Virginiamycin S1 is a cyclic hexadepsipeptide. Together with Virginiamycin M1 as a mixture, it works synergistically against Gram-positive bacteria with bateriostatic properties. Commercial preparations of Virginiamycin is 25% S1 and 75% M1. Virginiamycin S1 differs from Virginiamycin B in that it lacks the dimethylamino moiety of the phenyl ring.
Virginiamycin S1 is soluble in ethanol, methanol, DMSO, and DMF.