Trypanocidal effects of curcumin in vitro

In Vivo Efficacy of Curcumin and Curcumin Nanoparticle in Trypanosoma congolense, Broden 1904 (Kinetoplastea: Trypanosomatidae)-Infected Mice

Curcumin (CUR) is known for its wide folkloric effects on various infections; however, its solubility status has remained a hindrance to its bioavailability in the host. This study evaluated the comparative effects of CUR and CUR-nanoparticle in vitro on T. congolense, T. b. brucei, and T. evansi. Additionally, CUR and CUR-nanoparticle anti-Trypanosoma efficacy were assessed in vivo against T. congolense. All the CUR-nanoparticles were two folds more effective on the T. congolense as compared to CUR in vitro, with recorded efficacy of 3.67 ± 0.31; 7.61 ± 1.22; and 6.40 ± 3.07 μM, while the CUR-nanoparticles efficacy was 1.56 ± 0.50; 28.16 ± 9.43 and 13.12 ± 0.13 μM on T. congolense, T. b. brucei, and T. evansi, respectively. Both CUR and CUR-nanoparticles displayed moderate efficacy orally. The efficacy of CUR and CUR-nanoparticles in vivo was influenced by solubility, presence of food, and treatment period. CUR-treated mice were not cured of the infection; however, the survival rate of the orally treated mice was significantly prolonged as compared with intraperitoneal-treated mice. CUR-nanoparticles resulted in significant suppression of parasitemia even though relapsed was observed. In conclusion, CUR and CUR-nanoparticles possess moderate efficacy orally on the trypanosomes as compared to the intraperitoneal treatment.

Curcumin or quercetin loaded nutriosomes as oral adjuvants for malaria infections

Artemisinin, curcumin or quercetin, alone or in combination, were loaded in nutriosomes, special phospholipid vesicles enriched with Nutriose FM06®, a soluble dextrin with prebiotic activity, that makes these vesicles suitable for oral delivery. The resulting nutriosomes were sized between 93 and 146 nm, homogeneously dispersed, and had slightly negative zeta potential (around -8 mV). To improve their shelf life and storability over time, vesicle dispersions were freeze-dried and stored at 25 °C. Results confirmed that their main physico-chemical characteristics remained unchanged over a period of 12 months. Additionally, their size and polydispersity index did not undergo any significant variation after dilution with solutions at different pHs (1.2 and 7.0) and high ionic strength, mimicking the harsh conditions of the stomach and intestine. An in vitro study disclosed the delayed release of curcumin and quercetin from nutriosomes (∼53% at 48 h) while artemisinin was quickly released (∼100% at 48 h). Cytotoxicity assays using human colon adenocarcinoma cells (Caco-2) and human umbilical vein endothelial cells (HUVECs) proved the high biocompatibility of the prepared formulations. Finally, in vitro antimalarial activity tests, assessed against the 3D7 strain of Plasmodium falciparum, confirmed the effectiveness of nutriosomes in the delivery of curcumin and quercetin, which can be used as adjuvants in the antimalaria treatment. The efficacy of artemisinin was also confirmed but not improved. Overall results proved the possible use of these formulations as an accompanying treatment of malaria infections.

Protoscolicidal effects of curcumin nanoemulsion against protoscoleces of Echinococcus granulosus

BACKGROUND

The aim of the present study was to assess in vitro protoscolicidal effects of curcumin nanoemulsion (CUR-NE) against protoscoleces of cystic echinococcosis (CE)/hydatid cysts.

METHODS

The CUR-NE was prepared via spontaneous emulsification of soybean as the oil phase, a mixture of Tween 80 and Tween 85 as the surfactant, ethanol as the co-surfactant and distilled water. Various concentrations of CUR-NE (156, 312, 625 and 1250 µg/ml) were exposed to collected protoscoleces of infected sheep liver hydatid cysts for 10, 20, 30, 60 and 120 min. Viability of the protoscoleces were assessed using eosin exclusion test. Morphological changes of the protoscoleces were observed using differential interference contrast (DIC) microscopy.

RESULTS

The mean particle size and zeta potential of CUR-NE included 60.4 ± 14.8 nm and - 16.1 ± 1.1 mV, respectively. Results showed that the viability of the protoscoleces decreased significantly with increases in CUR-NE concentrations (p < 0.001). The mortality rates of protoscoleces with exposure to concentrations of 1250 and 625 µg/ml of CUR-NE for 60 min were 94 and 73.33%, respectively. Mortality of the protoscoleces was 100% after 120 min of exposure to 1250 and 625 µg/ml concentrations of CUR-NE. Using NIC microscopy, extensively altered tegumental surface protoscoleces was observed after protoscoleces exposure to CUR-NE.

CONCLUSION

The findings of the present study revealed the in vitro protoscolicidal potential of CUR-NE. Therefore, CUR-NEs are addressed as novel protoscolicidal agents, which can be used as an alternative natural medicine to kill the protoscoleces, owing to their low toxicity and significant inhibition potency. However, further studies are necessary to investigate pharmacologic and pharmacokinetics of CUR-NEs.

