Altered antibacterial activity of Curcumin in the presence of serum albumin, plasma and whole blood

Antibacterial effect is one of the major therapeutic activities of plant-derived Curcumin. This work evaluated the effect of serum albumin, human plasma, and whole blood on the in vitro activity of Curcumin against eight clinical bacterial isolates by standard broth microdilution and plate-counting methods. Toxicological effects of Curcumin towards human red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) were also investigated. Curcumin exhibited weak activity against gram-negative bacteria, except Escherichia coli and Shigella flexneri were susceptible and was most active against gram-positive bacteria: Staphylococcus aureus, Streptococcus pyogenes and Enterococcus faecalis. The antibacterial activity was impaired in the presence of bovine serum albumin (BSA), human plasma and whole blood. Curcumin was not toxic to PBMCs and RBCs at 200μg/mL. Furthermore, Curcumin showed synergistic activity in combination with antibiotics: Ciprofloxacin, Gentamicin, Vancomycin and Amikacin against Staphylococcus aureus. This study demonstrated that the interaction of Curcumin with plasma proteins diminishes its in vitro antibacterial activity. Curcumin derivatives with reduced affinity for plasma protein may improve the bioavailability and antibacterial activities.