Studies on novel HIF activators, A-503451s.I. Producing organism, fermentation, isolation and structural elucidation

In the course of our screening for activators of hypoxia-inducible factor (HIF), A-503451 A and virantmycin were isolated from the cultured broth of an actinomycete strain, Streptomyces sp. SANK 60101. From the same culture, the non-active homologs A-503451 B and D were also isolated. A-503451 A and virantmycin activated HIF-dependent reporter gene expression with EC₅₀ values of 8 and 17 ng ml^-1, respectively. They are highly potent activators of HIF and thus may be therapeutically useful for erythropoiesis and neural cell protection.