Nystatin conjugated double bonds

Pimaricin, also called natamycin, is a member of the family of polyene macrolides. These compounds consist of large macrolactone rings that have a characteristic series of conjugated double bonds, an exocyclic carboxyl group, and an unusual mycosamine sugar. In this chapter, we deal with pimaricin because this compound is the only one bearing an epoxy functionality. The other polyene macrolides such as nystatin, amphotericin, and candicidin will be treated in Sections 7.11.1 and 7.11.2. 

This polyene macroUde antibiotic is isolated from Strepto-tnyces nourseri and S. aMdus. Nystatin is considered too toxic for parenteral admirristration. It is composed of a number of tetraene compormds (compotmds that contain four conjugated double bonds), the principle component being nystatin Ai (Fig. 24.3) which has a very similar stmcture to amphotericin B. Its use is mainly reserved for the treatment of oral, perioral, intestinal, vulvovaginal or cutaneous Candida spp. infections. 

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