LIke other polyene antibiotics, Natamycin inhibits fungal growth by binding to sterols. Specifically, Natamycin binds to ergosterol in the plasma membrane, preventing ergosterol-dependent fusion of vacuoles, as well as membrane fusion and fission. This differs from the mechanism of most other polyene antibiotics, which tend to work by altering fungal membrane permeability instead.
Natamycin is an antifungal drug for topical ophthalmic administration. It is a tetraene polyene antibiotic derived from Streptomyces natalensis. It possesses in vitro activity against a variety of yeast and filamentous fungi, including Candida, Aspergillus, Cephalosporium, Fusarium and Penicillium. Although the activity against fungi is dose-related, natamycin is predominantly fungicidal. Natamycin is not effective in vitro against gram-positive or gram-negative bacteria. Topical administration appears to produce effective concentrations of natamycin within the corneal stroma but not in intraocular fluid.