Polyene antimycotics, sometimes referred to aspolyene antibiotics, are a class ofantimicrobialpolyenecompounds that targetfungi.[1] These polyene antimycotics are typically obtained from certain species ofStreptomyces bacteria. Previously, polyenes were thought to bind toergosterol in the fungal cell membrane, weakening it and causing leakage ofK+ andNa+ ions, which could contribute to fungal cell death. However, more detailed studies of polyene molecular properties have challenged this model suggesting that polyenes instead bind and extract ergosterol directly from the cellular membrane thus disrupting the many cellular functions ergosterols perform.[2][3]Amphotericin B,nystatin, andnatamycin are examples of polyene antimycotics. They are a subgroup ofmacrolides.[4]
Theirchemical structures feature a large ring of atoms (in essence, a cyclicester ring) containing multiple conjugated carbon-carbondouble bonds (hencepolyene) on one side of the ring and multiplehydroxyl groups bonded to the other side of the ring. Their structures also often have aD-mycosamine (a type of amino-glycoside) group bonded to the molecule.[5] The series of conjugated double bonds typically absorbs strongly in theultraviolet-visible region of theelectromagnetic spectrum, often resulting in the polyene antibiotics having a yellow color.
Chemical structure ofAmphotericin B. Amphotericin B is an example of a yellow polyene antimycotic agent. Note the alternating double and single bonds in the center and the mycosamine group in the bottom-right corner.Chemical structure ofNystatin.Chemical structure ofNatamycin, sometimes called pimaricin.
