Microgramma vacciniifolia Frond Lectin: In Vitro Anti-leishmanial Activity and Immunomodulatory Effects Against Internalized Amastigote Forms of Leishmania amazonensis.

PURPOSE: The treatment of leishmaniasis, an anthropozoonosis caused by Leishmania protozoa, is limited by factors, such as adverse effects, toxicity, and excessive cost, which has highlighted the importance of novel drugs. In this context, natural products have been considered as sources of antileishmanial agents. This study investigated the leishmanicidal activity of Microgramma vacciniifolia frond lectin (MvFL) on promastigotes and amastigotes of Leishmania amazonensis. METHODS: The effects of MvFL on promastigote proliferation and macrophage infection by amastigotes were evaluated and mean inhibitory concentrations (IC50) were calculated. As a safety assessment, the hemolytic capacity of MvFL (6.25-200 µg/mL) against mouse and human erythrocytes was determined. Additionally, the ability of MvFL (6.25-100 µg/mL) to modulate lysosomal and phagocytic activities and the nitric oxide (NO) production by murine peritoneal macrophages was also investigated. RESULTS: After 24 h, MvFL inhibited the proliferation of L. amazonensis promastigotes, with an IC50 of 88 µg/mL; however, hemolytic activity was not observed. MvFL also reduced macrophage infection by amastigotes with an IC50 of 52 µg/mL. Furthermore, treatment with MvFL reduced the number of amastigotes internalized by infected murine peritoneal macrophages by up to 68.9% within 48 h. At a concentration of 25 µg/mL, MvFL stimulated lysosomal activity of macrophages within 72 h, but did not alter phagocytic activity or induce NO production at any of the tested concentrations. CONCLUSION: MvFL exerts antileishmanial activity and further studies are needed to assess its therapeutic potential in in vivo experimental models of leishmaniasis.

Synthetic hydrazones: In silico studies and in vitro evaluation of the antileishmania potential.

Bioprospecting and synthesis of strategically designed molecules have been used in the search for drugs that can be in leishmaniasis. Hydrazones (HDZ) are promising compounds with extensive biological activities. The objective of this work was to perform in silico studies of hydrazones 1-5 and to evaluate their antileishmanial, cytotoxic and macrophage immunomodulatory potential in vitro. Hydrazones were subjected to prediction and molecular docking studies. Antileishmanial protocols on promastigotes and amastigotes of Leishmania amazonensis, cytotoxicity and macrophage immunomodulatory activity were performed. Hydrazones showed a good pharmacokinetic profile and hydrazone 3 and hydrazone 5 were classified as non-carcinogenic. Hydrazone 5 obtained the best conformation with trypanothione reductase. Hydrazone 1 and hydrazone 3 obtained the best mean inhibitory concentration (IC50) values for promastigotes, 4.4-61.96 µM and 8.0-58.75 µM, respectively. It also showed good activity on intramacrophagic amastigotes, with hydrazone 1 being the most active (IC50 = 6.79 µM) with selectivity index of 56. In cytotoxicity to macrophages hydrazone 3 was the most cytotoxic (CC50 = 256.3 ± 0,04 µM), while hydrazone 4 the least (CC50 = 1055.9 ± 0.03 µM). It can be concluded that the hydrazones revealed important pharmacokinetic and toxicological properties, in addition to antileishmania potential in reducing infection and infectivity in parasitized macrophages.

Four new cycloartane-type triterpenoids from the leaves of Combretum mellifluum Eichler: assessment of their antioxidant and antileishmanial activities.

The beneficial pharmacological actions including antioxidant effects as an antileishmanial, antibacterial, antifungal, antidiabetic, anti-inflammatory, antitumor, antiviral, and analgesic of compounds isolated from Combretum mellifluum Eichler (Combretaceae) are well established. The aim of the present study was to determine the phytochemistry as well as assess the antioxidant and antileishmanial activities of the leaves from Combretum mellifluum Eichler (Combretaceae). Analysis of ethanolic extract resulted in isolation and identification of two epimeric mixtures of four previously unknown cycloartane-type triterpenoids, methyl quadrangularate M and methyl 24-epiquadrangularate M, and 2α,3ß,24ß-trihydroxy-cycloart-25-ene and 2α, 3ß, 24α-trihydroxy-cycloart-25-ene, and eight known compounds. Their structures were using one-dimensional nuclear magnetic resonance (1D NMR), 2D NMR and high-resolution electrospray ionization mass spectroscopy (HRESIMS) analysis. Further, the extract and fractions were tested for antioxidant potential. The ethyl acetate and aqueous fractions demonstrated the highest antioxidant activity against 2,2-dipheny-1-picrylhydrazl (DPPH) free radicals, which correlated directly with total flavonoid content. All extracts and fractions from C. mellifluum Eichler were assessed for antileishmanial activity. The supernatant fraction exhibited highest potential, inhibiting the growth of Leishmania amazonensis with IC50 value 31.29 µg/ml. Our findings provide information on the chemical composition of C. mellifluum and the potential beneficial therapeutic usefulness as an antioxidant agent in various diseases.

