Chemical characterization and antimicrobial properties of essential oils of five aromatic herbs from Alentejo flora

Abstract

Aromatic plants, an important source of biologically active products, have been used for a variety of purposes for thousands of years and are recognized by their antibacterial, antifungal, antiviral, insecticidal, and antioxidant properties. The use of essential oils (EOs) are increasingly alongside in traditional medicine. Alentejo (southeast of Portugal) is a Mediterranean region rich in aromatic plants, often used by local populations in food preparations. The aim of current study was to evaluate the antimicrobial and toxicological properties of EOs of five aromatic herbs and to correlate with chemical composition. The aromatic plants selected for this study were: Calamintha nepeta (L.) Savi subsp nepeta (calamint), Lavandula stoechas L. subsp luisieri (Rozeira) Rozeira (topped lavender), Mentha spicata L. (spearmint), Rosmarinus officinalis L. (rosemary) and Foeniculum vulgare L. (fennel). EOs were extracted from the aerial parts of plants by hydrodistillation and chemical composition was evaluated by GC-FID. Antimicrobial activity was assessed by solid diffusion disk assay and minimal inhibitory concentration estimation (MIC) against Gram-positive and Gram-negative bacteria (Staphylococcus spp., Streptococcus spp., Enterobactereaceae strains and Pseudomonas aeruginosa) and against food spoilage fungi (Aspergillus spp., Fusarium oxysporum and Penicillium spp.).