The combination therapy of meglumine antimoniate and oxiranes (epoxy-α-lapachone and epoxymethyl-lawsone) enhance the leishmanicidal effect in mice infected by Leishmania (Leishmania) amazonensis

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.

Impetiginous Cutaneous Leishmaniasis after COVID-19 Infection in a Patient with Poor Cardiac Profile: A Case Report and Literature Review

Cutaneous leishmaniasis incidence has been rising in the past couple of decades. Standard therapy often includes antileishmanial drugs; however, due to their low safety and toxicity threshold, alternative treatments are being investigated. The association between COVID-19 and cutaneous leishmaniasis remains unclear and exploring this connection may offer crucial insights into the pathophysiology of and treatment strategies for infected patients. In this article, we describe a case of a male patient with a history of cardiac and other comorbidities who presented with cutaneous leishmaniasis in the form of impetigo-like skin lesions after being infected with COVID-19. Due to the patient's poor cardiac profile, sodium stibogluconate was not used and an alternative therapeutic approach was employed. The patient was treated with oral terbinafine, cryotherapy on specific lesions, and a course of cephalexin. Following the course of treatment and subsequent follow-up, the patient exhibited complete resolution and healing of the lesions with scarring, and no active lesions or recurrence were observed. This case highlights the potential for alternative treatment strategies for cutaneous leishmaniasis in patients with comorbidities and emphasizes the importance of further research to better understand the link between COVID-19 and 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 some 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 (25,000 IU/g). This work assessed the effects of nystatin cream administered on mice in an amount to completely cover the paw surface of BALB/c mice infected with L. (L.) amazonensis once a day, until a total of up to 20 doses. The data presented herein points to unequivocal evidence that this formulation is related to 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, infection reduction relates to a decrease in parasite load in the footpad (∼48%) and in draining lymph nodes (∼68%) at 8th 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.

Synergistic Antileishmanial Effect of Oregano Essential Oil and Silver Nanoparticles: Mechanisms of Action on Leishmania amazonensis

American tegumentary leishmaniasis, a zoonotic disease caused by the Leishmania genus, poses significant challenges in treatment, including administration difficulty, low efficacy, and parasite resistance. Novel compounds or associations offer alternative therapies, and natural products such as oregano essential oil (OEO), extracted from Origanum vulgare, have been extensively researched due to biological effects, including antibacterial, antifungal, and antiparasitic properties. Silver nanoparticles (AgNp), a nanomaterial with compelling antimicrobial and antiparasitic activity, have been shown to exhibit potent leishmanicidal properties. We evaluated the in vitro effect of OEO and AgNp-Bio association on L. amazonensis and the death mechanisms of the parasite involved. Our results demonstrated a synergistic antileishmanial effect of OEO + AgNp on promastigote forms and L. amazonensis-infected macrophages, which induced morphological and ultrastructural changes in promastigotes. Subsequently, we investigated the mechanisms underlying parasite death and showed an increase in NO, ROS, mitochondrial depolarization, accumulation of lipid-storage bodies, autophagic vacuoles, phosphatidylserine exposure, and damage to the plasma membrane. Moreover, the association resulted in a reduction in the percentage of infected cells and the number of amastigotes per macrophage. In conclusion, our findings establish that OEO + AgNp elicits a late apoptosis-like mechanism to combat promastigote forms and promotes ROS and NO production in infected macrophages to target intracellular amastigote forms.

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.

Chemical Characterization and Leishmanicidal Activity In Vitro and In Silico of Natural Products Obtained from Leaves of Vernonanthura brasiliana (L.) H. Rob (Asteraceae)

Vernonanthura brasiliana (L.) H. Rob is a medicinal plant used for the treatment of several infections. This study aimed to evaluate the antileishmanial activity of V. brasiliana leaves using in vitro and in silico approaches. The chemical composition of V. brasiliana leaf extract was determined through liquid chromatography-mass spectrometry (LC-MS). The inhibitory activity against Leishmania amazonensis promastigote was evaluated by the MTT method. In silico analysis was performed using Lanosterol 14alpha-demethylase (CYP51) as the target. The toxicity analysis was performed in RAW 264.7 cells and Tenebrio molitor larvae. LC-MS revealed the presence of 14 compounds in V. brasiliana crude extract, including flavonoids, flavones, sesquiterpene lactones, and quinic acids. Eriodictol (ΔGbind = -9.0), luteolin (ΔGbind = -8.7), and apigenin (ΔGbind = -8.6) obtained greater strength of molecular interaction with lanosterol demethylase in the molecular docking study. The hexane fraction of V. brasiliana showed the best leishmanicidal activity against L. amazonensis in vitro (IC₅₀ 12.44 ± 0.875 µg·mL^-1) and low cytotoxicity in RAW 264.7 cells (CC₅₀ 314.89 µg·mL^-1, SI = 25.30) and T. molitor larvae. However, the hexane fraction and Amphotericin-B had antagonistic interaction (FICI index ≥ 4.0). This study revealed that V. brasiliana and its metabolites are potential sources of lead compounds for drugs for leishmaniasis treatment.

