A target for antifungal drugs
Since ergosterol is a key component in cell membranes of fungi, yet absent in those of animals. It has become a very useful target for antifungal drugs. Ergosterol is also present in the cell membranes of some protists, such as trypanosomes. This also becomes the basis for the use of some antifungals against West African sleeping sickness.
Antifungal drugs targeting ergosterol includes Amphotericin B[2, 3], fluconazole, miconazole, itraconazole, and clotrimazole. Amphotericin B acts by binding to sterols (ergosterol) in the cell membrane of susceptible fungi[2, 3]. This creates a transmembrane channel, and the resultant change in membrane permeability allowing leakage of intracellular components. Ergosterol, the principal sterol in the fungal cytoplasmic membrane, is the target site of action of amphotericin B and the azoles. Amphotericin B, a polyene, binds irreversibly to ergosterol, resulting in disruption of membrane integrity and ultimately cell death[2, 3]. Amphotericin B, though has been replaced by safer agents in most circumstances, is still used, despite its side effects, for life-threatening fungal or protozoan infections.
Fluconazole, miconazole, itraconazole, and clotrimazole work in a different way, take effect through inhibiting synthesis of ergosterol from lanosterol by interfering with14α-demethylase[4, 5]. Fluconazole interacts with 14-α demethylase, a cytochrome P-450 enzyme necessary to convert lanosterol to ergosterol. As ergosterol is an essential component of the fungal cell membrane, inhibition of its synthesis results in increased cellular permeability causing leakage of cellular contents. Fluconazole may also inhibit endogenous respiration, interact with membrane phospholipids, inhibit the transformation of yeasts to mycelial forms, inhibit purine uptake, and impair triglyceride and/or phospholipid biosynthesis.
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