Efficacy of the treatment using a microemulsion loaded with epoxy-α-lapachone in combination with meglumine antimoniate against murine infection by Leishmania (Leishmania) amazonensis.

Leishmaniasis is a disease caused by Leishmania spp., affecting millions of people around the world. For decades, its treatment has been based on pentavalent antimonials, which notoriously cause toxic side effects in patients. In this study, epoxy-α-lapachone incorporated into an oil-in-water-type microemulsion (ELAP-ME) and meglumine antimoniate (MA) were assayed in monotherapy and in combination (ELAP-ME/MA) in BALB/c mice infected with Leishmania (Leishmania) amazonensis. In general, there was a reduction in paw lesion size (up to 37% reduction) and decreases of parasite loads in the footpad (∼40%) and lymph nodes (∼31%) of animals treated with ELAP-ME/MA, when compared to the non-treated control groups. Analyses of serum biochemical parameters revealed that the ELAP-ME/MA showed lower renal and hepatic toxicity when compared to MA 2-doses/week monotherapy. These findings indicate that the ELAP-ME/MA combination may be a promising approach for the treatment of cutaneous leishmaniasis.

Assessing nystatin cream treatment efficacy against Leishmania (L.) amazonensis infection in BALB/c model.

The current scenario for cutaneous leishmaniasis treatment includes the use of first and second-choice drugs, both therapeutic strategies presenting several adverse effects and being related to an increment of treatment-refractory parasite strains. These facts encourage the search for new treatment approaches, including repositioning drugs, such as nystatin. Although in vitro assays show that this polyene macrolide compound has leishmanicidal activity, no in vivo evidence for a similar activity has been shown so far for the commercial nystatin cream formulation. This work assessed the effects of nystatin cream (25,000 IU/g) administered on mice in an amount to completely cover the paw surface of BALB/c mice infected with Leishmania (L.) amazonensis once a day, until a total of up to 20 doses. The data presented herein points to unequivocal evidence that treatment with this formulation causes a statistically significant reduction of swelling/edema in mice paws when compared to animal groups not submitted to this treatment regimen after the fourth week of infection: lesion sizes at the sixth (p = 0.0159), seventh (p = 0.0079) and eighth (p = 0.0079) week. Furthermore, swelling/edema reduction relates to a decrease in parasite load in the footpad (∼48%) and in draining lymph nodes (∼68%) at eight weeks post-infection. This is the first report of the effectiveness of nystatin cream used as a topical treatment in BALB/c model for cutaneous leishmaniasis.

Development of a microemulsion loaded with epoxy-α-lapachone against Leishmania (Leishmania) amazonensis murine infection.

Epoxy-α-lapachone (ELAP), an oxirane-functionalized molecule synthesized from naturally occurring lapachol, has shown promising activity against murine infection with Leishmania (Leishmania) amazonensis. Herein, we report the successful development of oil-in-water-type (o/w) microemulsions (ME) loaded with ELAP (ELAP-ME) using Capmul MCM, Labrasol, and PEG 400. Stability studies revealed that ELAP-ME (100 µg/mL of ELAP), which was comprised of globule size smaller than 120.4 ± 7.7 nm, displayed a good stability profile over 73 days. ELAP-ME had an effect in BALB/c mice infected with L. (L.) amazonensis, causing reductions in paw lesions after two weeks of treatment (∼2-fold) when compared to untreated animals. Furthermore, there was also a reduction in the parasite load both in the footpad (60.3%) and in the lymph nodes (31.5%). Based on these findings, ELAP-ME emerges as a promising treatment for tegumentar leishmaniasis.

Epoxy-α-lapachone (2,2-Dimethyl-3,4-dihydro-spiro[2H-naphtho[2,3-b]pyran-10,2'-oxirane]-5(10H)-one): a promising molecule to control infections caused by protozoan parasites.

Natural products and their derivatives have been sources of search and research for new drugs for the treatment of neglected diseases. Naphthoquinones, a special group of quinones, are products of natural metabolites with a wide spectrum of biological activities and represent a group of interesting molecules for new therapeutic propositions. Among these compounds, lapachol stands out as a molecule from the heartwood of Tabebuia sp. whose structural changes resulted in compounds considered promising, such as epoxy-α-lapachone (ELAP). The biological activity of ELAP has been demonstrated, so far, for parasitic protozoa such as Leishmania spp., Trypanosoma cruzi and Plasmodium spp., species causing diseases needing new drug development and adequate health policy. This work gathers in vitro and in vivo studies on these parasites, as well as the toxicity profile, and the probable mechanisms of action elucidated until then. The potential of ELAP-based technology alternatives for a further drug is discussed here.

