Leishmanicidal effects of piperine, its derivatives, and analogues on Leishmania amazonensis

Piperine-loaded mesoporous silica nanoparticles as a promising strategy for targeting Echinococcus granulosus protoscoleces

Medical and surgical treatments for cystic echinococcosis (CE) are challenged by various complications. This study evaluates in vitro protoscolicidal activity of piperine-loaded mesoporous silica nanoparticles (PIP-MSNs) against protoscoleces of Echinococcus granulosus. MSNs were prepared by adding tetraethyl orthosilicate to cetyltrimethylammonium bromide and NaOH, and then loaded with PIP. The mean particle size and hydrodynamic diameter of MSNs were determined at 68 ± 4.5 and 101.4 ± 50.4 nm using transmission electron microscopy and dynamic light scattering, respectively. X-ray diffraction, Fourier-transform infrared analysis, and UV-spectrophotometry confirmed drug loading. Drug loading efficiency and drug loading capacity were calculated at 60% and 18%, respectively. The drug release profile confirmed a 75% PIP release plateau after about 24 h. The cytotoxicity assay showed cell viability > 90% in all concentrations used (≤ 512 µg/mL). E. granulosus protoscoleces were exposed to PIP-MSNs and their viability was assessed using the eosin exclusion test. In a dose-dependent manner (p < 0.001), exposure to 375 and 500 µg/mL of PIP-MSNs for 180 min killed 89.67 and 94.67% of protoscoleces, respectively. This study introduces PIP-MSNs as a potential protoscolicidal agent in the treatment of CE. Further studies are necessary to uncover safety aspects, biodistribution patterns, and potential combination therapies.

In vitro anti-parasitic effect of the alkaloids harmaline and piperine on Toxoplasma gondii

Toxoplasma gondii is a coccidian protozoan of zoonotic importance that causes toxoplasmosis. Although the current treatments for toxoplasmosis may be associated with adverse effects and limited efficacy for different biological forms of the parasite, evidence suggests that alkaloid molecules such as harmaline and piperine exhibit antiparasitic effects against protozoa parasites. This investigation aimed to evaluate the in vitro effect of harmaline and piperine against T. gondii tachyzoites in infected Vero cell cultures. After 24 hours of host cell infection, the cultures were treated with harmaline or piperine (0.49 to 15.63 µg/mL). Negative and positive controls were RPMI/DMSO (0.1%) and sulfadiazine (200 µg/mL). Harmaline significantly reduced parasite multiplication by 20% compared to the negative control, while piperine decreased between 55.56% and 88.89% in a dose-dependent manner. According to an intracellular parasite proportion scale, it was observed that the Vero cells with low or moderate parasitic proliferation were more prevalent after the alkaloid treatment. The study demonstrated that the alkaloids had antiparasitic effects on T. gondii, with piperine being the most effective. Additional studies must be carried out to clarify other aspects of the action of the alkaloids on parasites.

Piperine, quercetin, and curcumin identified as promising natural products for topical treatment of cutaneous leishmaniasis

Leishmania braziliensis (L. braziliensis) causes cutaneous leishmaniasis (CL) in the New World. The costs and the side effects of current treatments render imperative the development of new therapies that are affordable and easy to administer. Topical treatment would be the ideal option for the treatment of CL. This underscores the urgent need for affordable and effective treatments, with natural compounds being explored as potential solutions. The alkaloid piperine (PIP), the polyphenol curcumin (CUR), and the flavonoid quercetin (QUE), known for their diverse biological properties, are promising candidates to address these parasitic diseases. Initially, the in vitro cytotoxicity activity of the compounds was evaluated using U-937 cells, followed by the assessment of the leishmanicidal activity of these compounds against amastigotes of L. braziliensis. Subsequently, a golden hamster model with stationary-phase L. braziliensis promastigote infections was employed. Once the ulcer appeared, hamsters were treated with QUE, PIP, or CUR formulations and compared to the control group treated with meglumine antimoniate administered intralesionally. We observed that the three organic compounds showed high in vitro leishmanicidal activity with effective concentrations of less than 50 mM, with PIP having the highest activity at a concentration of 8 mM. None of the compounds showed cytotoxic activity for U937 macrophages with values between 500 and 700 mM. In vivo, topical treatment with QUE daily for 15 days produced cured in 100% of hamsters while the effectiveness of CUR and PIP was 83% and 67%, respectively. No failures were observed with QUE. Collectively, our data suggest that topical formulations mainly for QUE but also for CUR and PIP could be a promising topical treatment for CL. Not only the ease of obtaining or synthesizing the organic compounds evaluated in this work but also their commercial availability eliminates one of the most important barriers or bottlenecks in drug development, thus facilitating the roadmap for the development of a topical drug for the management of CL caused by L. braziliensis.

