Curcumin overcomes the inhibitory effect of nitric oxide on Leishmania

Mevalonate kinase of Leishmania donovani promotes its survival and plays a pivotal role in pathogenesis

The infectivity of Leishmania is determined by its ability to invade and evade host and its thriving capacity within the macrophage. Our study revealed the role of Leishmania donovani mevalonate kinase (MVK), an enzyme of mevalonate pathway in visceral leishmaniasis pathogenesis. Peritoneal exudate cells (PEC)-derived macrophages from BALB/c mice were infected with wild type (WT), MVK over expressing (MVK OE) and knockdown (KD) parasites and MVK OE parasites were found to be more infective than WT and MVK KD parasites. Incubation of macrophages with MVK OE parasites declined inducible nitric oxide synthase (iNOS) expression as well as nitric oxide (NO) production, both by 2 times in comparison to WT parasites. Moreover, ∼3 fold increase in Arginase1 expression indicated that MVK might induce polarization of macrophage towards M2, favouring the survival of parasite within the macrophages. Post 24 h infection of the macrophages with mutant strains, the levels of different cytokines (TNF-α, IL-12, IL-10 and IFN-γ) were measured. Infection of macrophages with MVK OE parasites showed an increase in the level of anti-inflammatory cytokine: IL-10 while infection with MVK KD parasites exhibited an increase in the level of pro-inflammatory cytokines: TNF-α, IL-12, and IFN-γ. Hence, Leishmania donovani mevalonate kinase (LdMVK) modulates macrophage functions and has a significant role in pathogenesis.

Therapeutic vulnerabilities of cancer stem cells and effects of natural products

Covering: 1995 to 2022Tumors possess both genetic and phenotypic heterogeneity leading to the survival of subpopulations post-treatment. The term cancer stem cells (CSCs) describes a subpopulation that is resistant to many types of chemotherapy and which also possess enhanced migratory and anchorage-independent growth capabilities. These cells are enriched in residual tumor material post-treatment and can serve as the seed for future tumor re-growth, at both primary and metastatic sites. Elimination of CSCs is a key goal in enhancing cancer treatment and may be aided by application of natural products in conjunction with conventional treatments. In this review, we highlight molecular features of CSCs and discuss synthesis, structure-activity relationships, derivatization, and effects of six natural products with anti-CSC activity.

Synthesis and characterization of bovine serum albumin-coated copper sulfide nanoparticles as curcumin nanocarriers

Cancer is among the most common causes of death in the world that affects a large number of people every year. Curcumin is one of the natural anticancer therapeutics with little or no negative effects. However, due to its hydrophobic nature, poor bioavailability, limited gastrointestinal uptake, and fast metabolism, its therapeutic applications are constrained. Therefore, the Bovine Serum Albumin-Coated Copper Sulfide anoparticles (CuS@BSA) for curcumin (CUR) drug delivery were synthesized and characterized, and then curcumin release from the nanosystem. Hemotoxicity, and cytotoxicity was investigated. This study involved the one-step synthesis of CuS@BSA nanoparticles first, followed by the addition of CUR. Then the synthesized nanoparticles were characterized employing Scanning Transient Electron Microscopy (STEM), Ultraviolet-visible spectroscopy (UV-vis) and Fourier-transform infrared spectroscopy (FT-IR) techniques. The Size and surface charge (zeta potential) of synthesized nanoparticles were determined by Dynamic Light Scattering (DLS) to be 120 nm and -13 eV, respectively. The results showed that the CUR loading was around 15% and also the release pattern of CUR was dependent on pH and increased in an acidic environment. The results of the hemolysis assay showed that the synthesized nanoparticles are not hemotoxic. The investigation of the cytotoxic effects of synthesized nanoparticles on cancer cells demonstrated that CuS@BSA nanoparticles did not exhibit any toxicity and therefore are an appropriate candidate for drug delivery.

The Effect of Curcumin on the Expression of INFγ, TNF-α, and iNOS Genes in PBMCs Infected with Leishmania major [MRHO/IR/75/ER]

BACKGROUND

Leishmaniasis, caused by the Leishmania parasite, is one of the most important tropical neglected diseases. The urgent search for effective, inexpensive, and preferably herbal anti-leishmanial agents, is needed.

OBJECTIVE

Curcumin is a natural polyphenolic compound derived from turmeric that is well known for its antioxidant, anti-inflammatory, anti-tumor, and anti-cancer activity.

METHODS

The present work evaluates the anti-leishmanial [Leishmania major] activity of curcumin. The infected PBMCs were treated with curcumin. The ROS level at 6, 12, 24 h and gene expression levels at 24, 48, and 72 h of PBMCs after treatment with curcumin were determined.

RESULTS

Based on the results, the curcumin concentrations of 268 μM [24 h] and 181.2 μM [72 h] were defined as IC50 against L. major promastigotes. Treatment of L. major infected-peripheral blood mononuclear cells [PBMCs] with IC50 concentrations of curcumin, depending on exposure time, significantly induced the reactive oxygen species [ROS] generation and increased the expression levels of interferongamma [IFN-γ], tumor necrosis factor-alpha [TNF-α], and nitric oxide synthase [iNOS] genes.

CONCLUSION

These findings suggest the potential of curcumin against Leishmaniasis.

