Cyclo(Tyr-Pro) shows antibacterial activity towards several marine bacterial species, it also shows weak antagonistic activity against VEGFR2 -CD. Cyclo(Tyr-Pro) and cyclo(Pro-Val) are toxic to both suspension cells and seedlings of Pinus thunbergii, whic

Various studies have shown the potentially beneficial biological activities of cyclic dipeptides and in particular, cyclo(L-tyrosyl-L-prolyl) (Cyclo(Tyr-Pro)) has shown fair antibacterial activity in vitro. This study aimed to determine if liposome encapsulation would have any significant effects on the antibacterial activity of this compound. METHODS AND RESULTS:The thin-film hydration method with extrusion was used to produce small unilamellar vesicles containing Cyclo(Tyr-Pro) that were shown to have an average encapsulation of 9.4% with a mean particle size of 160.4 nm. Minimum inhibitory concentrations tested against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Bacillus subtillis were shown to be lower in liposome encapsulated Cyclo(Tyr-Pro) than for the free form, while no antimicrobial activity was noted for either encapsulated nor non-encapsulated drug against the fungus Candida albicans or two methicillin-resistant strains of Staphylococcus aureus (MRSA). A positive control of liposome encapsulated amoxicillin was shown to be extremely active against both MRSA strains. CONCLUSIONS:The results confirm that liposome encapsulation has the potential to enhance activity as well as to overcome bacterial resistance towards current antibacterial agents.