Curcumin-arteether combination therapy of Plasmodium berghei-infected mice prevents recrudescence through immunomodulation

Therapeutical Utilization and Repurposing of Artemisinin and Its Derivatives: A Narrative Review

Artemisinin (ART) and its derivatives have great therapeutical utility as antimalarials and can be repurposed for other indications, such as viral infections, autoimmune diseases, and cancer. This review presents a comprehensive overview of the therapeutic effects of ART-based drugs, beyond their antimalarial effects. This review also summarizes the information on their repurposing in other pathologies, with the hope that it will guide the future optimization of the use of ART-based drugs and of the treatment strategies for the listed diseases. By reviewing related literature, ART extraction and structure as well as the synthesis and structure of its derivatives are presented. Subsequently, the traditional roles of ART and its derivatives against malaria are reviewed, including antimalarial mechanism and occurrence of antimalarial resistance. Finally, the potential of ART and its derivatives to be repurposed for the treatment of other diseases are summarized. The great repurposing potential of ART and its derivatives may be useful for the control of emerging diseases with corresponding pathologies, and future research should be directed toward the synthesis of more effective derivatives or better combinations.

In Vivo Antimalarial Activity of the Leaf Extract of Osyris quadripartita Salzm. ex Decne and Its Major Compound (–) Catechin

Background

The leaves of Osyris quadripartita Salzm. ex Decne, endemic to Ethiopia, are traditionally used for the treatment of malaria. Previous phytochemical investigations of Osyris species showed the presence of flavonoids, anthracene derivatives, and sesquiterpene lactones as the main constituents. The aim of the present study was to investigate the antimalarial activity of the leaf extract of O. quadripartita and its isolated constituent against mice infected with Plasmodium berghei.

Methods

Isolation of a compound was carried out on silica gel column chromatography of the extract eluting with gradient mixtures of CHCl₃/MeOH. Structural elucidation of the isolated compound was achieved by ESI-MS and 1D-and 2D-NMR spectral data. Peter's 4-day suppressive test method was used to determine the antimalarial activity of the test substances. Level of parasitemia, survival time, and body weight change were used to determine the antimalarial activity of the test substances.

Results

(–) Catechin was isolated and characterized from the hydroalcoholic extract of O. quadripartita. At a concentration of 400 mg/kg, both the extract and (–) catechin exhibited antimalarial activity with the highest chemosuppression values of 70.61% and 64.26%, respectively.

Conclusion

These findings indicate that O. quadripartita is endowed with genuine antimalarial activity attributed in part, to its (–) catechin content. Hence, the present study may validate the traditional use of the plant for the treatment of malaria.

Piperine Enhances the Antimalarial Activity of Curcumin in Plasmodium berghei ANKA-Infected Mice: A Novel Approach for Malaria Prophylaxis

Malaria is a prevalent vector-borne infectious disease in tropical regions, particularly in the absence of effective vaccines and because of the emergence resistance of Plasmodium to available antimalarial drugs. An alternative strategy for malaria eradication could be the combination of existing compounds that possess antimalarial activity to target multiple stages of the parasite. This study evaluated the antimalarial activity of a combination of curcumin and piperine in mice. A total of 42 mice were assigned to six groups depending on the treatment administered: group I (normal group) with aquadest; group II (negative control) with 0.2 ml DMSO; group III received a standard malarial drug (artesunate 5 mg/kg BW); groups IV, V, and VI with curcumin 300 mg/kg BW, curcumin 300 mg/kg BW and piperine 20 mg/kg BW, and piperine 20 mg/kg BW, respectively. The antimalarial activity was evaluated using prophylactic assays in Plasmodium berghei ANKA-infected mice, including the percentage parasitemia, clinical signs, survival rate, serum biochemical analysis, parasitic load in the liver, and liver histopathology. All treatments showed significant (p < 0.05) antiplasmodial activity, with considerable parasite inhibition (>50%), curcumin 300 mg/kg BW (60.22%), curcumin 300 mg/kg BW, and piperine 20 mg/kg BW (77.94%) except for piperine 20 mg/kg BW (47.20%), eliciting greater inhibition relative to that of artesunate (51.18%). The delayed onset of clinical symptoms and prolonged survival rate were also significant (p < 0.05) in the combination of curcumin and piperine treated group. In addition, the low parasitic load in the liver and mild histopathological changes in the liver suggest that the combination of curcumin and piperine had synergistic or additive effects. These findings demonstrate the promising use of these combined compounds as a malarial prophylactic. Further studies were recommended to assess their clinical usefulness.

Dihydroartemesinin and Curcumin Based Self-Microemulsifying Drug Delivery System for Antimalarial Activity

Malaria is a significant global problem which still persists despite the development of various effective antimalarial drugs. It is challenging to treat this disease due to the parasite's complex life cycle and high recrudensce of antimalarial drugs. A new self-micro emulsifying drug delivery system has been developed to improve the solubility of dihydroartemisinin and curcumin. The prepared formulation contained Dihydroartemesinin, curcumin, Groundnut Oil, Cremephor RH, and Tween 80. Self-micro emulsification time, zeta potential, droplet size, polydispersity index, transmission electron microscopy, drug release, and in-vivo studies were performed for characterization. The globule size was found to be 25.59±0.40 nm and the zeta potential was-5.75±0.18 mV. The globules prepared were spherical in shape. The in-vitro dissolution performance of formulation of dihydroartemisinin and curcumin self emulsifying drug delivery system showed significantly (p<0.05, Origin Pro 8.5) higher release as compared to the pure drugs. The results of the study suggested that the prepared self emulsifying drug delivery system combination of Dihydroartemesinin and curcumin has a better potential to cure parasitemia as compared to the individual drug.

Plants as Sources of Natural and Recombinant Antimalaria Agents

Malaria is one of the severe infectious diseases that has victimized about half a civilization billion people each year worldwide. The application of long-lasting insecticides is the main strategy to control malaria; however, a surge in antimalarial drug development is also taking a leading role to break off the infections. Although, recurring drug resistance can compromise the efficiency of both conventional and novel antimalarial medicines. The eradication of malaria is significantly contingent on discovering novel potent agents that are low cost and easy to administer. In this context, plant metabolites inhibit malaria infection progression and might potentially be utilized as an alternative treatment for malaria, such as artemisinin. Advances in genetic engineering technology, especially the advent of molecular farming, have made plants more versatile in producing protein drugs (PDs) to treat infectious diseases, including malaria. These recent developments in genetic modifications have enabled the production of native pharmaceutically active compounds and the accumulation of diverse heterologous proteins such as human antibodies, booster vaccines, and many PDs to treat infectious diseases and genetic disorders. This review will discuss the pivotal role of a plant-based production system that expresses natural antimalarial agents or host protein drugs to cure malaria infections. The potential of these natural and induced compounds will support modern healthcare systems in treating malaria infections, especially in developing countries to mitigate human fatalities.