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.

Krebs cycle enzymes for targeted therapeutics and immunotherapy for anti-leishmanial drug development using: Pathways, potential targets, and future perspectives

Leishmaniasis is a parasitic and neglected tropical disease which majorly impacts poor and developing nations. One of the significant factors that impacts the severity of the pathological condition includes the socioeconomic background of the affected region. The rise of drug-resistant Leishmania is a serious concern for the effectiveness of the present treatment. As a result, the drug options need to be relooked immediately. Leishmania employs Krebs cycle intermediates for its needs after infection for establishing various defense mechanisms to escape the host immune responses. Nevertheless, a variety of immunological reactions are also seen during infection, which clear the parasites. One of the more promising strategies in this regard would involve combining targeted therapy and immunotherapy. The targeted treatments work by obstructing vital pathways that are required for Leishmania to grow and survive. The mechanism of action of immunotherapy is the control of the host immune response, which entails the blockage of molecular pathways essential for the growth and maintenance of the parasite. The Krebs cycle intermediates have important biochemical roles. Additionally, in macrophages and dendritic cells, they play roles as signalling molecules for controlling inflammatory responses. The review brings together the available literature about the importance of Krebs cycle metabolites as potential treatment targets for leishmaniasis.

In silico and in vitro antileishmanial effects of gamma-terpinene: Multifunctional modes of action

INTRODUCTION

Leishmaniasis denotes a significant health challenge worldwide with no ultimate treatment. The current study investigated the biological effects of gamma-terpinene (GT) on Leishmania major in putative antileishmanial action, cytotoxicity, apoptosis induction, gene expression alteration, antioxidant activity, hemolysis, and ROS generation.

METHODS

GT and meglumine antimoniate (MA) were probed alone and in combination (GT/MA) for their anti-leishmanial potentials using the MTT biochemical colorimetric assay and a model macrophage cell. In addition, their immunomodulatory properties were assessed by analyzing their effect on the transcription of cytokines related to Th1 and Th2 responses. GT and MA, alone and in combination, were also assessed for their potential to alter metacaspase gene expression in L. major promastigotes by real-time RT-PCR. The hemolytic potential of GT and MA-treated promastigotes were also measured by routine UV absorbance reading. Electrophoresis on agarose gel was employed to analyze genomic DNA fragmentation.

RESULTS

GT demonstrated notable dose-dependent antileishmanial effects towards promastigotes and amastigotes of L. major. The IC₅₀ values for GT against L. major promastigotes and amastigotes were 46.76 mM and 25.89 mM, respectively. GT was considerably safer towards murine macrophages than L. major amastigotes with an SI value of 3.17. Transcriptional expression of iNOS, JAK-1, Interleukin (IL-10), and TGF-β was meaningfully decreased, while the levels of metacaspase mRNA were increased. Results also confirmed GT antioxidant activities. Also, increased levels of intracellular ROS were observed upon treatment of promastigotes with GT. The gel electrophoresis result indicated slight DNA fragmentation in the treated promastigotes by both drugs. A weak hemolytic effect was also observed for GT.

CONCLUSION

The results demonstrated that GT showed potent activity against L. major stages. It seems that its mechanism of action involves representing an immunomodulatory role towards upregulation of iNOS and JAK-1, while downregulation of IL-10 and TGF- β. Moreover, GT has an antioxidative potential and exerts its action through activating macrophages to kill the organism. Further in vivo and clinical studies are essential to explore its effect in future programs.

