ABSTRACT
Seventy-two strains of endophytic fungi were isolated from roots, stems and leaves of Pogostemon cablin and identified as 40 species of 25 genera based on ITS sequences analysis. Among them, Phomopsis, Colletotrichum and Fusarium were dominant genera. Distribution of endophytic fungi in P. cablin showed obvious tissue-specificity, and more strains were isolated from stems with an isolation rate of 78%. The bioassay results indicated that 34 strains of 15 genera displayed antimicrobial activities against at least one of test bacteria or plant pathogenic fungi. The results obtained in this study showed that endophytic fungi in P. cablin were rich in species diversity, and some strains exhibited strong antimicrobial activities, which deserve further research.
ABSTRACT
To study active secondary metabolites of endophytic fungus Diaporthe longicolla A616 isolated from Pogostemon cablin. Ten compounds were isolated from fermentation product of the strain 616 by silica gel, reverse phase silica gel, Sephadex-LH20, HPLC and so on. Their structures were identified as 1,3-diamino-1,3-dimethylurea(1),(7R,9R)-7-hydroxy-9-propyl-5-nonen-9-olide(2), Ergosta-5,7,22-trien-3β-ol(3),(22E,24R)-ergosta-4,6,8(14)-22-tetraen-3-one(4),(22E,24R)-3β,5α-dihydroxy-6β-ergosta-7,22-diene(5), citreoisocoumarin(6), glycerol monolinoleate(7), 1-(2-hydroxyethoxy)ethyl(E)-octadec-9-enoate(8), cyclo-(L-Pro-L-Ala)(9), cyclo(L)-Pro-(L)-Val(10), respectively, based on extensive spectroscopic analysis and literature comparisons. Compounds 6-10 were isolated from the genus Diaporthe for the first time. All isolated compounds were evaluated for in vitro cytotoxic activities against SF-268, MCF-7, NCI-H460 and HepG-2 tumor cell lines. Compounds 4 and 5 showed potent growth inhibitory activities against the four cell lines with IC₅₀ values of 5.3, 6.5, 12.2, 6.1μmol•L⁻¹ and 8.2, 5.2, 6.1, 9.4μmol•L⁻¹, respectively.