A Systematic Review of Curcumin and its Derivatives as Valuable Sources of Antileishmanial Agents

BACKGROUND

In recent years, antimonial agents and other synthetic antileishmanial drugs, such as amphotericin B, paromomycin, and many other drugs, have restrictions in use due to the toxicity risk, high cost, and emerging resistance to these drugs. The present study aimed to review the antileishmanial effects of curcumin, its derivatives, and other relevant pharmaceutical formulations on leishmaniasis.

METHODS

The present study was carried out according to the 06-preferred reporting items for systematic reviews and meta-analyses (PRISMA) guideline and registered in the CAMARADES-NC3Rs Preclinical Systematic Review and Meta-Analysis Facility (SyRF) database. Some English-language databases including PubMed, Google Scholar, Web of Science, EBSCO, Science Direct, and Scopus were searched for publications worldwide related to antileishmanial effects of curcumin, its derivatives, and other relevant pharmaceutical formulations, without date limitation, to identify all the published articles (in vitro, in vivo, and clinical studies). Keywords included "curcumin", "Curcuma longa", "antileishmanial", "Leishmania", "leishmaniasis", "cutaneous leishmaniasis", "visceral leishmaniasis", "in vitro", and "in vivo".

RESULTS

Out of 5492 papers, 29 papers including 20 in vitro (69.0%), 1 in vivo (3.4%), and 8 in vitro/in vivo (27.6%) studies conducted up to 2020, met the inclusion criteria for discussion in this systematic review. The most common species of the Leishmania parasite used in these studies were L. donovani (n = 13, 44.8%), L. major (n = 10, 34.5%), and L. amazonensis (n = 6, 20.7%), respectively. The most used derivatives in these studies were curcumin (n = 15, 33.3%) and curcuminoids (n = 5, 16.7%), respectively.

CONCLUSION

In the present review, according to the studies in the literature, various forms of drugs based on curcumin and their derivatives exhibited significant in vitro and in vivo antileishmanial activity against different Leishmania spp. The results revealed that curcumin and its derivatives could be considered as an alternative and complementary source of valuable antileishmanial components against leishmaniasis, which had no significant toxicity. However, further studies are required to elucidate this concluding remark, especially in clinical settings.

Effects of Curcumin and Its Analogues on Infectious Diseases

Infectious diseases (IDs) are life-threatening illnesses, which result from the spread of pathogenic microorganisms such as bacteria, viruses, fungi, and parasites. IDs are a major challenge for the healthcare systems around the world, leading to a wide variety of clinical manifestations and complications. Despite the capability of frontline-approved medications to partially prevent or mitigate the invasion and subsequent damage of IDs to host tissues and cells, problems such as drug resistance, insufficient efficacy, unpleasant side effects, and high expenses stand in the way of their beneficial applications. One strategy is to evaluate currently explored and available bioactive compounds as possible anti-microbial agents. The natural polyphenol curcumin has been postulated to possess various properties including anti-microbial activities. Studies have shown that it possess pleiotropic effects against bacterial- and parasitic-associating IDs including drug-resistant strains. Curcumin can also potentiate the efficacy of available anti-bacterial and anti-parasitic drugs in a synergistic fashion. In this review, we summarize the findings of these studies along with reported controversies of native curcumin and its analogues, alone and in combination, toward its application in future studies as a natural anti-bacterial and anti-parasitic agent.

A Systematic Literature Review of Curcumin with Promising Antileishmanial Activity

BACKGROUND

Curcumin (CUR) is a bright yellow chemical and it is used as an additive in foods. Recently CUR and its associated bioactive compounds have received much attention in the literature review. The aim of this systematic review is to overview the antileishmanial properties of CUR and its mechanism; perhaps the results of this study will be used for therapeutic and preventive purposes.

METHODS

Following the PRISMA guidelines, international databases were systematically searched for studies published until September 2019. Articles related to the subject were selected and included in this systematic review.

RESULTS

A total of 15 articles met our eligibility criteria. Then, the effect of CUR and its associated bioactive compounds on Leishmania species was evaluated. In most studies, CUR/derivatives were tested on L. major and in vitro condition. Most investigations were conducted on the promastigote rather than the more relevant intracellular amastigote stage. Our results showed that CUR overcomes the inhibitory effect of nitric oxide (NO) on Leishmania parasites.

CONCLUSION

This review indicated that CUR derivatives, instead of CUR alone showed a high potential to serve as an effective herbal drug against leishmaniasis. Moreover, we concluded that the antileishmanial activity of CUR/bioactive compounds is mostly due to increased oxidative stress and apoptosis.

Potential of nano-phytochemicals in cervical cancer therapy

Cervical cancer is common among women with a recurrence rate of 35% despite surgery, radiation, and chemotherapy. Patients receiving chemotherapy or radiotherapy routinely experience several side effects including toxicity, non-targeted damage of tissues, hair loss, neurotoxicity, multidrug resistance (MDR), nausea, anemia and neutropenia. Phytochemicals can interfere with almost every stage of carcinogenesis to prevent cancer development. Many natural compounds are known to activate/deactivate multiple redox-sensitive transcription factors that modulate tumor signaling pathways. Polyphenols have been found to be promising agents against cervical cancer. However, applications of phytochemicals as a therapeutic drug are limited due to low oral bioavailability, poor aqueous solubility and requirement of high doses. Nano-sized phytochemicals (NPCs) are promising anti-cancer agents as they are required in minute quantities which lowers overall treatment costs. Several phytochemicals, including quercetin, lycopene, leutin, curcumin, green tea polyphenols and others have been packaged as nanoparticles and proven to be useful in nano-chemoprevention and nano-chemotherapy. Nanoparticles have high biocompatibility, biodegradability and stability in biological environment. Nano-scale drug delivery systems are excellent source for enhanced drug specificity, improved absorption rates, reduced drug degradation and systemic toxicity. The present review discusses current knowledge in the involvement of phytochemical nanoparticles in cervical cancer therapy over conventional chemotherapy.

