α-Pinene Rich Bark Essential Oils of Zanthoxylum armatum DC. from Three Different Altitudes of Uttarakhand, India and their Antioxidant, in vitro Anti-inflammatory and Antibacterial Activity

Abstract

Zanthoxylum armatum DC. is a medicinally important deciduous shrub belonging to the family Rutaceae, which is widely distributed in Eastern and South Eastern Asia. The aim of the present study was to assess the chemical composition of essential oil of bark of Z. armatum collected from three different altitudes of Kumaun region, Uttarakhand, India, and to determine antioxidant, in vitro anti-inflammatory and antibacterial activity of the essential oils. The plant material was subjected to hydro-distillation using Clevenger apparatus in order to obtained volatile oil and analyzed for its volatile constituents by gas chromatography/mass spectrometry. The antioxidant activity of the oils was assessed by three different methods viz. reducing power assay, DPPH assay and effect on Fe+2 chelating activity. In vitro anti-inflammatory activity was examined by inhibition of protein denaturation method and the antibacterial activity of essential oils was determined by agar-well diffusion method. The essential oils revealed the presence of α-pinene and 2-undecanone as the major constituents. Monoterpene hydrocarbons contributed largely in the bark volatile oil collected from Bhimtal, Dharchula and Pithoragarh with α-pinene dominated amount of 33.9 %, 28.92 % and 35.9 % respectively. Z. armatum bark essential oil, from Dharchula possessed highest reducing power (RP50=17.91±0.07) compared to ascorbic acid (RP50=13.16±0.16). The essential oil from Pithoragarh collection showed a strong in vitro anti-inflammatory effect (IB50=6.40±0.48) relative to the standard drug. The essential oils were evaluated for antibacterial potential against two bacteria Escherichia coli and Staphylococcus aureus and exhibited moderate antibacterial activity.