In vitro antibacterial activity and volatile characterisation of organic Apis mellifera ligustica (Spinola, 1906) beeswax ethanol extracts

Apis mellifera beeswax is synthesized from honey sugars and secreted by specialized glands situated in the ventral side of the abdomen of worker bees from 12 to 18 days old. It is also characterized by several therapeutic properties of great interest for human health with applications for healing bruises, inflammation, burns and with antimicrobial activity. The aims of this investigation were to assess the antibacterial activity of three organic beeswax samples from different locations and to evaluate their volatile composition with HS-SPME/GC-MS analysis. The beeswax's volatile organic compounds (VOC) included 82 molecules belonging to different chemical classes, such as aldehydes, hydrocarbons, alcohols, esters, ketones, organic acids, and terpenes. The total VOC contents was 35 ± 5 and 40 ± 2 ppm for samples A and B, respectively. Aldehydes were the main class of VOC in the beeswax ethanol extracts, particularly linear aldehydes such as octanal, nonanal and decanal. Minimal inhibitory concentration (MIC) showed that Pseudomonas aeruginosa and Listeria monocytogenes were inhibited by all beeswax samples. Salmonella Typhimurium was the most resistant bacterial strain. Against the 13 Staphylococcus aureus wild strains tested, beeswax samples A was the most effective, followed by sample B and C.