Cytokine profile and nitric oxide levels in macrophages exposed to Leishmania infantum FML

Fucose-mannose ligand (FML) is a soluble antigen purified from Leishmania donovani complex and used for diagnosis, prognosis, and vaccine development against visceral leishmaniasis (VL). We aimed to explore the effects of FML on the production of cytokines, chemokines and nitric oxide (NO) by macrophages in vitro. Peritoneal macrophages from BALB/c mice were treated with various concentrations of FML purified from Leishmania infantum in the absence or presence of LPS Peritoneal macrophages. After 48hr, cell culture supernatants were recovered and the levels of TNF-α, IL-10, IL-12p70 and IP-10 measured by Sandwich ELISA and NO concentration by Griess reaction. We found that FML significantly increase NO, IL-12p70 and IP-10 production in both LPS-treated and untreated macrophages and increase IL-10 levels only in LPS-treated macrophages. However, FML could not alert TNF-α levels in both LPS-treated and untreated macrophages. Further analysis revealed that FML can also increase IL-12p70/IL-10 ratio in LPS-treated macrophages. We concluded that FML can polarize macrophages to an appropriate phenotype similar to M1 phenotype against Leishmania donovani complex, although IL10 and TNF results are controversial.

Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa Essential Oils: Chemical Composition, Antimicrobial and Antileishmanial Activity

The resistance mechanisms of bacteria and protozoans have evidenced the need of discover new compounds with potential pharmaceutical activity against pathogenic microorganisms. Medicinal plants have been for centuries a promising alternative as sources of new drugs. The objective of this work was to evaluate the chemical composition, antimicrobial and antileishmanial activities of Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa essential oils. Chemical analysis was performed by gas chromatography-mass spectrometry. Antimicrobial activity was performed by disk diffusion and minimum inhibitory concentration (MIC) test. Antileishmanial activity was performed against antipromastigote and intracellular amastigote of Leishmania amazonensis. Cytotoxic and nitrite production were realized in BALB/c peritoneal macrophages. The major compounds of the essential oils were cinnamic aldehyde (46.30%) in C. zeylanicum, cis-p-menth-2-en-1-ol (33.88%) and linalyl acetate (13.90%) in O. vulgare, and turmerone (55.43%) in C. longa. The MIC showed significant antimicrobial activity of C. longa essential oil against S. aureus (83.3 ± 14.43 µg/mL). Antipromastigote activity showed IC₅₀ values >500 µg/mL to C. zeylanicum, 308.4 ± 1.402 µg/mL to O. vulgare, and 405.5 ± 1.119 µg/mL to C. longa essential oil. Activity against intracellular amastigote of L. amazonensis showed IC₅₀ of 63.3 ± 1.369 µg/mL and cytotoxic was not observed, resulting in selectivity index higher than 15.79 to parasite. C. longa essential oil decreased nitrite production in peritoneal macrophages, but not in Leishmania-infected cells. The chemical composition of the three essential oils is directly associated to its potential biological action, as the antimicrobial activity. C. longa presented a potent antileishmanial activity against promastigote and intracellular amastigote of L. amazonensis, although this activity is not linked to nitric oxide, since C. longa essential oil inhibits its production.

Oxidative stress: therapeutic approaches for cervical cancer treatment

Oxidative stress results from an imbalance between the generation and elimination of oxidant species. This condition may result in DNA, RNA and protein damage, leading to the accumulation of genetic alterations that can favor malignant transformation. Persistent infection with high-risk human papillomavirus types is associated with inflammatory responses and reactive oxygen species production. In this context, oxidative stress, chronic inflammation and high-risk human papillomavirus can act in a synergistic manner. To counteract the harmful effects of oxidant species, protective molecules, known as antioxidant defenses, are produced by cells to maintain redox homeostasis. In recent years, the use of natural antioxidants as therapeutic strategies for cancer treatment has attracted the attention of the scientific community. This review discusses specific molecules and mechanisms that can act against or together with oxidative stress, presenting alternatives for cervical cancer prevention and treatment.

Chemoprevention of Leishmaniasis: In-vitro antiparasitic activity of dibenzalacetone, a synthetic curcumin analog leads to apoptotic cell death in Leishmania donovani

Curcumin is the major phenolic compound found in turmeric, a dry powder of rhizomes and roots of the plant, Curcuma longa L., which is widely used as spice and food colorant around the world, and in herbal medicinal practice in Asian countries. The present study reports the leishmanicidal activity of trans-dibenzalacetone (DBA), a synthetic monoketone analog of curcumin, against Leishmania donovani parasites. We for the first time report the antiproliferative effect of a curcumin analog (DBA) on the intracellular amastigotes of L. donovani, the clinically more relevant stage of the parasite than its promastigotes stage. The leishmanicidal effect of DBA was further confirmed by scanning and transmission electron microscopies. Cell growth was arrested in G0/G1 phase with increased concentration of cytosolic calcium and dissipation of mitochondrial membrane potential. Further, the unique trypanothione/trypanothione reductase (TR) system of Leishmania cells was significantly inhibited by DBA. This economically synthesizable simple monoketone analog of curcumin has the potential for field use against visceral leishmaniasis which is currently widespread in tropical and subtropical developing countries of the world. In conclusion, we have identified an analog of curcumin for potential applications against leishmaniasis, based on its strong antiparasitic activity and low toxicity. This curcumin analog compares favorably, at least in vitro, with the existing medication miltefosine.

