Penicillium citrinum, methyl

Lovastatin and mevastatin are new-generation drugs that were introduced into medicine for treating hyperlipocholesterolemia, and they are unique compounds. Lovastatin is isolated from Aspergillus terreus mushrooms. Mevastatin is a chemically analogous compound that differs only in the absence of a methyl group at C3 of the naphthaline system, and it is isolated from Penicillium citrinum mushrooms. 

Capillary gas chromatographic determination of optical purities, investigation of the conversion of potential precursors, and characterization of enzymes catalyzing these reactions were applied to study the biogenesis of chiral volatiles in plants and microorganisms. Major pineapple constituents are present as mixtures of enantiomers. Reductions, chain elongation, and hydration were shown to be involved in the biosynthesis of hydroxy acid esters and lactones. Reduction of methyl ketones and subsequent enantioselective metabolization by Penicillium citrinum were studied as model reactions to rationalize ratios of enantiomers of secondary alcohols in natural systems. The formation of optically pure enantiomers of aliphatic secondary alcohols and hydroxy acid esters using oxidoreductases from baker s yeast was demonstrated. 

Figure 4. Enantiomeric compositions of secondary alcohols isolated from corn (x= Golden Jubilee, A= Golden Bantam, Bonanza) and coconut ( ) and obtained after reduction of methyl ketones in a shake culture of Penicillium citrinum after 68 h (O).

Table III Quantitative distribution and enantiomeric compositions of secondary alcohols obtained by reduction of methyl ketones with Penicillium citrinum...

Asako, H., Wakita, R., Matsumura, K., Shimizu, M., Sakai, J., and Itoh, N. (2005) Purification and cDNA cloning of NADPH-dependent aldoketoreductase, involved in asymmetric reduction of methyl 4-bromo-3-oxobutyrate, from Penicillium citrinum IF04631. Appl. Environ. Microbiol., 71, 1101-1104. 

The biosynthesis of citrinin (XXXIX) was independently investigated with radioactive tracers by Birch et al. (1958c) utilizing Aspergillus candidus] and by ScHWENK and collaborators (1958) with labelled acetate and methionine-methyl-in Penicillium citrinum cultures. It was unequivocally demonstrated that this compound arises by cyclization of a poly j8-ketide made of 5 acetyl units, and that its two extra methyls and the carboxyl function arise from the Ci-pool (Fig. 16). It has subsequently been suggested (Hassall and Jones, 1962) that (XL) and 3>4-dihydro-6,8-dihydroxy-3,4,5"trimethylisocoumarin-carboxylic acid (XLI) are precursors to citrinin. This postulation followed the finings cf. Hassall, 1965) that one mutant strain of A, terreus produced only (XLI),... 

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