Evaluation of nephroprotective and immunomodulatory activities of antioxidants in combination with cisplatin against murine visceral leishmaniasis

Isolation of potent antileishmanial agents from Artemisia kermanensis Podlech using bioguided fractionation

Leishmaniasis is a major health problem worldwide with different clinical forms that depend on the parasite, the host's immune system, and immune-inflammatory responses. This study aimed to evaluate the secondary metabolites from Artemisia kermanensis Podlech by bioguided fractionation against Leishmania major. The chemical structures of the isolated compounds were determined based on analysis of mass and nuclear magnetic resonance spectra. Antileishmanial activity were determined on promastigotes and amastigotes. Chemical structures of the isolated compound were as 1-Acetoxy-3,7-dimethyl-7-hydroxy-octa-2E,5E-dien-4-one for compound 1 and 5,7-dihydroxy-3',4',6-trimethoxyflavone (Eupatilin) for compound 2, and 5,7,3'-Trihydroxy-6,4',5'-trimethoxyflavone for compound 3. Compound 2 were confirmed by significant activity with IC50 of less than 50 μg/ml for 24 and 48 h in clinical form (amastigotes). Compound 3 demonstrated high susceptibility with an IC50 of less than 30 μg/ml for promastigotes for 24 h. The bioguided fractionation of A. kermanensis resulted the isolation of potent antileishmanial agents with a low toxicity effect on macrophages. These plant metabolites can be a candidate as a drug for treating cutaneous leishmaniasis.

Nutrition, malnutrition, and leishmaniasis

Leishmaniasis is a vector-borne infectious disease with a long history of infecting humans and other animals. It is a known emerging or resurging disease. The host nutritional state has an indispensable role in defense against pathogens. The host defense system disorganization as a result of undernutrition is responsible for asymptomatic infections and even severe diseases. Host susceptibility and pathophysiologic severity to infection can be aggravated owing to undernourishment in a number of pathways, and infection also may aggravate preexisting poor nutrition or further increase host susceptibility. This study suggests that there may be some relationship between malnutrition and the endemicity of the parasite. The susceptibility to and severity of leishmanial infection can be altered by the body weight and serum levels of micronutrients. Nutrition not only affects the vulnerability of the host but also may affect the desire of sandfly to bite a specific host. Apart from host defense mechanism, nutritional stress also greatly influences vector competence and host-seeking behavior, especially during larvae development. The host and sandfly vector nutritional states could also influence the evolution of the parasite. It is essential to elucidate the roles that diets and nutrition play in the leishmanial life cycle. The aim of this article is to review the influences of nutrition and diets on the host susceptibility and severity of infection, preemptive and therapeutic strategy feedback, parasite evolution, and vector competence.

Evaluation of antileishmanial efficacy of Salidroside against the SSG-sensitive and resistant strain of Leishmania donovani

The successful control and eradication of leishmaniasis are still challenging in view of the lack of adequate chemotherapy and potential prophylaxis. Research is going on for finding an appropriate anti-leishmanial drug which should be acceptable in terms of cost and safety. In view of this, the current study investigated the anti-leishmanial efficacy of salidroside (SAL) which is a phenylpropanoid glycoside. The leishmanicidal capacity of SAL was verified in vitro as well as in vivo. The SAL exhibited leishmanicidal activity against the promastigotes of L. donovani which was further validated by propidium iodide staining and its ability to arrest the promastigotes at the sub G₀/G₁ stage. SAL decreased and controlled the VL infection in mice as estimated by real-time PCR. Active immunomodulation was exhibited upon SAL treatment in BALB/c mice. The characteristic features like pronounced DTH reaction, polarization of immune status to Th1 type of immune response, increased the production of CD4⁺ and CD8⁺ T cells indicated the immune-stimulatory property of SAL. In addition to this the expression of NF-ĸB, iNOS genes along with the levels of leishmanicidal species, NO and ROS were found to be augmented in SAL treated infected animals. Moreover, SAL exhibited minimal toxicity to the THP-1 cells and it revealed no toxicity against liver and kidney. The capability of SAL in promoting the immune status in favor of host during VL infection without causing any side-effects may be used as an effective strategy to fight the disease.