The effect of intravenous administration of liposomal curcumin in addition to sumatriptan treatment in an experimental migraine model in rats

BACKGROUND

Curcumin has antioxidative properties that could be useful in various diseases due to its ability to act on multiple targets of various cellular pathways. We aimed to assess the efficacy of liposomal curcumin compared with curcumin solution, when in addition to sumatriptan (ST) treatment, in an experimental migraine model induced with nitroglycerin (NTG) in rats.

METHODS

Seven groups of 9 rats each were investigated: control group without migraine (1 mL saline solution intraperitoneal injection [ip]), control group with induced migraine, NTG+ST group (ST), NTG+ST+curcumin1 (CC1) group - 1 mg/100 g body weight (bw), NTG+ST+CC2 - 2 mg/100 g bw, NTG+ST+liposomal curcumin1 (lCC1) group - 1 mg/100 g bw, and NTG+ST+lCC2 (lCC2) group - 2 mg/100 g bw. NTG and ST were administered as 1 mL ip NTG | 1 mg/100 g bw and 1 mL ip ST | 1 mg/100 g bw, respectively. Plasma total oxidative stress (TOS), malondialdehyde (MDA), nitric oxide (NOx), thiol levels, as well as total antioxidative capacity (TAC) were assessed. The nociception process was assessed by counting the number of flinches and shakes after the formalin test.

RESULTS

The plasma TOS, MDA, and NOx levels, as oxidative stress parameters, were significantly decreased in the curcumin-treated groups, especially where curcumin was in liposomal form. The thiol and TAC were also improved by the curcumin treatment, with the best results obtained for the liposomal curcumin. The closest number of flinches and shakes to the control group was obtained for the group treated with liposomal curcumin at a dose of 2 mg/100 g bw.

CONCLUSION

Liposomal curcumin in a dose of 2 mg/100 g bw when in addition to ST treatment could be an optimum therapeutic strategy for migraine attacks and could represent a base for future clinical research and application.

Curcumin alters the cytoskeleton and microtubule organization on trophozoites of Giardia lamblia

Giardia lamblia is a worldwide protozoan responsible for a significant number of intestinal infections. There are several drugs for the treatment of giardiasis, but they often cause side effects. Curcumin, a component of turmeric, has antigiardial activity; however, the molecular target and mechanism of antiproliferative activity are not clear. The effects of curcumin on cellular microtubules have been widely investigated. Since tubulin is the most abundant protein in the cytoskeleton of Giardia, to elucidate whether curcumin has activity against the microtubules of this parasite, we treated trophozoites with curcumin and the cells were analyzed by scanning electron microscopy and confocal microscopy. Curcumin inhibited Giardia proliferation and adhesion in a time-concentration-dependent mode. The higher inhibitory concentrations of curcumin (3 and 15μM) disrupted the cytoskeletal structures of trophozoites; the damage was evident on the ventral disk, flagella and in the caudal region, also the membrane was affected. The immunofluorescence images showed altered distribution of tubulin staining on ventral disk and flagella. Additionally, we found that curcumin caused a clear reduction of tubulin expression. By docking analysis and molecular dynamics we showed that curcumin has a high probability to bind at the interface of the tubulin dimer close to the vinblastine binding site. All the data presented indicate that curcumin may inhibit Giardia proliferation by perturbing microtubules.

The multifaceted role of curcumin in cancer prevention and treatment

Despite significant advances in treatment modalities over the last decade, neither the incidence of the disease nor the mortality due to cancer has altered in the last thirty years. Available anti-cancer drugs exhibit limited efficacy, associated with severe side effects, and are also expensive. Thus identification of pharmacological agents that do not have these disadvantages is required. Curcumin, a polyphenolic compound derived from turmeric (Curcumin longa), is one such agent that has been extensively studied over the last three to four decades for its potential anti-inflammatory and/or anti-cancer effects. Curcumin has been found to suppress initiation, progression, and metastasis of a variety of tumors. These anti-cancer effects are predominantly mediated through its negative regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other oncogenic molecules. It also abrogates proliferation of cancer cells by arresting them at different phases of the cell cycle and/or by inducing their apoptosis. The current review focuses on the diverse molecular targets modulated by curcumin that contribute to its efficacy against various human cancers.

"Squalenoylcurcumin" nanoassemblies as water-dispersible drug candidates with antileishmanial activity

Curcumin, a natural polyphenolic compound, showed antiparasitic potential, including trypanocidal and leishmanicidal activity, in several in vitro and in vivo models. The molecule is well tolerated in humans. However, it is insoluble in water and displays poor oral bioavailability as a result of low absorption. New derivatives of curcumin were prepared by esterification of one or two of its phenolic groups with 1,1',2-tris-norsqualenic acid. These "squalenoylcurcumins" were formulated as water-dispersible nanoassemblies of homogeneous size, and they proved to be stable. Squalenoylcurcumins were inactive against Trypanosoma brucei brucei trypomastigotes, even as nanoassemblies, in contrast with curcumin. However, against Leishmania donovani promastigotes, the activities of the squalenoylcurcumins and their nanoassemblies were enhanced relative to that of curcumin. In L. donovani axenic and intramacrophagic amastigotes, they showed activity in the range of miltefosine, with good selectivity indexes. In regard to their dispersibility in water and to the safety of curcumin, these nanoassemblies are promising candidates for preclinical study toward the treatment of visceral leishmaniasis.

