Phytochemical Investigation of Phenolic Constituents and In vitro Evaluation of Antioxidant Activity of Five Algerian Propolis

Background: Algerian propolis has gained interest in the last recent years. Many researches concerning both its biological effects and chemical composition were performed. Objective: The present study was designed to investigate the chemical composition in particular phenolic compounds and the antioxidant activity of five Algerian propolis collected from different geographical parts of the Algerian north namely: Constantine (CN), Boumerdes (BN), Mila (MN), Tebessa (TN) and Guelma (GN). Methods: Propolis extracts were obtained using solvents of varying polarity: petroleum ether, chloroform, ethyl acetate and finally methanol. Phenolic compounds were determined by liquid chromatography- tandem mass spectrometry (LC-MS/MS). In addition, total flavonoid and phenolic contents were also determined. Antioxidant activity was investigated using five complementary tests namely: DPPH., ABTS.+ assays for radical-scavenging activity, β-carotene-linoleic acid assay for lipid peroxidation activity, CUPRAC and FRAP assays for reduction capacity. Results: The main phenolic compounds detected in the present study were caffeic, p-coumaric, cinnamic and chlorogenic acids as well as naringenin and kampferol. Among the tested extracts, ethyl acetate and methanol extracts exhibited the highest phenolic and flavonoid contents and the strongest antioxidant activity. Propolis of Constantine was the most active one. Conclusion: Our results suggest the potential use of Algerian propolis as a natural source of bioactive compounds with antioxidant activity.