3-Nitropropionic acid (3-NPA), a potent antimycobacterial agent from endophytic fungi: is 3-NPA in some plants produced by endophytes?

Antimicrobial activity in cultures of endophytic fungi isolated fromGarciniaspecies

The aim of the present study was to screen for antimicrobial activity in endophytic fungi isolated from surface sterilized leaves and branches of five Garcinia plants, G. atroviridis, G. dulcis, G. mangostana, G. nigrolineata and G. scortechinii, found in southern Thailand. Fermentation broths from 377 isolated fungi were tested for antimicrobial activity by the agar diffusion method. Minimum inhibitory concentrations (MICs) were obtained for crude ethyl acetate extracts. Seventy isolates (18.6%) displayed antimicrobial activity against at least one pathogenic microorganism, such as Staphylococcus aureus, a clinical isolate of methicillin-resistant S. aureus, Candida albicans and Cryptococcus neoformans. The results revealed that 6-10%, 1-2% and 18% of the crude ethyl acetate extracts inhibited both strains of S. aureus (MIC 32-512 microg mL(-1)), Ca. albicans and Cr. neoformans (MIC 64-200 microg mL(-1)), and Microsporum gypseum (MIC 2-64 microg mL(-1)), respectively. Isolates D15 and M76 displayed the strongest antibacterial activity against both strains of S. aureus. Isolates M76 and N24 displayed strong antifungal activity against M. gypseum. Fungal molecular identification based on internal transcribed spacer rRNA gene sequence analysis demonstrated that isolates D15 (DQ480353), M76 (DQ480360) and N24 (DQ480361) represented Phomopsis sp., Botryosphaeria sp. and an unidentified fungal endophyte, respectively. These results indicate that some endophytic fungi from Garcinia plants are a potential source of antimicrobial agents.

Cyclopentenones, scaffolds for organic syntheses produced by the endophytic fungus mitosporic dothideomycete sp. LRUB20

Two new natural products, 2-hydroxymethyl-3-methylcyclopent-2-enone (1) (synthetically known) and cis-2-hydroxymethyl-3-methylcyclopentanone (2), and a known compound, asterric acid (3), were isolated from the endophytic fungus mitosporic Dothideomycete sp. LRUB20, which was isolated from the stem of the Thai medicinal plant Leea rubra. Compound 2 was separated and identified in the form of its 2,4-dinitrophenylhydrazone derivative (5). Compounds 1, 3, and hydrazone 5 exhibited mild antimycobacterial activity, both with MIC values of 200 microg/mL. Compounds 1, 3, and 4 were inactive (at 50 microg/mL) toward Vero, KB, NCI-H187, and BC cell lines. Hydrazone 5 showed only mild cytotoxicity against the Vero cell line with an IC(50) value of 21.7 microg/mL; however, it was inactive toward KB, NCI-H187, and BC cell lines. Endophytic fungi may be a source for the production of building blocks for organic syntheses.