Patrícia de Brum Vieira

Lycorine induces cell death in the amitochondriate parasite, Trichomonas vaginalis, via an alternative non-apoptotic death pathway

In this study, the mechanism of action of the pro-apoptotic alkaloid lycorine on an amitochondriate cell, the parasite Trichomonas vaginalis, was investigated. The cytotoxicity of lycorine against T. vaginalis was studied from 2.5 to 1000μM and several important ultrastructural alterations were observed by electron microscopy. Lycorine arrested the T. vaginalis cell cycle, although no hallmarks of apoptosis, such as apoptotic bodies, were observed. Consequently, the underlying mechanism of action fails to completely fulfill the criteria for apoptosis. However, some similarities to paraptotic cell death were observed.

Anti-Trichomonas vaginalis activity of saponins from Quillaja, Passiflora, and Ilex species

Trichomonas vaginalis is a flagellated protozoan that causes trichomonosis, the most prevalent non-viral STD worldwide. The pathogen has been associated with serious health consequences including predisposition to cervical cancer and adverse pregnancy outcomes and infertility. It also acts as a co-factor in HIV transmission and acquisition. The 5-nitroimidazole drugs are used in the treatment, however, treatment noncompliance is observed, and a growing number of T. vaginalis isolates resistant to the drugs have been related. Saponins are natural products possessing many biological activities such as antiprotozoan activity. The aim of this study was to evaluate the anti-T. vaginalis activity of saponins from Quillaja, Passiflora, and Ilex species. Saponins from Passiflora alata and Quillaja saponaria presented the best anti-T. vaginalis activity (MIC = 0.025%). In addition, all samples induced erythrocyte lysis and LDH release. As far as we know, this is the first report demonstrating the potential anti-T. vaginalis activity of these saponins.

Candimine-induced cell death of the amitochondriate parasite Trichomonas vaginalis.

Candimine (1), an alkaloid from the bulbs of Hippeastrum morelianum, was found to be cytotoxic for the amitochondriate parasite Trichomonas vaginalis. Candimine (1) induced cell death with an unprecedented group of effects that failed to fulfill the criteria for apoptosis and apoptosis-like death already reported in trichomonads. Arrest of the parasite cell cycle, and morphologic and ultrastructural alterations, including marked cytoplasmic vacuolization, were induced by 1. The present findings suggest some similarities to paraptotic cell death, described for multicellular organisms. This study contributes to both a better understanding of the biological effects of 1 and T. vaginalis cell biology.

Natural and synthetic compound anti-Trichomonas vaginalis: an update review.

Trichomonas vaginalis is a flagellate protozoan that causes trichomonosis, a sexually transmitted disease of worldwide importance. However, the infection has long received much less attention than other parasitic and sexually transmitted diseases. This negligence leads to poor diagnosis and underestimated prevalence values, and consequently, it has been associated to increasing acquisition and transmission of HIV, pregnancy outcomes, infertility, pelvic inflammatory disease, and cervical and prostate cancer. In view of increased resistance to drugs belonging to the nitroimidazole class, new treatment alternatives are urgently needed. Natural products provide an immeasurable wealth of active molecules, and a great number of new drugs have been originated from these compounds. In addition, new synthetic products or derivatives from old drugs also provide an alternative to treat trichomonosis. Albeit many studies have been performed with natural products against T. vaginalis, none of them progressed to clinical trials. Overall, inadequate financial investments are made, and no alternative treatment for trichomonosis has been discovered; meanwhile, hundreds of thousands of people will remain infected and suffering the serious consequences of this nonviral STD. Thus, it is highlighted that clinical trials for better understanding the potential in vitro are necessary and urgent in order to furnish a new therapeutic alternative for trichomonosis treatment. The current review attempts to give an overview on the potential of natural and synthetic products as antitrichomonal.

Screening and bioguided fractionation of Amaryllidaceae species with anti-Trichomonas vaginalis activity.

The Amaryllidaceae family is known by its ornamental and medicinal value and has attracted considerable attention due to the content of alkaloids of its species, which showed interesting biological properties. The present study evaluated the anti-Trichomonas vaginalis activity of eighteen extracts (12.5 to 0.19 mg/mL) and six isolated alkaloids (125 to 1.9 µg/mL) from Amaryllidaceae species. The alkaloids diminished the trophozoites viability (from 15 to 40 %). The extracts from Hippeastrum breviflorum demonstrated the highest anti-T. vaginalis activity (viability was 60 % reduced), and a bioguided study was conducted. Six fractions with antiprotozoal activity had lycorine and lycosinine as major components suggesting a synergistic effect, taking into account the higher anti-T. vaginalis activity of extracts when compared to isolated alkaloids. Our results point out the antiprotozoal potential of the Amaryllidaceae species against T. vaginalis. This parasite causes trichomonosis, the most prevalent nonviral sexually transmitted diseases (STD) worldwide and a public health problem that requires new therapeutic alternatives as well bioactive natural products.

