Synthesis and Biotransformation of Bicyclic Unsaturated Lactones with Three or Four Methyl Groups

Abstract

The aim of this study was to obtain new unsaturated lactones by chemical synthesis and their microbial transformations using fungal strains. Some of these strains were able to transform unsaturated lactones into different hydroxy or epoxy derivatives. Strains of Syncephalastrum racemosum and Absidia cylindrospora gave products with a hydroxy group introduced into a tertiary carbon, while the Penicillium vermiculatum strain hydroxylated primary carbons. The Syncephalastrum racemosum strain hydroxylated both substrates in an allylic position. Using the Absidia cylindrospora and Penicillium vermiculatum strains led to the obtained epoxylactones. The structures of all lactones were established on the basis of spectroscopic data.

Pleurotus ostreatus as a Biocatalyst to Obtain Bicyclic Hydroxylactones with Three or Four Methyl Groups

“…The purpose of this step was to check whether these strains were capable of conducting the transformation of selected lactones. An attempt was also made to answer the question of whether the products obtained as a result of the biotransformations carried out with the fungi of the Pleurotus ostreatus species would be identical or different to those obtained earlier with the use of filamentous fungi [31]. In the first version, biotransformations were carried out analogously to those carried on filamentous fungi, i.e., taking samples after 7 and 14 days.…”

“…Results of screening biotransformation of lactone 1 after 3, 5, and 7 days of incubation (in % according to GC). During previous studies [31], biotransformations of lactones 1 and 2 (also as mixtures of diastereoisomers A and B) were carried out using filamentous fungi of the genus Fusarium, Penicilium, Absidia, and Syncephalastrum. As a result, six hydroxylactones and two epoxylactones were obtained.…”

“…Epoxylactone 4 was obtained from substrate 1 using the Absidia cylindrospora AM336 strain. Hydroxylactone 5 was obtained from substrate 2 using Syncephalastrum racemosum AM105 and Absidia cylindrospora AM336 strains, while epoxylactone 6 was from the Penicilium vermiculatum AM30 strain [31]. It is worth noting that as a result of the biotransformations carried out using filamentous fungi, hydroxylactone 5 was obtained as a mixture of both isomers A and B.…”

“…However, by using fungi of the Pleurotus genus, the lactone 5 was obtained only from the A-isomer. Since the structure of the known biotransformation products have been described previously [31], here, a detailed analysis of the 1 H NMR spectra of the new compounds (3, 7, and 8) is presented.…”

“…During the biotransformation of unsaturated lactones that we have carried out so far, filamentous fungi have been used. As a result, both hydroxylactones and epoxylactones were obtained [28][29][30][31]. This time, we decided to use edible mushrooms as biocatalysts.…”