Pimaricin (also known as natamycin, INN) belongs to a naturally occurring antifungal agent produced through the fermentation of the bacterium Streptomyces natalensis. It is a kind of macrolide polyene antifungal used for the treatment of fungal keratitis, which is a kind of eye infection. In medical field, it can be used for the treatment of various kind of fungal infections caused by Candida, Aspergillus, Cephalosporium, Fusarium, and Penicillium. In food industry, it can be used as a natural preservative to prevent fungal outgrowth. Its mechanism of action is through binding to the ergosterol in the plasma membrane of fungi, inhibiting the process of ergosterol-dependent fusion of vacuoles and membrane fusion, further inhibiting the fungal growth. It also inhibit the transport of amino acid and glucose through inhibiting membrane transport proteins.