Antioxidant effect of leaf extracts from Cressa cretica against oxidation process in soybean oil.

Phenolic compounds from Cressa cretica leaves were extracted using different solvents (water and ethanol 70%) during 3-24 h by immersion method and were determined according to the Folin-Ciocalteu method. The antioxidant activities of the extracts were investigated by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, ferric reduction activity potential and total antioxidant capacity assays compared with synthetic antioxidant namely BHT. The results were shown that the most total phenol content was outcome of the ethanolic extract after 18 h (68.512 ± 0.36( )mg gallic acid/g dry extract) extraction. The results of different assays for determination of antioxidant potential of the extracts as well as their EC50 values were indicated antioxidant activities in order: BHT>ethanolic extract>aqueous extract. Also, the antioxidant activities were enhanced with increasing of the extracts and BHT concentrations. The results of Peroxide value (PV) and Thiobarbituric acid (TBA) tests were revealed that the ethanolic extract with various concentrations (200-1000 ppm) were suppressed the oxidation of soybean oil. The highest oxidation inhibitor was belonged to 1000 ppm concentration of the ethanolic extract so that can be good alternative for BHT.