The chemical structure- antimicrobial activity relationship of monoterpenoids evaluated in vapour phase

Our investigation was focused on the chemical structure-antimicrobial relationship of new anti-infective agents. This study used the broth microdilution volatilization method [1] to test the growth-inhibitory effect of selected monoterpenoids in liquid and vapour phase against standard strains of respiratory pathogens such as Haemophilus influenzae, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes. Thymoquinone (p-menthane) possessed the strongest antibacterial activity against all bacteria tested except P. aeruginosa with MICs ranging from 8 to 16 μg/mL in liquid and from 16 to 32 μg/mL in vapour phase. In addition, MICs of thymol, carvacrol (p-menthanes), and β-thujaplicin (cycloheptane monoterpenoid) against all pathogens tested vary between 32 to 1024 μg/mL and 128 to 1024 μg/mL in liquid and vapour phase, respectively. Representatives of acyclic monoterpenoids, m-menthanes, cyclohexane monoterpenoids, camphanes, fenchanes, pinanes, caranes, and thujanes did not show relevant antimicrobial activity. The results suggest, that the monoterpenoid subgroups p-menthanes and cycloheptane monoterpenoids characterized by a ring structure with hydroxyl- and/or keto groups have antimicrobial activity in liquid and vapour phase.

Publication History

Article published online:
13 December 2021

• References

• 1 Houdkova M.. et al. 2017; Fitoterapia 2017 118: 56-62