Macrolide derivatives having enhancing effect for activities of azole antifungal agents, acting at low concentration and within a short time against fungal infection and reducing the frequency of appearance of resistant microorganisms. One such substance is a compound represented by the formula [I]:
wherein R1 is Ac, R2 and R3 are Ac, and R4 is Me; when R1 is H, R2 and R3 are Ac, and R4 is Me; when R1 is H, R2 and R3 are Ac, and R4 is H, when R1 Bzl, R2 and R3 are Bzl, and R4 is Me; when R1 is Ac, R2 and R3 are Pr, and R4 is Me; when R1 is Ac, R2 and R3 are Hex, and R4 is Me; when R1 is Ac, R2 and R3 are Bzl, and R4 is Me; when R1 is H, R2 and R3 are Pr, and R4 is Me; when R1 is H, R2 and R3 are Hex, and R4 is Me; when R1 is H, R2 and R3 are Bzl, and R4 is Me; when R1 is H, R2 is H, R3 is Bzl, and R4 is Me; when R1 is H, R2 and R3 are Hex, and R4 is H, or when R1 is H, R2 and R3 are Hex, and R4 is Et.