A Systematic Review on Curcumin and Anti-Plasmodium berghei Effects

BACKGROUND

Turmeric (Curcuma longa L.) is a popular spice, containing curcumin that is responsible for its therapeutic effects. Curcumin with anti-inflammatory, antioxidant, anti-cancer, and antimicrobial activities has led to a lot of research focusing on it over the years. This systematic review aimed to evaluate researches on anti-Plasmodium berghei activity of curcumin and its derivatives.

METHODS

Our study was performed according to PRISMA guidelines and was recorded in the database of systematic review and preclinical meta-analysis of CAMARADESNC3Rs (SyRF). The search was performed in five databases, namely Scopus, PubMed, Web of Science, EMBASE, and Google Scholar from 2010 to 2020. The following keywords were searched: "Plasmodium berghei", "Medicinal Plants", "Curcumin", "Concentration", Animals kind", "Treatment Durations", "Routes of Administration" and "in vivo".

RESULTS

Of the 3,500 papers initially obtained, 14 articles were reliable and were thus scrutinized. Animal models were included in all studies. The most commonly used animal strain were Albino (43%) followed by C57BL/6 (22%). The other studies used various murine strains, including BALB/c (14%) and ICR (7%). Two (14%) studies did not mention the strain of animal model used. Curcumin alone or in combination with other compounds depending on the dose used, route of administration, and animal model showed a moderate to strong anti-Plasmodium berghei effect.

CONCLUSION

According to the studies, curcumin has anti-malarial effects on Plasmodium berghei and, however, its effect on human Plasmodium is unclear. Due to the side effects and drug resistance of current drugs in the treatment of human malaria, the use of new compounds with few or no side effects such as curcumin is recommended as an alternative or complementary treatment.

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

The Potential use of a Curcumin-Piperine Combination as an Antimalarial Agent: A Systematic Review

Malaria remains a significant global health problem, but the development of effective antimalarial drugs is challenging due to the parasite's complex life cycle and lack of knowledge about the critical specific stages. Medicinal plants have been investigated as adjuvant therapy for malaria, so this systematic review summarizes 46 primary articles published until December 2020 that discuss curcumin and piperine as antimalarial agents. The selected articles discussed their antioxidant, anti-inflammatory, and antiapoptosis properties, as well as their mechanism of action against Plasmodium species. Curcumin is a potent antioxidant, damages parasite DNA, and may promote an immune response against Plasmodium by increasing reactive oxygen species (ROS), while piperine is also a potent antioxidant that potentiates the effects of curcumin. Hence, combining these compounds is likely to have the same effect as chloroquine, that is, attenuate and restrict parasite development, thereby reducing parasitemia and increasing host survival. This systematic review presents new information regarding the development of a curcumin-piperine combination for future malaria therapy.

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.

Liposomes for malaria management: the evolution from 1980 to 2020

Malaria is one of the most prevalent parasitic diseases and the foremost cause of morbidity in the tropical regions of the world. Strategies for the efficient management of this parasitic infection include adequate treatment with anti-malarial therapeutics and vaccination. However, the emergence and spread of resistant strains of malaria parasites to the majority of presently used anti-malarial medications, on the other hand, complicates malaria treatment. Other shortcomings of anti-malarial drugs include poor aqueous solubility, low permeability, poor bioavailability, and non-specific targeting of intracellular parasites, resulting in high dose requirements and toxic side effects. To address these limitations, liposome-based nanotechnology has been extensively explored as a new solution in malaria management. Liposome technology improves anti-malarial drug encapsulation, bioavailability, target delivery, and controlled release, resulting in increased effectiveness, reduced resistance progression, and fewer adverse effects. Furthermore, liposomes are exploited as immunological adjuvants and antigen carriers to boost the preventive effectiveness of malaria vaccine candidates. The present review discusses the findings from studies conducted over the last 40 years (1980-2020) using in vitro and in vivo settings to assess the prophylactic and curative anti-malarial potential of liposomes containing anti-malarial agents or antigens. This paper and the discussion herein provide a useful resource for further complementary investigations and may pave the way for the research and development of several available and affordable anti-malarial-based liposomes and liposomal malaria vaccines by allowing a thorough evaluation of liposomes developed to date for the management of malaria.

Silver Nanoparticles Biosynthesized With Salvia officinalis Leaf Exert Protective Effect on Hepatic Tissue Injury Induced by Plasmodium chabaudi

Malaria is an important health problem in subtropical and tropical areas around the world. Infection with protozoan parasites of the Plasmodium genus, which grow inside host erythrocytes, causes malaria and may lead to morbidity and mortality. Liver tissue plays an important role in the pathogenesis of malaria and is closely involved in parasitic pre-erythrocytic development. Numerous published studies have demonstrated that the liver is not only the source of Plasmodium parasites prior to erythrocytic growth but is also a primary immune effector toward the blood stage of the malaria life cycle. Despite efforts to improve antimalarial drugs and vaccines, Plasmodium species that cause severe malaria are being detected increasingly frequently in endemic regions. In this study, Salvia officinalis (S. officinalis) leaf extract was employed to synthesize silver nanoparticles (Ag-NPs). This method is eco-friendly and represents a single-step technique for the biosynthetic process; therefore, it has attracted considerable attention. Accordingly, we biosynthesized Ag-NPs with extract of the S. officinalis leaf and examined the antimalarial activity of these nanoparticles in a murine model of Plasmodium chabaudi malaria (P. chabaudi malaria). Forty mice were chosen and classified into four types: infected group, healthy control, pretreated mice infected after treatment with 50 mg/kg of S. officinalis leaf extract-biosynthesized Ag-NPs for two weeks, and post-treated mice infected before treatment with 50 mg/kg of S. officinalis leaf extract-biosynthesized Ag-NPs (administered daily for 7 d). In this study, both pre-treatment and post-treatment with Ag-NPs produced a substantial reduction in parasitemia relative to the infected group. We investigated the antiplasmodial and hepatoprotective effects of S. officinalis leaf extract-biosynthesized Ag-NPs on P. chabaudi-induced inflammation and hepatic oxidative stress markers.