The anti-Leishmania potential of bioactive compounds derived from naphthoquinones and their possible applications. A systematic review of animal studies

Leishmaniasis affects millions of people worldwide, and available treatments have severe limitations. Natural and derivative products are significant sources of innovative therapeutic agents. Naphthoquinones are natural or synthetic chemical compounds with broad biological activity. This systematic review aimed to evaluate the potential anti-Leishmania activity of bioactive compounds derived from naphthoquinones in animal models. Conducted in accordance with PRISMA guidelines, two blocks of MeSH terms were assembled: group I, Leishmania OR Leishmaniasis; group II, Atovaquone OR Lapachol OR Beta lapachone OR Naphthoquinones. The search was performed on PubMed, Web of Science, SCOPUS, EMBASE, and Lilacs databases. Twenty-four articles were retrieved and submitted for quality assessment using the SYRCLE critical appraisal tool. The in vivo anti-Leishmania potential of naphthoquinones was evaluated in visceral and cutaneous leishmaniasis using several measurement parameters. Analyzed compounds varied in structure, association with reference drugs, and encapsulation using a drug delivery system. The study design, including treatment protocol, differed between studies. The findings of the studies in this systematic review indicate the anti-Leishmania potential of naphthoquinones in vivo, with different treatment regimens directed against different Leishmania species. The employed drug delivery systems improve the results concerning selectivity, distribution, and required therapeutic dose. The immunomodulatory action was shown to be beneficial to the host, favoring an adequate immune response against infection by Leishmania parasites since it favored Th₁ responses. All studies presented a moderate to high risk of bias. These findings suggest that more studies are needed to assess the overall effectiveness and safety of these treatments.

Treatment of Cutaneous Leishmaniasis and Insights into Species-Specific Responses: A Narrative Review

Cutaneous leishmaniasis (CL) is a complex skin infection that has imposed a heavy burden on many developing countries and is caused by more than 20 Leishmania species. This disease is predominantly associated with disfiguring scars and major social stigma upon infection. The severity of the disease seemingly depends on many factors including the species of parasite, the host, region of endemicity, socio-economic status and the accessibility to health facilities. Despite myriad studies that have been performed on current and novel therapies, the treatment outcomes of CL remain contentious, possibly because of the knowledge gaps that still exist. The differential responses to the current CL therapies have become a major drawback in disease control, and the dearth of information on critical analyses of outcomes of such studies is a hindrance to the overall understanding. On the basis of currently available literature on treatment outcomes, we discuss the most effective doses, drug susceptibilities/resistance and treatment failures of the Leishmania genus for both monotherapy and combination therapy. This review focuses on the available treatment modalities for CL caused by different Leishmania species, with insights into their species-specific efficacies, which would inform the selection of appropriate drugs for the treatment and control of leishmaniasis.

Searching for plant-derived antivirals against dengue virus and Zika virus

Background

The worldwide epidemics of diseases as dengue and Zika have triggered an intense effort to repurpose drugs and search for novel antivirals to treat patients as no approved drugs for these diseases are currently available. Our aim was to screen plant-derived extracts to identify and isolate compounds with antiviral properties against dengue virus (DENV) and Zika virus (ZIKV).

Methods

Seven thousand plant extracts were screened in vitro for their antiviral properties against DENV-2 and ZIKV by their viral cytopathic effect reduction followed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, previously validated for this purpose. Selected extracts were submitted to bioactivity-guided fractionation using high- and ultrahigh-pressure liquid chromatography. In parallel, high-resolution mass spectrometric data (MSn) were collected from each fraction, allowing compounds into the active fractions to be tracked in subsequent fractionation procedures. The virucidal activity of extracts and compounds was assessed by using the plaque reduction assay. EC₅₀ and CC₅₀ were determined by dose response experiments, and the ratio (EC₅₀/CC₅₀) was used as a selectivity index (SI) to measure the antiviral vs. cytotoxic activity. Purified compounds were used in nuclear magnetic resonance spectroscopy to identify their chemical structures. Two compounds were associated in different proportions and submitted to bioassays against both viruses to investigate possible synergy. In silico prediction of the pharmacokinetic and toxicity (ADMET) properties of the antiviral compounds were calculated using the pkCSM platform.