Oral activity of the antimalarial endoperoxide 6-(1,2,6,7-tetraoxaspiro[7.11]nonadec-4-yl)hexan-1-ol (N-251) against Leishmania donovani complex

Visceral leishmaniasis (VL) is a major problem worldwide and causes significant morbidity and mortality. Existing drugs against VL have limitations, including their invasive means of administration long duration of treatment regimens. There are also concerns regarding increasing treatment relapses as well as the identification of resistant clinical strains with the use of miltefosine, the sole oral drug for VL. There is, therefore, an urgent need for new alternative oral drugs for VL. In the present study, we show the leishmanicidal effect of a novel, oral antimalarial endoperoxide N-251. In our In vitro studies, N-251 selectively and specifically killed Leishmania donovani D10 amastigotes with no accompanying toxicity toward the host cells. In addition, N-251 exhibited comparable activities against promastigotes of L. donovani D10, as well as other L. donovani complex parasites, suggesting a wide spectrum of activity. Furthermore, even after a progressive infection was established in mice, N-251 significantly eliminated amastigotes when administered orally. Finally, N-251 suppressed granuloma formation in mice liver through parasite death. These findings indicate the therapeutic effect of N-251 as an oral drug, hence suggest N-251 to be a promising lead compound for the development of a new oral chemotherapy against VL.

Protective efficacy of Chlorophytum borivilianum root extract against murine visceral leishmaniasis by immunomodulating the host responses

BACKGROUND

The available drugs for treating visceral leishmaniasis are limited. Moreover, the disease is associated with suppression of immune function. Therefore, therapies with effective immunomodulatory agents are needed which can decrease parasitic burden and enhance adaptive immunity.

OBJECTIVES

The present study was planned to evaluate the antileishmanial efficacy of crude ethanolic extract of roots of Chlorophytum borivilianum (CBREE) against murine visceral leishmaniasis through immunomodulation.

MATERIALS AND METHODS

The in vitro studies were carried out to check leishmanicidal activity against promastigote form and cytotoxicity against HeLa cells. The parasite load in liver smears, immunological and biochemical changes induced by 500 and 1000 mg/kg b.wt. of CBREE were assessed on 1, 7, 14 and 21 post treatment days in infected and treated BALB/c mice.

RESULTS

CBREE showed inhibitory effect on growth of promastigotes with IC50 of 28.25 μg/mL and negligible cytotoxicity. The extract was toxicologically safe in BALB/c mice when administered orally with 5 g/kg b.wt. of extract. A significant reduction in parasite load was observed along with active immunomodulation through enhanced Th1 type of immune responses and suppressed Th2 type of immune responses.

CONCLUSION

The treatment with both doses showed no toxic effect as evidenced by normal liver and kidney function tests and normal histological observations of liver and kidney. Therefore, it should be further explored for its active components in pursuit of the new effective antileishmanial agents in the plant kingdom.

Trypanocidal Effects of Cisplatin alone and in Combination with Nigella sativa Oil on Experimentally Infected Mice with Trypanosoma evansi

BACKGROUND

Due to the limited number of the available drugs for the treatment of trypanosomiasis, this study was designed to evaluate the trypanocidal effects of cisplatin or/and Nigella sativa oil (NSO) in experimentally infected mice with T. evansi.

METHODS

During 2015 at the Parasitology Department, Menoufia University, Menoufia, Egypt, sixty Swiss albino mice were divided into six groups: normal control (I), infected control (II); cisplatin-treated (III); NSO-treated (IV); combined cisplatin + NSO-treated (V) and diminazene-treated (VI). The tested drugs were evaluated by the assessment of parasitaemia, measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, creatinine, serum IgM and a histopathological study.

RESULTS

NSO showed a trypanocidal effect, however; it was not as effective as cisplatin or diminazene. There were significant increases of AST, ALT, urea, and creatinine in group II and III, which were significantly reduced in cisplatin + NSO-treated group (V). Moreover, there were significant reductions in serum IgM and the pathological changes of the examined organs of group V when they were compared with other treated groups.

CONCLUSION

Cisplatin combined with NSO showed a trypanocidal effect against T. evansi with preservation of vital organs functions and architecture.

