Comparison of the chemical constitutions, antibacterial, anti-Candida, and antioxidant activity of Nepeta asterotricha Rech. F. essential oil

Abstract

Essential oils of eight populations of Nepeta asterotricha Rech. f. were isolated by hydro-distillation method. The obtained oil varied between 1.92-2.87% and 2.23-3.44% before and during full flowering stages, respectively. The GC-FID and GC–MS analyses identified 31 compounds among which 4aα, 7β, 7aα-nepetalactone (20.6-35.8%) was the major component in all populations. Bioassay results identified weak to acceptable activity against S. aureus and E. coli however; the oil exhibited a remarkable anti-Candida activity. Minimum inhibitory concentration (MIC) values for the tested bacteria varied between 1-2 mg/mL while for Cefixime, the value fluctuated from 1 to 64 µg/mL. Antioxidant activity of the oil was carried out with DPPH that showed suitable property. The strongest activity was exhibited by NaF-8 with an IC50 value of 5.06 µg/mL, which was as effective as BHT .