Functional diversity and pharmacological profiles of the FKBPs and their complexes with small natural ligands
- Andrzej Galat
- Cellular and Molecular Life Sciences
FR-900520 and FR-900523, novel neutral macrolide immunosuppressants, were isolated from the cultured broth of Streptomyces hygroscopicus subsp. yakushimaensis No. 7238. Their molecular formulae were determined as C43H69NO12 and C42H67NO12, respectively. The compounds suppressed immune response in vitro. IC50 values of FR-900520 and FR-900523 for mouse mixed lymphocyte reaction were 0.55 nM and 1.6 nM, respectively. FR-900520, the major component, clearly prolonged skin allograft survival in rats.