Curcumin and its derivatives: their application in neuropharmacology and neuroscience in the 21st century

Curcumin (diferuloylmethane), a polyphenol extracted from the plant Curcuma longa, is widely used in Southeast Asia, China and India in food preparation and for medicinal purposes. Since the second half of the last century, this traditional medicine has attracted the attention of scientists from multiple disciplines to elucidate its pharmacological properties. Of significant interest is curcumin's role to treat neurodegenerative diseases including Alzheimer's disease (AD), and Parkinson's disease (PD) and malignancy. These diseases all share an inflammatory basis, involving increased cellular reactive oxygen species (ROS) accumulation and oxidative damage to lipids, nucleic acids and proteins. The therapeutic benefits of curcumin for these neurodegenerative diseases appear multifactorial via regulation of transcription factors, cytokines and enzymes associated with (Nuclear factor kappa beta) NFκB activity. This review describes the historical use of curcumin in medicine, its chemistry, stability and biological activities, including curcumin's anti-cancer, anti-microbial, anti-oxidant, and anti-inflammatory properties. The review further discusses the pharmacology of curcumin and provides new perspectives on its therapeutic potential and limitations. Especially, the review focuses in detail on the effectiveness of curcumin and its mechanism of actions in treating neurodegenerative diseases such as Alzheimer's and Parkinson's diseases and brain malignancies.

Validity of silver, chitosan, and curcumin nanoparticles as anti-Giardia agents

This study was carried out to evaluate the anti parasitic potential of silver, chitosan, and curcumin nanoparticles as anti-Giardia agents. Non-treated infected control rats were inoculated with Giardia lamblia cysts in a dose of 2 × 10(5) cysts/rat. Experimental group was infected then treated with curcumin, curcumin nanoparticles, chitosan, chitosan nanoparticles, and silver nanoparticles as single or combined therapy. The number of Giardia cysts in stools and trophozoites in intestinal sections were detected. Toxicity of nanoparticles was evaluated by comparing hematological and histopathological parameters of the normal control group and treated non-infected control group. The amount of silver was also measured in the liver, kidney, small intestine, lung, and brain of rats treated with silver nanoparticles. The number of the parasites in stool and small intestinal sections decreased in treated infected rats compared with infected non-treated ones. The effect in the single therapy was better with nanoparticles, and the best effect was detected in nano-silver. The combined therapy gave better results than single. Combination between nanoparticles was better than the combination of nano-forms and native chitosan and curcumin. The best effect was detected in combinations of nano-silver and nano-chitosan but with no full eradication. In conclusion, the highest effect and complete cure was gained by combining the three nano-forms. The parasite was successfully eradicated from stool and intestine. None of the treatments exhibited any toxicity. Accumulated silver in different organs was within the safe limits.

Peroxisome Proliferator-Activated Receptor-γ-Mediated Polarization of Macrophages in Leishmania Infection

Infection is the outcome of a contest between a pathogen and its host. In the disease leishmaniasis, the causative protozoan parasites are harbored inside the macrophages. Leishmania species adapt strategies to make the infection chronic, keeping a balance between their own and the host's defense so as to establish an environment that is favorable for survival and propagation. Activation of peroxisome proliferator-activated receptor (PPAR) is one of the tactics used. This ligand-activated nuclear factor curbs inflammation to protect the host from excessive injuries by setting a limit to its destructive force. In this paper, we report the interaction of host PPARs and the pathogen for visceral leishmaniasis, Leishmania donovani, in vivo and in vitro. PPAR expression is induced by parasitic infection. Leishmanial activation of PPARγ promotes survival, whereas blockade of PPARγ facilitates removal of the parasite. Thus, Leishmania parasites harness PPARγ to increase infectivity.

Novel anti-Cryptosporidium activity of known drugs identified by high-throughput screening against parasite fatty acyl-CoA binding protein (ACBP)

BACKGROUND

Cryptosporidium parvum causes an opportunistic infection in AIDS patients, and no effective treatments are yet available. This parasite possesses a single fatty acyl-CoA binding protein (CpACBP1) that is localized to the unique parasitophorous vacuole membrane (PVM). The major goal of this study was to identify inhibitors from known drugs against CpACBP1 as potential new anti-Cryptosporidium agents.

METHODS

A fluorescence assay was developed to detect CpACBP1 activity and to identify inhibitors by screening known drugs. Efficacies of top CpACBP1 inhibitors against Cryptosporidium growth in vitro were evaluated using a quantitative RT-PCR assay.

RESULTS

Nitrobenzoxadiazole-labelled palmitoyl-CoA significantly increased the fluorescent emission upon binding to CpACBP1 (excitation/emission 460/538 nm), which was quantified to determine the CpACBP1 activity and binding kinetics. The fluorescence assay was used to screen a collection of 1040 compounds containing mostly known drugs, and identified the 28 most active compounds that could inhibit CpACBP1 activity with sub-micromolar IC(50) values. Among them, four compounds displayed efficacies against parasite growth in vitro with low micromolar IC(50) values. The effective compounds were broxyquinoline (IC(50) 64.9 μM), cloxyquin (IC(50) 25.1 μM), cloxacillin sodium (IC(50) 36.2 μM) and sodium dehydrocholate (IC(50) 53.2 μM).