Assessment of In Vitro Anti-melanoma Potential of Ephedranthus pisocarpus R.E.Fr.

BACKGROUND/AIM: Despite being a rare disease, melanoma is considered the most dangerous skin cancer due to its highly invasive and aggressive nature, and still requires for more effective treatments. The aim of this study was to evaluate the in vitro anti-melanoma potential of Ephedranthus pisocarpus R.E.Fr. (Annonaceae), a popular Brazilian plant with medicinal properties. MATERIALS AND METHODS: Initially, the ethanolic extract (EtOH) was obtained from E. pisocarpus leaves and later partitioned using increasing polarity solvents. The anti-melanoma potential of E. pisocarpus was assessed by spectrophotometry and its cytotoxicity determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and confocal microscopy. RESULTS: We demonstrated that the EtOH extract and fractions from E. pisocarpus had a moderate photoprotective action (FPS 3.0-5.0) against UVA radiation. Interestingly, the dichloromethane fraction presented higher anti-melanoma activity against B16-F10 (IC50=46.8 µg/ml) and SK-MEL-28 cells (IC50=40.1 µg/ml) and lesser toxicity on normal cells. Additionally, our study reported that spathulenol, one of the major constituents from E. pisocarpus, acts through an apoptosis-dependent mechanism in SK-MEL-28 cells. CONCLUSION: The present study demonstrated, for the first time, the in vitro anti-melanoma potential of E. pisocarpus against melanoma cells.

preADMET analysis and clinical aspects of dogs treated with the Organotellurium compound RF07: A possible control for canine visceral leishmaniasis?

Tellurium compounds have been described as potential leishmanicides, bearing promising leishmanicidal and antimalarial effects. Therefore, the present study investigated the pharmacological potential of the organotellurane compound RF07 through preADMET parameters, such as absorption, distribution, metabolism and excretion. After studying the pharmacokinetic properties of RF07, studies were carried out on dogs naturally infected with visceral leishmaniasis after the administration of RF07, in order to assess pathophysiological parameters. Thus, dogs were divided into 4 groups with administration of daily intraperitoneal injections for 3 weeks (containing RF07 or placebo). During the trial, hematological parameters, renal and hepatic toxicity were evaluated. Serum urea, creatinine, alkaline phosphatase, transaminases (GOT and GPT), as well as hemogram results, were evaluated before the first administration and during the second and third weeks after the start of the treatment. In dogs with VL, RF07 improved liver damage, regulated GPT levels and significantly decreased leukocyte count, promoting its regularization. These phenomena occurred at the end of the third week of treatment. The administration of RF07 promoted a significant decrease in the average levels of GOT and GPT after the third week of treatment and did not significantly alter the hematological parameters. The application of RF07 in the treatment of visceral leishmaniasis suggests that it is an alternative to the disease, since the reversal of clinical signs in dogs with VL requires the use of 0.6 mg/kg.

Amphotericin B-Loaded Emulgel: Effect of Chemical Enhancers on the Release Profile and Antileishmanial Activity In Vitro.

Cutaneous leishmaniasis is a neglected parasitic disease. Treatment is preferably performed with pentavalent antimony associated or not with amphotericin B (AmB). This study aimed to develop an emulgel with different chemical enhancers of cutaneous release. Initially, AmB emulsions were obtained with the chemical promoters, oleic acid and geraniol and without promoter, then for the evaluation of the formulations, a preliminary stability study was carried out where the formulations were submitted to centrifugation, before and after the freeze-thaw cycle and analyzed appearance, color, pH, spreadability, viscosity, conductivity, droplet size, assay, in vitro release study, in vitro antileishmania activity in Leishmania major promastigotes, and macrophage toxicity in the MTT test. The emulsions were yellowish, with no signs of instability after the centrifugation test. The pH range corresponded to that of the skin, which is 4.6 to 5.8, before and after the freeze-thaw cycle, the formulations had good spreadability and did not present significant viscosity differences before and after the freeze-thaw cycle, presenting a non-Newtonian characteristic. AmB content was within the kinetic model of zero order release, the formulation of 3% AmB and 5% oleic acid (formulation 1) was chosen to proceed with the antileishmania activity test and showed potential activity against the in vitro parasite with significant reduction of cytotoxicity on murine macrophages, indicating that the formulation is promising for the treatment of cutaneous leishmaniasis.

