Efophylins A and B, Two C2-Asymmetric Macrodiolide Immunosuppressants from Streptomyces malaysiensis.

Genomics-inspired isolation led to the identification of two new natural congeneric C2-asymmetric macrodiolide immunosuppressants, named efophylins A (1) and B (2), from Streptomyces malaysiensis DSM 4137. Their structures were elucidated by spectroscopic and computational methods and were in agreement with biosynthetic predictions from the efophylin gene cluster. Compound 2 exhibited potent immunosuppressive activity and demonstrated to inhibit the activation of the NFAT and block NFAT dephosphorylation in vitro. The immunosuppressive activity of compound 2 is possibly at least in part via the CaN/NFAT signaling pathway.