Screening and bioguided fractionation of Amaryllidaceae species with activity against Trichomonas vaginalis

The Amaryllidaceae family is known by its ornamental and medicinal value and has attracted considerable attention due their content of alkaloids. Taking into account the noteworthy popular use of Amaryllidaceae in sexually transmitted diseases (STD) treatment, the investigation of their anti-Trichomonas vaginalis potential is a significant issue. Trichomonas vaginalis is a flagellated protozoan that parasitizes the urogenital human tract and causes trichomonosis, the most prevalent non-viral STD worldwide. In this context, this work evaluated Amaryllidaceae plants to anti-T. vaginalis activity. Dichloromethane and n-butanol extracts from Hippeastrum and Rhodophiala species and alkaloids isolated from these plants were tested in seven concentrations (12.5 to 0.19mg/ml and 125 to 1.9µg/ml, respectively). All alkaloids (lycorine, montanine, pretazettine, tazettine, hippeastrine, and lycosinine) diminished the trophozoites viability, ranging from 15 to 40% citotoxicity. The dichloromethane extract from R. bifida, H. breviflorum, H. vittatum, and H. psittacinum reduced the viability of the trophozoites of T. vaginalis in about 30–60% in the lower concentration. The H. breviflorum extracts demonstrated the highest anti-T. vaginalis activity (60% of viability reduction) and a bioguided study were realized. Nine alkaloids enriched dichloromethane and n-butanol fractions were obtained and tested. Among these fractions the one butanol fraction is the most active against T. vaginalis because reduced the viability at 100%. All the active fractions contain lycorine and lycosinine as major components and a synergism can occur considering the higher anti-T. vaginalis activity of extracts than alkaloids.