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