Elaiophylin is a highly characteristic metabolite produced by Streptomyces hygroscopicus. Elaiophylin inhibits testosterone 5-reductase. Elaiophylin is synergistic with its co-metabolite, rapamycin, as an antifungal. Elaiophylin also has anthelmintic and immunosuppressive activity and inhibits NO synthesis. Elaiophylin displays broad, albeit weak, biological activity against bacteria, nematodes, protozoa and mammalian tumor cells.