###### Abstract  
Methylglyoxal (MGO) is recognized as being the bioactive component responsible for the antibacterial activity of mannuka honey. MGO content was investigated by high-performance liquid chromatography (HPLC-UV), in isocratic elution, to assess the occurrence of this compound in mono- and multi-floral honey samples representative of different botanical and geographic origins in Italy. Specifically, 110 honey samples from sweet cherry tree (_Prunus avium_ L.), thyme (_Thymus vulgaris_ L.), almond tree (_Prunus amygdala_ L.), eucalyptus (_Eucalyptus camildulensis_ L.), oriander (_Coriandrum sativium_ L.), cornflower (_Centurate cyanus_ L.), thistle (_Silybunk uranium_ L.), acacia (_Robinia pseuducacia_ L.), citrus, honeydew and multififord honey were considered. The amount of MGO found in different types of honey was ranging from 0.4 to 24.1 mg/kg. This study provides, for the first time, data on MGO levels in Italian cherry and almond honey, which showed higher concentrations of MGO compared to honey from other botanical species. I 2020 2020 14 January 2 acids is also responsible for its anti-inflammatory effect. Among these, galangin and chrysin are involved respectively in the inhibition of cyclooxygenase (COX) and lipo-oxygenase activity, and the suppression both of COX-2 pro-inflammatory activities and of inducible nitric oxide synthase (iNOS), the enzyme involved in the inflammatory process [3; 20; 21]. Regarding antibacterial activity, many studies have highlighted honey's broad- spectrum action against various agents (bacteria, viruses, fungi) [5]. Its antimicrobial effect involves several mechanisms attributed to various synergistic factors [22; 23], such as low pH, osmotic pressure, high sugar concentration and the presence of low moisture contents, hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)), phenolic acids, flavonoid, lysozyme and bee defensin-1 [2; 6; 23; 24; 25; 26]. Generally, hydrogen peroxide is used to investigate this property--H\({}_{2}\)O\({}_{2}\) derives, from the action of the enzyme, glucose oxidase, added by bees, which converts glucose into H\({}_{2}\)O\({}_{2}\) and gluconic acid [6]. Even though different honeys have shown efficacy in the treatment of a number of infections, in recent years researchers' attention has focused on one particular substance contained in some types of honey, methylglyoxal (MGO), which shows greater antibacterial activity compared to non-MGO honey. 1,2-dicarbonyl compounds such as 3-deoxyglucose (3-DG ), glyoxal (GO), and methylglyoxal (MGO) are typically formed during the Maillard reaction or caramelization reactions as degradation products in many foods and beverages, such as bread, yogurt, wine, beer and other foodstuffs. These reactive compounds can also be formed endogenously by cell metabolism, glucose oxidation and lipid peroxidation, and are thus potential precursors of advanced glycation end products (AGEs). AGEs are complex heterogeneous compounds related to protein cross-linking and the alteration of the function of many important enzymes or immunological proteins, with adverse effects on immune response [27]. AGEs are also involved in the progression of chronic diseases and diabetes complications. Not all AGEs have been identified and the occurrence of AGEs in honey has been poorly investigated. Scientists have produced very different assessments of the ingestion of high MGO concentrations as potentially harmful to intestinal microbiota [28]. Methylglyoxal is a reactive \(\alpha\)-dicarbonyl compound present in high levels of up to 800 mg/kg in manuka honey [29], derived from the manuka tree (_Leptospermum scoarium_) in New Zealand, and has been identified as being directly responsible for the \"non-peroxide\" antibacterial activity. Manuka honey has shown strong activity against a wide range of microorganisms, including multiresistant strains of important human pathogens [30; 31; 32; 33]. Nectar source is decisive in honey MGO concentration because methylglyoxal is a signaling molecule in plants subjected to abiotic stress.