Microbial transformations of natural antitumor agents. 3. Conversion of thalicarpine to (+)-hernandalinol by Streptomyces punipalus.

Microbial transformation studies were conducted with the antitumor alkaloid thalicarpine. Streptomyces punipalus (NRRL 3529) converted thalicarpine to (+)-hernandalinol, the structure of which was determined spectroscopically and by synthesis from the known alkaloid hernandaline. This unusual biotransformation reaction most likely occurs by oxidative cleavage of the isoquinoline ring from thalicarpine through the intermediate hernandaline, which then undergoes further reduction to hernandalinol.