Antimicrobial activity of nisin, diclofenac sodium, amlodipine and their pharmaceutical compositions regarding reference strains of microorganisms

Abstract

One of the promising methods of combating pathogenic bacteria is the use of bacteriocins. The most famous representative of bacteriocins is nisin. It may be promising to combine nisin with resistance inhibitors, which do not have a direct antimicrobial effect, but somehow bind the resistance factors of bacteria, restoring their sensitivity to classical antibiotics. The search for helper substances among already known and well-studied substances is considered a promising direction in the fight against the resistance of microorganisms. The aim of the work is the microbiological substantiation of the feasibility of creating pharmaceutical compositions based on nisin, diclofenac sodium and amlodipine for the treatment of infectious and purulent-inflammatory diseases. Materials & methods. The antimicrobial activity of 1.0% aqueous solutions of nisin, diclofenac sodium, amlodipine and their combinations was studied. Modified nisin was obtained using biochemical methods by acetylation with acetic anhydride. 8 reference test cultures of microorganisms belonging to different taxonomic groups were used for microbiological research of the studied substances. The antimicrobial activity of the studied substances was determined by the diffusion method of "wells" with the measurement of the diameters of the growth retardation zones of microorganisms. Results & discussion. A moderate degree of sensitivity of the test strains S. aureus АТСС 6538-Р and B. subtilis АТСС 6633 to 1.0 % aqueous solution of unmodified nisin was established. Among the studied gram-negative test strains of microorganisms only P.aeruginosa ATCC 9027 showed moderate sensitivity to 1,0 % aqueous solution of unmodified nisin. For E. coli ATCC 25922, P. aeruginosa ATCC 27853, P. vulgaris ATCC 4636 and C. albicans ATCC 885-653 a weak antimicrobial effect of 1,0 % aqueous solution of unmodified nisin was established. A moderate degree of sensitivity of all investigated reference test strains of gram-positive microorganisms to 1.0 % aqueous solution of diclofenac sodium in isolated form was established. The activity of 1.0 % aqueous solution of diclofenac sodium against the vast majority of tested test strains of gram-negative microorganisms and C. albicans ATCC 885-653 to 1.0 % aqueous solution of diclofenac sodium was weak. The test strain P.aeruginosa ATCC 9027 was completely insensitive to 1.0 % aqueous solution of diclofenac sodium. A moderate degree of sensitivity of the test strains of gram-positive microorganisms to 1.0 % aqueous solution of amlodipine was established. Among the examined gram-negative microorganisms, the test strain E. coli ATCC 25922 showed moderate sensitivity to a 1.0% aqueous solution of amlodipine. Regarding the rest of the examined test strains of gram-negative microorganisms and C. albicans ATCC 885-653, the 1.0 % aqueous solution of amlodipine showed weak antimicrobial activity. When combining unmodified nisin and diclofenac sodium, a moderate antimicrobial effect was established against all tested gram-positive and the vast majority of gram-negative reference strains. A similar effect was established when combining 1.0 % aqueous solutions of nisin and amlodipine. With the triple combination of 1.0 % aqueous solutions of unmodified nisin, diclofenac sodium and amlodipine in a ratio of 1:1:1, the degree of sensitivity of all investigated reference strains of microorganisms increased insignificantly and remained moderate for gram-positive and gram-negative bacteria and weak for C. albicans ATCC 653- 885. When diclofenac sodium and amlodipine were combined with acetylated nisin (1.0 % aqueous solutions in a 1:1 ratio), there was some increase in sensitivity, but within moderate limits, to double combinations of test strains of gram-positive and gram-negative microorganisms. Susceptibility of C.albicans ATCC 653-885 to double combinations of acetylated nisin with both diclofenac sodium and amlodipine remained weak. With a triple combination of 1.0 % aqueous solutions of acetylated nisin, diclofenac sodium and amlodipine in a ratio of 1:1:1, the degree of sensitivity of test strains of gram-positive microorganisms increased to high and remained moderate for gram-negative bacteria. The moderate antifungal effect of the triple combination of acetylated nisin with diclofenac sodium and amlodipine against the test strain C.albicans ATCC 653-885 was also investigated. Conclusion. It was established that 1.0 % aqueous solutions of unmodified nisin, diclofenac sodium and amlodipine in isolated form exerted a moderate antimicrobial effect mainly on gram-positive microorganisms and, when combined, on gram-positive and gram-negative microorganisms. Modification of nisin by acetylation led to an increase in its antimicrobial effect in combinations with diclofenac sodium and amlodipine. The triple combination of 1.0 % aqueous solutions of acetylated nisin, diclofenac sodium, and amlodipine showed the highest antimicrobial effect against reference strains of gram-positive microorganisms.

Key words: nisin, diclofenac sodium, amlodipine, pharmaceutical compositions, microorganisms, antimicrobial activity