Which antifungal binds to ergosterol?

Amphotericin B is the antifungal that binds to ergosterol, a key component of fungal cell membranes. This binding disrupts the integrity of the cell membrane, leading to increased permeability and ultimately causing cell death. Amphotericin B creates pores in the membrane, allowing for the leakage of essential intracellular components, which is particularly effective against a wide range of fungi.

Fluconazole and itraconazole are both azole antifungals that inhibit the synthesis of ergosterol rather than binding to it. They interfere with an enzyme involved in ergosterol biosynthesis, preventing the formation of functional cell membranes. This mechanism is different from that of Amphotericin B, as they do not directly interact with ergosterol itself.

Caspofungin belongs to the echinocandin class of antifungals and works by inhibiting the synthesis of glucan in the fungal cell wall, which is a completely different target compared to ergosterol in the cell membrane.

Therefore, the mechanism of action of Amphotericin B specifically involving the binding to ergosterol distinguishes it from the other antifungals listed.