Thiocillin I is a thiopeptide antibiotic and has in vitro antibacterial activity against Gram-positive bacterial strains(MIC of Thiocillin I against S. aureus 1974149, E. faecalis 1674621, B. subtilis ATCC 6633 and S. pyogenes 1744264 are 2 μg mL, 0.5 μg mL, 4 μg mL and 0.5 μg mL, respectively).