Evaluation of in vitro and in vivo antileishmanial potential of bergenin rich Bergenia ligulata (Wall.) Engl. root extract against visceral leishmaniasis in inbred BALB/c mice through immunomodulation

BACKGROUND

Medicinal plants with immunomodulatory properties can provide good alternative therapeutics for curing visceral leishmaniasis. Bergenia ligulata (Wall.) Engl. is an interesting plant with strong antioxidant, antimicrobial, immunomodulatory and hepatoprotective properties.

AIM

The present study was planned to determine the antileishmanial activity of plant extract by modulating the immune responses of inbred BALB/c mice.

METHODOLOGY

Bergenin, the principle active component of B. ligulata, was quantitated in crude extract by performing RP-HPLC. The therapeutic potential was assessed through in vitro antileishmanial activity and in mice model through parasite load, cytokine assays, IgG antibody levels, DTH responses, histopathology and biochemical enzyme assays.

RESULTS

B. ligulata showed the presence of glycosides, saponins, carbohydrates, tannins, flavonoids and bergenin which contributed to the antileishmanial activity of extract with IC50 of 22.70 μg/mL. Furthermore, the higher dose significantly reduced the parasite load by 95.56 %. The reduction was further associated with significant enhancement of IL-12 and IFN-γ levels in comparison to IL-10 and IL-4 cytokines. The switching towards Th1 type of immune response was also confirmed by elevated antibody levels of IgG2a isotype as compared to IgG1 as well as increased DTH responses. The histology of liver and kidney further complimented the non toxic nature of plant extract in addition to its negligible toxicity on HeLa cells.

CONCLUSIONS

The current study revealed the significant antileishmanial and immunomodulatory properties of this plant extract against murine visceral leishmaniasis. Further, the bioactive components will be explored to assess their efficacy for the development of safe and cost effective drug.

Evaluation of the Protective Role of Glycine max Seed Extract (Soybean Oil) in Drug-Induced Nephrotoxicity in Experimental Rats

This study was conducted to evaluate the nephroprotective effect of Glycine max seed extract (soybean oil) against gentamicin- and rifampicin-induced nephrotoxicity in Sprague-Dawley rats and to compare its effects with those of vitamin E, which has well-established antioxidant and nephroprotective effects. Sixty male Sprague-Dawley rats (body weight 150-210 g) were divided into 10 groups. The first five groups were treated for 14 consecutive days with normal saline (5 ml/kg, by mouth [p.o.]); gentamicin (80 mg/kg intraperitoneally [i.p.]); gentamicin (80 mg/kg, i.p.) + vitamin E (250 mg/kg p.o.); gentamicin (80 mg/kg i.p.) + soybean oil (2.5 ml/kg p.o.); and gentamicin (80 mg/kg, i.p.) + soybean oil (5 ml/kg p.o.), respectively. For the next five groups, the same group allocation was done, but gentamicin was replaced with rifampicin (1 g/kg i.p.). Various biomarkers for nephrotoxicity in serum and urine were evaluated along with histopathological examination of kidneys. Analysis of variance (ANOVA) was done following Tukey's multiple comparison test; p < .05 was considered significant. Soybean oil in both doses significantly (p < .005) decreased serum blood urea nitrogen, creatinine, urea, uric acid and urine volume, kidney weight, urinary sodium, urinary potassium, and total protein and significantly (p < .005) increased serum total protein and urine creatinine in gentamicin- and rifampicin-treated animals, exhibiting nephroprotective effects. Soybean oil also showed strong antioxidant effects, causing significant (p < .005) increase in kidney homogenate catalases, glutathione peroxidase, and superoxide dismutase and significant (p < .005) decrease in lipid peroxidase in gentamicin- and rifampicin-treated animals. Soybean oil demonstrated good nephroprotective activity due to antioxidant effects.

Vitamin E-rich Nanoemulsion Enhances the Antitumor Efficacy of Low-Dose Paclitaxel by Driving Th1 Immune Response

PURPOSE

To overcome the drawbacks of high dose regimen and improve the outcomes of chemotherapy at a low dose, an immunotherapeutic nanoemulsion based combination of chemotherapeutic agent (paclitaxel) with immunomodulatory agent (vitamin E) was developed and evaluated for their antitumor effect against breast cancer.

