Laurus nobilis L., comparative chemical composition and antimicrobial activity of essential oils from fresh leaves, flowers and fruits

The present study deals with the investigation of the chemical composition and antimicrobial activity of the essential oils of Laurus nobilis L. growing wild in Lebanon. Essential oils from fresh leaves, flowers and fruits were extracted using hydrodistillation method (HD) and were analyzed by GC/GC-MS. The chemical composition of the oils from the three plant parts were compared to each other and to literature data. Twenty compounds accounting for 97.2% of the total oil, with 1% oil yield were identified in the essential oil of the leaves, the major components were 1,8-cineole (55%), alpha-pinene (10.4%) and gamma-terpinene (4.5%). Twenty-four compounds, accounting for 91.7% with 0.32% oil yield were identified in the essential oil of the flowers, their major components were 1,8-cineole (28.3%) and trans-beta-ocimene (5.2%). Twenty-two compounds accounting for 90.3% with 0.26% oil yield were identified in the essential oil of the fruits, their major components were trans-beta-ocimene (31.9%), alpha-phellandrene (14.3%), 1,8-cineole (12.3%) and alpha-pinene (7.4%). Essential oil was also subject to a screening for potential antimicrobial activity in vitro against three strains of pathogenic bacteria and one of the yeast Candida albicans using the disk diffusion method. Essential oil showed activity against three microorganisms, but not against Pseudomonas aeruginosa. The various essential oils showed almost identical activities and MICs were determined from the most active essential oil on agar medium. Our results clearly demonstrate that the essential oils of L. nobilis may present an interesting natural antimicrobial alternative.