The Therapeutic Effects of Curcumin-coated Gold Nanoparticle Against Leishmania Major Causative Agent of Zoonotic Cutaneous Leishmaniasis (ZCL): An In Vitro and In Vivo Study

We synthesized and characterized curcumin-coated gold nanoparticles (Cur@AuNPs) and investigated their stability, cytotoxicity, leishmanicidal activity in in vitro and in in vivo experiments. Cur@AuNPs synthesized through a simple one-pot green chemistry technique. The in vitro leishmanicidal activity of curcumin-coated gold nanoparticles against extracellular promastigotes and intracellular amastigotes of protozoan parasite Leishmania major (L. major) was determined by applying the tetrazolium reduction colorimetric quantitative MTT technique. For in vivo assessment, the footpad lesion size and parasite burden in two infection site organs including lymph nodes and footpads of susceptible BALB/c mice infected with L. major were measured. Mice immune responses in all study groups were quantified by measuring the levels of gamma interferon (IFN-γ) and interleukin-4 (IL-4). Viability of Leishmania promastigotes significantly diminished with the inhibition in promastigotes growth (IC₅₀) of 64.79 μg/mL and 29.89 μg/mL for 24 h and 48 h, respectively. In vitro nanoparticles treatment efficiently cleared the L. major amastigotes explanted in macrophages but had no harmful toxicity on the mice cells. In the in vivo condition, in the treated infected BALB/c mice the CL lesion size, Leishmania parasite burden, and IL-4 were decreased, while IFN-γ was significantly increased. The results suggest that Cur@AuNP was an effective compound against Leishmania parasite in vitro and in vivo, efficiently induced T-helper 1 (Th1) responses and augmented host cellular immune responses, and ending in a reduced Leishmania parasite burden. Therefore, it may be identified as a novel potential therapeutic approach for the local therapy of zoonotic CL treatment with high cure rates.

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.

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 novel delivery of curcumin by the efficient nanoliposomal approach against Leishmania major

Several side effects and drug resistance accompany the current therapies for Leishmaniasis. Nanoliposomal curcumin is applied as a new therapy approach instead of current therapy. In this study, nanoliposomal curcumin was prepared using thin-film hydration method and characterized based on encapsulation efficiency, size, and zeta potential. Curcumin was successfully loaded into nanoliposomes with an encapsulation efficiency of 92%. The surface charge of the nanoparticle was neutral, and the size of nanoparticle was 176.5 nm. Nanoliposomal curcumin is in spherical shape without any agglomeration. Cell viability assay was performed on HFF cell line to show biocompatibility of liposome nanoparticles. Anti-Leishmanial effect of different concentrations of liposomal curcumin (0.05-30 μg mL^-1) and amphotericin B (25 μg mL^-1) were studied on Leishmania major [MRHO/IR/75/ER] at various hours (24, 48, and 72) using hemocytometer technique. Nanoliposomal curcumin inhibitory concentration (IC50) at hours 24, 48, and 72 were 6.41, 3.8, and 2.33 µg mL^-1, respectively. As prepared nanoliposomal curcumin showed a significant antileishmanial effect and induced a better and more tangible effect on the survival of L. major promastigotes and could be suitable candidates for further investigations.

Anti-proliferative and apoptosis induction activities of curcumin on Leishmania major

Leishmaniasis is a major vector-borne disease triggered by an obligate intracellular protozoan parasite of the genus Leishmania and transmitted by the bite of phlebotomine female sand flies. This parasite causes a wide range of human diseases, from localized self-healing cutaneous lesions to fatal visceral infections. The aim of this study was to investigate the cytotoxic, antiproliferative, and apoptotic effects of curcumin on Leishmania major promastigotes (MHOM/SA/84/JISH) and to assess these effects on the cell cycle of promastigotes. The MTT colorimetric assay was used to evaluate the cytotoxicity and proliferation of promastigotes. Additionally, flow cytometry was used to analyze the cell cycle. The Annexin V/propidium iodide staining technique followed by flow cytometry was used to study the cell death induced by curcumin. In this study curcumin showed a potent antileishmanial effect, exhibiting cytotoxicity against L. major promastigotes. At 80μM, the survival in curcumin treated promastigotes reached 22%; however, the median lethal concentration of curcumin (LC₅₀) was 35μM. The drug exerted its cytotoxic effect by inducing apoptosis. Curcumin-induced cell death in promastigotes reached 82.5% at 80μM concentration. In addition, curcumin delayed the cell cycle in the S-phase inhibiting cell proliferation. Thus, curcumin was shown to be effective against L. major promastigotes. Therefore, curcumin merits further research studies to demonstrate its efficacy in treating cutaneous leishmaniasis.