METHODS

A total of five nanoemulsions loaded with various content of vitamin E were prepared and characterized. The immunoregulatory effects of vitamin E along with the overall antitumor efficacy of vitamin E-rich nanoemulsion with a low dose of paclitaxel were investigated through in vitro and in vivo experiments.

RESULTS

Vitamin E-rich nanoemulsion exhibited relatively narrow size distribution, high entrapment efficiency and controlled in vitro release profile. In RAW264.7 cells, vitamin E-rich nanoemulsion significantly enhanced the secretion of Th1 cytokines and down-regulated the secretion of Th2 cytokine. In a co-culture system, vitamin E-rich nanoemulsion induced a high apoptosis rate in MDA-MB-231 cells as compared with vitamin E-low nanoemulsion. Furthermore, vitamin E-rich nanoemulsion exhibited superior in vivo antitumor efficacy in comparison with Taxol and vitamin E-low nanoemulsion at a paclitaxel dose of 4 mg/kg.

CONCLUSIONS

Vitamin E-rich nanoemulsion has great potential for the treatment of breast cancers with a low dose of paclitaxel via driving Th1 immune response.

Immunotherapeutic Potential of Eugenol Emulsion in Experimental Visceral Leishmaniasis

BACKGROUND

The therapy of visceral leishmaniasis (VL) is limited by resistance, toxicity and decreased bioavailability of the existing drugs coupled with dramatic increase in HIV-co-infection, non-availability of vaccines and down regulation of cell-mediated immunity (CMI). Thus, we envisaged combating the problem with plant-derived antileishmanial drug that could concomitantly mitigate the immune suppression of the infected hosts. Several plant-derived compounds have been found to exert leishmanicidal activity via immunomodulation. In this direction, we investigated the antileishmanial activity of eugenol emulsion (EE), complemented with its immunomodulatory and therapeutic efficacy in murine model of VL.

METHODOLOGY/PRINCIPAL FINDINGS

Oil-in-water emulsion of eugenol (EE) was prepared and size measured by dynamic light scattering (DLS). EE exhibited significant leishmanicidal activity with 50% inhibitory concentration of 8.43±0.96 μg ml-1 and 5.05±1.72 μg ml─1, respectively against the promastigotes and intracellular amastigotes of Leishmania donovani. For in vivo effectiveness, EE was administered intraperitoneally (25, 50 and 75 mg/kg b.w./day for 10 days) to 8 week-infected BALB/c mice. The cytotoxicity of EE was assessed in RAW 264.7 macrophages as well as in naive mice. EE induced a significant drop in hepatic and splenic parasite burdens as well as diminution in spleen and liver weights 10 days post-treatment, with augmentation of 24h-delayed type hypersensitivity (DTH) response and high IgG2a:IgG1, mirroring induction of CMI. Enhanced IFN-γ and IL-2 levels, with fall in disease-associated Th2 cytokines (IL-4 and IL-10) detected by flow cytometric bead-based array, substantiated the Th1 immune signature. Lymphoproliferation and nitric oxide release were significantly elevated upon antigen revoke in vitro. The immune-stimulatory activity of EE was further corroborated by expansion of IFN-γ producing CD4+ and CD8+ splenic T lymphocytes and up-regulation of CD80 and CD86 on peritoneal macrophages. EE treated groups exhibited induction of CD8+ central memory T cells as evidenced from CD62L and CD44 expression. No biochemical alterations in hepatic and renal enzymes were observed.

CONCLUSIONS

Our results demonstrate antileishmanial activity of EE, potentiated by Th1 immunostimulation without adverse side effects. The Th1 immune polarizing effect may help to alleviate the depressed CMI and hence complement the leishmanicidal activity.

