The present invention relates to levocarrimycin, its pharmaceuticalcompositions,preparation methods and pplication. Levocarrimycin is a mixture ofisovalerylspiramycinIII, II and I as main components and contains some isobutyrylspiramycin IIIand II,butyrylspiramycin III and II, propionylspiramycin III and II, as well asacetylspiramycinIII and II, among which, the content of isovalerylspiramycin III is no lessthan 30 wt%, thetotal content of isovalerylspiramycin III, II and I is no less than 60 wt%,and the content ofacylspiramycin is 80-98 wt%. Specific optical rotation of said levocarrimycinis [.alpha.]D =-52° - -57° in the solution of 0.02g/ml chloroform attemperature of 25°C. The presentinvention also relates to the crystalline compound of isovalerylspiramycinIII, II or I inlevocarrimycin, and pharmaceutical compositions containing the saidlevocarrimycin. Inpresent invention, the active components in levocarrimycin or itspharmaceuticalcompositions have optical activity and excellent anti-infective effect.
