engleski

Antibacterial Activity of Various Honey Types Against Different Pathogens

Because of the remarkable therapeutic potential, honey has been used as a remedy for thousands of years. Consequently, the apitherapy has recently entered into the focus of attention as an unconven-tional method for treating certain conditions and diseases, especially infections as well as promotion of the health and human well-being. Antimicrobial activity of honey has been attributed to hydrogen-peroxide, which is produced by glucose-oxidase and phenolic compounds. The total polyphenol con-tent in honey partially reflect their antioxidant capacity. The presence and concentration of phyto-chemicals, especially flavonoids as well as phenolic acid, can vary and depend significantly upon ho-ney origin. In order to assess the antimicrobial activity of various honeys, total of 23 samples repre-senting fewer honey types deriving from different floral sources and geographical locations in Croatia were evaluated for their ability to inhibit the growth of nine gram (+) and gram (-) bacteria and two moulds. The bioassay applied for determination of the antimicrobial effects took up the well-agar dif-fusion method (preliminary screening method). The micro-dilution method with TTC (2, 3, 5-triphenyl tetrazolium chloride) indicated the viability of bacteria and resulted with the Minimum inhibitory con-centration (MIC) values. The total phenolic content was screened by the modified Folin-Ciocalteu method and the antioxidant activity was assessed by means of the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system. In addition, the color and pH of honey samples were analyzed. All honey samples showed antimicrobial activity at variable levels, depending upon the floral source and the geographical origin. A well-agar diffusion assay revealed the development of inhibition zones de-pending on the type and concentration of honey involved as well as the test pathogen. Gram (-) bacte-ria were found to be more susceptible as compared to gram (+). The majority of tested pathogens showed MIC values in the range of 12-20% of honey. Generally, dark colored honeys showed more inhibitory properties than light colored. Phenolic content, expressed as gallic acid equivalent, ranged from 34.2 to 261.4 mg/kg and was highly correlated to the values of honey antioxidant capacity. Higher antioxidative and scavenging activity was observed for dark honey samples, too. This study showed that honey samples possess certain antibacterial activity against test microorganisms that can be of certain use when considering an alternative therapy in some conditions. Moreover, it gave the characterization of the antioxidant potential as well as of the phenolic content of honey samples with some regard to the therapeutic efficacy and sanitary benefits for different purposes. Moreover, the re-sults of the study imply that specific honeys tend to have certain capacity for the food spoilage preven-tion as the result of the growth inhibition of food-borne microorganisms. It suggests that they could be potentially considered for the use as food preservatives for some foods and under appropriate condi-tions what should be further proved by additional research.

honey; Croatia; antimicrobial activity; MIC; phenolic content; antioxidant capacity

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