Leishmanicidal Activity of Piper nigrum Bioactive Fractions is Interceded via Apoptosis In Vitro and Substantiated by Th1 Immunostimulatory Potential In Vivo

Visceral leishmaniasis (VL) is a life-threatening protozoal infection chiefly impinging the rural and poor population in the tropical and sub-tropical countries. The deadly affliction is rapidly expanding after its association with AIDS, swiftly defying its status of a neglected disease. Despite successful formulation of vaccine against canine leishmaniasis, no licensed vaccine is yet available for human VL, chemotherapy is in appalling state, and the development of new candidate drugs has been painfully slow. In face of lack of proper incentives, immunostimulatory plant preparations owing antileishmanial efficacy bear potential to rejuvenate awful antileishmanial chemotherapy. We have earlier reported profound leishmanicidal activity of Piper nigrum hexane (PNH) seeds and P. nigrum ethanolic (PNE) fractions derived from P. nigrum seeds against Leishmania donovani promastigotes and amastigotes. In the present study, we illustrate that the remarkable anti-promastigote activity exhibited by PNH and PNE is mediated via apoptosis as evidenced by phosphatidylserine externalization, DNA fragmentation, arrest in sub G₀/G₁ phase, loss of mitochondrial membrane potential and generation of reactive oxygen species. Further, P. nigrum bioactive fractions rendered significant protection to L. donovani infected BALB/c mice in comparison to piperine, a known compound present in Piper species. The substantial therapeutic potential of PNH and PNE was accompanied by elicitation of cell-mediated immune response. The bioactive fractions elevated the secretion of Th1 (INF-γ, TNF-α, and IL-2) cytokines and declined IL-4 and IL-10. PNH and PNE enhanced the production of IgG2a, upregulated the expression of co-stimulatory molecules CD80 and CD86, augmented splenic CD4⁺ and CD8⁺ T cell population, induced strong lymphoproliferative and DTH responses and partially stimulated NO production. PNH and PNE were devoid of any hepatic or renal toxicity. These encouraging findings merit further exploration of P. nigrum bioactive fractions as a source of potent and non-toxic antileishmanials.

Immucillins ImmA and ImmH Are Effective and Non-toxic in the Treatment of Experimental Visceral Leishmaniasis

BACKGROUND

Immucillins ImmA (IA), ImmH (IH) and SerMe-ImmH (SMIH) are synthetic deazapurine nucleoside analogues that inhibit Leishmania (L.) infantum chagasi and Leishmania (L.) amazonensis multiplication in vitro without macrophage toxicity. Immucillins are compared to the Glucantime standard drug in the chemotherapy of Leishmania (L.) infantum chagasi infection in mice and hamsters. These agents are tested for toxicity and immune system response.

METHODOLOGY/PRINCIPAL FINDINGS

BALB/c mice were infected with 107 amastigotes, treated with IA, IH, SMIH or Glucantime (2.5mg/kg/day) and monitored for clinical variables, parasite load, antibody levels and splenocyte IFN-γ, TNF-α, and IL-10 expression. Cytokines and CD4+, CD8+ and CD19+ lymphocyte frequencies were assessed in uninfected controls and in response to immucillins. Urea, creatinine, GOT and GPT levels were monitored in sera. Anti-Leishmania-specific IgG1 antibodies (anti-NH36) increased in untreated animals. IgG2a response, high levels of IFN-γ, TNF-α and lower levels of IL-10 were detected in mice treated with the immucillins and Glucantime. Immucillins permitted normal weight gain, prevented hepato-splenomegaly and cleared the parasite infection (85-89%) without renal and hepatic toxicity. Immucillins promoted 35% lower secretion of IFN-γ in uninfected controls than in infected mice. IA and IH increased the CD4+ T and CD19+ B cell frequencies. SMIH increased only the proportion of CD-19 B cells. IA and IH also cured infected hamsters with lower toxicity than Glucantime.

CONCLUSIONS/SIGNIFICANCE

Immucillins IA, IH and SMIH were effective in treating leishmaniasis in mice. In hamsters, IA and IH were also effective. The highest therapeutic efficacy was obtained with IA, possibly due to its induction of a TH1 immune response. Low immucillin doses were required and showed no toxicity. Our results disclose the potential use of IA and IH in the therapy of visceral leishmaniasis.

