Polyene antimycotics, sometimes referred to as polyene antibiotics, are a class of
antimicrobial polyene compounds that target
fungi.
These polyene antimycotics are typically obtained from some species of ''
Streptomyces
''Streptomyces'' is the largest genus of Actinomycetota and the type genus of the family Streptomycetaceae. Over 500 species of ''Streptomyces'' bacteria have been described. As with the other Actinomycetota, streptomycetes are gram-positive, ...
'' bacteria. Previously, polyenes were thought to bind to
ergosterol
Ergosterol (ergosta-5,7,22-trien-3β-ol) is a sterol found in cell membranes of fungi and protozoa, serving many of the same functions that cholesterol serves in animal cells. Because many fungi and protozoa cannot survive without ergosterol, the ...
in the fungal cell membrane and thus weakening it and causing leakage of
K+ and
Na+ 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.
Amphotericin B,
nystatin, and
natamycin are examples of polyene antimycotics. They are a subgroup of
macrolides.
Structures
Their
chemical structures feature a large ring of atoms (in essence, a cyclic
ester ring) containing multiple conjugated carbon-carbon
double bonds (hence ''
polyene'') on one side of the ring and multiple
hydroxyl groups bonded to the other side of the ring. Their structures also often have a
D-
mycosamine
D-Mycosamine is an amino sugar found in several polyene antimycotics. Structural analogs of these agents lacking this monosaccharide component do not exhibit substantial antifungal
An antifungal medication, also known as an antimycotic medicat ...
(a type of amino-
glycoside) group bonded to the molecule. The series of conjugated double bonds typically absorbs strongly in the
ultraviolet-visible region of the
electromagnetic spectrum, often resulting in the polyene antibiotics having a yellow color.
Biosynthesis
The natural route to synthesis includes
polyketide synthase components.
Other examples of polyenes
*
Rimocidin
*
Filipin
*
Candicin
*
Hamycin
Hamycin is a pair polyene antimycotic organic compounds described in India. It is a heptaene antifungal compound rather similar in chemical structure to amphotericin B except that it has an additional aromatic group bonded to the molecule. When ...
*
Perimycin
Perimycin, also known as aminomycin and fungimycin, is polyene antibiotic produced by ''Streptomyces coelicolor'' var. aminophilus. The compound exhibits antifungal properties.
__TOC__ Composition
Perimycin is produced naturally as a mixture of t ...
*
Dermostatin
References
Antifungals
Macrolides
Polyenes
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