Results

We detected antiviral activity against DENV-2 and ZIKV in 21 extracts obtained from 15 plant species. Hippeastrum (Amaryllidaceae) was the most represented genus, affording seven active extracts. Bioactivity-guided fractionation of several extracts led to the purification of lycorine, pretazettine, narciclasine, and narciclasine-4-O-β-D-xylopyranoside (NXP). Another 16 compounds were identified in active fractions. Association of lycorine and pretazettine did not improve their antiviral activity against DENV-2 and neither to ZIKV. ADMET prediction suggested that these four compounds may have a good metabolism and no mutagenic toxicity. Predicted oral absorption, distribution, and excretion parameters of lycorine and pretazettine indicate them as candidates to be tested in animal models.

Conclusions

Our results showed that plant extracts, especially those from the Hippeastrum genus, can be a valuable source of antiviral compounds against ZIKV and DENV-2. The majority of compounds identified have never been previously described for their activity against ZIKV and other viruses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01751-z.

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.

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.

Efficacy of Spironolactone Treatment in Murine Models of Cutaneous and Visceral Leishmaniasis

Translational studies involving the reuse and association of drugs are approaches that can result in higher success rates in the discovery and development of drugs for serious public health problems, including leishmaniasis. If we consider the number of pathogenic species in relation to therapeutic options, this arsenal is still small, and each drug possesses a disadvantage in terms of toxicity, efficacy, price, or treatment regimen. In the search for new drugs, we performed a drug screening of L. amazonensis promastigotes and intracellular amastigotes of fifty available drugs belonging to several classes according to their pharmacophoric group. Spironolactone, a potassium-sparing diuretic, proved to be the most promising drug candidate. After demonstrating the in vitro antileishmanial activity, we evaluated the efficacy on a murine experimental model with L. amazonensis and L. infantum. The treatment controlled the cutaneous lesion and reduced the parasite burden of L. amazonensis significantly, as effectively as meglumine antimoniate. The treatment of experimental visceral leishmaniasis was effective in reducing the parasite load on the main affected organs (spleen and liver) via high doses of spironolactone. The association between spironolactone and meglumine antimoniate promoted better control of the parasite load in the spleen and liver compared to the group treated with meglumine antimoniate alone. These results reveal a possible benefit of the concomitant use of spironolactone and meglumine antimoniate that should be studied more in depth for the future possibility of repositioning for leishmaniasis co-therapy.

New phenalenone analogues with improved activity against Leishmania species

The in vitro activity against Leishmania spp. of five novel designed compounds, phenalenone derivatives, is described in this study. Previous works have shown that some phenalenones present leishmanicidal activity, some of which could induce programmed cell death events in L. amazonensis parasites. In this research, we focused on the determination of the programmed cell death evidence by detecting the characteristic features of the apoptosis-like process, such as phosphatidylserine exposure and mitochondrial membrane potential, among others. The results showed that the new derivatives have comparable or better activity and selectivity than the commonly prescribed anti-leishmanial drug. This result was obtained by inducing stronger mitochondrial depolarization or more intense phosphatidylserine exposure than miltefosine, highlighting compound 8 with moreover 9-times better selectivity index. In addition, the new five molecules activated the apoptosis-like process in the parasite. All the signals observed were indicative of the death process that the parasites were undergoing.

Aqueous ozone therapy improves the standard treatment of leishmaniasis lesions in animals leading to local and systemic alterations

The current treatment of leishmaniasis presents some problems, such as cell toxicity, parenteral route, and time of treatment. Ozone emerges as an option to accelerate the standard treatment due to the immunomodulatory, antioxidant, and wound healing activity reported in the literature. This work aimed to evaluate the efficacy of aqueous ozone as an adjuvant to the standard treatment of cutaneous lesions caused by Leishmania amazonensis in an experimental model. For in vivo experiments, mice were randomly distributed in 6 groups, which were infected with L. amazonensis and treated in five different schedules using the standard treatment with Glucantime® with or without aqueous ozone. After the last day of treatment, the animals were euthanized and were analyzed: the thickness of lesions; collagen deposition, the parasitic burden of the lesions; blood leukocyte number; NO; and cytokine dosages and arginase activity from peritoneal macrophages. All treated groups showed a decrease in the lesion, but with a significative deposition of collagen in lesions with local ozone treatment. The parasite burden showed that ozone enhanced the leishmanicidal activity of the reference drug. The reduction of NO production and blood leukocyte count and increases in the arginase activity showed an immunomodulatory activity of ozone in the treated animals. Thus, ozone therapy has been shown to work as an adjuvant in the treatment of Leishmania lesions, enhancing leishmanicidal and wound healing activity of standard treatment.