Question

What is the mechanism of action of the three main antifungal drugs in use polyenes, azoles, and allylamines?

Answer 1

Polyenes-They are fungicidal. Their mode of action is disruption of the fungal cell membrane by binding to ergosterol, the main sterol in the membrane. This results in pore formation and leakage of cellular cations and anions leading to fungal cell death.

Azoles- The mode of action of azole is the inhibition of 14alpha lanosterol demethylase a key enzyme in ergosterol biosynthesis resulting in depletion of ergosterol and accumulation of toxic 14 alpha methylated sterol in membrane of susceptible yeast species.

Allylamines - They inhibit squalene epoxidase which converts squalene to ergosterol. Inhibition of this enzyme causes squalene, a substance toxic to fungal cells to accumulate intercellulary and leads to rapid cell death.