Effect of curcuminoids and curcumin derivate products on thioredoxin-glutathione reductase from Taenia crassiceps cysticerci. Evidence suggesting a curcumin oxidation product as a suitable inhibitor

Curcuma is a traditional ingredient of some Eastern cuisines, and the spice is heralded for its antitumoral and antiparasitic properties. In this report, we examine the effect of the curcuminoides which include curcumin, demethoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC), as well as curcumin degradation products on thioredoxin glutathione reductase from Taenia crassiceps cysticerci Results revealed that both DMC and BDMC were inhibitors of TGR activity in the micromolar concentration range. By contrast, the inhibitory ability of curcumin was a time-dependent process. Kinetic and spectroscopical evidence suggests that an intermediary compound of curcumin oxidation, probably spiroepoxide, is responsible. Preincubation of curcumin in the presence of NADPH, but not glutathione disulfide (GSSG), resulted in the loss of its inhibitory ability, suggesting a reductive stabilizing effect. Similarly, preincubation of curcumin with sulfhydryl compounds fully protected the enzyme from inhibition. Degradation products were tested for their inhibitory potential, and 4-vinylguaiacol was the best inhibitor (IC₅₀ = 12.9 μM), followed by feruloylmethane (IC₅₀ = 122 μM), vanillin (IC₅₀ = 127 μM), and ferulic aldehyde (IC₅₀ = 180 μM). The acid derivatives ferulic acid (IC₅₀ = 465 μM) and vanillic acid (IC₅₀ = 657 μM) were poor inhibitors. On the other hand, results from docking analysis revealed a common binding site on the enzyme for all the compounds, albeit interacting with different amino acid residues. Dissociation constants obtained from the docking were in accord with the inhibitory efficiency of the curcumin degradation products.

Scolicidal Effects of Chitosan-Curcumin Nanoparticles on the Hydatid Cyst Protoscolices

PURPOSE

In the current era, cystic echinococcosis (CE), as larval stage of Echinococcus granulosus, is considered as a threat to human health. Scolicidal agents used in the surgery of cysts have different side effects. Therefore, the present study aimed to assess the effects of chitosan nanoparticles containing curcumin (Ch-Cu NPs) on the protoscolices of the hydatid cyst in vitro.

METHODS

Ch-Cu NPs were synthesized using a simple co-precipitation method and their structural and morphological properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta analyzer, and Fourier transform infrared (FT-IR) spectroscopy. Then, the effects of different concentrations of Ch-Cu NPs (0.25, 0.05, 1, 2, and 4 mg/mL) on the fatality rate, and the length and width of protoscolices in different times (5, 10, 20, 30, and 60 min) were investigated. In addition, the SEM technique was used to evaluate the structure of the protoscolices after treatment.

RESULTS

Based on the results, the presence of curcumin on the chitosan nanoparticles was confirmed by FT-IR analysis. Further, XRD analysis approved the crystal structure of chitosan NPs. Furthermore, the highest fatality rate was 68% in 4 mg/mL concentration of Ch-Cu NPs. The length and width of protoscolices decreased based on the high concentrations of Ch-Cu NPs, compared to the control group.

CONCLUSION

Finally, Ch-Cu NPs expressed good scolicidal activities, which made them suitable to be considered as an anti-protoscolex agent.

Some Biological Properties of Curcumin: A Review

Curcumin (diferuloyl methane), a small-molecular weight compound isolated from the roots of Curcuma longa L. (family Zingiberaceae), has been used traditionally for centuries in Asia for medicinal, culinary and other purposes. A large number of in vitro and in vivo studies in both animals and man have indicated that curcumin has strong antioxidant, anti-carcinogenic, anti-inflammatory, anti-angiogenic, antispasmodic, antimicrobial, anti-parasitic and other activities. The mechanisms of some of these actions have recently been intensively investigated. Curcumin inhibits the promotion/ progression stage of carcinogenesis by induction of apoptosis and the arrest of cancer cells in the S, G2/M cell cycle phase. The compound inhibits the activity of growth factor receptors. The anti-inflammatory properties of curcumin are mediated through their effects on cytokines, lipid mediators, eicosanoids and proteolytic enzymes. Curcumin scavenges the superoxide radical, hydrogen peroxide and nitric oxide, and inhibits lipid peroxidation. These actions may be the basis for many of its pharmacological and therapeutic properties.

Curcumin is a nutraceutical of low toxicity, which has been used successfully in a number of medical conditions that include cataracts, cystic fibrosis, and prostate and colon cancers.

