viridiol and viridin

Biotransformation of viridin, an antifungal produced by biocontrol agent, with non-viridin producing microorganisms is studied. The results show that some environmental non-targeted microorganisms are able to reduce it in the known phytotoxin viridiol, and its 3-epimer. Consequently, this reduction, which happens in some cases by detoxification mechanism, could be disastrous for the plant in a biocontrol of plant disease. However, a process fermentation/biotransformation could be an efficient approach for the preparation of this phytotoxin.

Topics: Androstenediols; Androstenes; Antifungal Agents; Bacteriocins; Biotransformation; Dose-Response Relationship, Drug; Fermentation; Hypocrea; Microbial Sensitivity Tests; Molecular Structure; Structure-Activity Relationship

Herein we describe concise enantioselective chemical syntheses of (-)-viridin and (-)-viridiol. Our convergent approach couples two achiral fragments of similar complexity and employs an enantioselective intramolecular Heck reaction to set the absolute stereochemical configuration of an all-carbon quaternary stereocenter. To complete the syntheses of these base- and nucleophile-sensitive natural products, we conduct carefully orchestrated site- and diastereoselective oxidations and other transformations. Our work is the first to generate these targets as single enantiomers.

Topics: Androstenediols; Androstenes; Bacteriocins; Molecular Structure; Stereoisomerism

The fungistatic compound viridin, produced by the fungus Gliocladium virens, was found to be irreversibly reduced to the phytotoxin viridiol in liquid culture. Conversion occurred only in the presence of viridin-producing fungi and was subsequent to viridin production. Radiolabelled viridin was rapidly taken up by the mycelium of G. virens and reduced to radiolabelled viridiol, while labelled viridiol was not taken up to any significant extent by the mycelium. Reduction of viridin to viridiol was independent of culture pH, carbon source, and nitrogen source or quantity. A simple production system consisting of peat moss amended with dextrose and calcium nitrate and inoculated with G. virens supported production of 86 micrograms viridiol/g peat. This production system, when applied to soil, may have value as a herbicide.

Topics: Androstenediols; Androstenes; Antifungal Agents; Bacteriocins; Carbon Radioisotopes; Methionine; Mitosporic Fungi