Antioxidant Activities and Phenolic Composition of Extracts from Nepeta Plant Species

The aim of this study was to assess antioxidant properties of four in Lithuanian growing Nepeta varieties, namely N. cataria, N. cataria var. citriodora, N. transcaucasica and N. bulgaricum. The plants were extracted using different polarity solvents, namely acetone, methanol, ethanol and water. The antioxidant properties were assessed by determining total content of phenolics, using free DPPH• radical scavenging assay, accelerated oil stability test and peroxide value measurement. Antioxidant activities of the analysed herb extracts were greatly dependent on the extraction solvent. Methanolic extract of N. cataria exhibited significantly higher antioxidant capacity comparing to other extracts. The sub-fractions isolated from the plant material were analysed by HPLC-MS and the concentration of some phenolic acids was determined. Rosmarinic acid was the major component in all extracts; luteolin, and caffeic acid were other identified constituents, however present in considerably lower amounts.