CONCLUSIONS

The fluorescence ACBP assay can be effectively used to screen known drugs or other compound libraries. Novel anti-Cryptosporidium activity was observed in four top CpACBP1 inhibitors, which may be further investigated for their potential to be repurposed to treat cryptosporidiosis and to serve as leads for drug development.

Multifaceted roles of curcumin: two sides of a coin!

INTRODUCTION

Curcumin has been a front-line topic of mainstream scientific research for a variety of diseases from cancer to Alzheimer's to infectious diseases. Curcumin suppresses the type 1 immune response, which might lead to alleviation of type 1 immune response disorders. However, the inhibition of type 1 immune response might invite infections with opportunistic pathogens. Considering its low bioavailability, several curcumin derivatives have been designed to improve its functionality.

AREAS COVERED

This is a consolidated review which aims to compare and contrast diverse aspects of curcumin in variety of diseases. The intricate underlying mechanisms and the functional determinants of curcumin are discussed.

EXPERT OPINION

Curcumin being considered as a spicy panacea, is not a remedy for all diseases. However, its ability to act differentially as an anti-oxidant or pro-oxidant akin to that of a double-edged sword/friend turning foe can be either beneficial or harmful for the host. It exhibits anti-oxidant properties at concentrations achievable in the body, making the host vulnerable to infections due to the suppression of innate immune responses. With the increase in knowledge of its functional groups, production of analogues of curcumin is underway to enhance its bioavailability and hence its therapeutic potency.

Curcumin, the golden spice from Indian saffron, is a chemosensitizer and radiosensitizer for tumors and chemoprotector and radioprotector for normal organs

Curcumin (diferuloylmethane), the yellow pigment in Indian saffron (Curcuma longa; also called turmeric, haldi, or haridara in the East and curry powder in the West), has been consumed by people for centuries as a dietary component and for a variety of proinflammatory ailments. Extensive research within the last decade in cell culture and in rodents has revealed that curcumin can sensitize tumors to different chemotherapeutic agents including doxorubicin, 5-FU, paclitaxel, vincristine, melphalan, butyrate, cisplatin, celecoxib, vinorelbine, gemcitabine, oxaliplatin, etoposide, sulfinosine, thalidomide, and bortezomib. Chemosensitization has been observed in cancers of the breast, colon, pancreas, gastric, liver, blood, lung, prostate, bladder, cervix, ovary, head and neck, and brain and in multiple myeloma, leukemia, and lymphoma. Similar studies have also revealed that this agent can sensitize a variety of tumors to gamma radiation including glioma, neuroblastoma, cervical carcinoma, epidermal carcinoma, prostate cancer, and colon cancer. How curcumin acts as a chemosensitizer and radiosensitizer has also been studied extensively. For example, it downregulates various growth regulatory pathways and specific genetic targets including genes for NF-κB, STAT3, COX2, Akt, antiapoptotic proteins, growth factor receptors, and multidrug-resistance proteins. Although it acts as a chemosensitizer and radiosensitizer for tumors in some cases, curcumin has also been shown to protect normal organs such as liver, kidney, oral mucosa, and heart from chemotherapy and radiotherapy-induced toxicity. The protective effects of curcumin appear to be mediated through its ability to induce the activation of NRF2 and induce the expression of antioxidant enzymes (e.g., hemeoxygenase-1, glutathione peroxidase, modulatory subunit of gamma-glutamyl-cysteine ligase, and NAD(P)H:quinone oxidoreductase 1, increase glutathione (a product of the modulatory subunit of gamma-glutamyl-cysteine ligase), directly quench free radicals, and inhibit p300 HAT activity. These preclinical studies are expected to lead to clinical trials to prove the potential of this age-old golden spice for treating cancer patients.

Peroxisome proliferator-activated receptor (PPAR): balance for survival in parasitic infections

Parasitic infections induce a magnitude of host responses. At the opposite ends of the spectrum are those that ensure the host's needs to eliminate the invaders and to minimize damage to its own tissues. This review analyzes how parasites would manipulate immunity by activating the immunosuppressive nuclear factor, peroxisome proliferator-activated receptors (PPARs) with type 2 cytokines and free fatty acids from arachidonic acid metabolism. PPARs limit the action of type 1 immunity, in which classically activated macrophages act through the production of proinflammatory signals, to spare the parasites. They also favor the development of alternately activated macrophages which control inflammation so the host would not be destroyed. Possibly, the nuclear factors hold a pivotal role in the establishment of chronic infection by delicately balancing the pro- and anti-inflammatory signaling mechanisms and their ligands may be used as combination therapeutics to limit host pathology.

Preventive effect of curcumin and quercetin against nitric oxide mediated modification of goat lung cystatin

Cysteine proteinase inhibitors are of prime physiologic importance inside the cells, controlling the activities of lysosomal cysteine proteases. The present work aimed to realize the effects of nitric oxide on the structure and function of goat lung cystatin (GLC) and to evaluate antinitrostative efficacy of curcumin and quercetin. Nitric oxide induced structural modifications were followed by fluorescence spectroscopy and PAGE and functional inactivation by monitoring the inhibition of caseinolytic activity of papain. Ten millimolar sodium nitroprusside (SNP) caused time dependent inactivation of GLC-I with complete functional loss precipitating at 180 min. Curcumin (50 microM) and quercetin (250 microM) opposed such loss in papain inhibitory activity of GLC-I. Loss in tertiary structure of GLC-I (fluorescence quenching and 15 nm red shift) was observed on SNP treatment. Inhibition of functional and structural SNP mediated damage of GLC-I by curcumin (50 microM) and quercetin (250 microM) reaffirms their NO scavenging potency.

