Phenolic Profile and Antioxidant Activity of Propolis Extracts From Poland

Abstract

Propolis is a natural material collected by honeybees, containing bioactive compounds that exhibit biological activity. The aim of this study was to assess the chemical composition of Polish propolis extracted with two different concentrations of ethanol, namely 70% and 96%, and to evaluate their antioxidant activity depending on extraction conditions. Samples of Polish propolis were extracted with 70% and 96% ethanol in order to obtain the ethanolic propolis extracts EEP70 and EEP96, respectively. Concentrations of 10 flavonoids and 6 phenolic acids were determined using the UPLC-PDA-TQD system. The antioxidant properties were determined based on the DPPH • free radical scavenging activity, Fe 3+ reducing power assay, and ferrous ions (Fe 2+) chelating activity assays. Moreover, the effects of the propolis extracts on human red blood cell morphology , the selective permeability of their membrane, as well as on free radicals-induced hemolysis were also assessed. Qualitative and quantitative analyses of both propolis extracts indicated that 70% ethanolic extract contained higher amounts of phenolic compounds than 96% ethanolic extract. The levels of antioxidant activity indicated that both Polish propolis extracts exhibited a high and comparable antioxidant power. The concentration of ethanol used for extraction had no effect on the antioxidant potential of propolis. The presented results indicate that the extracts of Polish propolis are rich in phenolic compounds and are very effective as antioxidant agents. Therefore, they may be applied as a constituent of products used in phytotherapy regardless of the concentration of ethanol used in propolis extraction.

Effect of the Solvent on Propolis Phenolic Profile and its Antifungal, Antioxidant, and In Vitro Cytoprotective Activity in Human Erythrocytes Under Oxidative Stress

“…Pinocembrin, galangin, and chrysin ( Table 1 ), which were detected in all the tested propolis extracts at the highest concentrations, were previously reported in propolis collected from various regions of Poland, and they are regularly detected in propolis from around of the world [ 4 , 11 , 14 , 19 , 28 , 34 , 36 , 37 , 38 , 39 ]. Pinocembrin concentration in all the examined extracts (26.17–35.89 mg/g of propolis extract) was lower than in propolis extracts from Hungary (40.57–87.85 mg/g of propolis extract) and samples from the central–western region of Poland (41.55–51.55 mg/g of propolis extract) [ 19 , 37 ].…”

“…The examined propolis extracts showed a high antiradical potential, which was also characteristic of propolis extracts originating from different geographical regions, including samples from New Zealand, Brazil, Morocco, Hungary, Slovenia, India, or various parts of Poland [ 9 , 28 , 34 , 37 , 43 , 44 , 45 , 46 ]. The antiradical activity of all extracts (29.38–31.25%) confirmed in the DPPH· assay was higher than that observed for ethanolic extracts of propolis collected from the Wielkopolska Province of Poland (27.70–29.10%) [ 34 ]. The Fe 2+ -chelating activity of all the extracts (34.00–43.33%) was comparable to that of propolis extracts from central Poland (35.41–38.85%) [ 19 , 34 ].…”

“…The antiradical activity of all extracts (29.38–31.25%) confirmed in the DPPH· assay was higher than that observed for ethanolic extracts of propolis collected from the Wielkopolska Province of Poland (27.70–29.10%) [ 34 ]. The Fe 2+ -chelating activity of all the extracts (34.00–43.33%) was comparable to that of propolis extracts from central Poland (35.41–38.85%) [ 19 , 34 ]. Moreover, the propolis extracts exhibited a stronger chelating effect on ferrous ions than methanolic extracts of Portuguese propolis (4.33–29.68%) [ 47 ].…”

“…Human RBCs are used as a cell model for screening of the antioxidant activity of bioactive compounds [ 19 , 34 , 51 , 52 ]. The evaluation of hemolytic activity of potential blood-contacting compounds is the most important criterion for their future in vivo applicability [ 53 ].…”

“…Over the past few years, the biological activities of Polish propolis were studied intensively, and its chemopreventive, antioxidant, antibacterial, antiproliferative, and antifungal activity was observed [ 4 , 5 , 8 , 9 , 30 , 31 , 32 , 33 ]. Moreover, propolis collected from an apiary located in the central–western part of Poland effectively protected human red blood cells (RBC) in vitro against 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative hemolysis [ 19 , 34 ]. To the best of our knowledge, the impact of the solvent used for the extraction of Polish propolis on its phenolic profile and the antifungal and antioxidant properties, especially on the protective effect of extracts against in vitro oxidative hemolysis of human erythrocytes, has not been reported to date.…”