A Novel Sterol Isolated from a Plant Used by Mayan Traditional Healers Is Effective in Treatment of Visceral Leishmaniasis Caused by Leishmania donovani

Visceral leishmaniasis (VL), caused by the protozoan parasite Leishmania donovani, is a global health problem affecting millions of people worldwide. Treatment of VL largely depends on therapeutic drugs such as pentavalent antimonials, amphotericin B, and others, which have major drawbacks due to drug resistance, toxicity, and high cost. In this study, for the first time, we have successfully demonstrated the synthesis and antileishmanial activity of the novel sterol pentalinonsterol (PEN), which occurs naturally in the root of a Mexican medicinal plant, Pentalinon andrieuxii. In the experimental BALB/c mouse model of VL induced by infection with L. donovani, intravenous treatment with liposome-encapsulated PEN (2.5 mg/kg) led to a significant reduction in parasite burden in the liver and spleen. Furthermore, infected mice treated with liposomal PEN showed a strong host-protective TH1 immune response characterized by IFN-γ production and formation of matured hepatic granulomas. These results indicate that PEN could be developed as a novel drug against VL.

Studies on the protective efficacy of second-generation vaccine along with standard antileishmanial drug in Leishmania donovani infected BALB/c mice

It is well established that visceral leishmaniasis (VL; also known as Kala azar) causes immunosuppression, and a successful drug treatment is associated with the development of cell-mediated immunity. Therefore combining a drug with an immune enhancer can provide a better approach for the treatment of the disease. Keeping this in mind, the in vivo antileishmanial efficacy of immunochemotherapy was evaluated with the use of a 78 kDa antigen with or without monophosphoryl lipid A (MPL-A) along with a traditional drug sodium stibogluconate (SSG) in Leishmania donovani infected BALB/c mice. Mice were infected intracardially with promastigotes of L. donovani, and 30 days after infection, these animals were given specific immunotherapy (78 kDa/78 kDa+MPL-A) or chemotherapy (SSG) or immunochemotherapy (SSG+78 kDa/SSG+78 kDa+MPL-A). Animals were euthanased on 1, 15 and 30 post-treatment days. The antileishmanial potential of the immunochemotherapy was revealed by significant reduction in the parasite burden (P<0·001). These animals were also found to exhibit increased delayed type hypersensitivity (DTH) responses, higher IgG2a levels, lower IgG1 levels and greater cytokine (IFN-γ and IL-2) concentrations compared with chemotherapy or immunotherapy alone, pointing towards the generation of a strong protective (Th1) type of immune response. Immunochemotherapy with SSG+78 kDa+MPL-A was found to be most effective in protecting mice against VL and therefore can be an alternative option for treatment of VL.

Apoptosis mediated leishmanicidal activity of Azadirachta indica bioactive fractions is accompanied by Th1 immunostimulatory potential and therapeutic cure in vivo

BACKGROUND

Exploration of immunomodulatory antileishmanials of plant origin is now being strongly recommended to overcome the immune suppression evident during visceral leishmaniasis (VL) and high cost and toxicity associated with conventional chemotherapeutics. In accordance, we assessed the in vitro and in vivo antileishmanial and immunomodulatory potential of ethanolic fractions of Azadirachta indica leaves (ALE) and seeds (ASE).

METHODS

A. indica fractions were prepared by sequential extraction of the powdered plant parts in hexane, ethanol and water. Erythrosin B staining was employed to appraise the anti-promastigote potential of ALE and ASE. Cytostatic or cytocidal mode of action was ascertained and alterations in parasite morphology were depicted under oil immersion light microscopy. Study of apoptotic correlates was performed to deduce the mechanism of induced cell death and anti-amastigote potential was assessed in Leishmania parasitized RAW 264.7 macrophages. In vivo antileishmanial effectiveness was evaluated in L. donovani infected BALB/c mice, accompanied by investigation of immunomodulatory potential of ALE and ASE. Adverse toxicity of the bioactive fractions against RAW macrophages was studied by MTT assay. In vivo side effects on the liver and kidney functions were also determined. Plant secondary metabolites present in ALE and ASE were analysed by Gas chromatography-mass spectrometry (GC-MS).

RESULTS

ALE and ASE (500 μg ml(-1)) exhibited leishmanicidal activity in a time- and dose-dependent manner (IC₅₀ 34 and 77.66 μg ml(-1), respectively) with alterations in promastigote morphology and induction of apoptosis. ALE and ASE exerted appreciable anti-amastigote potency (IC₅₀ 17.66 and 24.66 μg ml(-1), respectively) that was coupled with profound in vivo therapeutic efficacy (87.76% and 85.54% protection in liver and 85.55% and 83.62% in spleen, respectively). ALE exhibited minimal toxicity with selectivity index of 26.10 whereas ASE was observed to be non-toxic. The bioactive fractions revealed no hepato- and nephro-toxicity. ALE and ASE potentiated Th1-biased cell-mediated immunity along with upregulation of INF-γ, TNF-α and IL-2 and decline in IL-4 and IL-10 levels. GC-MS analysis revealed several compounds that may have contributed to the observed antileishmanial effect.

