Composition and profiling of essential oil, volatile and crude extract constituents of Micromeria inodora growing in western Algeria

Abstract

The chemical constituents of the aerial parts of Micromeria inodora (Desf.) Benth. (Lamiaceae) collected in western Algeria, an aromatic shrub traditionally consumed as an herbal remedy, have been characterized. Secondary metabolites were extracted using sequential extractions with solvents at different polarity, and they were determined using an integrated nuclear magnetic resonance (NMR) and high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) approach. The composition of the essential oil obtained by hydrodistillation was characterized by gas chromatography-mass spectrometry (GC-MS), and the aroma profile was analysed by head-space solid phase micro extraction (HS-SPME) coupled with GC-MS. NMR and LC-MSⁿ analyses revealed the presence of aglyconic and glycosylated flavonoids, phenylpropanoid derivatives and triterpenoid acids, mainly in the methanol, dichloromethane and n-hexane extracts. The analysis of the essential oil allowed to identify 66 components, mainly oxygenated mono- and sesquiterpenes (38.2 % and 32.0 %, respectively) and sesquiterpene hydrocarbons (10.8 %). The aroma profile revealed by HS-SPME-GC-MS was characterized by 45 volatile compounds, among which oxygenated monoterpenes appeared to be the most abundant (65.8 %), followed by sesquiterpene hydrocarbons (16.4 %) and monoterpene hydrocarbons (10.6 %). Overall, these data indicate that M. inodora could be a potential source of antioxidants and bioactive compounds, and they represent a starting point for further research on this plant species.

Keywords: Bioactive secondary metabolites; Essential oil; GC–MS; HPLC-MS; Micromeria inodora; NMR.