In vitro effect of curcumin on Schistosoma species viability, tegument ultrastructure and egg hatchability

Schistosomiasis remains a severe problem of public health in developing countries. The development of resistance to praziquantel (PZQ) has justified the search for new alternative chemotherapies with new formulations, more effective, and without adverse effects. Curcumin (CUR), the major phenolic compound present in rhizome of turmeric (Curcuma longa L.), has been traditionally used against various diseases including parasitic infections. Here, the antischistosomal activity of CUR (50-500 μM), evaluated in parallel against S. mansoni and S. haematobium adult worms, appeared significant (P < 0.05 to < 0.0001) in a time- and dose-dependent manner. Two h incubation with CUR (500 μM) caused 100% irreversible killing of both schistosomal species. CUR (250 μM) caused the death of S. haematobium and S. mansoni worms after 2 h and 4 h, respectively. As CUR concentration decreases (50 μM), all coupled adult worms were separated into individual male and female but the worms remained viable up to 4 h. Scanning and transmission electron microscopy revealed that S. haematobium are more sensitive than S. mansoni to CUR schistosomicidal effects. In support, CUR was found to affect the antigenicity of surface membrane molecules of S. haematobium, but not S. mansoni. Of importance, CUR significantly (P < 0.05 to < 0.0001) affected S. mansoni eggs hatchability and viability, a ground for its use in chemotherapy of schistosomiasis mansoni and japonicum because of its increased bioavailability in the gastrointestinal tract. The data together emphasize that CUR is a promising potential schistosomicidal drug.

Curcumin nanoemulsion as a novel chemical for the treatment of acute and chronic toxoplasmosis in mice

Background

The aim of this study was to prepare curcumin nanoemulsion (CR-NE) to solve the problems associated with poor water solubility and low bioavailability of CR and to test its efficiency in the treatment of acute and chronic toxoplasmosis in mouse models.

Materials and methods

CR-NE 1% was prepared using spontaneous emulsification by soybean as oil phase; a mixture of Tween 80 and Tween 85 as surfactant; ethanol as cosurfactant and distilled water. Particle size and zeta potential of NE were assessed using Nano-ZS90 dynamic light scattering. Stability testing of NE was assessed after storage for 2 months at room temperature. In vivo experiments were carried out using 50 BALB/c mice inoculated with virulent RH strain (type I) and 50 BALB/c mice inoculated with avirulent Tehran strain (type II) of Toxoplasma gondii and treated with CR-NE (1% w/v), CR suspension (CR-S, 1% w/v), and NE without CR (NE-no CR).

Results

The mean particle size and zeta potential of CR-NE included 215.66±16.8 nm and −29.46±2.65 mV, respectively, and were stable in particle size after a three freeze–thaw cycle. In acute phase experiment, the survival time of mice infected with RH strain of T. gondii and treated with CR-NE extended from 8 to 10 days postinoculation. The differences were statistically significant between the survival time of mice in CR-NE-treated group compared with negative control group (P<0.001). Furthermore, CR-NE significantly decreased the mean counts of peritoneum tachyzoites from 5,962.5±666 in negative control group to 627.5±73 in CR-NE-treated mice (P<0.001). Growth inhibition rates of tachyzoites in peritoneum of mice receiving CR-NE, CR-S, and NE-no CR included 90%, 21%, and 11%, respectively, compared with negative control group. In chronic phase experiment, the average number and size of tissue cysts significantly decreased to 17.2±15.6 and 31.5±6.26 µm, respectively, in mice inoculated with bradyzoites of T. gondii Tehran strain and treated with CR-NE compared with that in negative control group (P<0.001). Decrease of cyst numbers was verified by downregulation of BAG1 in treatment groups compared with negative control group with a minimum relative expression in CR-NE (1.12±0.28), CR-S (11.76±0.87), and NE-no CR (14.67±0.77), respectively, (P<0.001).

Conclusion

Results from the current study showed the potential of CR-S and CR-NE in treatment of acute and chronic toxoplasmosis in mouse models for the first time. However, CR-NE was more efficient than CR-S, and it seems that CR-NE has a potential formula for the treatment of acute and chronic toxoplasmosis, especially in those with latent bradyzoites in brain.

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.

Antiplasmodial Activity and Toxicological Assessment of Curcumin PLGA-Encapsulated Nanoparticles

Curcumin is a polyphenolic pigment isolated from the rhizomes of Curcuma longa (turmeric), a medicinal plant widely used in the ancient Indian and Chinese medicine. The antiplasmodial activity of curcumin is often hampered by its fast metabolism and poor water solubility, thus its incorporation into a delivery system could circumvent this problem. This study aimed to evaluate the in vivo antiplasmodial activity and the toxicity assessment of curcumin incorporated into poly (lactic-co-glycolic) acid (PLGA) nanoparticles. Curcumin was loaded with poly (D,L-lactic-co-glycolic acid) (PLGA) using solvent evaporation from oil-in-water single emulsion method. The nanoparticles were characterized and evaluated in vivo for antimalarial activities using Peter’s 4-day suppressive protocol in mice model. Hematological and hepatic toxicity assays were performed on whole blood and plasma, respectively. In vivo anti-parasitic test and toxicity assays for free and encapsulated drug were performed at 5 and 10 mg/kg. In vitro cytotoxicity of free and PLGA encapsulated curcumin (Cur-PLGA) to RAW 264.7 cell line was also determined at varying concentrations (1000–7.8 μg/mL). The size and entrapment efficiency of the nanoparticulate drug formulated was 291.2 ± 82.1 nm and 21.8 ± 0.4 respectively. The percentage parasite suppression (56.8%) at 5 mg/kg was significantly higher than in free drug (40.5%) of similar concentration (p < 0.05) but not at 10 mg/kg (49.5%) at 4-day post-treatment. There were no significant differences in most of the recorded blood parameters in free curcumin and PLGA encapsulated nanoparticulate form (p > 0.05) except in lymphocytes which were significantly higher in Cur-PLGA compared to the free drug (p < 0.05). There were no significant differences in hepatotoxic biomarkers; aspartate aminotransferase and alanine aminotransferase concentrations in various treatment groups (p > 0.05). At higher concentrations (1000 and 500 μg/mL), Cur-PLGA entrapped nanoparticle showed higher toxicity compared with the free drug (p < 0.05) in exposed RAW 264.7 cell line. The cell viability was, however, higher in Cur-PLGA nanoparticles than in free curcumin at lower concentrations (p > 0.05). The antiplasmodial activity and safety of Cur-PLGA was better at lower concentration.

