Chemical Profiling of Latvian Propolis: Regional Variations and Botanical Origins

Propolis is a resinous natural product produced by honeybees from plant exudates and beeswax. Its complex chemical composition varies significantly with geographical origin and seasonal factors. This study aimed to characterize the chemical composition of propolis samples collected from different regions of Latvia using gas chromatography-mass spectrometry (GC-MS). In total, 47 metabolites were identified, with chemical profiles dominated by phenolic acids and their esters-compounds typical of European propolis. Regional variations reflected differences in local vegetation, and two samples exhibited flavonoid constituents indicative of poplar-type botanical sources. The Daugavpils sample, which showed a particularly rich chemical profile, was further fractionated chromatographically, leading to the isolation of twelve metabolites: 2',4',6'-trihydroxy-4-methoxy dihydrochalcone, 2',6',4-trihydroxy-4'-methoxy dihydrochalcone, 2',6'-dihydroxy-4,4'-dimethoxy dihydrochalcone, 2',6'-dihydroxy-4'-methoxy dihydrochalcone, 2',4',6'-trihydroxy dihydrochalcone, palmitic acid, benzyl benzoate, cinnamyl cinnamate, pinostrobin, pinostrobin chalcone, pinocembrin, and pinobanksin. Given the limited prior research on Latvian propolis, this study provides valuable insights into its chemical diversity and the influence of regional flora on its composition.