Abstract

The essential oils from the aerial part of two Lamiaceae species namely, Ajuga bracteosaand Lavandula dentata growing in Yemen were obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography mass spectrometry (GC/MS). Parallel to that, evaluation of their antimicrobial and antioxidant activities was also carried out. The investigation led to the identification of 47 and 48 components for both plants respectively. Both oils were rich in oxygenated monoterpenes (34 to 51%). A. bracteosa oil contained as well a high content of aliphatic acids (30.3%). Borneol (20.8%) and hexadecanoic acid (16.0%) were the main constituents of the oil of A. bracteosa. Camphor (12.4%), trans-pinocarveol (7.5%), β-eudesmol (7.1%) and α-guiaol (6.1%) predominated inL. dentata. Both essential oils possessed antimicrobial activity with MIC-values between 0.33 and 12.2 mg/ml. Moreover, the DPPH-radical scavenging assay exhibited a significant antioxidant activity for A. bracteosa (78%) at 1.0 mg/ml.   

Key words: Ajuga bracteosa, Lavandula dentata, antimicrobial, antioxidant, essential oils, gas chromatography mass spectrometry (GC/MS).