Lipase-catalyzed synthesis of lauroyl tripeptide-KHA with multi-functionalities: Its surface-active, antibacterial,...

Lipase-catalyzed acylation of a hydrophilic tripeptide-KHA (TP-KHA; amino acid sequence Lys-His-Ala) with a lipophilic lauric acid was performed to produce a multi-functional compound, lauroyl tripeptide-KHA (TPL-KHA), with surface, antibacterial, and antioxidant activities. The significant acylation reaction parameters were optimized as follows: organic solvent of 2-methyl-2-butanol, reaction temperature at 55 °C, substrate molar ratio (lauric acid:TP-KHA) of 4.0, and reaction time for 72 h. Structural analyses by LC-ESI-MS and ¹H NMR identified that N^ε-lauroyl tripeptide-KHA was chemo-selectively synthesized by the acylation reaction under the optimum conditions. TPL-KHA showed the surface activity at the air-water interface with critical micelle concentration (CMC) of 2.71 mM and γ_CMC of 30.44 mN/m. TPL-KHA exhibited bacteriostatic and bactericidal effects on Gram-positive and Gram-negative foodborne pathogens (minimum inhibitory concentrations: 2.83-4.00 mM, minimum bactericidal concentrations: 3.17-5.83 mM). Moreover, it was demonstrated that TPL-KHA had the ability to scavenge ABTS⁺ radicals and inhibit the lipid oxidation.