CONCLUSION

Dual antileishmanial and immunostimulatory efficacy exhibited by the bioactive fractions merits their use alone or as adjunct therapy for VL.

Protective role of silymarin against manganese-induced nephrotoxicity and oxidative stress in rat

Metal toxicity may occur after exposure from many sources. Oxidative stress is thought to be involved in manganese-induced toxicity and leads to various health disorders. Silymarin (SIL), a natural flavonoid, has been reported to have many benefits and medicinal properties. The aim of this study was to assess the toxicity of manganese (Mn) on oxidative stress and DNA damage in the kidney of rats and its alleviation by SIL. Manganese was given orally in drinking water (20 mg MnCl2 /mL) with or without SIL administration (100 mg /kg intraperitoneally) for 30 days. Our data showed that SIL significantly prevented Mn induced nephrotoxicity, indicated by both diagnostic indicators of kidney injury like plasma urea, uric acid and creatinine and urinary electrolyte levels and by histopathological analysis. Moreover, Mn-induced profound elevation of the production of reactive oxygen species (ROS) and altered the levels of oxidative stress related biomarkers in kidney tissue. This is evidenced by the increase of lipid peroxidation, protein carbonylation, DNA fragmentation and urinary hydrogen peroxide, while, the activities of enzymatic antioxidant and glutathione level were decreased. Treatment with SIL reduced the alterations in the renal and urine markers, decreasing lipid peroxidation markers, increasing the antioxidant cascade and decreasing the Mn-induced damage. All these changes were supported by histopathological observations. These findings suggested that the inhibition of Mn-induced damage by SIL was due at least in part to its antioxidant activity and its capacity to modulate the oxidative damage.

A comparative evaluation of efficacy of chemotherapy, immunotherapy and immunochemotherapy in visceral leishmaniasis-an experimental study

Visceral leishmaniasis (VL) represents the second most challenging infectious disease worldwide, leading to nearly 500,000 new cases and 60,000 deaths annually. Ninety per cent of VL cases occur in five countries namely Bangladesh, India, Nepal, Sudan and Brazil. No licensed vaccine is available till date against any form of leishmaniasis. High toxicity and increasing resistance to the current chemotherapeutic regimens have further complicated the situation in VL endemic regions of the world. To combat this situation, immunochemotherapy can provide a solution. In the present study, an attempt has been made to assess the in vivo antileishmanial efficacy of chemotherapy, immunotherapy and immunochemotherapy with the use of a first generation antigen Killed Leishmania donovani (KLD) along with a standard drug sodium stibogluconate (SSG) and a newly tested antileishmanial cisplatin. Inbred BALB/c mice were infected with 10(7) promastigotes/0.1 ml of Leishmania donovani. A month after infection, these animals were given specific immunotherapy (KLD/KLD+MPL-A) or chemotherapy (SSG/cisplatin) or immunochemotherapy (SSG+KLD/SSG+KLD+MPL-A/cisplatin+KLD/cisplatin+KLD+MPL-A). Animals were sacrificed on 1, 15 and 30(th) day post treatment. The efficacy of these combinations was assessed in terms of parasite load and by immunological investigations. Infected mice and normal mice served as controls. Results showed that combination of drug and KLD significantly reduced the parasite burden, enhanced the DTH (Delayed Type Hypersensitivity) responses, showed increased levels of IgG2a and decreased levels of IgG1 as compared to mice given chemotherapy or immunotherapy alone. Further maximum protection was provided by SSG+KLD+MPL-A and it was most effective as depicted by 98.5% reduction in parasite load, a potent increase in IFN-γ levels and a significant decrease in IL-10 and IL-4 levels thus skewing the immune response towards Th1 type. Hence, immunochemotherapy is more effective in control of VL in comparison to chemotherapy or immunotherapy.

