pyrenophorin and pyrenophorol

The extracts of five foliar fungal endophytes isolated from Pinus strobus (eastern white pine) that showed antifungal activity in disc diffusion assays were selected for further study. From these strains, the aliphatic polyketide compound 1 and three related sesquiterpenes 2-4 were isolated and characterized. Compound 2 is reported for the first time as a natural product and the E/Z conformational isomers 3 and 4 were hitherto unknown. Additionally, the three known macrolides; pyrenophorol (5), dihydropyrenophorin (6), and pyrenophorin (7) were isolated and identified. Their structures were elucidated by spectroscopic analyses including 2D NMR, HRMS and by comparison to literature data where available. The isolated compounds 1, 2, and 5 were antifungal against both the rust Microbotryum violaceum and Saccharomyces cerevisae.

Topics: Antifungal Agents; Ascomycota; Base Sequence; Basidiomycota; Endophytes; Heterocyclic Compounds; Ketones; Lactones; Macrolides; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Molecular Sequence Data; Pinus; Plant Leaves; Polyketides; Saccharomyces; Sequence Analysis, DNA; Sesquiterpenes

The acute toxicities of the fungal phytotoxins (8R,16R)-(-)-pyrenophorin and (5S,8R,13S,16R)-(-)-pyrenophorol on Vibrio fischeri, Oscillatoria perornata, Pseudokirchneriella subcapitata, Lemna minor and Artemia fransiscana were evaluated. (8R,16R)-(-)-pyrenophorin was more toxic than (5S,8R,13S,16R)-(-)-pyrenophorol to V. fischeri, O. perornata, L. minor and A. fransiscana. The highest acute toxicity of (8R,16R)-(-)-pyrenophorin was exhibited on V. fischeri (5 min median effective concentration of 3.57 M 10(-5)) whereas the corresponding value for (5S,8R,13S,16R)-(-)-pyrenophorol was 801 M 10(-5). P. subcapitata exhibited a lack of sensitivity (median inhibitory concentration of >10 M 10(-5)) to both phytotoxins.

Topics: Animals; Araceae; Artemia; Bacteria; Heterocyclic Compounds; Ketones; Lactones; Water Pollutants, Chemical