title: In vitro antibacterial phenolic extracts from "sugarbag" pot-honeys of Australian stingless bees (Tetragonula carbonaria).
abstract: Australian stingless bee honeys have been shown to exert antioxidant and in vitro antimicrobial properties; however their bioactive factors remained unidentified. This study investigated the antibacterial properties of phenolic extracts from Tetragonula carbonaria honeys. Honeys were harvested from beehives in three sites of South East Australia. Liquid-liquid extractions yielded the phenolic concentrates, for analyses by liquid and gas chromatography mass spectrometry. Antibacterial assays were conducted against Staphylococcus aureus and Klebsiella pneumoniae by in vitro agar diffusion and broth dilution assays. The phenolic extracts averaged to 5.87 mg/100 g of raw honeys, and constituents were 3-phenyllactic acid, lumichrome, diglycosylflavonoids, norisoprenoids. The honeys did not contain methylglyoxal, dihydroxyacetone or phenolics characteristic of Leptospermum nectars. Hydrogen peroxide content amounted up to 155.8 μM in honeys. Beside the bactericidal effects of hydrogen peroxide at 760 μM, other antibacterial factors were the phenolic extracts of "sugarbag" honeys that were active at minimum bactericidal concentrations of 1.2-1.8 mg/mL.
authors.affiliation: Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast , Maroochydore DC, Queensland, Australia.
authors.forename: C Flavia
authors.initials: CF
authors.lastname: Massaro
authors.forename: Daniel
authors.initials: D
authors.lastname: Shelley
authors.forename: Tim A
authors.initials: TA
authors.lastname: Heard
authors.forename: Peter
authors.initials: P
authors.lastname: Brooks
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001315:Australia; D001516:Bees / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006722:Honey / Q000032:analysis*; D007711:Klebsiella pneumoniae / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010636:Phenols / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D010636:Phenols
keywords: Meliponini; S. aureus; flavonoids; norisoprenoids; phloroglucinols; propolis