Antibacterial and antifungal activities of essential oils from medicinal plants found in the South Pacific

Abstract

Natural products such as essential oils have been studied since ancient times to understand their biological properties. Essential oils are noted for their antimicrobial activity. Thus, the focus of this study was to evaluate the antimicrobial effect of five essential oils (EOs) from selected medicinal plants found in the South Pacific, on selected human pathogenic bacteria and fungi affecting agricultural industries. The disc diffusion method was carried out and the diameter of inhibition zones (mm) (DZI) using 0.25, 0.5, 5, 25, 50 and 100% (v/v) of essential oil concentrations were reported. The activity of Cananga odorata essential oils against Thermus thermophiles and Pseudomonas aeruginosa were among the selected bacteria that only showed the susceptibility at the lowest concentration (0.25% v/v). The diameter inhibition zones were 1.60 mm and 4.20 mm, respectively. The inhibitory effect of Ocimum tenuiflorum L essential oils at the highest concentration (100%) showed DZI ranging above 14 mm for all the selected bacteria and above 25 mm for the all selected fungi. The inhibitory effect of selected bacteria and fungi increased with stronger concentrations of essential oils. Hence, the essential oils from medicinal plants found in the South Pacific hold great potential for the antibacterial and antifungal properties.