Epoxy-α-lapachone(2,2-Dimethyl-3,4-dihydro-spiro[2H-naphtho[2,3-b]pyran-10,2′-oxirane]-5(10H)-one): a promising molecule to control infections caused by protozoan parasites

ABSTRACT Natural products and their derivatives have been sources of search and research for new drugs for the treatment of neglected diseases. Naphthoquinones, a special group of quinones, are products of natural metabolites with a wide spectrum of biological activities and represent a group of interesting molecules for new therapeutic propositions. Among these compounds, lapachol stands out as a molecule from the heartwood of Tabebuia sp. whose structural changes resulted in compounds considered promising, such as epoxy-a-lapachone (ELAP). The biological activity of ELAP has been demonstrated, so far, for parasitic protozoa such as Leishmania spp., Trypanosoma cruzi and Plasmodium spp., species causing diseases needing new drug development and adequate health policy. This work gathers in vitro and in vivo studies on these parasites, as well as the toxicity profile, and the probable mechanisms of action elucidated until then. The potential of ELAP-based technology alternatives for a further drug is discussed here.

In Silico Insights into the Mechanism of Action of Epoxy-α-Lapachone and Epoxymethyl-Lawsone in Leishmania spp.

Epoxy-α-lapachone (Lap) and Epoxymethyl-lawsone (Law) are oxiranes derived from Lapachol and have been shown to be promising drugs for Leishmaniases treatment. Although, it is known the action spectrum of both compounds affect the Leishmania spp. multiplication, there are gaps in the molecular binding details of target enzymes related to the parasite's physiology. Molecular docking assays simulations were performed using DockThor server to predict the preferred orientation of both compounds to form stable complexes with key enzymes of metabolic pathway, electron transport chain, and lipids metabolism of Leishmania spp. This study showed the hit rates of both compounds interacting with lanosterol C-14 demethylase (-8.4 kcal/mol to -7.4 kcal/mol), cytochrome c (-10.2 kcal/mol to -8.8 kcal/mol), and glyceraldehyde-3-phosphate dehydrogenase (-8.5 kcal/mol to -7.5 kcal/mol) according to Leishmania spp. and assessed compounds. The set of molecular evidence reinforces the potential of both compounds as multi-target drugs for interrupt the network interactions between parasite enzymes, which can lead to a better efficacy of drugs for the treatment of leishmaniases.

Potential of Piper spp. as a source of new compounds for the leishmaniases treatment.

Current treatment guidelines for leishmaniasis is based on chemotherapy with drugs that show a set of limitations such as high cost, toxicity, difficult route of administration, and lack of efficacy in endemic areas. In this context, phytopharmaceutical products and herbal medicines emerge as promising alternatives for developing new treatment against leishmaniasis. This review discusses the perspectives of leishmaniasis treatment based on natural products and phytotherapy highlighting the Piper genus, especially P. aduncun and P. mollicomum Kunth covering the period of 1998 to 2020. Leishmanicidal activity of pure compounds of Piper spp. [3-(3,4,5-trimethoxyphenyl) propanoic acid, 3-chlorosintenpyridone, 2'-hydroxy-3',4',6'-trimethoxy-chalcone, cardamonin, conocarpan, cubebin, eupomatenoid, flavokavain B, ( +)-(7R,8S)-epoxy-5,6-didehydrokavain, N-[7-(3',4'-methylenedioxypheny l-2(E),4(E)-heptadienoyl-pyrrolidine, N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl-pyrrolidine, piperovatine, pellitorine, and piplartine (piperlongumine)] were proved against the promastigote and amastigote forms of parasite related with cutaneous (L. (L.) amazonensis, L. (V.) braziliensis, and L. (V.) guyanensis) and visceral (L. (L.) donovani, L. (L.) chagasi, and L. (L.) infantum). We also discussed the perspective of leishmaniasis treatment, considering the potential synergism between different promising species of Piper, presenting some interesting interaction possibilities for future studies between plants. Finally, the necessary steps for technological development of phytomedicines and herbal medicines with the desirable quality requirements for medicines are highlighted. The data presented here highlight the use of Piper spp. as source of pharmacological compounds that can lead to effective, safe, and inexpensive treatments for leishmaniasis.

