Total phenolic content, antioxidant, antibacterial and antidiabetic properties of selected Algerian propolis samples

Abstract

Propolis is a resinous substance collected by honeybees from trees and plants and contains a variety of bioactive compounds with diverse biological properties. Consequently, it has diverse applications in both nutritional and pharmaceutical fields. The present study aimed to investigate the biological properties of Algerian propolis. In this purpose, seven propolis samples were collected from different regions of Algeria and extracted using ethanol as the solvent. The total phenolic and flavonoid contents of the ethanolic extracts were determined using spectrophotometric methods. The antioxidant activity was assessed using two assays: the DPPH radical scavenging test and the β-carotene bleaching test. The antibacterial activity of the extracts was evaluated in vitro against five pathogenic bacterial strains and two beneficial bacteria. Additionally, the antidiabetic potential of propolis was examined through an α-amylase inhibition assay. The results showed that all propolis samples contained high levels of total phenols and flavonoids, ranging from 29.10 to 95.35 mg GAE/g and 5.19 to 48.23 mg QE/g, respectively. Both the DPPH and β-carotene assays demonstrated significant antioxidant activity of the extracts (P<0.05). The propolis samples exhibited strong inhibitory effects against Gram-positive bacteria, with inhibition zone diameters ranging from 8.33 ± 0.28 to 15.50 ± 1 mm, and moderate activity against Gram-negative bacteria. Furthermore, the extracts displayed a high capacity to inhibit α-amylase. These findings suggest that Algerian propolis possesses considerable biological potential and may serve as a valuable source of natural antioxidant, antibacterial, and antidiabetic agents.