Host-directed Therapy: A New Arsenal to Come

The emergence of drug-resistant strains among the variety of pathogens worsens the situation in today's scenario. In such a situation, a very heavy demand for developing the new antibiotics has arisen, but unfortunately, very limited success has been achieved in this arena till now. Infectious diseases usually make their impression in the form of severe pathology. Intracellular pathogens use the host's cell machinery for their survival. They alter the gene expression of several host's pathways and endorse to shut down the cell's innate defense pathway like apoptosis and autophagy. Intracellular pathogens are co-evolved with hosts and have a striking ability to manipulate the host's factors. They also mimic the host molecules and secrete them to prevent the host's proper immune response against them for their survival. Intracellular pathogens in chronic diseases create excessive inflammation. This excessive inflammation manifests in pathology. Host directed therapy could be alternative medicine in this situation; it targets the host factors, and abrogates the replication and persistence of pathogens inside the cell. It also provokes the anti-microbial immune response against the pathogen and reduces the exacerbation by enhancing the healing process to the site of pathology. HDT targets the host's factor involved in a certain pathway that ultimately targets the pathogen life cycle and helps in eradication of the pathogen. In such a scenario, HDT could also play a significant role in the treatment of drugsensitive as well with drug resistance strains because it targets the host's factors, which favors the pathogen survival inside the cell.

Synergistic effects of curcumin and its analogs with other bioactive compounds: A comprehensive review

Curcumin, as a natural compound, extracted from plant Curcuma longa, is abundant in the Indian subcontinent and Southeast Asia, and have been used in a diverse array of pharmacological activities. Although curcumin has some limitations like low stability and low bioavailability, it has been proved that this compound induced apoptosis signaling and is also known to block cell proliferation signaling pathway. Recently, extensive research has been carried out to study the application of curcumin as a health improving agent, and devise new methods to overcome to the curcumin limitations and incorporate this functional ingredient into foods. Combinational chemotherapy is one of the basic strategies is using for 60 years for the treatment of various health problems like cancer, malaria, inflammation, diabetes and etc. Molecular hybridization is another strategy to make multi-pharmacophore or conjugated drugs with more synergistic effect than the parent compounds. The aim of this review is to provide an overview of the pharmacological activity of curcumin and its analogs in combination with other bioactive compounds and cover more recent reports of anti-cancer, anti-malarial, and anti-inflammatory activities of these analogs.

Nanotized curcumin-benzothiophene conjugate: A potential combination for treatment of cerebral malaria

The declining effectiveness of the available antimalarial drugs due to drug resistance requires a continued effort to develop new therapeutic approaches. In this context, combination therapies hold a great promise for developing effective first-line antimalarial treatments for reducing malaria mortality. The present study explores the antimalarial efficacy of nanotized formulation of curcumin in combination with benzothiophene compound 6 (3-bromo-N-(4-fluorobenzyl)-benzo[b]thiophene-2-carboxamide) with a view to achieve better efficacy at a very low dose in comparison to that accomplished with monotherapy alone. Herein, we formulated nanotized conjugate of curcumin and compound 6 (cur-compound 6) in the size range of 30-90 nm as observed via TEM, AFM and DLS analysis in the study. The nanotized preparation was found to be readily dispersible in water, physically and chemically stable and exhibited sustained release profile of both curcumin and compound 6 till 48 hr. Treatment of P. falciparum parasites with the nanotized conjugate for 24 hr resulted in rapid clearance of the parasites. Furthermore, P. berghei infected mice treated with nanotized conjugate formulation survived till 90 days with complete eradication of the parasites from RBC. This improved efficacy of the nanotized formulation was possible because of the increased absorption of the compounds via oral administration owing to enhanced dispersibility of the formulation in aqueous medium. Moreover, an improved oral bioavailability of the nanotized formulation lowered the dosage at which the pharmacological effect was achieved while avoiding any observable adverse harmful side effects.

The modulatory effect of Artemisia annua L. on toll-like receptor expression in Acanthamoeba infected mouse lungs

The genus Acanthamoeba, which may cause different infections in humans, occurs widely in the environment. Lung inflammation caused by these parasites induces pulmonary pathological changes such as pulmonary necrosis, peribronchial plasma cell infiltration, moderate desquamation of alveolar cells and partial destruction of bronchial epithelial cells, and presence of numerous trophozoites and cysts among inflammatory cells. The aim of this study was to assess the influence of plant extracts from Artemisia annua L. on expression of the toll-like receptors TLR2 and TLR4 in lungs of mice with acanthamoebiasis. A. annua, which belongs to the family Asteraceae, is an annual plant that grows wild in Asia. In this study, statistically significant changes of expression of TLR2 and TLR4 were demonstrated. In the lungs of infected mice after application of extract from A. annua the expression of TLRs was observed mainly in bronchial epithelial cells, pneumocytes (to a lesser extent during the outbreak of infection), and in the course of high general TLR expression. TLR4 in particular was also visible in stromal cells of lung parenchyma. In conclusion, we confirmed that a plant extract of A. annua has a modulatory effect on components of the immune system such as TLR2 and TLR4.

Impact of curcumin on toll-like receptors

Toll-like receptors (TLRs) have a pivotal role in the activation of innate immune response and inflammation. TLRs can be divided into two subgroups including extracellular TLRs that recognize microbial membrane components (TLR1, 2, 4, 5, 6, and 10), and intracellular TLRs that recognize microbial nucleic acids (TLR3, 7, 8, and 9). Curcumin is a dietary polyphenol from Curcuma longa L. that is reputed to have diverse biological and pharmacological effects. Extensive research has defined the molecular mechanisms through which curcumin mediates its therapeutic effects. One newly defined and important target of curcumin is the TLR, where it exerts an inhibitory effect. In the current study, we focus upon the TLR antagonistic effect of curcumin and curcumin's therapeutic effect as mediated via TLR inhibition. The available evidence indicates that curcumin inhibits the extracellular TLR 2 and 4 and intracellular TLR9 and thereby exerts a therapeutic effect in diseases such as cancer, inflammation, infection, autoimmune, and ischemic disease. Curcumin effectively modulates the TLR response and thereby exerts its potent therapeutic effects.

