In vitro Anti-Trichomonas vaginalis Activity of Cyprus Endemic Plant Origanum majorana Essential Oil and Synergistic...

Currently, the treatment of Trichomonas vaginalis (T. vaginalis) typically involves the use of 5-nitroimidazoles (such as metronidazole and tinidazole). However, an increasing failure in treatment is observed due to resistance developed to these drugs. For this reason, alternative drugs have been investigated, especially by using natural products. In our study, the anti-T. vaginalis activity of the Origanum majorana essential oil (OMEO), which is a Cyprus endemic plant, and its synergistic effect with metronidazole were investigated. The essential oil was extracted through hydrodistillation of the dried flowering tops of the plant. Gas chromatography and mass spectrometry (GC-MS) analyses were performed using the Agilent 5975 GC-MSD system. L929 mouse fibroblast cell line was used to determine cytotoxic activity. Two clinical strains and one metronidazole-resistant T. vaginalis standard strain were used. LC₅₀, and MLC (minimum lethal concentration) values of OMEO and metronidazole were determined by the broth microdilution method in vitro in aerobic and anaerobic conditions. The combination of OMEO with metronidazole was investigated against all strains by the checkerboard method. The major compounds in the OMEO content were determined as cis-sabinene hydrate (29.1%) and terpinen-4-ol (19.6%). In cytotoxic analyses, it was observed that the cell viability remained stable at low doses. OMEO is effective against all three T. vaginalis strains. There is a significant difference between the IC₅₀ averages at the 24^th and 48^th hours (333.03 µg/mL and 226.43 µg/mL, respectively) in aerobic conditions (p=0.003). In addition, there is a statistically significant relationship between the results of the 24^th and 48^th hours (348.77 µg/mL and 238.80 µg/mL, respectively) in the anaerobic conditions (p=<0.0001). In general, OMEO has been shown to have a synergistic effect with metronidazole. In conclusion, we believe that OMEO is a potential natural agent that can be particularly used in the treatment of protozoan infections, including T. vaginalis.