The Effectiveness of Natural Diarylheptanoids against Trypanosoma cruzi: Cytotoxicity, Ultrastructural Alterations and Molecular Modeling Studies

Curcumin (CUR) is the major constituent of the rhizomes of Curcuma longa and has been widely investigated for its chemotherapeutic properties. The well-known activity of CUR against Leishmania sp., Trypanosoma brucei and Plasmodium falciparum led us to investigate its activity against Trypanosoma cruzi. In this work, we tested the cytotoxic effects of CUR and other natural curcuminoids on different forms of T. cruzi, as well as the ultrastructural changes induced in epimastigote form of the parasite. CUR was verified as the curcuminoid with more significant trypanocidal properties (IC₅₀ 10.13 μM on epimastigotes). Demethoxycurcumin (DMC) was equipotent to CUR (IC₅₀ 11.07 μM), but bisdemethoxycurcumin (BDMC) was less active (IC₅₀ 45.33 μM) and cyclocurcumin (CC) was inactive. In the experiment with infected murine peritoneal macrophages all diarylheptanoids were more active than the control in the inhibition of the trypomastigotes release. The electron microscopy images showed ultrastructural changes associated with the cytoskeleton of the parasite, indicating tubulin as possible target of CUR in T. cruzi. The results obtained by flow cytometry analysis of DNA content of the parasites treated with natural curcuminoids suggested a mechanism of action on microtubules related to the paclitaxel`s mode of action. To better understand the mechanism of action highlighted by electron microscopy and flow cytometry experiments we performed the molecular docking of natural curcuminoids on tubulin of T. cruzi in a homology model and the results obtained showed that the observed interactions are in accordance with the IC₅₀ values found, since there CUR and DMC perform similar interactions at the binding site on tubulin while BDMC do not realize a hydrogen bond with Lys163 residue due to the absence of methoxyl groups. These results indicate that trypanocidal properties of CUR may be related to the cytoskeletal alterations.

Curcumin inspired synthesis of unsymmetrical diarylpentanoids with highly potent anti-parasitic activities: in silico studies and DFT-based stereochemical calculation

Unsymmetrical diarylpentanoid analogues of curcumin have been synthesized by Claisen–Schmidt condensation of different aldehydes and ketones.

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.

"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.

Formulation of nanotized curcumin and demonstration of its antimalarial efficacy

Aim

The present study was conducted to overcome the disadvantages associated with the poor water solubility and low bioavailability of curcumin by synthesizing nanotized curcumin and demonstrating its efficacy in treating malaria.

Materials and methods

Nanotized curcumin was prepared by a modified emulsion-diffusion-evaporation method and was characterized by means of transmission electron microscopy, atomic force microscopy, dynamic light scattering, Zetasizer, Fourier transform infrared spectroscopy, and differential thermal analysis. The novelty of the prepared nanoformulation lies in the fact that it was devoid of any polymeric matrices used in conventional carriers. The antimalarial efficacy of the prepared nanotized curcumin was then checked both in vitro and in vivo.

Results

The nanopreparation was found to be non-toxic and had a particle size distribution of 20–50 nm along with improved aqueous dispersibility and an entrapment efficiency of 45%. Nanotized curcumin (half maximal inhibitory concentration [IC₅₀]: 0.5 μM) was also found to be ten-fold more effective for growth inhibition of Plasmodium falciparum in vitro as compared to its native counterpart (IC₅₀: 5 μM). Oral bioavailability of nanotized curcumin was found to be superior to that of its native counterpart. Moreover, when Plasmodium berghei-infected mice were orally treated with nanotized curcumin, it prolonged their survival by more than 2 months with complete clearance of parasites in comparison to the untreated animals, which survived for 8 days only.

Conclusion

Nanotized curcumin holds a considerable promise in therapeutics as demonstrated here for treating malaria as a test system.