Macrophage plasticity, polarization and function in response to curcumin, a diet-derived polyphenol, as an immunomodulatory agent

Monocytes and macrophages are important cells of the innate immune system that have diverse functions, including defense against invading pathogens, removal of dead cells by phagocytosis, antigen presentation in the context of MHC class I and class II molecules, and production of various pro-inflammatory cytokines and chemokines such as IL-1β, IL-6, TNF-α and MCP-1. In addition, pro-inflammatory (M1) and anti-inflammatory (M2) macrophages clearly play important roles in the progression of several inflammatory diseases. Therefore, therapies that target macrophage polarization and function by either blocking their trafficking to sites of inflammation, or skewing M1 to M2 phenotype polarization may hold clinical promise in several inflammatory diseases. Dietary-derived polyphenols have potent natural anti-oxidative properties. Within this group of polyphenols, curcumin has been shown to suppress macrophage inflammatory responses. Curcumin significantly reduces co-stimulatory molecules and also inhibits MAPK activation and the translocation of NF-κB p65. Curcumin can also polarize/repolarize macrophages toward the M2 phenotype. Curcumin-treated macrophages have been shown to be highly efficient at antigen capture and endocytosis via the mannose receptor. These novel findings provide new perspectives for the understanding of the immunopharmacological role of curcumin, as well as its therapeutic potential for impacting macrophage polarization and function in the context of inflammation-related disease. However, the precise effects of curcumin on the migration, differentiation, polarization and immunostimulatory functions of macrophages remain unknown. Therefore, in this review, we summarized whether curcumin can influence macrophage polarization, surface molecule expression, cytokine and chemokine production and their underlying pathways in the prevention of inflammatory diseases.

Long circulatory liposomal maduramicin inhibits the growth of Plasmodium falciparum blood stages in culture and cures murine models of experimental malaria

Malaria continues to be one of the deadliest infectious diseases and a global health menace. The emergence and spread of drug-resistant strains of malaria parasites have further made the process of disease management grimmer. Thus, there is an urgent need to identify promising antimalarial strategies that can target the blood stages as well as block parasite transmission. Maduramicin is one such ionophore selected out of a recent screen of gametocytocidal compounds that exhibit potent antiplasmodial activity. However, maduramicin's strong hydrophobic nature and associated toxicity restrict its application in chemotherapy. To alleviate this problem, we have developed a liposomal formulation loaded with the ionophore maduramicin for the treatment of chloroquine sensitive and resistant Plasmodium infections. Here, we show that maduramicin in PEGylated liposomal formulations displayed enhanced antiplasmodial activity in vitro compared to free maduramicin. Significantly, four consecutive doses of 1.5 mg kg-1 body weight of PEGylated maduramicin loaded lipid vesicles completely cured cerebral and chloroquine resistant murine models of malaria without any obvious toxic effects and suppressed the key inflammatory markers associated with the progression of the disease. PEGylated liposomal maduramicin also exhibited a prolonged plasma clearance rate, implying a greater chance of interaction and uptake by infected RBCs. Furthermore, we also provide evidence that the detrimental effect of liposomal maduramicin on parasite survival is mediated by increased ROS generation and subsequent perturbation of parasite mitochondrial membrane potential. This study presents the first report to demonstrate the potent antimalarial efficacy of maduramicin liposomes, a strategy that holds promise for the development of successful therapeutic intervention against malaria in humans.

Curcumin-Artesunate Based Polymeric Nanoparticle; Antiplasmodial and Toxicological Evaluation in Murine Model

Mainstay chemotherapy for malaria is often faced with the problem of instability and poor bio-distribution thus resulting in impaired pharmacokinetics. Nanomedicine has been acclaimed for its success in drug delivery and improved efficacy. The aim of the study was to assess the antiplasmodial efficacy and safety of curcumin-artesunate co-entrapped nanoparticle in mice model. Curcumin (C) and artesunate (A) were loaded in poly (d,l-lactic-co-glycolic acid) (PLGA) using solvent evaporation from oil-in-water single emulsion method. The nanoparticle formed was characterized for size, polydispersity index (PDI), zeta potential, and entrapment efficiency. The in vitro release of the drug was also determined. The in vivo antiplasmodial activity of CA-PLGA nanoparticle was tested on Plasmodium berghei at 5 and 10 mg/kg doses. The drug efficacy was determined at day 5 and 8. Hematological and hepatic toxicity assays were performed. The mean particle size of drug entrapped PLGA-nanoformulation was 251.1 ± 12.6 nm. The drug entrapment efficiency was 22.3 ± 0.4%. There was a sustained drug release from PLGA for 7 days. The percentage suppression of P. berghei was consistently significantly higher in CA-PLGA 5 mg/kg at day 5 (79.0%) and day 8 (72.5%) than the corresponding values 65.3 and 64.2% in the positive control group (p < 0.05). Aspartate aminotransferase (AST) was significantly lower in mice exposed to 5 mg/kg (42.0 ± 0.0 U/L) and 10 mg/kg (39.5 ± 3.5 U/L) nanotized CA-PLGA compared with the negative control (45.0 ± 4.0 U/L) (p < 0.05). Although alanine aminotransferase (ALT) was lower in nanotized CA-PLGA, the variation was not significant compared with the negative control (p > 0.05). No significant difference in the mean values of the different blood parameters in all exposed groups with the exception of platelets which were significantly higher in the positive control group. A simple method of dual entrapment of curcumin and artesunate with better antiplasmodial efficacy and low toxicity has been synthesized.

Antimalarial Activity of Orally Administered Curcumin Incorporated in Eudragit®-Containing Liposomes

Curcumin is an antimalarial compound easy to obtain and inexpensive, having shown little toxicity across a diverse population. However, the clinical use of this interesting polyphenol has been hampered by its poor oral absorption, extremely low aqueous solubility and rapid metabolism. In this study, we have used the anionic copolymer Eudragit® S100 to assemble liposomes incorporating curcumin and containing either hyaluronan (Eudragit-hyaluronan liposomes) or the water-soluble dextrin Nutriose® FM06 (Eudragit-nutriosomes). Upon oral administration of the rehydrated freeze-dried nanosystems administered at 25/75 mg curcumin·kg−1·day−1, only Eudragit-nutriosomes improved the in vivo antimalarial activity of curcumin in a dose-dependent manner, by enhancing the survival of all Plasmodium yoelii-infected mice up to 11/11 days, as compared to 6/7 days upon administration of an equal dose of the free compound. On the other hand, animals treated with curcumin incorporated in Eudragit-hyaluronan liposomes did not live longer than the controls, a result consistent with the lower stability of this formulation after reconstitution. Polymer-lipid nanovesicles hold promise for their development into systems for the oral delivery of curcumin-based antimalarial therapies.

