Phenolic contents and antioxidant activities of Caucasian bee propolis at different locations, solvents, and temperatures

Propolis is a natural substance produced by honey bees by processing the secretions collected from various plants with their own enzymes. Caucasian honey bee is one of the productive bee races known in the world and its homeland in Türkiye is Northeastern Anatolia. This study is the first comprehensive research to determine, compare, and correlate the effects of various solvents and temperatures on 17 different Caucasian bee propolis obtained from different locations in terms of phenolic content and antioxidant activity. The highest total polyphenol and flavonoid contents (TPC and TFC) in Caucasian bee propolis extracts varied between 23.37-97.62 mg gallic acid per gram (GA/g) of propolis and 6.73-43.75 mg quercetin per gram (Q/g) of propolis in ethanolic extract at 60°C. While ferric reducing antioxidant power (FRAP) did not differ at both temperatures, the highest was determined in ethanolic extracts. Analyses of propolis samples according to locations did not show any significant differences in terms of TPC, TFC, and FRAP. By Pearson's correlation analysis, it was found that each of the extracts showed a positive correlation between TPC, TFC, and FRAP. As a result, it was revealed that the main difference in the phenolic content and antioxidant activities of propolis obtained from gene centers of Caucasian bee race was due to the polarity of the solvent used and temperature, and that there was no difference between locations within a single bee race. This pioneering study shows that Caucasian bee propolis has a high potential that can pave the way for different research in this field.