Drug Discovery for Cutaneous Leishmaniasis: A Review of Developments in the Past 15 Years

Leishmaniasis is a group of vector-borne, parasitic diseases caused by over 20 species of the protozoan Leishmania spp. The three major disease classifications, cutaneous, visceral, and mucocutaneous, have a range of clinical manifestations from self-healing skin lesions to hepatosplenomegaly and mucosal membrane damage to fatality. As a neglected tropical disease, leishmaniasis represents a major international health challenge, with nearly 350 million people living at risk of infection a year. The current chemotherapeutics used to treat leishmaniasis have harsh side effects, prolonged and costly treatment regimens, as well as emerging drug resistance, and are predominantly used for the treatment of visceral leishmaniasis. There is an undeniable need for the identification and development of novel chemotherapeutics targeting cutaneous leishmaniasis (CL), largely ignored by concerted drug development efforts. CL is mostly non-lethal and the most common presentation of this disease, with nearly 1 million new cases reported annually. Recognizing this unaddressed need, substantial yet fragmented progress in early drug discovery efforts for CL has occurred in the past 15 years and was outlined in this review. However, further work needs to be carried out to advance early discovery candidates towards the clinic. Importantly, there is a paucity of investment in the translation and development of therapies for CL, limiting the emergence of viable solutions to deal with this serious and complex international health problem.

Anti-leishmanial, immunomodulatory and additive potential effect of Piperine on Leishmania major: The in silico and in vitro study of Piperine and its combination

BACKGROUND

Piperine (Pn), an indole alkaloid compound found in pepper, is an effective compound with anti-leishmanial medications that administered alone or in combination. This study aimed to use Pn for possible biochemical targets and to assess mechanisms of anti-leishmanial action and immunomodulatory roles.

METHODS

The ability of Pn to bind to interleukin-12P40 (IL-12P40) and interferon-γ (IFN-γ) was investigated using molecular docking. The leishmanicidal effect of Pn, meglumine antimoniate (Glucantime®; MA), and Pn plus MA was assessed on Leishmania major promastigotes and amastigotes. A real-time PCR was applied to quantify cytokines gene expression in drug-treated murine macrophages.

RESULTS

The molecular docking findings indicated that Pn could bind to IL-12P40/IFN-γ. In silico analyses showed an affinity of Pn to IL-12P40/IFN-γ, with the MolDock score of -236.91 and -64.87 kcal/mol, respectively. Pn plus MA reduced the proliferation rate of promastigote and amastigote forms of L. major compared to each drug alone (IC50 = 43.22 and 19.41 μg/mL, respectively). Moreover, the combination drug demonstrated no cytotoxicity as the selectivity index (SI) was 14.81. Also, Th1-related cytokines were upregulated, while Th2-related cytokines were downregulated in Pn combination-treated murine macrophages.

CONCLUSIONS

The superior effectiveness of combination therapy on L. major warrants further investigations on the clinical potential of this combination in the treatment of leishmaniasis.

Improved Activity of Herbal Medicines through Nanotechnology

Phytochemicals or secondary metabolites are substances produced by plants that have been shown to have many biological activities, providing a scientific basis for using herbs in traditional medicine. In addition, the use of herbs is considered to be safe and more economical compared to synthetic medicine. However, herbal medicines have disadvantages, such as having low solubility, stability, and bioavailability. Some of them can undergo physical and chemical degradation, which reduces their pharmacological activity. In recent decades, nanotechnology-based herbal drug formulations have attracted attention due to their enhanced activity and potential for overcoming the problems associated with herbal medicine. Approaches using nanotechnology-based delivery systems that are biocompatible, biodegradable, and based on lipids, polymers, or nanoemulsions can increase the solubility, stability, bioavailability, and pharmacological activity of herbals. This review article aims to provide an overview of the latest advances in the development of nanotechnology-based herbal drug formulations for increased activity, as well as a summary of the challenges these delivery systems for herbal medicines face.