Co-nanoencapsulation of antimalarial drugs increases their in vitro efficacy against Plasmodium falciparum and decreases their toxicity to Caenorhabditis elegans

Drugs used for the treatment and prevention of malaria have resistance-related problems, making them ineffective for monotherapy. If properly associated, many of these antimalarial drugs may find their way back to the treatment regimen. Among the therapeutic arsenal, quinine (QN) is a second-line treatment for uncomplicated malaria but has side effects that limit its use. Curcumin (CR) is a natural compound with anti-plasmodial activities and low bioavailability. In this context, the aim of this work was to develop and characterize co-encapsulated QN + CR-loaded polysorbate-coated polymeric nanocapsules (NC-QC) to evaluate their activity on Plasmodium falciparum and the safety of the nanoformulations for Caenorhabditis elegans. NC-QC displayed a diameter of approximately 200 nm, a negative zeta potential and a slightly basic pH. The drugs are homogeneously distributed in the NCs in the amorphous form. Co-encapsulated NCs exhibited a significant reduction in P. falciparum parasitemia, better than QN/CR. The worms exposed to NC-QC showed higher survival and longevity and no decrease in their reproductive capacity compared to free and associated drugs. It was possible to prove that the NCs were absorbed orally by the worms using fluorescence microscopy. Co-encapsulation of QN and CR was effective against P. falciparum, minimizing the toxic effects caused by chronic exposure of the free drugs in C. elegans.

Pharmaceutical cocrystals: walking the talk

Pharmaceutical cocrystals belong to a sub-class of cocrystals wherein one of the components is a drug molecule (or an active pharmaceutical ingredient, API) and the second is a benign food or drug grade additive (generally regarded as safe, GRAS). The two components are hydrogen-bonded in a fixed stoichiometric ratio in the crystal lattice. In the past decade, pharmaceutical cocrystals have demonstrated significant promise in their ability to modify the physicochemical and pharmacokinetic properties of drug substances, such as the solubility and dissolution rate, bioavailability, particle morphology and size, tableting and compaction, melting point, physical form, biochemical and hydration stability, and permeability. In this feature review, we highlight some prominent examples of drug cocrystals which exhibit variable hardness/softness and elasticity/plasticity depending on coformer selection, improvement of solubility and permeability in the same cocrystal, increase of the melting point for solid formulation, enhanced color performance, photostability and hydration stability, and a longer half-life. Cocrystals of flavanoids and polyphenols can make improved pharmaceuticals and also extend to the larger class of nutraceuticals. The application of crystal engineering to assemble ternary cocrystals expands this field to drug-drug cocrystals which may be useful in multi-drug resistance, mitigating side effects of drugs, or attenuating/enhancing drug action synergistically by rational selection. The advent of new techniques for structural characterization beyond the standard X-ray diffraction will provide a better understanding of drug phases which are at the borderline of crystalline-amorphous nature and even newer opportunities in the future.

Optimization of Curcuma Oil/Quinine-Loaded Nanocapsules for Malaria Treatment

Quinine, a treatment used in chloroquine-resistant falciparum malaria, was loaded into poly(ɛ-caprolactone) or Eudragit^® RS100 nanocapsules using Curcuma oil as the oil-based core. Until now, the effect of cationic nanocapsules on malaria has not been reported. A 2⁴ factorial design was adopted using, as independent variables, the concentration of Curcuma oil, presence of quinine, type of polymer, and aqueous surfactant. Diameter, zeta potential, and pH were the responses studied. The formulations were also evaluated for drug content, encapsulation efficiency, photostability, and antimalarial activity against Plasmodium berghei-infected mice. The type of polymer influenced all of the responses studied. Quinine-loaded Eudragit^® RS100 (F13) and PCL nanocapsules (F9), both with polysorbate 80 coating, showed nanometric particle size, positive zeta potential, neutral pH, high drug content, and quinine photoprotection ability; thus, these nanocapsules were selected for in vivo tests. Both formulations showed lower levels of parasitemia from the beginning of the experiment (5.78 ± 3.60 and 4.76 ± 3.46% for F9 and F13, respectively) and highest survival mean time (15.3 ± 2.0 and 14.9 ± 5.6 days for F9 and F13, respectively). F9 and F13 showed significant survival curve compared to saline, thus demonstrating that nanoencapsulation improved bioefficacy of QN and co-encapsulated curcuminoids, regardless of the surface charge.

Curcumin: pharmaceutical solids as a platform to improve solubility and bioavailability

The remarkable improvements in the pharmacokinetics and high bioavailability of curcumin polymorphs, amorphous, cocrystals, eutectics, and coamorphous solids are discussed. The importance of pharmaceutical solids in the advanced formulation development of herbal and bioactive molecule curcumin is presented.

Antimalarial Activity of Acetylenic Thiophenes from Echinops hoehnelii Schweinf

Malaria is one of the world’s most severe endemic diseases and due to the emergence of resistance to the currently available medicines, the need for new targets and relevant antimalarial drugs remains acute. The crude extract, four solvent fractions and two isolated compounds from the roots of Echinops hoehnelii were tested for their antimalarial activity using the standard four-day suppressive method in Plasmodium berghei-infected mice. The 80% methanol extract exhibited suppression of 4.6%, 27.8%, 68.5% and 78.7% at dose of 50, 100, 200 and 400 mg/kg respectively. The dichloromethane fraction displayed chemosuppression of 24.9, 33.5 and 43.0% dose of 100, 200 and 400 mg/kg of body weight. Five acetylenicthiophenes were isolated from the dichloromethane fraction of which 5-(penta-1,3-diynyl)-2-(3,4-dihydroxybut-1-ynyl)-thiophene decreased the level of parasitaemia by 43.2% and 50.2% while 5-(penta-1,3-diynyl)-2-(3-chloro-4-acetoxy-but-1-yn)-thiophene suppressed by 18.8% and 32.7% at 50 and 100 mg/kg, respectively. The study confirmed the traditional claim of the plant to treat malaria and could be used as a new lead for the development of antimalarial drugs.