In vitro bioactivity and cytotoxicity of films based on mesocarp of Orbignya sp. and carboxymethylcellulose as a tannic acid release matrix.

This study aims to obtain mesocarp films of Orbignya sp. (MB) and carboxymethylcellulose (CMC) for application as a drug release matrix. Tannic acid (TA) was used as a standard drug. The films were evaluated by infrared, swelling power, TA release profile, bioactivity and in vitro cytotoxicity. Infrared results indicated absorption at 1.205 cm-1, which is characteristic of ester group from the incorporated tannin. The MB-CMC film had 449.15% swelling power, release of 71.01% of TA of the matrix after 24 h. Films showed scavenger activity of radicals DPPH (79.07 ± 1.71% to 82.17 ± 1.94%) and ABTS+ (82.20 ± 0.30% to 88.90 ± 1.05). The MB-CMC film also showed in vitro cytotoxicity on sarcoma-180 (91.86 ± 9.97%) and on promastigote forms of Leishmania major (100%). Polymers showed good compatibility in the mixture and the results suggest the films obtained are promising as drug release matrices.

In Vitro Effects of the Neolignan 2,3-Dihydrobenzofuran Against Leishmania Amazonensis.

Leishmaniasis is an infectious disease complex caused by protozoa from the Leishmania genus, which presents a broad spectrum of clinical manifestations: cutaneous, mucocutaneous and visceral forms. The current treatments are unsatisfactory considering that few drugs are available and present some level of toxicity. Many lignans and neolignans have been used for the development of new antileishmania drugs. The capability in vitro of the neolignan 2,3-dihydrobenzofuran (2,3-DBF), a commonly found constituent of propolis and other plants, to inhibit the growth of promastigote and macrophage-internalized amastigote forms of Leishmania amazonensis was investigated. The cytotoxicity of this compound was assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test in BALB/c murine macrophages and human erythrocyte lysis assay. The 2,3-DBF was active against promastigote (IC50 =1.042 µM) and amastigote (IC50 =1.43 µM) forms, indicating a potent antileishmanial effect. There was no evidence of cytotoxicity to macrophages or erythrocytes at concentrations ranging from 13 to 0.5 µM, after 48 hr of exposure. The antileishmanial activity is probably mediated by the activation of macrophages, because treatment with 2,3-DBF increases both phagocytic and lysosomal activities, as well as the nitrite (NO2- ) levels. These results suggest that 2,3-DBF may be a potential candidate for the development of a new promising antileishmanial drug. Further studies are needed to determine its potential in vivo effect as well as additional mechanisms underlying the antileishmanial and immunomodulatory activities.

Cytotoxic and leishmanicidal properties of garcinielliptone FC, a prenylated benzophenone from Platonia insignis.

Garcinielliptone FC (GFC), a natural prenylated benzophenone, was extracted from Platonia insignis Mart. (Clusiaceae), a native plant commonly known as bacuri and used in traditional Brazilian medicine for the treatment of skin diseases. The aim of this study was to evaluate the cytotoxic and leishmanicidal effects of GFC using in vitro models. The experimental data demonstrated that the polyisoprenylated benzophenone GFC possesses cytotoxic and leishmanicidal activities.

Factors associated to Montenegro skin test positivity in Teresina, Brazil.

Visceral leishmaniasis (VL) is an emerging infectious disease of urban areas in Brazil. To better understand this process, we have studied the association between reaction to the Montenegro skin test (MST), and demographic, socioeconomic and environmental factors in an urban area with high force of transmission. Associations between variables were expressed by prevalence ratios and their respective 95% confidence intervals estimated by using Poisson regression models with robust variance. Higher prevalence of positivity to MST was detected among male and older participants, and among subjects who owned dogs for 3 or more years. Individuals with higher literacy and living in households with three or more persons showed lower prevalence of MST reaction. These results suggest that the identification of high-risk groups might be feasible and useful for targeting interventions.