Enantiomeric Composition of the trans-Dihydrodiols Produced from Phenanthrene by Fungi.

The trans-dihydrodiols produced during the metabolism of phenanthrene by Cunninghamella elegans, Syncephalastrum racemosum, and Phanerochaete chrysosporium were purified by high-performance liquid chromatography (HPLC). The enantiomeric compositions and optical purities of the trans-dihydrodiols were determined to compare interspecific differences in the regio- and stereoselectivity of the fungal enzymes. Circular dichroism spectra of the trans-dihydrodiols were obtained, and the enantiomeric composition of each preparation was analyzed by HPLC with a chiral stationary-phase column. The phenanthrene trans-1,2-dihydrodiol produced by C. elegans was a mixture of the 1R,2R and 1S,2S enantiomers in variable proportions. The phenanthrene trans-3,4-dihydrodiol produced by P. chrysosporium was the optically pure 3R,4R enantiomer, but that produced by S. racemosum was a 68:32 mixture of the 3R,4R and 3S,4S enantiomers. The phenanthrene trans-9,10-dihydrodiol produced by P. chrysosporium was predominantly the 9S,10S enantiomer, but those produced by C. elegans and S. racemosum were predominantly the 9R,10R enantiomer. The results indicate that although different fungi may exhibit similar regioselectivity, there still may be differences in stereoselectivity that depend on the species and the cultural conditions.