Determination of antioxidant activities of solvent extracts from an endemic plant: Phlomis leucophracta

The members of the genus Phlomis have been traditionally used for therapeutic purposes in Turkey. In this study, the antioxidant properties of different extracts from P. leucophracta were investigated. Antioxidant properties were evaluated by different assays including free radical scavenging (DPPH assay), reducing power (potassium ferricyanide method), β-carotene/linoleic acid, metal chelating and phosphomolybdenum. Moreover, total phenolic and flavonoid contents were detected for each extracts. Total phenolic and flavonoid contents were detected as 30.86-55.00 mg GAE/g extract and 4.93-26.09 mg QE/g extract, respectively. The methanol and water extracts exhibited higher DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and reducing power abilities as compared to ethyl acetate and hexane extracts. The best activity was observed by the hexane extract in β-carotene/linoleic acid assay (94.35% at 2 mg/mL). In metal chelating ability, those samples exhibited the following order (at 0.25 mg/mL concentration): Water (73.90%)>Hexane(64.87%)>Ethyl acetate(4.88%)>Methanol (2.28%). Based on our results, P. leucophracta may be utilized as a natural source of antioxidant compounds in food and pharmaceutical areas.