Volatile compounds composition and antioxidant activity of bee pollen collected in Lithuania

Characterization of volatile compounds composition and evaluation of antioxidant properties of bee pollen collected in Lithuania is presented in the paper, which is the first study on pollen of Lithuanian origin to our knowledge. Three polyfloral pollen samples collected by honey bees were analyzed. Characterization of volatile compounds was performed using solid phase microextraction (SPME) and GC-MS. Styrene was predominant in all samples contributing 19.6-27.0 mass %. Sample A distinguished by a high amount of limonene, 9.0 mass %, sample B differed from the rest by a high content of hexanal, 9.3 mass %, and nonanal, 12.3 mass %, while sample C showed the highest content of 1-tridecene, 43.3 mass %. Screening of antioxidant properties was carried out by spectrophotometric methods and liquid chromatography coupled with a post-column 1,1-diphenyl-2-picrylhydrazyl (DPPH) reaction detector and electrochemical detector. Total phenolic and flavonoid contents together with radical scavenging activity in the free radical (DPPH) model system were evaluated in the tested samples. Total phenolic content varied from 24.4 mg g(-1) to 38.9 mg g(-1), total flavonoid content was in the range of 7.3-10.0 mg g(-1) and radical scavenging activity was found between 30.7 mg g(-1) and 34.9 mg g(-1), all data are expressed in rutin equivalents. To process the collected data statistically and classify the bee pollen samples to clusters according to their volatile composition and antioxidant activity, principal component analysis, hierarchical cluster analysis and non-linear discriminant analysis were applied. (C) 2014 Institute of Chemistry, Slovak Academy of Sciences