Microbial transformation of a macrolide immunosuppressant by the microorganism Streptomyces sp., (Merck Culture Collection MA 6960) ATCC No. 55387 yields a compound of the structural formula (I): ( * See Patent for Chemical Structure * ) I ( * See Patent for Tabular Presentation * ) This compound is an immunosuppressant useful in a mammalian host for the treatment of autoimmune diseases, infectious diseases, the prevention of rejection of foreign organ transplants and/or related afflictions, diseases and illnesses.