A new cyclodepsipeptide, designated roseocardin, was isolated from the culture broth of Trichothecium roseum TT103. Roseotoxin B and destruxins A and B were also isolated during the same procedure. The structure of roseocardin was determined by EI-MS, NMR and X-ray crystallographic analysis. Roseocardin as well as the other cyclodepsipeptides were shown to produce positive inotropic effects on rat heart muscles.