Punch in the gut: Parasite tolerance of phytochemicals reflects host diet

Gut parasites of plant-eating insects are exposed to antimicrobial phytochemicals that can reduce infection. Trypanosomatid gut parasites infect insects of diverse nutritional ecologies as well as mammals and plants, raising the question of how host diet-associated phytochemicals shape parasite evolution and host specificity. To test the hypothesis that phytochemical tolerance of trypanosomatids reflects the chemical ecology of their hosts, we compared related parasites from honey bees and mosquitoes-hosts that differ in phytochemical consumption-and contrasted our results with previous studies on phylogenetically related, human-parasitic Leishmania. We identified one bacterial and ten plant-derived substances with known antileishmanial activity that also inhibited honey bee parasites associated with colony collapse. Bee parasites exhibited greater tolerance of chrysin-a flavonoid found in nectar, pollen, and plant resin-derived propolis. In contrast, mosquito parasites were more tolerant of cinnamic acid-a product of lignin decomposition present in woody debris-rich larval habitats. Parasites from both hosts tolerated many compounds that inhibit Leishmania, hinting at possible trade-offs between phytochemical tolerance and mammalian infection. Our results implicate the phytochemistry of host diets as a potential driver of insect-trypanosomatid associations, and identify compounds that could be incorporated into colony diets or floral landscapes to ameliorate infection in bees. This article is protected by copyright. All rights reserved.

Molecular and pharmacological aspects of piperine as a potential molecule for disease prevention and management: evidence from clinical trials

BACKGROUND

Piperine is a type of amide alkaloid that exhibits pleiotropic properties like antioxidant, anticancer, anti-inflammatory, antihypertensive, hepatoprotective, neuroprotective and enhancing bioavailability and fertility-related activities. Piperine has the ability to alter gastrointestinal disorders, drug-metabolizing enzymes, and bioavailability of several drugs. The present review explores the available clinical and preclinical data, nanoformulations, extraction process, structure-activity relationships, molecular docking, bioavailability enhancement of phytochemicals and drugs, and brain penetration properties of piperine in the prevention, management, and treatment of various diseases and disorders.

MAIN BODY

Piperine provides therapeutic benefits in patients suffering from diabetes, obesity, arthritis, oral cancer, breast cancer, multiple myeloma, metabolic syndrome, hypertension, Parkinson's disease, Alzheimer's disease, cerebral stroke, cardiovascular diseases, kidney diseases, inflammatory diseases, and rhinopharyngitis. The molecular basis for the pleiotropic activities of piperine is based on its ability to regulate multiple signaling molecules such as cell cycle proteins, anti-apoptotic proteins, P-glycoprotein, cytochrome P450 3A4, multidrug resistance protein 1, breast cancer resistance protein, transient receptor potential vanilloid 1 proinflammatory cytokine, nuclear factor-κB, c-Fos, cAMP response element-binding protein, activation transcription factor-2, peroxisome proliferator-activated receptor-gamma, Human G-quadruplex DNA, Cyclooxygenase-2, Nitric oxide synthases-2, MicroRNA, and coronaviruses. Piperine also regulates multiple signaling pathways such as Akt/mTOR/MMP-9, 5'-AMP-activated protein kinase-activated NLR family pyrin domain containing-3 inflammasome, voltage-gated K+ current, PKCα/ERK1/2, NF-κB/AP-1/MMP-9, Wnt/β-catenin, JNK/P38 MAPK, and gut microbiota.

SHORT CONCLUSION

Based on the current evidence, piperine can be the potential molecule for treatment of disease, and its significance of this molecule in the clinic is discussed.

