Comparative chemical analysis of volatile compounds of Echinops ilicifolius using hydrodistillation and headspace solid-phase microextraction and the antibacterial activities of its essential oil.

Razieh Mohebat,Mina Zare Bidoki

doi:10.1098/rsos.171424

Abstract

The volatile compounds from various parts of Echinops ilicifolius (Compositae) such as flowers, leaves and roots obtained by hydrodistillation (HD) and headspace solid-phase microextraction (HS-SPME) methods were subsequently analysed by GC and GC/MS and compared. Thirty-seven and 20 components of the flower of E. ilicifolius were characterized, representing 99.7% and 100.0% of the total compositions using the HD and HS-SPME methods, respectively. The major constituents of the hydrodistilled oil were identified as linalool (58.6%), geraniol (17.4%), n-dodecane (10.9%) and nerol (5.4%), whereas HS-SPME extract was rich in n-octane (34.0%), n-decane (25.1%), p-cymene (11.1%), γ-terpinene (5.3%) and 1,8-cineole (5.1%). n-Hexadecanoic acid (32.3%), linalool (16.4%) and geraniol (8.3%) were the main components among 43 constituents identified in hydrodistilled extract of the leaf, representing 99.5% of the total components detected, whereas 16 compounds representing 99.9% of the HS-SPME method were identified, among which n-decane (32.6%), p-cymene (14.0%), n-octane (10.3%), limonene (9.2%), γ-terpinene (9.1%), 1,8-cineole (7.9%) and α-pinene (5.9%) were the major ones. Among 23 components comprising 91.2% of the total hydrodistilled oil detected, n-decane (23.1%), n-dodecane (14.5%), silphiperfol-4,7(14)-diene (11.1%), selin-11-en-4-a-ol (9.5%), n-hexadecanoic acid (7.8%) and n-tetradecane (5.3%) were the main constituents in the root of E. ilicifolius, whereas 1,8-cineole (29.0%), n-decane (12.6%), n-octane (12.6%), camphor (12.0%), p-cymene (9.6%) and γ-terpinene (5.9%) were the main components among the 20 constituents characterized in HS-SPME extract, representing 99.9% of the total components detected. The antibacterial activity of the flower, leaf and root oils of E. ilicifolius against six Gram-positive and Gram-negative bacteria was determined using the MIC method. The growth inhibitory zone (mm) was also measured.

Highlights

Echinops is one of the most important and largest genera of the Compositae family comprising more than 120 species worldwide [1]
The chemical analysis results obtained by HD and headspace solid-phase microextraction (HS-SPME) methods from E. ilicifolius are presented in table 1
HS-SPME analysis of flowers and leaves led to identification of nine and 16 components accounting for 100.0% and 99.9%, respectively

Summary

Introduction

Echinops is one of the most important and largest genera of the Compositae family comprising more than 120 species worldwide [1] These plants are distributed from Eastern Europe to Central Asia and from the South to the tropical mountains of Africa [2], of which about 54 species are represented in Iran [3]. Diverse species of this genus are extensively applied in Chinese and Indian folk medicine as a stimulant for milk secretion, analgesic, antityphus, to expel miasma, calm stomach ache diuretic and reduce asthma attack [4,5]. Tehrani et al investigated the effect of the methanol extract of Echinops ilicifolius on peripheral blood mononuclear cells proliferation and interleukin (IL)-4 secretions [30]

Methods

Results

Conclusion