Combination therapy with nitazoxanide and amphotericin B, Glucantime®, miltefosine and sitamaquine against Leishmania (Leishmania) infantum intracellular amastigotes

Leishmaniasis is a neglected disease that affects poorest population mainly in developing countries, representing one of the major causes of mortality and morbidity. Therefore, efforts to find new chemotherapeutics for leishmaniasis remain a priority. Previous reports demonstrated the in vitro and in vivo antileishmanial activity of nitazoxanide, an antiprotozoan agent used in the treatment of infectious diarrhea. The present work was carried out to determine the effect of nitazoxanide in combination with current antileishmanial drugs. Mouse peritoneal macrophages were infected with Leishmania (Leishmania) infantum amastigotes in order to calculate the 50% and 90% inhibitory concentration values. Drug interactions were assessed with fixed ratio isobologram method and fractional inhibitory concentrations (FIC50 and FIC90); sum of FIC (ΣFIC50 and ΣFIC90) and overall mean ΣFIC (xΣFIC50 and xΣFIC90) were calculated for each combination. The nature of interactions was classified according to the xΣFIC50 and xΣFIC90. The combination between nitazoxanide and amphotericin B, Glucantime(®), miltefosine and sitamaquine showed xΣFIC50 values of 1.13, 0.83, 1.06 and 0.94, respectively, indicating additive interaction. Considering the in vitro activity of nitazoxanide and the obtained results, further in vivo studies may be considered to evaluate possible drug interactions in visceral leishmaniasis.

Liposomal resiquimod for the treatment of Leishmania donovani infection

OBJECTIVES

The imidazoquinoline family of drugs are Toll-like receptor 7/8 agonists that have previously been used in the treatment of cutaneous leishmaniasis. Because of the hydrophobic nature of imidazoquinolines, they are traditionally not administered systemically for the treatment of visceral leishmaniasis. We formulated liposomal resiquimod, an imidazoquinoline, for the systemic treatment of visceral leishmaniasis.

METHODS

By using lipid film hydration with extrusion, we encapsulated resiquimod in liposomes. These liposomes were then injected intravenously to treat BALB/c mice infected with Leishmania donovani.

RESULTS

Treatment with liposomal resiquimod significantly decreased the parasite load in the liver, spleen and bone marrow. In addition, resiquimod treatment increased interferon-γ and interleukin-10 production in an antigen recall assay. Resiquimod was shown to be non-toxic in histology and in vitro culture experiments.

CONCLUSIONS

FDA-approved resiquimod, in a liposomal formulation, displays promising results in treating visceral leishmaniasis.

Antineoplastic drug, carboplatin, protects mice against visceral leishmaniasis

In the present study, the leishmanicidal effect of two doses (5 and 10 mg/kg body weight) of the carboplatin was studied in Leishmania donovani-infected BALB/c mice. Mice were infected intracardially with promastigotes of L. donovani, and a month after infection, they were treated intraperitoneally with the two doses of the drug (5 and 10 mg/kg body weight) for five continuous days. Animals were sacrificed on 1 and 15 posttreatment days. Hepatic parasite load was assessed on Geimsa-stained imprints. Immune responses were studied by measuring delayed-type hypersensitivity (DTH) responses, serum IgG isotype levels (IgG1 and IgG2a) and cytokine levels [γ-interferon (IFN-γ), interleukin (IL)-10 and IL-2] in spleen cell cultures by ELISA. To study the drug-induced side effects, various haematological (haemoglobin and total leukocyte count), biochemical (liver and kidney function tests) and histological investigations (kidney, liver and spleen) were carried out. The antileishmanial potential of the drug was revealed by significant reduction in the parasite burden. The infected and treated animals were also found to exhibit increased DTH responses, higher IgG2a levels, lower IgG1 levels and greater cytokine (IFN-γ, IL-10 and IL-2) concentrations pointing towards the generation of mixed Th1/Th2 response. Liver and kidney function tests and histological studies of kidney, liver and spleen of treated mice revealed no side effects. Carboplatin cures mice of visceral leishmaniasis without causing any serious side effects, and the drug was found be more effective at a dose of 10 mg/kg body weight as compared to 5 mg/kg body weight.