Differential Antimicrobial Effectiveness of Camel Lactoferrin-Oleic Acid and Bovine Lactoferrin-Oleic Acid Complexes against Several Pathogens

Abstract

Considering the superior biological activities of Camel Lactoferrin (cLf) over lactoferrin from other animal species; which we previously confirmed and continuing the analysis of antimicrobial effectiveness of cLf; we started in previous studies, the current study aimed to formulate a protein-fatty acid complex of cLf and Oleic Acid (OA) and to compare it’s in vitro antimicrobial activities against different pathogens with those of a similar Bovine Lactoferrin (bLf)-OA complex. Antimicrobial activity of these complexes was evaluated by agar disc diffusion method, broth microdilution assay, and ELISAestimating Lf and its complexes binding to bacterial outer membrane proteins. Agar disc diffusion assay results revealed that inhibitory activity of both free cLf and cLf-OA against 13 test pathogens (Methicillin-Resistant Staphylococcus Aureus (MRSA), Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella typhi, Shigella sonnei, Klebsiella pneumonia, Pseudomonas aeruginosa, Proteus vulgaris, Serratia marcescens, Candida albicans, Aspergillus niger, and Aspergillus flavus) noticeably exceeded that of corresponding bLf and bLf-OA. Additionally, free OA exhibited antimicrobial activity against MRSA, S. aureus, B. cereus, and C. albicans and to a lesser extent against E. coli, K. pneumonia as well as A. niger and A. flavus. Consequently, synergy was evident between cLf/bLf and OA (mostly higher in case of cLf) in prepared complexes against MRSA, S. aureus, B. cereus, and C. albicans. cLf-OA demonstrated 4 times lower Minimum Inhibitory Concentration (MIC) values against MRSA, B. cereus, and C. albicans than bLf-OA; indicating more superiority in case of cLf-OA than free cLf that showed only twice the activity of bLf. ELISA signals confirmed binding of biotinylated cLf/bLf and cLf/bLf-OA to bacterial membrane proteins. This study proves that cLf obtains enhanced antimicrobial activities after complex formation with fatty acids such as OA even than its free form which has already superior activity than other Lf species; thus this complex may be used as a cure of various microbial infections.