Antibacterial effect of the combination of terpenoids.

Terpenoids are natural compounds originating from five-carbon isoprene units. Over 60,000 terpenoid structures have been identified, and they contribute to the flavor, color, growth, and development of plants. There are several reports on various physiological activities of terpenoids, such as antioxidative and anticancer activities. This study revealed that combinations of terpenoids have activities against a spectrum of bacteria. The combination of carvacrol and thymol has bacteriostatic and bactericidal activities. Four terpenoids (carvacrol, thymol, eugenol, and nootkatone) exhibited bacteriostatic and bactericidal activities when used at low concentrations for 5‒10 min. The most effective bactericidal activity was observed for gram-negative bacteria. A very weak bactericidal activity was observed against Staphylococcus aureus and Enterococcus faecalis. This study revealed the antibacterial potential of different combinations of terpenoids against several bacteria that were tested. Thus, new candidates for the development of antibacterial medicines are reported here for the effective treatment of infectious bacterial diseases.