Antimicrobial and antioxidant properties of honeys produced by Apis mellifera in Thailand

Honey samples produced by Apis mellifera, both unifloral and multifloral (i.e. longan, sabsua, lychee, rambutan, sunflower, kapok, sesame, para rubber and wild flowers) from different sources in Thailand were examined for their antibacterial and antifungal activities as well as antioxidant properties. An agar incorporation technique was used to assess the minimum inhibition concentration (MIC) of honey against fourteen species of bacteria (Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli, Micrococcus luteus, Staphylococcus epidermidis, Streptococcus pyogenes, Listeria monocytogenes, Proteus mirabilis, Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus, Serratia marcescens, Salmonella typhimurium and Propionibacterium acnes) and two species of yeasts (Candida albicans and Saccharomyces cerevisiae). The Folin-Ciocalteu assay was used to measure phenol content and the 2,2-diphenyl-picrylhydrazyl (DPPH) assay was used to determine the scavenging activity of the honey samples. The honey samples were found to inhibit all of the tested bacteria but not the two species of yeasts. Antioxidant properties, determined by average phenol content was in the range of 493.79 ± 34.78 -1,160.39 ± 348.66 mg GAE/kg. The DPPH radical scavenging assay was found to have an IC50 in the range of 5.8 ± 1.55-19.76 ± 6.09 mg/mL.