GRAPHICAL ABSTRACT

Piperine analogs arrest c-myc gene leading to downregulation of transcription for targeting cancer

G-quadruplex (G4) structures are considered a promising therapeutic target in cancer. Since Ayurveda, Piperine has been known for its medicinal properties. Piperine shows anticancer properties by stabilizing the G4 motif present upstream of the c-myc gene. This gene belongs to a group of proto-oncogenes, and its aberrant transcription drives tumorigenesis. The transcriptional regulation of the c-myc gene is an interesting approach for anticancer drug design. The present study employed a chemical similarity approach to identify Piperine similar compounds and analyzed their interaction with cancer-associated G-quadruplex motifs. Among all Piperine analogs, PIP-2 exhibited strong selectivity, specificity, and affinity towards c-myc G4 DNA as elaborated through biophysical studies such as fluorescence emission, isothermal calorimetry, and circular dichroism. Moreover, our biophysical observations are supported by molecular dynamics analysis and cellular-based studies. Our study showed that PIP-2 showed higher toxicity against the A549 lung cancer cell line but lower toxicity towards normal HEK 293 cells, indicating increased efficacy of the drug at the cellular level. Biological evaluation assays such as TFP reporter assay, quantitative real-time PCR (qRT- PCR), and western blotting suggest that the Piperine analog-2 (PIP-2) stabilizes the G-quadruplex motif located at the promoter site of c-myc oncogene and downregulates its expression. In conclusion, Piperine analog PIP-2 may be used as anticancer therapeutics as it affects the c-myc oncogene expression via G-quadruplex mediated mechanism.

An Update on Natural Antileishmanial Treatment Options from Plants, Fungi and Algae

Efficient drugs for the treatment of leishmaniasis, which is classified as a neglected tropical disease, are sought for. This review covers potential drug candidates from natural plant, fungus and algae sources, which were described over the last six years. The identification of these natural antileishmanials often based on the knowledge of traditional medicines. Crucial insights into the activities of these natural remedies against Leishmania parasites and against infections caused by these parasites in laboratory animals or patients are provided and compared with selected former active examples published more than six years ago. In addition, immuno-modulatory natural antileishmanials and recent developments on combination therapies including natural products and approved antileishmanials are discussed. The described natural products revealed promising data warranting further efforts on the discovery and development of new antileishmanials based on patterns from nature.

Anethum sowa Roxb. ex fleming: A review on traditional uses, phytochemistry, pharmacological and toxicological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Anethum sowa Roxb. ex Fleming (Syn. Peucedanum sowa Roxb. ex Fleming, Family: Apiaceae) is a pharmacologically important as aromatic and medicinal plant. Various parts of this plant are used in traditional medicine systems for carminative, uterine and colic pain, digestion disorder, flatulence in babies, appetite-stimulating agent and used to treat mild flue and cough. The essential oil is used for aromatherapy. It is also used as a spice for food flavouring and culinary preparations in many Asian and European countries.

AIM OF THE REVIEW

This review aims to provide a comprehensive and critical assessment from the reported traditional and pharmaceutical uses and pharmacological activities of the extracts, essential oil and phytoconstituents with emphasis on its therapeutic potential as well as toxicological evaluation of A. sowa.

MATERIALS AND METHODS

Online search engines such as SciFinder®, GoogleScholar®, ResearchGate®, Web of Science®, Scopus®, PubMed and additional data from books, proceedings and local prints were searched using relevant keywords and terminologies related to A. sowa for critical analyses.

RESULTS

The literature studies demonstrated that A. sowa possesses several ethnopharmacological activities, including pharmaceutical prescriptions, traditional applications, and spice in food preparations. The phytochemical investigation conducted on crude extracts has been characterized and identified various classes of compounds, including coumarins, anthraquinone, terpenoids, alkaloid, benzodioxoles, phenolics, polyphenols, phenolic and polyphenols, fatty acids, phthalides and carotenoids. The extracts and compounds from the different parts of A. sowa showed diverse in vitro and in vivo biological activities including antioxidant, antiviral, antibacterial, analgesic and anti-inflammatory, Alzheimer associating neuromodulatory, cytotoxic, anticancer, antidiabetes, insecticidal and larvicidal.

CONCLUSION

A. sowa is a valuable medicinal plant which is especially used in food flavouring and culinary preparations. This review summarized the pertinent information on A. sowa and its traditional and culinary uses, as well as potential pharmacological properties of essential oils, extracts and isolated compounds. The traditional uses of A. sowa are supported by in vitro/vivo pharmacological studies; however, further investigation on A. sowa should be focused on isolation and identification of more active compounds and establish the links between the traditional uses and reported pharmacological activities with active compounds, as well as structure-activity relationship and in vivo mechanistic studies before integrated into the medicine. The toxicological report confirmed its safety. Nonetheless, pharmacokinetic evaluation tests to validate its bioavailability should be encouraged.

