The total phenolic content and antioxidant activity in vitro in linden honey from Lithuania

Abstract

Introduction. Honey is one of the most valued natural products. It has antioxidant properties due to its chemical composition, mainly phenolic compounds. The chemical composition and biological properties of honey highly depends on the source of the floral origin and on the qualitative and quantitative composition of compounds. Therefore, it is important to investigate the phytochemical composition and biological properties of different kind of honey samples obtained from different regions of Lithuania. Materials and methods. Linden honey samples were collected in 2023 from three different apiaries. They were located in Kaunas, Jonava and Druskininkai districts. 1 g honey was dissolved in 10 ml 70% ethanol. The total phenolic content (TPC) was investigated by Folin-Ciocâlteu spectrophotometric assay, antioxidant activity in vitro was determined by ABTS and CUPRAC assays [1]. Statistical analysis was performed using "Microsoft Office Excel 2023" ("Microsoft", Redmond, Washington, USA) and SPSS 29.0.2 ("IBM", Chicago, Illinois, USA). Results and discussion. TPC determined in the linden honey samples ranged between 0.29±0.01 mg GAE/g and 0.48±0.01 mg GAE/g. The highest TPC was evaluated in the linden honey samples collected in Kaunas and Jonava districts (0.48±0.01 mg GAE/g and 0.47±0.01 mg GAE/g respectively). The lowest TPC was found in the linden honey samples collected from Druskininkai district (0.29±0.01 mg GAE/g). The coefficient of variation (CV) was 24.8%, this indicates a medium variability of the total phenolic content of the linden honey samples. The reducing activity in vitro of linden honey varied between 0.43±0.006 µmol TE/g and 0.71±0.01 µmol TE/g. The strongest reducing activity in vitro using CUPRAC assay was determined in a sample from Kaunas district (0.71±0.01 µmol TE/g, p<0.05). The weakest reducing activity was detected in the linden honey samples collected from Druskininkai district (0.43±0.006 µmol TE/g). The CV was 24.58%, which indicates a medium variability of reducing activity in vitro of linden honey samples. The antiradical activity in vitro determined using ABTS assay varied between 16.27±0.35% and 17.94±0.07%. The CV was 5.3%, which also indicates a weak variability of antiradical activity in vitro of linden honey samples. Conclusions. The results of our research have shown that all investigated samples of linden honey contain phenolic compounds and possess antioxidant (both, antiradical and reducing) activities. Research shown that samples with highest compounds is from central part of Lithuania (Kaunas and Jonava districts). The strongest reducing activity in vitro and the highest total phenolic content contained was found in a sample from Kaunas district.