Stereoselective biocatalytic reduction of α-ionone by Glomerella cingulata

The biotransformation of (±)-α-ionone (1) by Glomerella cingulata was investigated. Compound 1 was transformed into two compounds (2,3). The ketone was reduced to α-ionol and the olefin was reduced to dihydrio-α-ionol, respectively. (−)-(6S,9R)- and (+)-(6R,9S)-α-ionol proceeded the corresponding allylic alcohols in high enantiomeric excess >99%; (−)-(S)-α-ionone is preferentially metabolized by hydroxylation in the ketone at C-9. Especially on the metabolic pathway, olefine reduction was via after ketone reduction.