Determination of antioxidant activities of Nepeta fissa and Nepeta nuda subsp. albiflora by different in vitro methods and analyses of their phenolic compounds by HPLC

The main aim of this study is to determine the antioxidant activities of ethanol and water extracts of Nepeta nuda subsp. albiflora and Nepeta fissa and evaluate the phenolic compounds of these plants by HPLC. In order to determine the antioxidant activity of these ligands and complexes; tiocyanate antioxidant assay, ABTS cation radical scavenging activity, DPPH∙ free radical scavenging activity, FRAP method (ferric ions reducing antioxidant potential), and CUPRAC method (cupric ions reducing antioxidant capacity) in vitro bioanalytical methods were studied. The results were compared to BHA, BHT, tocopherol, trolox, and ascorbic acid as standard antioxidant compounds. Aqueous and ethanol extracts of Nepeta nuda subsp. albiflora and Nepeta fissa presented moderate antioxidant potential on ABTS, DPPH, FRAP, and CUPRAC assays. Additionally, determination of phenolic compounds by HPLC were achieved for plant samples. It was determined that the ethanol extract was determined to contain higher phenolic compounds than to the water extract for both Nepeta nuda subsp. albiflora and Nepeta fissa. It was also determined that apigenin and rosmarinic acid were the major phenolic compounds for plant species.