Quinupristin is a streptogramin antibiotic that blocks peptide bond formation and peptide extension in bacteria. Quinupristin is usually combined with another streptogramin antibiotic, dalfopristin , to produce quinupristin-dalfopristin complex , known commercially as Synercid. While both quinupristin and dalfopristin have bacteriostatic effects, they act synergistically to kill Gram-positive bacteria, as well as some Gram-negative and anaerobic bacteria.
Quinupristin is a semi-synthetic analogue of virginiamycin B (ostreogrycin B, pristinamycin IA, streptogramin B) formed by a Mannich condensation and elimination to generate an exocyclic methylene alpha to the ketone of the 4-piperidinone. Addition of quinucidinylthiol to the methylene group affords quinupristin. The structural changes provide a more hydrophobic compound with a readily ionisable group for generating a salt. Quinupristin is used commercially in synergistic combination with dalfopristin (30:70). There is little published data on the synthesis, biological or antibiotic activity of quinupristin alone, however the combination product is highly effective, including activity against antibiotic resistant strains.