Characterization of nucleoside triphosphate diphosphohydrolase activity in Trichomonas gallinae and the influence of penicillin and streptomycin in extracellular nucleotide hydrolysis

Here we described an nucleoside triphosphate diphosphohydrolase (NTPDase) activity in living trophozoites of Trichomonas gallinae. The enzyme hydrolyzes a variety of purine and pyrimidine nucleoside di- and triphosphates in an optimum pH range of 6.0-8.0. This enzyme activity was activated by high concentrations of divalent cations, such as calcium and magnesium. Contaminant activities were ruled out because the enzyme was not inhibited by classical inhibitors of ATPases (ouabain, 5.0 mM sodium azide, oligomycin) and alkaline phosphatases (levamisole). A significant inhibition of ATP hydrolysis (38%) was observed in the presence of 20 mM sodium azide. Sodium orthovanadate inhibited ATP and ADP hydrolysis (24% and 78%), respectively. The apparent K(M) (Michaelis constant) values were 667.62+/-13 microM for ATP and 125+/-5.3 microM for ADP. V(max) (maximum velocity) values were 0.44+/-0.007 nmol Pi min(-1) per 10(6) trichomonads and 0.91+/-0.12 nmol Pi min(-1) per 10(6) trichomonads for ATP and ADP, respectively. Moreover, we showed a marked decrease in ATP, ADP and AMP hydrolysis when the parasites were grown in the presence of penicillin and streptomycin. The existence of an NTPDase activity in T. gallinae may be involved in pathogenicity, protecting the parasite from the cytolytic effects of the extracellular nucleotides.

Challenges and Persistent Questions in the Treatment of Trichomoniasis

Trichomoniasis is a sexually transmitted disease (STD) caused by infection with the protozoan parasite Trichomonas vaginalis. It is considered the most prevalent non-viral sexually transmitted disease worldwide. Recently, the infection has been associated with adverse outcomes of pregnancy and increased risks of HIV acquisition and transmission, as well as an association with cervical and prostate cancers. The consequences of trichomoniasis are likely much greater than previously recognized, both at the individual and the community level. Since many cases are asymptomatic, and the most common approach used for diagnosis (wet mount) is also one of the least sensitive, millions of T. vaginalis infections remain undiagnosed and therefore untreated. The purpose of this review is to address what is known about the treatment of T. vaginalis infections and what additional approaches could be pursued. The increasing recognition of the potential public health implications of trichomoniasis has resulted in greater attention to improving effectiveness of the interventions for affected individuals. Currently, treatment relies almost solely on one class of drugs, the 5- nitroimidazoles, which causes concern should widespread drug resistance arise. There are also concerns regarding which 5-nitroimidazole to use as not all of them are active against T. vaginalis. Finally, new therapeutic targets and active compounds with treatment potential are considered.

Anti-Trichomonas vaginalis activity of betulinic acid derivatives

Caused by Trichomonas vaginalis, trichomoniasis is the most common non-viral STD worldwide. Currently, metronidazole and tinidazole are the only drugs approved for treatment of the condition. However, problems such as metronidazole-resistant T. vaginalis isolates and allergic reactions have been reported. Based on data previously published by our group, structural changes in betulinic acid (1) were performed, generating three new compounds that were tested for in vitro anti-T.vaginalis activity in this study. Whereas derivative 2 did not demonstrate anti-T. vaginalis activity, derivatives 3 and 4 reduced trophozoite viability by 100%, with MIC values of 50μM. The structural difference of two compounds was performed only on the C-28 position. Derivative 3 showed low cytotoxicity against Vero cells in 24h; however, derivative 4 was highly cytotoxic, but efficient when associated with metronidazole in the synergism assay. ROS production by neutrophils was reduced, and derivative 3 showed anti-inflammatory effect. Collectively, the results of this study provide in vitro evidence that betulinic acid derivatives 3 and 4 are potential compounds with anti-T. vaginalis activity.

Morphological aspects of Monocercomonas sp. and investigation on probable pseudocysts occurrence.

Monocercomonas sp. is a flagellate protozoan found in the large intestine of snakes and in insects. Light microscopy revealed the measurements of morphological features of the trophozoites. Scanning electron microscopy showed in detail the emergence of the three anterior flagella, the recurrent flagellum, the axostyle, and the absence of undulating membrane. In addition, we described spherical forms which are probably pseudocysts. The investigation on the occurrence of this process was carried out through the incubation of Monocercomonas sp. trophozoites in several stressful conditions, such as pH change, nutrient depletion and different temperatures. Results revealed high pseudocyst formation at acidic pH values (4.0, 5.0, and 6.0), in absence of serum and in incubation at 37°C. The occurrence of these pseudocystic forms in trichomonads life cycle is under investigation. This study describes the external structure of Monocercomonas sp., as demonstrated by light and scanning electron microscopy. Moreover, to our knowledge, this is the first time that formation of probable pseudocysts is shown in Monocercomonas sp., contributing to the research field on termite protozoa biology.

Iron from haemoglobin and haemin modulates nucleotide hydrolysis in Trichomonas vaginalis

Extracellular ATP may act as a danger signalling molecule, inducing inflammation and immune responses in infection sites. The ectonucleotidases NTPDase and ecto-5’-nucleotidase are enzymes that modulate extracellular nucleotide levels; these enzymes have been previously characterised in Trichomonas vaginalis. Iron plays an important role in the complex trichomonal pathogenesis. Herein, the effects of iron on growth, nucleotide hydrolysis and NTPDase gene expression in T. vaginalis isolates from female and male patients were evaluated. Iron from different sources sustained T. vaginalis growth. Importantly, iron from haemoglobin (HB) and haemin (HM) enhanced NTPDase activity in isolates from female patients and conversely reduced the enzyme activity in isolates from male patients. Iron treatments could not alter the NTPDase transcript levels in T. vaginalis. Furthermore, our results reveal a distinct ATP, ADP and AMP hydrolysis profile between isolates from female and male patients influenced by iron from HB and HM. Our data indicate the participation of NTPDase and ecto-5’-nucleotidase in the establishment of trichomonas infection through ATP degradation and adenosine production influenced by iron.