Medicinal plants from the Yanesha (Peru): evaluation of the leishmanicidal and antimalarial activity of selected extracts

AIM OF THE STUDY

Ninety-four ethanolic extracts of plants used medicinally by the Yanesha, an Amazonian Peruvian ethnic group, for affections related to leishmaniasis and malaria were screened in vitro against Leishmania amazonensis amastigotes and against a Plasmodium falciparum chloroquine resistant strain.

MATERIALS AND METHODS

The viability of Leishmania amazonensis amastigote stages was assessed by the reduction of tetrazolium salt (MTT) while the impact on Plasmodium falciparum was determined by measuring the incorporation of radio-labelled hypoxanthine.

RESULTS AND CONCLUSIONS

Six plant species displayed good activity against Plasmodium falciparum chloroquine resistant strain (IC(50) < 10 microg/ml): a Monimiaceae, Siparuna aspera (Ruiz & Pavon), A. DC., two Zingiberaceae, Renealmia thyrsoidea (Ruiz & Pavon) Poepp. & Endl. and Renealmia alpinia (Rottb.), two Piperaceae (Piper aduncum L. and Piper sp.) and the leaves of Jacaranda copaia (Aubl.) D. Don (Bignoniaceae). Eight species displayed interesting leishmanicidal activities (IC50 < 10 microg/ml): Carica papaya L. (Caricaceae), Piper dennisii Trel (Piperaceae), Hedychium coronarium J. König (Zingiberaceae), Cestrum racemosum Ruiz & Pav. (Solanaceae), Renealmia alpinia (Rottb.) Zingiberaceae, Lantana sp. (Verbenaceae), Hyptis lacustris A. St.-Hil. ex Benth. (Lamiaceae) and Calea montana Klat. (Asteraceae). Most of them are used against skin affections by Yanesha people. Results are discussed herein, according to the traditional use of the plants and compared with data obtained from the literature.

Long-term use of an antiinflammatory, curcumin, suppressed type 1 immunity and exacerbated visceral leishmaniasis in a chronic experimental model

Inflammation is considered the underlying cause of numerous disorders, and the practice of taking antiinflammatories as diet supplements has become increasingly prevalent. This study addresses the bioavailablity of a well-established dietary antiinflammatory, curcumin, and examines its effect on adaptive immunity. Visceral leishmaniasis is a major parasitic disease which protection relies on cell-mediated immunity and production of nitric oxide. We found that long-term, low-dose, oral consumption of curcumin activates peroxisome proliferator-activated receptor-gamma, deactivates type 1 response, inhibits inducible nitric oxide synthase, and interferes with adaptive immunity to exacerbate the pathogenesis of Leishmania donovani infection in vivo. These in vivo effects can be correlated to activities on infected residential macrophages in vitro. Therefore, when reactive radicals generated from inflammation play the dominant role in elimination of pathogens, excessive use of the antioxidative supplements may compromise microbial defense. Nonetheless, it should be noted with equal importance that our finding, conversely, also strengthens the prospect that curcumin may alleviate type 1 response disorders.

Changes in the proteome and infectivity of Leishmania infantum induced by in vitro exposure to a nitric oxide donor

Leishmania species are protozoan parasites that exhibit an intracellular amastigote form within mammalian macrophages and an extracellular promastigote form inside the sandfly vector. The generation of nitric oxide (NO) upon activation of macrophages is surely the principal killing effector of intracellular amastigotes but little is known about the potential action of NO against the promastigote phase during its multiplication inside the digestive tract of the sandfly vector. Therefore, we have approached this issue by using an in vitro model to study the effect of an NO donor, 3-morpholinosydnonimine (SIN-1), on the proteome and infectivity of promastigotes of Leishmania infantum. Exposure of promastigotes to SIN-1 during its logarithmic growth phase caused a dramatic effect on parasite protein expression and viability, consequently killing about 60-70% of the promastigotes. The significant changes in the proteome included the over-expression of enolase, peroxidoxin precursors, and heat-shock protein 70 (HSP70), under-expression of 20S proteasome alpha 5 unit, and phosphomannomutase and induced expression of 3-hydroxy-3-methyglutaryl-CoA (HMG-CoA) synthase and prostaglandine f2-alpha (PGD2) synthase. Interestingly, promastigotes that resisted treatment showed enhanced infectivity to J774 macrophages in comparison to the controls. This finding together with the appearance of the PGD2S and an over-expression of HSP70 isoforms in treated promastigotes led us to speculate the existence of NO-mediated programmed cell death (PCD) events as a potential mechanism of population regulation and selection of properly infecting forms that predominantly operate on the promastigote stage.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Diagnostic approach and significance of inducible nitric oxide positivity in human cutaneous leishmaniasis caused by leishmania tropica

AIM

To determine the usefulness of polymerase chain reaction (PCR) in the diagnosis of leishmaniasis and to emphasize the importance of inducible nitric oxide (iNOS).

