The Bioactive Metabolites Of D4115, An Endophytic Fungus Isolated From Rhoiptelea Chiliantha

Endophytes are microorganisms whose infection is generally inconspicuous, the host tissues infected are at least transiently symptomless, and the microbial colonization can be demonstrated to be internal, either through histological means, by isolation from strongly surface disinfected tissue, or, most recently, through direct amplification of fungal nuclear DNA from colonized plant tissue. The secondary metabolites of the endophytic fungi are extremely abundant, which demonstrated antitumor, antimicrobial and insecticidal bioactivities.The endophytic fungus D4115 was isolated from Rhoiptelea chiliantha, which exhibited stronger antifungal activities in previous study. In present paper, we reported the isolation, the antimicrobioal and antitumor assays of the bioactive metabolites from D4115. The results showed that the filtrates and the mycelia of D4115 exhibited antifungal activities against Phytophthora nicotianae and Fusarium solani. Further study indicated that the active metabolites exhisited in the the ethyl acetate extracts of the filtrates and the ethyl acetate extracts of the mycelia as well as the n-butanol extracts of the mycelia.Employing Thin-Layer Chromatorgaphy (TLC), Silica Column Chromatography, Dextran gel Column Chromatography,5 compounds were isolated from the secondary metabolites of D4115. Among them, the structures of 2 were established by MS and NMR analyses asβ-D-Glucopyranoside, methyl (LSS4) and 6,7,8,8a- tetrahydro -4aH-pyrano[3, 3-b]pyrazin-7,8-diol (LSS6) respectively. In which LSS6 was a new compound and LSS4 was a known compound. In addition,2 compounds were isolated from the products of biotransformation of Paris polyphylla by D4115. Whereas, the structures of the 2 compounds were still unidentified, further work was going on.In antimicrobial tests, compound LSS4 exhibited no activies against anyone of the tested microorganisms. However, compound LSS5 demonstrated remarkable antimicrobial activities against Fusarium solani, Phytophthora nicotianae, Escherichia coli and Staphylococcus aureus. The minimal inhibitory concentration of the S. aureus was 25μg/piece.According to the morphology of the fungal culture, the mechanism of spore production, the characteristics of spore as well as its r DNA ITS sequence analysis, D4115 was identified to be Colletotrichum gloeosporioides (Penz.) Penz.& Sacc.Our study indicated that Rhoiptelea chiliantha endophytic fungi D4115 was a potential fungus for novel metabolites.