The aim of the study was to analyze phenolic acids in Lithuanian propolis and to compare it with the composition of propolis in neighboring countries (Latvia and Poland) according to the predominant flora in the collecting places. The study was also aimed at the evaluation of the effect of the layer thickness (mm) of the harvested propolis on the quality of the raw material in determining the amount of phenolic acids.
Materials and methods: The object of the study was propolis collected in Lithuania, Poland, and Latvia in late July of 2006 and 2007. The qualitative and quantitative analysis of phenolic acids was performed using the high-performance liquid chromatography technique (HPLC).
Results: The results of the study showed that the quantitative and qualitative composition of phenolic acids in propolis depended on the plants from which the bees in the area collected substances for the raw material of propolis. The predominant phenolic acids were determined to be ferulic and coumaric acids, and they may be among the main indicators of quality in the standardization of the raw material and preparations of propolis.
Conclusion: We created an HPLC-based analysis method for the identification and quantification of phenolic acids in propolis. The variety of phenolic acids in propolis depends on the vegetation predominating in the harvesting area. Studies have shown that the highest amount of phenolic acids is observed in propolis harvested in areas characterized by the predominance of deciduous trees and meadows. Results have also shown that ferulic and coumaric acids are the predominant phenolic acids in propolis. The thickness of the layer of the collected propolis in the hive also influences its chemical composition.