Anti-Trypanosomal Activity of Diarylheptanoids Isolated from the Bark ofAlnus japonica

The crude extract of Alnus japonica bark exhibited a strong effect on the growth of Trypanosoma brucei. Subsequent chromatographic separation resulted in the isolation of two novel diarylheptanoids, known as alnuside C (2) and alnuside D (3), and three known compounds, 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptan-3(R)-O-β-D-glucopyranoside (1), oregonin (4) and hirsutanone (5). The structures of the isolates were elucidated based on the use of extensive spectroscopic and chemical methods. Among the isolated diarylheptanoids, oregonin (4) (a major component of plant bark) and hirsutanone (5) exhibited potent in vitro inhibitory activity against T. brucei growth in the bloodstream with IC50values of 1.14 and 1.78 μM, respectively. We confirmed that oregonin (4) and hirsutanone (5) were not toxic to human normal skin fibroblast cells (NB1RGB) and colon cancer cells (HCT-15) at a concentration of 50 μM; however, lower levels of toxicity were observed for leukemia cells. To determine the structure activity relationships of the isolated components, we performed Conformation Search and found that the 3-oxo function of the heptane chain in the diarylheptanoid molecule is required for their trypanocidal activity.

Trypanocidal activity of free and nanoencapsulated curcumin on Trypanosoma evansi

This study aimed to evaluate in vitro and in vivo trypanocidal activity of free and nanoencapsulated curcumin against Trypanosoma evansi. In vitro efficacy of free curcumin (CURC) and curcumin-loaded in lipid-core nanocapsules (C-LNCs) was evaluated to verify their lethal effect on T. evansi. To perform the in vivo tests, T. evansi-infected animals were treated with CURC (10 and 100 mg kg(-1), intraperitoneally [i.p.]) and C-LNCs (10 mg kg(-1), i.p.) during 6 days, with the results showing that these treatments significantly attenuated the parasitaemia. Infected untreated rats showed protein peroxidation and an increase of nitrites/nitrates, whereas animals treated with curcumin showed a reduction on these variables. As a result, the activity of antioxidant enzymes (superoxide dismutase and catalase) differs between groups (P<0.05). Infected animals and treated with CURC exhibited a reduction in the levels of alanine aminotransferase and creatinine, when compared with the positive control group. The use of curcumin in vitro resulted in a better parasitaemia control, an antioxidant activity and a protective effect on liver and kidney functions of T. evansi-infected adult male Wistar rats.

Effects of curcumin on the parasite Schistosoma mansoni: a transcriptomic approach

Schistosomiasis remains a severe problem of public health in developing countries. Several reports show that praziquantel, the drug of choice for treating schistosomiasis, can select Schistosoma mansoni strains resistant to the drug. Thus, developing new drugs against this parasitosis is a highly desirable goal. Curcumin, a phenolic compound deriving from the plant Curcuma longa, has been shown to have anticancer, anti-inflammatory and antiparasitic effects. Recently, our group has demonstrated that curcumin causes the separation of S. mansoni adult worm pairs, eggs infertility, decreased oviposition and parasite viability, leading to death. In the present work, we have investigated the effects of curcumin on S. mansoni gene expression in adult worms through microarray analyses. Our results showed 2374 genes that were significantly and differentially expressed, of which 981 were up-regulated and 1393 were down-regulated. Among the differentially expressed genes there were components of important signaling pathways involved in embryogenesis and oogenesis such as Notch and TGF-β. Gene networks most significantly enriched with altered genes were identified, including a network related to Cellular Function and Maintenance, Molecular Transport, Organ Development, which is connected to the TGF-β signaling pathway and might be related to the effect of curcumin on pairing of adult worm pairs, egg production and viability of worms. qPCR validation experiments with 7 genes have confirmed the expression changes detected with arrays. Here we suggest that transcriptional repression observed in Notch and TGF-β pathways could explain the effects on oviposition and egg development described in the literature.

Discovery of curcumin, a component of golden spice, and its miraculous biological activities

1. Curcumin is the active ingredient of the dietary spice turmeric and has been consumed for medicinal purposes for thousands of years. Modern science has shown that curcumin modulates various signalling molecules, including inflammatory molecules, transcription factors, enzymes, protein kinases, protein reductases, carrier proteins, cell survival proteins, drug resistance proteins, adhesion molecules, growth factors, receptors, cell cycle regulatory proteins, chemokines, DNA, RNA and metal ions. 2. Because of this polyphenol's potential to modulate multiple signalling molecules, it has been reported to possess pleiotropic activities. First demonstrated to have antibacterial activity in 1949, curcumin has since been shown to have anti-inflammatory, anti-oxidant, pro-apoptotic, chemopreventive, chemotherapeutic, antiproliferative, wound healing, antinociceptive, antiparasitic and antimalarial properties as well. Animal studies have suggested that curcumin may be active against a wide range of human diseases, including diabetes, obesity, neurological and psychiatric disorders and cancer, as well as chronic illnesses affecting the eyes, lungs, liver, kidneys and gastrointestinal and cardiovascular systems. 3. Although many clinical trials evaluating the safety and efficacy of curcumin against human ailments have already been completed, others are still ongoing. Moreover, curcumin is used as a supplement in several countries, including India, Japan, the US, Thailand, China, Korea, Turkey, South Africa, Nepal and Pakistan. Although inexpensive, apparently well tolerated and potentially active, curcumin has not been approved for the treatment of any human disease. 4. In the present article, we discuss the discovery and key biological activities of curcumin, with a particular emphasis on its activities at the molecular and cellular levels, as well as in animals and humans.

