Chemical Composition and Antioxidant Activity of Rhododendron lepidotum Wall. ex D. Don, Essential Oil from Nepal

Abstract

The essential oil in the fresh leaves of Rhododendron lepidotum Wall. ex D. Don was isolated using Clevenger-type hydrodistillation apparatus and its chemical compositions were analyzed by GC-MS analytical method. A total numbers of 21 chemical constituents were identified and quantified occupying 96.68% of total oil composition. The chemical constituent of Rhododendron oil composes of monoterpene hydrocarbons, oxygenated montoterpines and sesquiterpine hydrocarbons. The major chemical constituents were α-pinene (39.35%) and β-pinene (13.82%) along with trans-caryophyllene (9.79%), δ-cadinene (9.4%), β-myrcene (7.25%) and α-amorphene (3.77%). The antioxidant activity of Rhododendron lepidotum oil was studied based on DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical scavenging activity by finding IC ₅₀ value and comparing its IC ₅₀ value with standard ascorbic acid. IC ₅₀ value associated with it was 12.22 µg/ml which is nearly closer with standard ascorbic acid (4.42µg/ml) indicating that the fresh leaves of Rhododendron lepidotum essential oil shows good potential antioxidant activities.