Immune modulation by curcumin: The role of interleukin-10

Cytokines are small secreted proteins released by different types of cells with specific effects on cellular signaling and communication via binding to their receptors on the cell surface. IL-10 is known to be a pleiotropic and potent anti-inflammatory and immunosuppressive cytokine that is produced by both innate and adaptive immunity cells including dendritic cells, macrophages, mast cells, natural killer cells, eosinophils, neutrophils, B cells, CD8⁺ T cells, and T_H1, T_H2, and T_H17 and regulatory T cells. Both direct and indirect activation of the stress axis promotes IL-10 secretion. IL-10 deregulation plays a role in the development of a large number of inflammatory diseases such as neuropathic pain, Parkinson's disease, Alzheimer's disease, osteoarthritis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus, type 1 diabetes, inflammatory bowel disease, and allergy. Curcumin is a natural anti-inflammatory compound able to induce the expression and production of IL-10 and enhancing its action on a large number of tissues. In vitro and in pre-clinical models curcumin is able to modulate the disease pathophysiology of conditions such as pain and neurodegenerative diseases, bowel inflammation, and allergy, but also of infections and cancer through its effect on IL-10 secretion. In humans, at least one part of the positive effects of curcumin on health could be related to its ability to enhance IL-10 -mediated effects.

Nanocurcumin is superior to native curcumin in preventing degenerative changes in Experimental Cerebral Malaria

Curcumin has many pharmacological activities despite its poor bioavailability and in vivo stability. Here, we show that a nanoformulated curcumin (PLGA-curcumin) has better therapeutic index than native curcumin in preventing the onset of neurological symptoms and delaying the death of mice in experimental cerebral malaria. Oral PLGA-curcumin was at least as effective as native curcumin at a 15-fold lower concentration in preventing the breakdown of blood-brain barrier and inhibition of brain mRNAs for inflammatory cytokines, chemokine receptor CXCR3 and its ligand CXCL10, with an increase in the anti-inflammatory cytokine IL-10. This was also reflected in serum cytokine and chemokine levels. At equivalent concentrations, a single oral dose of PLGA-curcumin was more effective in inhibiting serum IFNγ levels and enhancing IL-10 levels than native curcumin. Even at low concentrations, PLGA-curcumin was superior to native curcumin in inhibiting the sequestration of parasitized-RBCs and CD8⁺ T cells in the brain. A single oral dose of 5 mg PLGA-curcumin containing 350 μg of curcumin resulted in 3–4 fold higher concentration and prolonged presence of curcumin in the brain than that obtained with 5 mg of native curcumin, indicating better bioavailability of PLGA-curcumin. PLGA-curcumin has potential as an adjunct drug to treat human cerebral malaria.

The Antimalarial Effect of Curcumin Is Mediated by the Inhibition of Glycogen Synthase Kinase-3β

Curcumin, a bioactive compound in Curcuma longa, exhibits various pharmacological activities, including antimalarial effects. In silico docking simulation studies suggest that curcumin possesses glycogen synthase kinase-3β (GSK3β)-inhibitory properties. The involvement of GSK3 in the antimalarial effects in vivo is yet to be demonstrated. In this study, we aimed to evaluate whether the antimalarial effects of curcumin involve phosphorylation of host GSK3β. Intraperitoneal administration of curcumin into Plasmodium berghei NK65-infected mice resulted in dose-dependent chemosuppression of parasitemia development. At the highest dose tested (30 mg/kg body weight), both therapeutic and prophylactic administrations of curcumin resulted in suppression exceeding 50% and improved median survival time of infected mice compared to control. Western analysis revealed a 5.5-fold (therapeutic group) and 1.8-fold (prophylactic group) increase in phosphorylation of Ser 9 GSK3β and 1.6-fold (therapeutic group) and 1.7-fold (prophylactic group) increase in Ser 473 Akt in liver of curcumin-treated infected animals. Following P. berghei infection, levels of pro- and anti-inflammatory cytokines, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-10, and IL-4 were elevated by 7.5-, 35.0-, 33.0-, and 2.2-fold, respectively. Curcumin treatment (therapeutic) caused a significant decrease (by 6.0- and 2.0-fold, respectively) in serum TNF-α and IFN-γ level, while IL-10 and IL-4 were elevated (by 1.4- and 1.8-fold). Findings from the present study demonstrate for the first time that the antimalarial action of curcumin involved inhibition of GSK3β.

Curcumin Enhances the Anti-Trypanosoma cruzi Activity of Benznidazole-Based Chemotherapy in Acute Experimental Chagas Disease

Although curcumin can increase the effectiveness of drugs against malaria, combination therapies using the molecule have never been investigated in Chagas disease (ChD). Therefore, we evaluated the efficacy of curcumin as a complementary strategy to benznidazole (Bz)-based chemotherapy in mice acutely infected with Trypanosoma cruzi Eighty-four 12-week-old Swiss mice were equally randomized into seven groups: uninfected (NI), T. cruzi infected and untreated (INF), infected and treated with 100 mg/kg of body weight Bz (B100), 50 mg/kg Bz (B50), 100 mg/kg curcumin (C100), 100 mg/kg Bz plus 100 mg/kg curcumin (B100 plus C100), and 50 mg/kg Bz plus 100 mg/kg curcumin (B50 plus C100). After microscopic identification of blood trypomastigotes (4 days after inoculation), both drugs were administered by gavage once a day for 20 days. Curcumin showed limited antiparasitic, anti-inflammatory, and antioxidant effects when administered alone. When curcumin and Bz were combined, there was a drastic reduction in parasitemia, parasite load, mortality, anti-T. cruzi IgG reactivity, circulating levels of cytokines (gamma interferon [IFN-γ], interleukin 4 [IL-4], and MIP1-α), myocardial inflammation, and morphological and oxidative cardiac injury; these results exceeded the isolated effects of Bz. The combination of Bz and curcumin was also effective at mitigating liver toxicity triggered by Bz, increasing the parasitological cure rate, and preventing infection recrudescence in noncured animals, even when the animals were treated with 50% of the recommended therapeutic dose of Bz. By limiting the toxic effects of Bz and enhancing its antiparasitic efficiency, the combination of the drug with curcumin may be a relevant therapeutic strategy that is possibly better tolerated in ChD treatment than Bz-based monotherapy.

KM. The identification of FERM domain protein in serum infected with Plasmodium berghei

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FERM domain is upregulated in P. berghei infected host serum.

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FERM domain has several protein partners to provide a link in cytoskeleton signals.

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FERM domain is recognized by erythrocyte cytoskeleton associated proteins like MESA and PHIST.

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We predict that FERM domain is involved in the merozoites entry and protein trafficking.

Malaria continues to affect 500 million people worldwide every year. In this study, we compared the protein profile of uninfected and Plasmodium berghei-infected serum samples by one dimensional SDS-PAGE analysis, MALDI-TOF/TOF mass spectrometry and confirmed by semi-quantitative RT-PCR. Also the protein interacting networks were established using STRING protein⿿protein interaction analysis. We observed for the first time the upregulation of FERM domain during P. berghei infection. We predict that FRMD5 along with the other protein partners (identified by STRING analysis) are involved in the merozoites entry or protein trafficking where cell to cell interaction happens with the host erythrocyte; hence, upregulation.

