Chemical analysis and antioxidant activity of four propolis samples collected from different regions of Lebanon

Abstract

Propolis samples were collected from four different regions of Lebanon characterized by high biodiversity and high honey production. The samples were analyzed for their total phenolic contents (TPC), total flavonoid contents (TFC), chemical profiles, and antioxidant activity. The TPC was determined using Folin-Ciocalteu method while the TFC using the AlCl3 method. The antioxidant activity of propolis was examined by two different methods, namely free radical scavenging assay and reducing ability. The chemical profiles of the samples were assessed by thin-layer chromatography (TLC), UV-Vis, and gas chromatography/mass spectrometry GC-MS analysis. Total phenolic content ranged from 53.35 ± 7.09 to 148.27 ± 15.08 mg GAE/g, total flavonoid content ranged from 45.73 ± 2.8 to 134.5 ± 8.46 mg RUE/g. GC/MS analysis revealed the presence of 9-octadecene and tetradecene as major compounds that have been previously reported to demonstrate antioxidant activity. In addition, Berqayel propolis sample showed high content of phenolic compounds and high antioxidant activity and contained mainly hydrocarbons, while samples from Wadi Faara recorded poor chromatograms with the absence of most of the compounds present in Berqayel samples. The majority of propolis samples showed relatively interesting antioxidant activity, which was also correlated with TPC and TFC. Our results provide additional evidence on the importance of the chemical composition of propolis and its usefulness in the pharmaceutical industry.