An investigation of the biotransformation of organic selenides by fungi

Chiral sulfoxidation by biotransformation of organic sulfides

“…In a more recent systematic investigation of selenide biotransformation by fungi, Holland and Carter first examined phenyl methyl selenide (57), using four different fungi of established sulfoxidizing capability. 47 Although control experiments established that phenyl methyl selenoxide was stable under the conditions used, no evidence was obtained for its formation from 57, the predominant route for the latter's metabolism being by demethylation. A further series of experiments designed to investigate the formation of decomposition products following selenoxidation of 58 and 59 also failed to provide any evidence for microbial selenoxide formation.…”

“…The rates of sulfoxidation of substrates 47 by the fungus M. isabellina have been determined by monitoring product formation and reported to proceed with a p value of -0.67.46 This value is lower than that reported for oxidation with potassium persulfate (p = -0.87), a process thought to involve formation of a sulfonium ion intermediate,111 and is not incompatible with the formation of a radical cation such as that of route A, Figure 5. The difference between this value and that reported for the isolated enzyme may reflect an additional degree of stabilization of the intermediate in the latter case45 or the choice of inappropriate kinetic parameters in the assay of the isolated enzyme system.…”

7.28 Oxidation of Sulfur, Selenium, and Tellurium

“…459 Biological oxidations of selenides to selenoxides with whole-cell systems proved to be unsuccessful. 460 Optical resolution of racemic seleninic acids and selelenamides via chiral HPLC analysis demonstrated that sterically demanding aromatic enantiomers, once separated, are less prone to racemization. 461 The oxidative approach to the synthesis of enantioenriched telluroxides has been poorly investigated, as they equilibrate with the hydrate form, thus suffering facile racemization (equation 22, Scheme 59).…”

Enzymatic reactions involving the heteroatoms from organic substrates

“…These observations can prove that the mechanism should undergo via a dealkylation process followed by selenium oxidation to give the final product, seleninic acid. Holland and Carter (1983) described the incubation of a series of phenyl selenides with Aspergillus niger, Aspergillus foetidus, Mortierella isabellina, and Helminthosporium sp. The selenoxide was not detected among the products after incubation with the selected fungi.…”