Phenolic Extract from Propolis and Bee Pollen: Composition, Antioxidant and Antibacterial Activities

Abstract

Bee products (e.g., propolis and bee pollen) are traditional healthy foods. In this study, antioxidant properties and in vitro antibacterial activity of honeybee pollen and propolis methanol extracts were determined. Propolis with higher phenolic content showed significant greater activity over pollen extracts. Caffeic acid, ferulic acid, rutin, and p-coumaric acid were detected as main phenolic compounds in propolis extract. 3,4-Dimethoxycinnamic acid was the major phenolic component in pollen extract. Propolis extract (5 μg/mL) exhibited 28% antiradical action against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The scavenging activity of propolis and pollen extracts against 2,2′-Azinobis (3-ethylbenzothiazoline-6 sulfonic acid) (ABTS) reached a maximum of 94.3 and 76.5%, respectively, at an extract concentration of 25 μg/mL. Stabilization factor of propolis extract was 13.7, while it was 6 for pollen. Results revealed that both extracts showed highly antibacterial action against gram-positive bacteria with a minimal inhibitory concentration ranging from 0.2 to 0.78 mg/mL. To best of our knowledge, this is the first study showing elevated antibacterial activity against gram-negative bacteria Salmonella enterica. Practical Applications Besides their potential pharmaceutical use, propolis and pollen could be efficient protective agents for use as natural antioxidant and antibacterial additives in food systems. It has been observed that the biological activities of propolis and pollen depend on their chemical composition, which, in turn, depends on geographical diversity and the genetic variety of the queens. On the basis of the present study, propolis extract showed higher antioxidant and antibacterial activities compared with the pollen extract. This may be due to its higher amounts in caffeic, ferulic and p-coumaric acids. To our knowledge, this is the first report comparing the antioxidant and antibacterial activities of Egyptian bee pollen and propolis extracts and their chemical constituents.