Streptogramin derivatives, their preparation and compositions containing them

A pharmaceutical composition comprising (1) at least one group A streptogramin compound of formula (I) or a salt thereof, (2) at least one group B streptogramin compound, and optionally (3) at least one pharmaceutically acceptable diluent or adjuvant, wherein formula (I) has the following formula:

• in which
• R1 is chosen from a halogen atom, an azido group, and a thiocyanato group;
• R2 is chosen from a hydrogen atom, a methyl group, and an ethyl group;
• 3 is chosen from a hydrogen atom, an aliphatic ester, a cycloaliphatic ester, an aromatic ester, an araliphatic ester, a heterocyclic ester, and a heterocyclylaliphatic ester, wherein said esters may be substituted or unsubstituted;
• and
• the bond --- represents a single bond (stereochemistry 27R) or a double bond.