Leishmanicidal effect of 1,3,4-thiadiazolium mesoionic salts on Leishmania amazonensis in vitro

Leishmaniasis is a neglected broad clinical spectrum disease caused by protozoa of the genus Leishmania, which affect millions of people annually in the world and the treatment has severe side effects and resistant strains have been reported. Mesoionic salts are a subclass of the betaine group with extensive biological activity such as microbicide and anti-inflammatory In this work, we analyze the cytotoxic effects of mesoionic salts, 4-phenyl-5-(X-phenyl)-1,3,4-thiadiazolium-2-phenylamine chloride (X = 4 Cl; 3,4 diCl and 3,4 diF), on Leishmania amazonensis in vitro. Initially, Mesoionic salts toxicity were evaluated by XTT assay on L. amazonensis promastigotes. Our results show that the mesoionic salts MI-3,4 diCl, MI-4 Cl and MI-3,4 diF were toxic to the promastigote parasite with IC₅₀ values of 14.3, 40.1 and 61.8 μM, respectively. The amastigote survival was evaluated in treated infected-macrophages, and the results demonstrate that MI-4 Cl (IC₅₀ = 33 μM) and MI-3,4 diCl (IC₅₀ = 43 μM) have a toxic effect against these forms. None of the mesoionic compounds tested present host cell toxicity up to the tested concentration of 100 μM. The selectivity index for MI-3,4 diCl and MI-4 Cl were 3.94 and 6.97, respectively. Nitric oxide (NO) production assayed by Griess reagent, in LPS-activated macrophages or not, in the presence of the salts showed that only the MI-3,4 diCl compound reduced NO levels. Lipid profile analysis of treated-promastigotes showed no alteration of neutral lipids. Evaluation of mitochondrial membrane potential (∆Ψm) showed that the MI-4Cl compound was able to reduce (∆Ψm) by 50%. Therefore, our results suggest that the chlorinated compounds are promising biomolecules, which cause inhibition of L.amazonensis promastigotes, amastigotes, leading to mitochondrial damage.

Determination and risk characterisation of bio-active piperine in black pepper and selected food containing black pepper consumed in Korea

Piperine is a bio-active compound found in pepper, including Piper nigrum L. and P. longum L. It has a strong, pungent flavour and several pharmacologic benefits. However, the risks of piperine have not yet been characterized. In this study, piperine in black pepper and some selected foods was determined to characterise the risk of exposure to piperine. Piperine in black pepper, curry and noodle was analysed by high-performance liquid chromatography-ultraviolet detection, which was validated through the measurement of performance parameters. The mean concentrations of piperine in black pepper, powdered curry, retorted curry, instant noodle and cup noodle were 4,418, 28, 3.4, 4.3 and 4.2 mg/100 g, respectively. The estimated dietary exposure to piperine was 123.66 μg/kg body weight/day, and the margin of exposure calculated by the no-observed-adverse-effect level of piperine, was 162. The piperine from food does not cause an adverse health effect to the public in Korea.

Development of new combination anti-leishmanial complexes: Triphenyl Sb(V) mono-hydroxy mono-quinolinolates

In seeking to develop single entity combination anti-Leishmanial complexes six heteropletic organometallic Sb(V) hydroxido quinolinolate complexes of general formula [SbPh₃(C₉H₄NORR')(OH)] have been synthesised and characterised, derived from a series of halide substituted quinolinols (8-hydroxyquinolines). Single crystal X-ray diffraction on all the complexes show a common distorted six-coordinate octahedral environment at the Sb(V) centre, with the aryl groups and nitrogen atom of quinolinolate ligand bonding in the equatorial planes, with the two oxygen atoms (hydroxyl and quinolinolate) occupying the axial plane in an almost linear configuration. Each complex was tested for their anti-promastigote activity and mammalian cytotoxicity and a selectivity indices established. The complexes displayed excellent anti-promastigote activity (IC₅₀: 2.03-3.39 μM) and varied mammalian cytotoxicity (IC₅₀: 12.7-46.9 μM), leading to a selectivity index range of 4.52-16.7. All complexes displayed excellent anti-amastigote activity with a percentage infection range of 2.25%-9.00%. All complexes performed substantially better than the parent quinolinols and comparable carboxylate complexes [SbPh₃(O₂CRR')₂] indicating the synergistic role of the Sb(V) and quinolinol moieties in increasing parasite mortality. Two of the complexes [SbPh₃(C₉H₄NOBr₂)(OH)] 4, [SbPh₃(C₉H₄NOI₂)(OH)] 5, provide an ideal combination of high selective and good activity towards the leishmanial amastigotes and offer the potential as good lead compounds.

