Comparison of Phenolic Compounds and Antioxidant Activities of the Extracts of Grape Seed, Rosemary, Green Tea and Olive Leaf

Abstract

Objective: Total antioxidant activities and phenolic compounds of ethanol extract of grape seed, rosemary, green tea and olive leaf were investigated in this study.Material and Methods: The total antioxidant activities of plant extracts were analyzed by two different methods, including 2.2-diphenyl-1-picrylhydrazyl hydrate (DPPH) radical scavenging activity and trolox equivalent antioxidant capacity (TEAC). Carnosic acid, rosmarinic acid in rosemary extract (RE), total catechins in green tea extract (GTE) and oleuropein in olive leaf extract (OLE) were identified by high performance liquid chromatography (HPLC) method. Condensed tannins of grape seed extract (GSE) was analyzed by butanol-HCl method.Results: The total phenolic contents of plant extracts determined by the Folin-Ciocalteu method ranged from 141.7 to 315.56 mg of gallic acid equivalents (GAE) g-1. According to results obtained this study, RE exhibited the highest DPPH radical scavenging activity, and GTE exhibited highest TEAC activity. Additionally, obtained data revealed high linear correlation (r=0.82) between total phenolic contents and TEAC values and low linear correlation (r=0.47) between total phenolic contents and DPPH values.Conclusion: The potent antioxidant activity of plant extracts provided from agro-industrial by-products, medicinal and aromatic plants makes it possible used them as natural sources of antioxidants in feed, food and pharmaceutical industries.