Abstract
Propolis is a resinous vegetal exudate modified by bees, and is interesting as a preservative and potentially functional product. This work dealt with studying the common phenolic profiles and antioxidant capacities of 13 bee propolis from different geographical areas. Both hyaluronidase and angiotensin converting enzyme (ACE) inhibitory activities were also assessed and related when possible with particular phenolic compounds. High performance liquid chromatography-ultraviolet detection (HPLC-UV) analysis showed that every propolis contained p-coumaric acid (1.2–12.2 mg/g) and ferulic acid (0.3–11.0 mg/g). Pinocembrin, catechin, and caffeic acid phenethyl ester (CAPE) plus galangin were the main flavonoids. Antioxidant activities were higher than 280 µmol trolox/g for trolox equivalent antioxidant capacity (TEAC), 0.099 mmol uric acid/g for radical-scavenging effect on hydroxyl radicals, and 0.19 mg/mL for half maximal inhibitory concentration (IC50) of antioxidant activity against superoxide anion radical. Working with solutions of 10 mg/mL propolis, hyaluronidase inhibitory activity ranged between 0% and 68.20%, being correlated to ferulic acid content. ACE inhibitory effect determined by HPLC was higher than 78%, being correlated with catechin and p-coumaric acid. Therefore, propolis could be useful for food, pharmaceutical, and cosmetic companies, also helping to reduce risk factors for diseases related to oxidative damage, inflammatory processes, and hypertension. This research also highlights the necessity for harmonized analysis methods and the expression of results for propolis.
Highlights
Propolis is a resinous product made by bees mixing plant exudates with beeswax and other substances, such as salivary secretions
The aims of this study were: first, to research possible common phenolics’ profiles of bee-propolis from distant geographical areas; second, to assess for first time, a broad spectrum of antioxidant capacity by determining trolox equivalent antioxidant capacity (TEAC), and antioxidant activities against hydroxyl and superoxide radicals that are important from a physiological point of view, and third, to evaluate hyaluronidase and angiotensin converting enzyme (ACE) inhibitory activities, eventually studying possible correlations between each biological capacity and a particular phenolic group or phenolic compound
This study highlights the importance of setting up and proposing harmonized propolis analysis methods and the expression of results for phenolic compounds and antioxidant capacities, since common extraction procedures, reagents, and the expression of results are essential for efficient data comparison
Summary
Propolis is a resinous product made by bees mixing plant exudates with beeswax and other substances, such as salivary secretions. Its composition varies depending on the geographic location, botanical origin, and climatic factors [1]. More than 300 compounds have been found in different propolis. Propolis is mainly composed of 40–70% balsam (flavonoids and phenolic acids), 1–3%. Essential oils, 20–35% waxes and 5% other substances (most of them coming from pollen or being provided by the bees), such as minerals, polysaccharides, and proteins [2]. Bees use raw materials from different botanical species, depending on the flora available in each geographical area, which determines propolis chemical diversity. The basic plant source of European propolis
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