Anti-Pentatrichomonas hominis activity of newly synthesized benzimidazole derivatives — in vitro studies

Pentatrichomonas hominis, a parasitic protozoan often detected in human diarrheic stools, is the cause of severe morbidity in newborns and children, particularly in tropical zones. The flagellate is resistant to many disinfectants and anti-protozoan drugs. Therefore in this study we have synthesized three novel 4,5,6,7-tetrabromobenzimidazole (TBBI) derivatives carrying a polyfluoroalkyl substituent in position 2 of the benzimidazole scaffold, namely 2-trifluoromethyl-TBBI (CF3-TBBI), 2-nonafluorobutyl-TBBI (C4F9-TBBI), and 2-nonadecafluorononyl-TBBI (C9F19-TBBI), that next we tested for their in vitro activity against P. hominis.Widely applied anti-protozoal drug, metronidazole as a reference was used. All the investigated agents were added to 24 h P. hominis cultures; each of them was administered at three different concentrations. Number of the moving trichomonads was determined and compared with the control cultures. Different anti-trichomonal activity occurred depending on a kind of compound and its concentration. C4F9-TBBI was the most effective TBBI derivative tested: the agent, at the highest concentration 24.2 μg/ml, after 72 h reduced the number of viable trichomonads to 44.3%; C9F19-TBBI, at the concentration 24 μg/ml reduced the number of the flagellates to 58.5%. Paradoxically, metronidazole after the same time given at the highest concentration increased trophozoite counts by 464.6% in comparison with the control cultures (100%).