Chemical analysis of Greek pollen - Antioxidant, antimicrobial and proteasome activation properties

<p>Abstract</p> <p>Background</p> <p>Pollen is a bee-product known for its medical properties from ancient times. In our days is increasingly used as health food supplement and especially as a tonic primarily with appeal to the elderly to ameliorate the effects of ageing. In order to evaluate the chemical composition and the biological activity of Greek pollen which has never been studied before, one sample with identified botanical origin from sixteen different common plant taxa of Greece has been evaluated.</p> <p>Results</p> <p>Three different extracts of the studied sample of Greek pollen, have been tested, in whether could induce proteasome activities in human fibroblasts. The water extract was found to induce a highly proteasome activity, showing interesting antioxidant properties. Due to this activity the aqueous extract was further subjected to chemical analysis and seven flavonoids have been isolated and identified by modern spectral means. From the methanolic extract, sugars, lipid acids, phenolic acids and their esters have been also identified, which mainly participate to the biosynthetic pathway of pollen phenolics. The total phenolics were estimated with the Folin-Ciocalteau reagent and the total antioxidant activity was determined by the DPPH method while the extracts and the isolated compounds were also tested for their antimicrobial activity by the dilution technique.</p> <p>Conclusions</p> <p>The Greek pollen is rich in flavonoids and phenolic acids which indicate the observed free radical scavenging activity, the effects of pollen on human fibroblasts and the interesting antimicrobial profile.</p

Harvesting Season and Botanical Origin Interferes in Production and Nutritional Composition of Bee Pollen

ABSTRACT We aimed to evaluate the frequency of bee pollen production, its botanical origin and chemical composition when collected in different seasons. Our results indicate that higher proteins (22.80 ± 3.09%) and flavonoids (2789.87 ± 1396.00 μg 100g-1) levels were obtained in the winter season, which also showed greater pollen production (134.50 ± 35.70 grams) and predominance of the Myrtaceae family. As for spring we found high concentrations of lipids (4.62 ± 2.26%) and low ash content (2.22 ± 0.39%). Regarding the amino acid composition and vitamin C content, we found no differences between the averages throughout the seasons. Our results highlight the importance of understanding not only the botanical origin and the chemical composition of bee pollen, but also the harvesting frequency of this product by bees, so that it becomes possible to supplement the colonies in times of natural food resources shortage

Effects of hot-air and vacuum drying on drying kinetics, bioactive compounds and color of bee pollen

This study aims to investigate drying kinetics of bee pollen as thick as 5 mm and change of color, total phenolic content, total flavonoid content, and antioxidant capacity of fresh and dried bee pollen by using both hot-air and vacuum drying at 40, 45 and 50 degrees C. Six well-known thin-layer drying models were used to predict drying kinetics by nonlinear analysis of regression. The Midilli & Kucuk model best fitted the experimental data for the whole range of temperatures. The moisture diffusivity coefficient at each temperature was determined by Fick's second law of diffusion, in which their value varied from 8.40 x 10(- 11) to 6.29 x 10(- 10) m(2)/s over the mentioned temperature range. The dependence of effective diffusivity coefficient on temperature was expressed by an Arrhenius type equation. The calculated values of the activation energy of moisture diffusion were 49.47 and 33.57 kJ/mol for hot-air and vacuum dryers, respectively. After drying processes, total phenolic content, total flavonoid content and antioxidant activity of bee pollen decreased. Higher total phenolic and total flavonoid content values were obtained in a vacuum drying at 45 degrees C. In addition, the total color change of bee pollen dried at vacuum conditions was lower than dried at hot-air conditions