In vitro evaluation of schistosomicidal potential of curcumin against Schistosoma japonicum

Curcumin is a polyphenol derived from the dietary spice turmeric. The aim of this study was to investigate the in vitro effect of curcumin against eggs, cercariae, pre-adults, and adults of Schistosoma japonicum compared to praziquantel. After incubated by different concentration of curcumin or praziquantel in different time, the percent hatching rates of eggs, the percent dead rates of cercariae, and the number of dead worms were observed. Curcumin showed time- and dose-dependent schistosomicidal effects on every life stages of S. japonicum. In addition, curcumin exhibited an optimal activity against the adult stage with no differential sensitivity between male and female worms and decreased motor activity of these worms without tegumental alterations. The promising in vitro effects on all stages of S. japonicum warrants further evaluation for the prophylactic and therapeutic values in the early and late schistosomiasis in field trials.

Lysine acetylation: elucidating the components of an emerging global signaling pathway in trypanosomes

In the past ten years the number of acetylated proteins reported in literature grew exponentially. Several authors have proposed that acetylation might be a key component in most eukaryotic signaling pathways, as important as phosphorylation. The enzymes involved in this process are starting to emerge; acetyltransferases and deacetylases are found inside and outside the nuclear compartment and have different regulatory functions. In trypanosomatids several of these enzymes have been described and are postulated to be novel antiparasitic targets for the rational design of drugs. In this paper we overview the most important known acetylated proteins and the advances made in the identification of new acetylated proteins using high-resolution mass spectrometry. Also, we summarize what is known so far about the acetyltransferases and deacetylases in eukaryotes, focusing on trypanosomes and their potential use as chemotherapeutic targets.

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.

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.

Curcuminoid analogs with potent activity against Trypanosoma and Leishmania species

The natural curcuminoids curcumin (1), demethoxycurcumin (2) and bisdemethoxycurcumin (3) have been chemically modified to give 46 analogs and 8 pairs of 1:1 mixture of curcuminoid analogs and these parent curcuminoids and their analogs were assessed against protozoa of the Trypanosoma and Leishmania species. The parent curcuminoids exhibited low antitrypanosomal activity (EC(50) for our drug-sensitive Trypanosoma brucei brucei line (WT) of compounds 1, 2 and 3 are 2.5, 4.6 and 7.7 microM, respectively). Among 43 curcuminoid analogs and 8 pairs of 1:1 mixture of curcuminoid analogs tested, 8 pure analogs and 5 isomeric mixtures of analogs exhibited high antitrypanosomal activity in submicromolar order of magnitude. Among these highly active analogs, 1,7-bis(4-hydroxy-3-methoxyphenyl)hept-4-en-3-one (40) was the most active compound, with an EC(50) value of 0.053+/-0.007 microM; it was about 2-fold more active than the standard veterinary drug diminazene aceturate (EC(50) 0.12+/-0.01 microM). Using a previously characterized diminazene-resistant T. b. brucei (TbAT1-KO) and a derived multi-drug resistant line (B48), no cross-resistance of curcuminoids was observed to the diamidine and melaminophenyl arsenical drugs that are the current treatments. Indeed, curcuminoids carrying a conjugated keto (enone) motif, including 40, were significantly more active against T. b. brucei B48. This enone motif was found to contribute to particularly high trypanocidal activity against all Trypanosoma species and strains tested. The parent curcuminoids showed low antileishmanial activity (EC(50) values of compounds 1 and 2 for Leishmania mexicana amastigotes are 16+/-3 and 37+/-6 microM, respectively) while the control drug, pentamidine, displayed an EC(50) of 16+/-2 microM. Among the active curcuminoid analogs, four compounds exhibited EC(50) values of less than 5 microM against Leishmania major promastigotes and four against L. mexicana amastigotes. No significant difference in sensitivity to curcuminoids between L. major promastigotes and L. mexicana amastigotes was observed. The parent curcuminoids and most of their analogs were also tested for their toxicity against human embryonic kidney (HEK) cells. All the curcuminoids exhibited lower toxicity to HEK cells than to T. b. brucei bloodstream forms and only one of the tested compounds showed significantly higher activity against HEK cells than curcumin (1). The selectivity index for T. b. brucei ranged from 3-fold to 1500-fold. The selectivity index for the most active analog, the enone 40, was 453-fold.

