Honeys derived from plants of the coastal sandplains of Western Australia: antibacterial and antioxidant activity, and other characteristics
Honeys produced by Apis mellifera from different flowering plants can vary widely in their characteristics. Some floral sources yield honeys with especially high antibacterial and/or antioxidant activity, which may be candidates for further evaluation as therapeutic agents. This study investigated 115 honeys harvested from three Western Australian coastal bioregions: the Swan coastal plain, Geraldton sandplains and Dampierland. Honeys were derived from a range of floral sources, including Agonis, Banksia, Calothamnus, Callistemon, Eucalyptus, Leptospermum and Melaleuca, and several multifloral honeys including wildflower honey were also included. HPTLC fingerprinting was used to analyse the phenolics fractions of all honeys and fingerprints were analysed to attempt to verify the floral source of each honey. Typical fingerprints were discernible for the four honeys derived from Agonis flexuosa, Banksia sessilis, Banksia menziesii and Calothamnus. Antibacterial and anti-oxidant activity was quantified for all honeys and showed that Calothamnus honeys had the highest activity for both, and also contained the highest levels of phenolics. Hydrogen peroxide, colour and water content were also determined. Data obtained for all 115 honeys were analysed by principal component analysis to investigate broad trends, and showed that colour, total phenolics and antioxidant activity correlated strongly, whereas antibacterial activity was not strongly correlated with any other factors. Data obtained for individual floral sources were analysed by one-way analysis of variance and revealed significant differences between some honey types, supporting the hypothesis that honeys derived from different floral sources vary in important characteristics such as antibacterial and antioxidant activity.