Assessment of in vivo antimalarial activity of arteether and garlic oil combination therapy

The study evaluates in vivo antimalarial activity of arteether and garlic pearl oil combination in Plasmodium berghei-infected mouse model of malaria. 72 h (Day 3) post infection, at 2–4% parasitemia, mice were treated with single dose intramuscular injection of α-β arteether, at 750 μg, in combination with three 100 μL oral doses of garlic pearl oil on Day 3, Day 4 and Day 5. Following the treatment, 100% protection and survival of mice were observed. Inhibition of parasitemia in combination treated animals and protection during recrudescence interval of α-β arteether monotherapy was observed in Giemsa-stained blood smears. In addition, a striking increase in anti-parasite antibody IgG contributing protective immunity during the recrudescence phase was observed. These results correlate with western blot analysis, where sera from the recrudescence stage and later period of arteether and garlic oil combination treated animals found to interact with several parasite specific proteins as compared to controls. The present approach shows that arteether and garlic pearl oil combination provides complete protection in P. berghei-infected mice. Thus, for the first time, garlic pearl oil appears to be an ideal antimalarial candidate in artemisinin combination therapy.

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Garlic pearl oil enhanced antimalarial activity of α-β arteether.

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Garlic pearl oil and α-β arteether combination effectively evaded recrudescence.

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Garlic pearl oil and α-β arteether combination may elicit immunomodulatory effect.

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This combination therapy resulted in a striking increase in anti-parasite antibody.

Curcumin as an Adjunct Drug for Infectious Diseases

Curcumin, by virtue of its ability to function as an immunomodulator, has the potential to serve as an adjunct drug to treat infectious diseases and provide long-term protection. The current need is to establish clinical trials with curcumin as an adjunct drug against specific infectious diseases.

Simultaneously targeting inflammatory response and parasite sequestration in brain to treat Experimental Cerebral Malaria

Malaria afflicts around 200 million people annually, with a mortality number close to 600,000. The mortality rate in Human Cerebral Malaria (HCM) is unacceptably high (15–20%), despite the availability of artemisinin-based therapy. An effective adjunct therapy is urgently needed. Experimental Cerebral Malaria (ECM) in mice manifests many of the neurological features of HCM. Migration of T cells and parasite-infected RBCs (pRBCs) into the brain are both necessary to precipitate the disease. We have been able to simultaneously target both these parameters of ECM. Curcumin alone was able to reverse all the parameters investigated in this study that govern inflammatory responses, CD8⁺ T cell and pRBC sequestration into the brain and blood brain barrier (BBB) breakdown. But the animals eventually died of anemia due to parasite build-up in blood. However, arteether-curcumin (AC) combination therapy even after the onset of symptoms provided complete cure. AC treatment is a promising therapeutic option for HCM.

Identification of β-hematin inhibitors in the MMV Malaria Box

The Malaria Box, assembled by the Medicines for Malaria Venture, is a set of 400 structurally diverse, commercially available compounds with demonstrated activity against blood-stage Plasmodium falciparum. The compounds are a representative subset of the 20,000 in vitro antimalarials identified from the high-throughput screening efforts of St. Jude Children's Research Hospital (TN, USA), Novartis and GlaxoSmithKline. In addition, a small set of active compounds from commercially available libraries was added to this group, but it has not previously been published. Elucidation of the biochemical pathways on which these compounds act is a major challenge; therefore, access to these compounds has been made available free of charge to the investigator community. Here, the Malaria Box compounds were tested for activity against the formation of β-hematin, a synthetic form of the heme detoxification biomineral, hemozoin. Further, the mechanism of action of these compounds within the malaria parasite was explored. Ten of the Malaria Box compounds demonstrated significant inhibition of β-hematin formation. In this assay, dose–response data revealed IC₅₀ values ranging from 8.7 to 22.7 μM for these hits, each of which is more potent than chloroquine (a known inhibitor of hemozoin formation). The in vitro antimalarial activity of these ten hits was confirmed in cultures of the chloroquine sensitive D6 strain of the parasite resulting in IC₅₀ values of 135–2165 nM, followed by testing in the multidrug resistant strain, C235. Cultures of P. falciparum (D6) were then examined for their heme distribution following treatment with nine of the commercially available confirmed compounds, seven of which disrupted the hemozoin pathway.

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Ten of 400 Malaria Box compounds were found to be potent β-hematin inhibitors.

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We confirmed similar in vitro antimalarial activity to results from previous screens.

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7 of the 9 commercially available hits were validated hemozoin inhibitors in culture.

Arteether resistance reversal by ketoconazole/fluconazole in rodent malaria parasite Plasmodium vinckei

Artemisinin and its derivative arteether (ART) are fast acting antimalarial drugs against chloroquine-resistant. There are several partner drugs that are identified as a potential drug for artemisinin combination therapy (ACT) to develop as the antimalarial drug. Limited studies have been carried out in ART drug combination that may have more promising as ACT for resistant Plasmodium parasite. Here, we are the first to show the ART drug resistance reversal in Plasmodium vinckei by using antifungal azole compounds ketoconazole (KTZ) and fluconazole (FCZ). Our previous study has shown that higher antioxidant enzyme, glutathione, and less hemozoin may be correlated with ART resistance in P. vinckei (PvAR). We further hypothesized that glutathione and heme catabolism may be interfered by KTZ and FCZ, resulting in an increased efficacy of ART in PvAR parasite. The results of present study demonstrate synergetic effect of KTZ and FCZ against PvAR parasite, since none of the mice developed infection up to day 10 after combination with ART. These results further showed that ED90 of ART was reduced from 17.23 to 2.19 and 2.56 mg/kg when used in combination with KTZ and FCZ, respectively. Resultant, activity enhancement index (AEI) of ART is significantly increased to 8.60 and 6.73 with partner agents. These studies propose the possibility of ART drug combination that may be helpful in prolonging the life of drug and a promising lead to reduce the chance of resistance development of artemisinin and its derivative.

