Phytochemical screening, antioxidant activity, total polyphenols and flavonoids content of different extracts of propolis from Tekel (Ngaoundal, Adamawa region, Cameroon)

Abstract

Five extracts of propolis of Adamawa Cameroon were obtained by percolation and maceration with five different solvents: hexane, ethyl acetate, ethanol, methanol and water, in order of increasing polarity. Phytochemical screening was carried out on the extracts and the total content in flavonoids and polyphenols were evaluated by photometric methods. The total flavonoid content was evaluated using the Neu reagent (2-aminodiethyl diphenylborinate) and quercetin as standard and the results varied from 0.84±0.02 gQE/100gRM in ethyl acetate extract to 1.52±0.06 gQE/100gRM in ethanol extract. The total polyphenol content was evaluated using Folin-Ciocalteu reagent and gallic acid as standard and results varied from 2.32±0.37 gGAE/100gRM in the ethyl acetate extract which is the least to 8.64±0.47 gGAE/100gRM in the aqueous extract. The antiradical activities of the extracts were evaluated through their inhibition on DPPH• and IC50 values varied from 1.88 mg/mL in the aqueous extract which showed highest antioxidant power to 5.06 mg/mL in the ethyl acetate extract with the least antioxidant power. BHT and vitamin C were used as synthetic and natural standards respectively and they showed higher antioxidant power compared to the propolis extracts. Ferrous iron chelating capacities of the extracts were determined using potassium ferricyanide reagent and EDTA as standard. Using Stat Graphics software and Durbin-Watson statistics test, the extracts showed significant correlation between flavonoid content and polyphenol content with DPPH• scavenging activity. The ethyl acetate extract showed least ferrous ion chelating capacity while the methanol extract showed highest ferrous ion chelating capacity.