Establishment of suitable reference genes for studying relative gene expression during the transition from trophozoites to cyst-like stages and first evidences of stress-induced expression of meiotic genes in Trichomonas vaginalis.

Trichomonas vaginalis is a parasite of the human urogenital tract and the causative agent of trichomoniasis, a sexually transmitted disease of worldwide importance. This parasite is usually found as a motile flagellated trophozoite. However, when subjected to stressful microenvironmental conditions, T. vaginalis trophozoites can differentiate into peculiar cyst-like stages, which exhibit notable physiological resistance to unfavourable conditions. Although well documented in morphological and proteomic terms, patterns of gene expression changes involved in the cellular differentiation into cyst-like stages are mostly unknown. The real-time reverse transcription polymerase chain reaction (RT-qPCR) is recognized as a sensitive and accurate method for quantification of gene expression, providing fluorescence-based data that are proportional to the amount of a target RNA. However, the reliability of relative expression studies depends on the validation of suitable reference genes, which RNAs exhibit a minimum of variation between tested conditions. Here, we attempt to determine suitable reference genes to be used as controls of invariant expression during cold-induced in vitro differentiation of T. vaginalis trophozoites into cyst-like forms. Furthermore, we reveal that the mRNA from the meiotic recombinase Dmc1 is upregulated during this process, indicating that cryptic sexual events may take place in cyst-like stages of T. vaginalis.

Morphologic study of the effect of iron on pseudocyst formation in Trichomonas vaginalis and its interaction with human epithelial cells

BACKGROUND Trichomonas vaginalis is the aetiological agent of human trichomoniasis, which is one of the most prevalent sexually transmitted diseases in humans. Iron is an important element for the survival of this parasite and the colonisation of the host urogenital tract. OBJECTIVES In this study, we investigated the effects of iron on parasite proliferation in the dynamics of pseudocyst formation and morphologically characterised iron depletion-induced pseudocysts. METHODS We performed structural and ultrastructural analyses using light microscopy, scanning electron microscopy and transmission electron microscopy. FINDINGS It was observed that iron depletion (i) interrupts the proliferation of T. vaginalis, (ii) induces morphological changes in typical multiplicative trophozoites to spherical non-proliferative, non-motile pseudocysts, and (iii) induces the arrest of cell division at different stages of the cell cycle; (iv) iron is the fundamental element for the maintenance of typical trophozoite morphology; (v) pseudocysts induced by iron depletion are viable and reversible forms; and, finally, (vi) we demonstrated that pseudocysts induced by iron depletion are able to interact with human epithelial cells maintaining their spherical forms. MAIN CONCLUSIONS Together, these data suggest that pseudocysts could be induced as a response to iron nutritional stress and could have a potential role in the transmission and infection of T. vaginalis.

Morphologic study of the effect of iron on pseudocyst formation in Trichomonas vaginalis and its interaction with human epithelial cells.

BACKGROUND: Trichomonas vaginalis is the aetiological agent of human trichomoniasis, which is one of the most prevalent sexually transmitted diseases in humans. Iron is an important element for the survival of this parasite and the colonisation of the host urogenital tract. OBJECTIVES: In this study, we investigated the effects of iron on parasite proliferation in the dynamics of pseudocyst formation and morphologically characterised iron depletion-induced pseudocysts. METHODS: We performed structural and ultrastructural analyses using light microscopy, scanning electron microscopy and transmission electron microscopy. FINDINGS: It was observed that iron depletion (i) interrupts the proliferation of T. vaginalis, (ii) induces morphological changes in typical multiplicative trophozoites to spherical non-proliferative, non-motile pseudocysts, and (iii) induces the arrest of cell division at different stages of the cell cycle; (iv) iron is the fundamental element for the maintenance of typical trophozoite morphology; (v) pseudocysts induced by iron depletion are viable and reversible forms; and, finally, (vi) we demonstrated that pseudocysts induced by iron depletion are able to interact with human epithelial cells maintaining their spherical forms. MAIN CONCLUSIONS: Together, these data suggest that pseudocysts could be induced as a response to iron nutritional stress and could have a potential role in the transmission and infection of T. vaginalis.