Metabolomic approach of the antiprotozoal activity of medicinal Piper species used in Peruvian Amazon

ETHNOPHARMACOLOGICAL RELEVANCE

In the Peruvian Amazon as in the tropical countries of South America, the use of medicinal Piper species (cordoncillos) is common practice, particularly against symptoms of infection by protozoal parasites. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point of this work was a set of interviews of people living in six rural communities from the Peruvian Amazon (Alto Amazonas Province) about their uses of plants from Piper genus: one community of Amerindian native people (Shawi community) and five communities of mestizos. Infections caused by parasitic protozoa take a huge toll on public health in the Amazonian communities, who partly fight it using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help to identify new antiprotozoal compounds.

AIMS OF STUDY

To record and validate the use of medicinal Piper species by rural people of Alto Amazonas Province (Peru) and annotate active compounds using a correlation study and a data mining approach.

MATERIALS AND METHODS

Rural communities were interviewed about traditional medication against parasite infections with medicinal Piper species. Ethnopharmacological surveys were undertaken in five mestizo villages, namely: Nueva Arica, Shucushuyacu, Parinari, Lagunas and Esperanza, and one Shawi community (Balsapuerto village). All communities belong to the Alto Amazonas Province (Loreto region, Peru). Seventeen Piper species were collected according to their traditional use for the treatment of parasitic diseases, 35 extracts (leaves or leaves and stems) were tested in vitro on P. falciparum (3D7 chloroquine-sensitive strain and W2 chloroquine-resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Assessments were performed on HUVEC cells and RAW 264.7 macrophages. The annotation of active compounds was realized by metabolomic analysis and molecular networking approach.

RESULTS

Nine extracts were active (IC₅₀ ≤ 10 μg/mL) on 3D7 P. falciparum and only one on W2 P. falciparum, six on L. donovani (axenic and intramacrophagic amastigotes) and seven on Trypanosoma brucei gambiense. Only one extract was active on all three parasites (P. lineatum). After metabolomic analyses and annotation of compounds active on Leishmania, P. strigosum and P. pseudoarboreum were considered as potential sources of leishmanicidal compounds.

CONCLUSIONS

This ethnopharmacological study and the associated in vitro bioassays corroborated the relevance of use of Piper species in the Amazonian traditional medicine, especially in Peru. A series of Piper species with few previously available phytochemical data have good antiprotozoal activity and could be a starting point for subsequent promising work. Metabolomic approach appears to be a smart, quick but still limited methodology to identify compounds with high probability of biological activity.

Anti-Leishmania amazonensis activity of the terpenoid fraction from Eugenia pruniformis leaves

Leishmaniasis is caused by protozoan parasites belonging to the genus Leishmania and includes cutaneous, mucocutaneous and visceral clinical forms. Drugs currently available for leishmaniasis treatment present high toxicity, and development of parasite resistance. Plants constitute an important source of compounds with leishmanicidal potential. This study aimed to evaluate the anti-Leishmania amazonensis activity of the terpenoid fraction of Eugenia pruniformis leaves (TF-EpL). TF-EpL was active against the promastigote and intracellular amastigote forms of L. amazonensis with IC50(24h) value of 43.60μg/mL and 44.77μg/mL, respectively. TF-EpL altered the cell cycle of the parasite, increasing 2.32-fold the cells in the Sub-G0/G1 phase. TF-EpL also changed the ΔΨm and increased ROS and the number of annexin-V-PI positive promastigotes, which suggests incidental death. β-sitosterol, ursolic acid, corosolic acid and asiatic acid were isolated from TF-EpL. The results showed the antileishmanial activity of E. pruniformis terpenoids and its potential for further studies as a source of new drugs for leishmaniasis.

