| abstract |
Described is a new immunosuppressant, L-687,819, a C-31 demethylated derivative of L-683,795 (FK-523), produced under fermentation conditions utilizing the new mutant microorganism, Streptomyces hygroscopicus subsp. ascomyceticus (Merck Culture Collection MA 6646) ATCC No. 53855, being a blocked mutant of Streptomyces hygroscopicus subsp. ascomyceticus (MA 6475) ATCC No. 14891. The macrolide immunosuppressant is useful in preventing human host rejection of foreign organ transplants, e.g. bone marrow and heart transplants. |