Effects of curcumin on Cryptosporidium parvum in vitro

Cryptosporidium parvum is a zoonotic protozoan parasite having peculiarities among the apicomplexa that could be responsible for its resistance to some drugs and disinfectants against coccidia. The awareness of Cryptosporidium as a health problem in man and animal is increasing and potent drugs are urgently needed. Curcumin, a natural polyphenolic compound, has been found to be active against a variety of diseases including anticarcinogenic, antimicrobial, and antiprotozoal effects. We investigated the effects of curcumin on infectivity and development of C. parvum in a recently established in vitro system combining infection of human ileocecal adenocarcinoma cell cultures with quantification of intracellular parasites by quantitative polymerase chain reaction. Curcumin was found to be effective (>95% inhibition of parasite growth) at 50 microM for 24 h when infected cultures were exposed for more than 12 h. Withdrawal of curcumin after 24 h of exposure did not result in a significant resumption of C. parvum growth. The invasion of host cells by sporozoites (infectivity) was found to be inhibited at least 65% in the presence of 200 microM curcumin. No significant reduction of viability of C. parvum oocysts after incubation with curcumin was recorded. Altogether, curcumin showed promising anticryptosporidial effects under in vitro conditions and deserves further exploration.

Immunomodulatory effects of curcumin treatment on murine schistosomiasis mansoni

Curcumin is a polyphenol derived from the dietary spice turmeric. It has been shown to regulate numerous transcription factors, cytokines, adhesion molecules, and enzymes that have been linked to inflammation. In addition to inhibiting the growth of a variety of pathogens, curcumin has been shown to have nematocidal activity. The present study was designed to evaluate the schistosomicidal activity of curcumin in vivo as well as immunomodulation of granulomatous inflammation and liver pathology in acute schistosomiasis mansoni. Mice were infected each with 80 Schistosoma (S.) mansoni cercariae and injected intraperitoneally with curcumin at a total dose of 400mg/kg body weight. Curcumin was effective in reducing worm and tissue-egg burdens, hepatic granuloma volume and liver collagen content by 44.4%, 30.9%, 79%, and 38.6%, respectively. Curcumin treatment restored hepatic enzymes activities to the normal levels and enhanced catalase activity in the liver tissue of infected mice. Moreover, hepato-spleenomegaly and eosinophilia induced by S. mansoni infection were largely improved with curcumin treatment. Infected mice treated with curcumin showed low serum level of both interleukin (IL)-12 and tumor necrosis factor alpha (TNF-alpha), but IL-10 level was not significantly altered. Specific IgG and IgG1 responses against both soluble worm antigen (SWAP) and soluble egg antigen (SEA) were augmented with curcumin treatment, but IgM and IgG2a responses were not significantly changed. In conclusion, curcumin treatment modulates cellular and humoral immune responses of infected mice and lead to a significant reduction of parasite burden and liver pathology in acute murine schistosomiasis mansoni.

In vitro schistosomicidal activity of curcumin against Schistosoma mansoni adult worms

The in vitro schistosomicidal activity of curcumin (doses ranging from 5 to 100 microM) was carried out against Schistosoma mansoni adult worms. Curcumin (at 50 and 100 microM) caused death of all worms. When tested at the doses of 5 and 20 microM, it decreased the worm viability in comparison with negative (Roswell Memorial Park Institute (RPMI) 1640 medium alone or RPMI 1640 medium with 10% dimethyl sulfoxide) and positive (heat-killed worms at 56 degrees C or praziquantel 10 microM) control groups. All pairs of coupled adult worms were separated into individual male and female by the action of curcumin at the doses of 20 to 100 microM. When tested at 5 and 10 microM, curcumin reduced egg production by 50% in comparison with the positive control group. It is the first time that the schistosomicidal activity has been reported for curcumin.

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".

Curcumin Affects Development of Zebrafish Embryo

Embryotoxic and teratogenic effects of curcumin on the development of zebrafish embryo were investi-gated in this study. The LD(50) values of curcumin (24-h incubation) were estimated at 7.5 microM and 5 microM for embryos and larvae, respectively. The developmental defects caused by curcumin treatments include bent or hook-like tails, spinal column curving, edema in pericardial sac, retarded yolk sac resorption, and shorter body length. In curcumin-treated larvae, fluorescence signals of curcumin were found in edamae sac and some skin cells. Together, these results indicate that zebrafish are suitable model organisms to study the toxic effects of curcumin.

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.

Biological properties of curcumin-cellular and molecular mechanisms of action

Curcuminoids, a group of phenolic compounds isolated from the roots of Curcuma longa (Zingiberaceae), exhibit a variety of beneficial effects on health and on events that help in preventing certain diseases. A vast majority of these studies were carried out with curcumin (diferuloyl methane), which is a major curcuminoid. The most detailed studies using curcumin include anti-inflammatory, antioxidant, anticarcinogenic, antiviral, and antiinfectious activities. In addition, the wound healing and detoxifying properties of curcumin have also received considerable attention. As a result of extensive research on the therapeutic properties of curcumin, some understanding on the cellular, molecular, and biochemical mechanism of action of curcumin is emerging. These findings are summarized in this review.