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  Zanko J Med Sci:  Apr. 2017; 21 (1): 1561-1566

Evaluation of the antibacterial activity of human cathelicidin peptide-LL-37 in the presence of acidified nitrite

Safaa Toma Hanna Aka*

* Department of Pharmacogonsy, College of Pharmacy, Hawler Medical University, Erbil, Iraq.


Background and objective: Bacterial resistance to conventional antibacterial agents has increased recently and this resistance results in complicated infections. Multiple protective mechanisms can evolve in mammalians to maintain the body protected from infections. Human cathelicidin antimicrobial peptide LL-37 and acidified nitrite are important components of the innate immune system that partake in preventing infections. Cathelicidin peptide LL-37 can be produced by epithelial tissues as well as by macrophages after microbial infections. This study was carried out to evaluate the antibacterial activity of LL-37 and acidified nitrite (AN) both individually and combined for their effect against the standard the strains of E.coli ATCC 25922 and S. aureus ATCC 25923.   

Methods: Flat-bottom micro well plates (96 wells) were used for the determination of bacteriostatic activity. Sodium nitrite (NaNO2) and ascorbic acid (AA) were used to produce acidified nitrite (AN). The singular and combined forms of the antibacterial agents were used for evaluating the antibacterial activities of LL-37 through estimation optical density values at 480nm (OD480nm).

Results: The LL-37 peptide showed antibacterial activity against E.coli ATCC 25922 and S. aureus ATCC 25923. The antibacterial efficacy was enhanced when the peptide was tested in combination with AN (P <0.001). In contrast, the combination of LL-37 with NaNO2 and AA has an antagonistic effect (P <0.001) on its antimicrobial properties.

Conclusion: The combination of LL-37 with AN has a synergistic on the peptide’s antimicrobial effect. Therefore, LL-37 which might show little antibacterial activity when used alone can provide protection when used in combination therapy with other antimicrobial agents. 

Keywords: Antibacterial; Cathelicidin LL-37; Acidified nitrite.


1. Lundberg J, Carlsson S, Engstrand L, Morcos E, Wiklund N, Weitzberg E. Urinary nitrite: more than a marker of infection. Urology 1997; 50(2):189–91.

2. Gallo RL, Hooper LV. Epithelial antimicrobial defence of the skin and intestine. Nature Reviews Immunology 2012; 12(7):503–16.

3. Waterer GW. Airway defense mechanisms. Clin Chest Med 2012; 33(2):199–209.

4. Do TQ, Moshkani S, Castillo P, Anunta S, Pogosyan A, Cheung A, et al. Lipids including cholesteryl linoleate and cholesteryl arachidonate contribute to the inherent antibacterial activity of human nasal fluid. J Immunol 2008; 181(6):4177–87.

5. Chromek M, Slamová Z, Bergman P, Kovács L, Podracká Lu, Ehrén I, et al. The antimicrobial peptide cathelicidin protects the urinary tract against invasive bacterial infection. Nat Med 2006; 12(6):636–41.

6. Levy O. Innate immunity of the newborn: basic mechanisms and clinical correlates. Nat Rev Immunol 2007; 7(5):379–90.

7. Newell A, Riley P, Rodgers M. Resistance patterns of urinary tract infections diagnosed in a genitourinary medicine clinic. Int J STD AIDS 2000; 11(8):499–500.

8. Benjamin N, O'Driscoll F, Dougall H, Duncan C, Smith L, Golden M, et al. Stomach NO synthesis. Nature 1994; 7(6471):502.

9. De Groote MA, Fang FC. NO inhibitions: antimicrobial properties of nitric oxide. Clin Infect Dis 1995; 21(Supplement 2):S162–5.

10. Carlsson S, Wiklund N, Engstrand L, Weitzberg E, Lundberg J. Effects of pH, nitrite, and ascorbic acid on nonenzymatic nitric oxide generation and bacterial growth in urine. Nitric oxide 2001; 5(6):580–6.

11. Dykhuizen R, Frazer R, Duncan C, Smith C, Golden M, Benjamin N, et al. Antimicrobial effect of acidified nitrite on gut pathogens: importance of dietary nitrate in host defense. Antimicrob Agents Chemother 1996; 40(6):1422–5.

12. Weller R, Pattullo S, Smith L, Golden M Ormerod A, Benjamin N. Nitric oxide is generated on the skin surface by reduction of sweat nitrate. J Invest Dermatol 1996; 107(3):327–31.

13. Lundberg JO. Nitrate transport in salivary glands with implications for NO homeostasis. Proc Nati Acad Sci 2012; 109(33):13144–5.

14. McKnight G, Duncan C, Leifert C, Golden M. Dietary nitrate in man: friend or foe? Br J Nutr 1999; 81(05):349–58.

15. Shai Y. Mechanism of the binding, insertion and destabilization of phospholipid bilayer membranes by α-helical antimicrobial and cell non-selective membrane-lytic peptides. Biochim Biophys Acta 1999; 1462(1):55–70.

16. Wu M, Maier E, Benz R, Hancock RE. Mechanism of interaction of different classes of cationic antimicrobial peptides with planar bilayers and with the cytoplasmic membrane of Escherichia coli. Biochemistry 1999; 38(22): 7235–42.

17. Bechinger B. Towards membrane protein design: pH-sensitive topology of histidine-containing polypeptides. J Mol Biol 1996; 263(5):768–75.

18. Aisenbrey C, Bechinger B, Gröbner G. Macromolecular crowding at membrane interfaces: adsorption and alignment of membrane peptides. J Mol Biol 2008; 375(2):376–85.

19. Noore J, Noore A, Li B. Cationic antimicrobial peptide LL-37 is effective against both extra-and intracellular Staphylococcus aureus. Antimicrob Agents Chemother 2013; 57(3):1283–90.

20. Alaiwa MHA, Reznikov LR, Gansemer ND, Sheets KA, Horswill AR, Stoltz DA, et al. pH modulates the activity and synergism of the airway surface liquid antimicrobials β-defensin-3 and LL-37. Proceed Nati Acad Sci 2014; 111(52):18703–8.

21. Bower JM, Gordon-Raagas HB, Mulvey MA. Conditioning of uropathogenic Escherichia coli for enhanced colonization of host. Infect Immun 2009; 77(5):2104–12.

22. Ciornei C, Egesten A, Bodelsson M. Effects of human cathelicidin antimicrobial peptide LL37 on lipopolysaccharideinduced nitric oxide release from rat aorta in vitro. Acta Anaesthesiol Scand 2003; 47(2):213–20.

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