MATERIALS AND METHODS

Twenty-nine patients with cutaneous leishmaniasis diagnosed according to clinical criteria who live in rural areas of Antakya-Hatay/Turkey were included in this study. Twenty-five patients free of leishmaniasis were accepted as a control group. Punch biopsies and smears were obtained from lesions of the patients in the study group. Half of each punch biopsy specimen was processed in routine tissue processing. After routine tissue processing hematoxylin-eosin and iNOS immunohistochemical staining were applied. The remaining half of the biopsy specimens was studied by PCR method. INOS-positive stained macrophages were determined.

RESULTS

The positive detection rates in 29 cases of cutaneous leishmaniasis (CL) were 96.5% by PCR, 86.2% by direct microscopic evaluation of biopsy and 58.6% by direct visualization of smear in this study. iNOS reaction was mildly positive in three cases, moderately positive in six cases and strongly positive in 20 cases.

CONCLUSION

iNOS yielded positive reaction in all cases but this positivity showed differences with respect to the age of the lesions or the effect of iNOS on the immune mechanism. This reveals an inverse correlation between iNOS reactivity and duration of lesion (Spearman correlation r = -0.53, P = 0.003). There was no correlation between iNOS reactivity and patient age (Spearman correlation: r = 0.13, P = 0.5). In terms of gender, there was no association with iNOS.

Immune response modulation by curcumin in a latex allergy model

Background

There has been a worldwide increase in allergy and asthma over the last few decades, particularly in industrially developed nations. This resulted in a renewed interest to understand the pathogenesis of allergy in recent years. The progress made in the pathogenesis of allergic disease has led to the exploration of novel alternative therapies, which include herbal medicines as well. Curcumin, present in turmeric, a frequently used spice in Asia has been shown to have anti-allergic and inflammatory potential.

Methods

We used a murine model of latex allergy to investigate the role of curcumin as an immunomodulator. BALB/c mice were exposed to latex allergens and developed latex allergy with a Th2 type of immune response. These animals were treated with curcumin and the immunological and inflammatory responses were evaluated.

Results

Animals exposed to latex showed enhanced serum IgE, latex specific IgG₁, IL-4, IL-5, IL-13, eosinophils and inflammation in the lungs. Intragastric treatment of latex-sensitized mice with curcumin demonstrated a diminished Th2 response with a concurrent reduction in lung inflammation. Eosinophilia in curcumin-treated mice was markedly reduced, co-stimulatory molecule expression (CD80, CD86, and OX40L) on antigen-presenting cells was decreased, and expression of MMP-9, OAT, and TSLP genes was also attenuated.

Conclusion

These results suggest that curcumin has potential therapeutic value for controlling allergic responses resulting from exposure to allergens.

Cytotoxic effect of curcumin on malaria parasite Plasmodium falciparum: inhibition of histone acetylation and generation of reactive oxygen species

The emergence of multidrug-resistant parasites is a major concern for malaria control, and development of novel drugs is a high priority. Curcumin, a natural polyphenolic compound, possesses diverse pharmacological properties. Among its antiprotozoan activities, curcumin was potent against both chloroquine-sensitive and -resistant Plasmodium falciparum strains. Consistent with findings in mammalian cell lines, curcumin's prooxidant activity promoted the production in P. falciparum of reactive oxygen species (ROS), whose cytotoxic effect could be antagonized by coincubation with antioxidants and ROS scavengers. Curcumin treatment also resulted in damage of both mitochondrial and nuclear DNA, probably due to the elevation of intracellular ROS. Furthermore, we have demonstrated that curcumin inhibited the histone acetyltransferase (HAT) activity of the recombinant P. falciparum general control nonderepressed 5 (PfGCN5) in vitro and reduced nuclear HAT activity of the parasite in culture. Curcumin-induced hypoacetylation of histone H3 at K9 and K14, but not H4 at K5, K8, K12, and K16, suggested that curcumin caused specific inhibition of the PfGCN5 HAT. Taken together, these results indicated that at least the generation of ROS and down-regulation of PfGCN5 HAT activity accounted for curcumin's cytotoxicity for malaria parasites.

Cytotoxic effect of curcumin on Giardia lamblia trophozoites

Giardia lamblia is one of the most important worldwide causes of intestinal infections produced by protozoa. Thus, the search for new alternative therapeutic approaches for this parasitic disease is very important. Common drugs used to control and eradicate this infection, frequently exhibit side effects that force patients to abandon treatment. The present work evaluates the anti-protozoan activity of curcumin, the main constituent of turmeric. Axenic G. lamblia (Portland 1 strain) cultures were exposed to different concentrations of curcumin. Its effects were evaluated on parasite growth, adhesion capacity and parasite morphology. We also evaluated the capacity of curcumin to induce an apoptosis-like effect. All curcumin concentrations inhibited trophozoite growth and adhesion in more than 50% in dose and time dependent manner. Morphological changes were described as protrusions formed under the cytoplasmic membrane, deformation due to swelling and cell agglutination. Curcumin induced apoptosis-like nuclear staining in dose and time dependent manner. In conclusion, curcumin exhibited a cytotoxic effect in G. lamblia inhibiting the parasite growth and adherent capacity, induced morphological alterations, provoked apoptosis-like changes. Future in vitro and in vivo experiments are endowed to elucidate the effect of curcumin in an experimental model of G. lamblia infection, analyze the involvement of ion channels in the swelling effect of curcumin during an apparent osmotic deregulation in G. lamblia trophozoites. This will lead to the proposal of the action mechanism of curcumin as well as the description of mechanism involved during the activation process for the apoptotic-like effect.