nuclear magnetic resonance spectroscopy,circular dichroism,mass spectrometry and other methods.N ine compounds were isolated from P.rolfsii Y17,namely 10-acetyl-phomanoxide(1),penirolide A(2),penirolide B(3),aurasperone A(4),pughiinin A(5),(S)-13-hydroxy-9Z,11E-octadecadienoic acid(6),cyclo(Leu-Ile)(7),cyclo(Phe-Leu)(8),β-adenosine(9)。N ine compounds were isolated from P.sumatraense Y20,namely curvularin(10),5-Methoxycurvularin(11),indole-3-acetic acid(12),1-hexadecanoyl propan-2,3-diol(13),Methyl Indole-3-acetate(14),uracil(15),(R)-mevalonolactone(16),(N)-demethylmelearoride A(17),melearoride A(18).Compounds 1,2 and 3 were new compounds.Using in vitro biological activity screening models,the 96-well plate micro method was used to test the compounds that may have antibacterial activity initially screened by this group.Among them,compounds 10 and 11 of papaya endophytic fungi P.rolfsii Y17 and P.sumatraense Y20 have certain inhibitory effects on Staphylococcus aureus and Escherichia coli.The minimum inhibitory concentration for Escherichia coli is 4 μg/m L,and the minimum inhibitory concentration for Staphylococcus aureus is 8 μg/m L.Compound 16 has an inhibitory effect on Bacillus subtilis,and the minimum inhibitory concentration is 16 μg/m L.Compound 15 Staphylococcus aureus has inhibitory effect.The minimum inhibitory concentration is 16 μg/m L.Among the compounds of Aspergillus sp.HNMF114,compound 19 has a certain inhibitory effect on the growth of Escherichia coli,and the minimum inhibitory concentration(MIC)is 2 μg/m L.Compounds 22 and 27 have certain inhibitory effects on Staphylococcus aureus,and the minimum inhibitory concentrations are 1 μg/m L and 4 μg/m L,respectively.Compound 23 has a certain inhibitory effect on Bacillus subtilis,and the minimum inhibitory co ncentration is 8 μg/m L.Compounds 22,23 and 26 have a certain inhibitory effect on Listeria,and the minimum inhibitory concentrations are 4,4,and 8 μg/m L,respectively.In this paper,the secondary metabolites and antibacterial activities of two papaya endophytic fungi have been investigated.It laid the foundation for the follow-up study of papaya pharmacological effects and effective ingredients.