Potent trypanocidal curcumin analogs bearing a monoenone linker motif act on trypanosoma brucei by forming an adduct with trypanothione

We have previously reported that curcumin analogs with a C7 linker bearing a C4-C5 olefinic linker with a single keto group at C3 (enone linker) display midnanomolar activity against the bloodstream form of Trypanosoma brucei. However, no clear indication of their mechanism of action or superior antiparasitic activity relative to analogs with the original di-ketone curcumin linker was apparent. To further investigate their utility as antiparasitic agents, we compare the cellular effects of curcumin and the enone linker lead compound 1,7-bis(4-hydroxy-3-methoxyphenyl)hept-4-en-3-one (AS-HK014) here. An AS-HK014-resitant line, trypanosomes adapted to AS-HK014 (TA014), was developed by in vitro exposure to the drug. Metabolomic analysis revealed that exposure to AS-HK014, but not curcumin, rapidly depleted glutathione and trypanothione in the wild-type line, although almost all other metabolites were unchanged relative to control. In TA014 cells, thiol levels were similar to untreated wild-type cells and not significantly depleted by AS-HK014. Adducts of AS-HK014 with both glutathione and trypanothione were identified in AS-HK014-exposed wild-type cells and reproduced by chemical reaction. However, adduct accumulation in sensitive cells was much lower than in resistant cells. TA014 cells did not exhibit any changes in sequence or protein levels of glutathione synthetase and γ-glutamylcysteine synthetase relative to wild-type cells. We conclude that monoenone curcuminoids have a different mode of action than curcumin, rapidly and specifically depleting thiol levels in trypanosomes by forming an adduct. This adduct may ultimately be responsible for the highly potent trypanocidal and antiparasitic activity of the monoenone curcuminoids.

Curcumin may impair iron status when fed to mice for six months

Curcumin has been shown to have many potentially health beneficial properties in vitro and in animal models with clinical studies on the toxicity of curcumin reporting no major side effects. However, curcumin may chelate dietary trace elements and could thus potentially exert adverse effects. Here, we investigated the effects of a 6 month dietary supplementation with 0.2% curcumin on iron, zinc, and copper status in C57BL/6J mice. Compared to non-supplemented control mice, we observed a significant reduction in iron, but not zinc and copper stores, in the liver and the spleen, as well as strongly suppressed liver hepcidin and ferritin expression in the curcumin-supplemented mice. The expression of the iron-importing transport proteins divalent metal transporter 1 and transferrin receptor 1 was induced, while hepatic and splenic inflammatory markers were not affected in the curcumin-fed mice. The mRNA expression of other putative target genes of curcumin, including the nuclear factor (erythroid-derived 2)-like 2 and haem oxygenase 1 did not differ between the groups. Most of the published animal trials with curcumin-feeding have not reported adverse effects on iron status or the spleen. However, it is possible that long-term curcumin supplementation and a Western-type diet may aggravate iron deficiency. Therefore, our findings show that further studies are needed to evaluate the effect of curcumin supplementation on iron status.

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0.2% dietary curcumin for 6 months reduced iron stores in murine liver and spleen.

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Curcumin chelated iron but not zinc and copper in vivo.

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Liver hepcidin and ferritin expression was strongly suppressed in curcumin-fed mice.

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Curcumin induced expression of hepatic iron transporters DMT1 and TfR1.

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Curcumin did not affect hepatic and splenic inflammatory and oxidative markers.

Epigenetic regulation of the Plasmodium falciparum genome

Recent research has highlighted some unique aspects of chromatin biology in the malaria parasite Plasmodium falciparum. During its erythrocytic lifecycle P. falciparum maintains its genome primarily as unstructured euchromatin. Indeed there is no clear role for chromatin-mediated silencing of the majority of the developmentally expressed genes in P. falciparum. However discontinuous stretches of heterochromatin are critical for variegated expression of contingency genes that mediate key pathogenic processes in malaria. These range from invasion of erythrocytes and antigenic variation to solute transport and growth adaptation in response to environmental changes. Despite lack of structure within euchromatin the nucleus maintains functional compartments that regulate expression of many genes at the nuclear periphery, particularly genes with clonally variant expression. The typical components of the chromatin regulatory machinery are present in P. falciparum; however, some of these appear to have evolved novel species-specific functions, e.g. the dynamic regulation of histone variants at virulence gene promoters. The parasite also appears to have repeatedly acquired chromatin regulatory proteins through lateral transfer from endosymbionts and from the host. P. falciparum chromatin regulators have been successfully targeted with multiple drugs in laboratory studies; hopefully their functional divergence from human counterparts will allow the development of parasite-specific inhibitors.

Modulation of cerebral malaria by curcumin as an adjunctive therapy

Cerebral malaria is the most severe and rapidly fatal neurological complication of Plasmodium falciparum infection and responsible for more than two million deaths annually. The current therapy is inadequate in terms of reducing mortality or post-treatment symptoms such as neurological and cognitive deficits. The pathophysiology of cerebral malaria is quite complex and offers a variety of targets which remain to be exploited for better therapeutic outcome. The present review discusses on the pathophysiology of cerebral malaria with particular emphasis on scope and promises of curcumin as an adjunctive therapy to improve survival and overcome neurological deficits.

Treatment of Plasmodium chabaudi Parasites with Curcumin in Combination with Antimalarial Drugs: Drug Interactions and Implications on the Ubiquitin/Proteasome System

Antimalarial drug resistance remains a major obstacle in malaria control. Evidence from Southeast Asia shows that resistance to artemisinin combination therapy (ACT) is inevitable. Ethnopharmacological studies have confirmed the efficacy of curcumin against Plasmodium spp. Drug interaction assays between curcumin/piperine/chloroquine and curcumin/piperine/artemisinin combinations and the potential of drug treatment to interfere with the ubiquitin proteasome system (UPS) were analyzed. In vivo efficacy of curcumin was studied in BALB/c mice infected with Plasmodium chabaudi clones resistant to chloroquine and artemisinin, and drug interactions were analyzed by isobolograms. Subtherapeutic doses of curcumin, chloroquine, and artemisinin were administered to mice, and mRNA was collected following treatment for RT-PCR analysis of genes encoding deubiquitylating enzymes (DUBs). Curcumin was found be nontoxic in BALB/c mice. The combination of curcumin/chloroquine/piperine reduced parasitemia to 37% seven days after treatment versus the control group's 65%, and an additive interaction was revealed. Curcumin/piperine/artemisinin combination did not show a favorable drug interaction in this murine model of malaria. Treatment of mice with subtherapeutic doses of the drugs resulted in a transient increase in genes encoding DUBs indicating UPS interference. If curcumin is to join the arsenal of available antimalarial drugs, future studies exploring suitable drug partners would be of interest.