Antibacterial potency of lavender and rosemary honey

Introduction: Because of its remarkable therapeutic potential, honey has been used as a remedy for thousands of years, but only recently apitherapy has become into focus as an alternative for treating certain conditions and diseases, especially infections. Antimicrobial activity of honey has been attributed to several compounds (hydrogen-peroxide, phenol, flavonoids, bee-defensin) which presence and concentrations depend on honey origin. Materials and methods: To study the antimicrobial activity of lavender and rosemary honey, several samples from different geographical locations in Croatia were evaluated for their ability to inhibit the growth of gram-positive and gram-negative bacteria, and molds. The bioassay applied employs the well-agar diffusion method and determination of minimal inhibitory concentrations (microdilution method with TTC). The total phenolic content was assesed by the modified Folin-Ciocalteu method and flavonoids using aluminium chloride colorimetric method. The antioxidant activity was assessed by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system and ferric reducing antioxidant power (FRAP) assay. Results: All honey samples showed antimicrobial activity at variable levels, depending upon the geographical origin. Most tested pathogens have MIC values in the range of 12-20 % of honey. Phenolic content ranged from 198.2 to 561.4 mgGAE/kg and flavonoids from 23.6 to 68.7 mgCE/kg. Both were highly correlated to honey antioxidant capacity values. Conclusions: The study showed that honey has antibacterial activity and, at some level, can provide an alternative therapy in certain conditions. Moreover, we characterized the antioxidant potential and phenolic and flavonoid content of honey samples with regard to the therapeutic efficacy and health benefits.