Antioxidant Acitvity and Chemical Composition of Essential Oils of Fresh and Air-dried Jordanian Nepeta curviflora Boiss.

Abstract

This study was designed to examine the chemical composition and the in-vitro antioxidant activity of the essential oils obtained from fresh and air-dried flowering aerial parts of Nepeta curviflora growing wild in Jordan. The oils were analyzed by GC-MS and GC-FID. The oil obtained from fresh flowering parts was composed mainly of sesquiterpenes hydrocarbons (55.27%) while air-dried N. curviflora was composed mainly of oxygentated monoterpenes (50.31%). The major components identified in the oils of fresh and air-dried N. curviflora were 4aα,7α,7aα-Nepetalactone (17.76%, 43.85%, respectively), E-caryophyllene (16.37%, 11.53%, respectively) and γ-muurolene (18.54%, 10.47%, respectively). The oil obtained from both the fresh and air-dried N. curviflora were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assays. The oil obtained from the dried plant was more active (IC₅₀ (mg/mL) 0.30 ± 7.07*10^-3 DPPH; 0.18 ± 4.71*10^-4ATBS) as compared to that obtained from the fresh plant material (IC₅₀ (mg/mL) 0.54 ± 0.02 DPPH; 0.29 ±1.63*10^-3ATBS).

Key words:

• Nepeta curviflora
• Essential oil
• Antioxidant
• Nepetalactone
• GC-MS