Resveratrol, Curcumin and Piperine Alter Human Glyoxalase 1 in MCF-7 Breast Cancer Cells

Breast cancer is the leading cause of cancer mortality in women worldwide. Conventional cancer treatment is costly and results in many side effects. Dietary bioactive compounds may be a potential source for breast cancer prevention and treatment. In this scenario, the aim of this study was to investigate the effects of the bioactive compounds resveratrol, curcumin and piperine (R-C-P) on MCF-7 breast cancer cells and to associate them to Glyoxalase 1 (GLO1) activity. The findings indicate that R-C-P exhibits cytotoxicity towards MCF-7 cells. R-C-P decreased mitochondrial membrane potential (ΔΨm) by 1.93-, 2.04- and 1.17-fold, respectively. Glutathione and N-acetylcysteine were able to reverse the cytotoxicity of the assessed bioactive compounds in MCF-7 cells. R-C-P reduced GLO1 activity by 1.36-, 1.92- and 1.31-fold, respectively. R-C-P in the presence of antimycin A led to 1.98-, 1.65- and 2.16-fold decreases in D-lactate levels after 2 h of treatment, respectively. Glyoxal and methylglyoxal presented cytotoxic effects on MCF-7 cells, with IC₅₀ values of 2.8 and 2.7 mM and of 1.5 and 1.4 mM after 24 and 48 h of treatment, respectively. In conclusion, this study demonstrated that R-C-P results in cytotoxic effects in MCF-7 cells and that this outcome is associated with decreasing GLO1 activity and mitochondrial dysfunction.

Synthesis and evaluation of novel chromanone and quinolinone analogues of uniflorol as anti-leishmanial agents

Within this work, we describe the design and synthesis of a range of novel chromanones and quinolinones, based on natural products reported to possess anti-leishmanial action. The core heterocycles were obtained either via classical or ionic liquid mediated Kabbe condensation in the case of chromanones, or aqueous Sonogashira based alkynylation followed by acid-catalysed cyclisation in the case of quinolinones. Upon testing in promastigotes, axenic amastigotes and Leishmania-infected macrophages, compound 13c was identified as displaying interesting activity, inhibiting axenic amastigotes and intracellular amastigotes with IC₅₀s of 25.3 and 24.6μM respectively.

Novel indol-3-yl-thiosemicarbazone derivatives: Obtaining, evaluation of in vitro leishmanicidal activity and ultrastructural studies

Parasitic diseases still represent serious public health problems, since the high and steady emergence of resistant strains is evident. Because parasitic infections are distributed predominantly in developing countries, less toxic, more efficient, safer and more accessible drugs have become desirable in the treatment of the infected population. This is the case of leishmaniasis, an infectious disease caused by a protozoan of the genus Leishmania sp., responsible for triggering pathological processes from the simplest to the most severe forms leading to high rates of morbidity and mortality throughout the world. In the search for new leishmanicidal drugs, the thiosemicarbazones and the indole fragments have been identified as promising structures for leishmanicidal activity. The present study proposes the synthesis and structural characterization of new indole-thiosemicarbazone derivatives (2a-j), in addition to performing in vitro evaluations through cytotoxicity assays using macrophages (J774) activity against forms of Leishmania infantum and Leishmania amazonensis promastigote as well as ultrastructural analyzes in promastigotes of L. infantum. Results show that the indole-thiosemicarbazone derivatives were obtained with yield values varying from 32.09 to 94.64%. In the evaluation of cytotoxicity, the indole-thiosemicarbazone compounds presented CC₅₀ values between 53.23 and 357.97 μM. Concerning the evaluation against L. amazonensis promastigote forms, IC₅₀ values ranged between 12.31 and  > 481.52 μM, while the activity against L. infantum promastigotes obtained IC₅₀ values between 4.36 and 23.35 μM. The compounds 2d and 2i tested against L. infantum were the most promising in the series, as they showed the lowest IC₅₀ values: 5.60 and 4.36 respectively. The parasites treated with the compounds 2d and 2i showed several structural alterations, such as shrinkage of the cell body, shortening and loss of the flagellum, intense mitochondrial swelling and vacuolization of the cytoplasm leading the parasite to cellular unviability. Therefore, the indole-thiosemicarbazone compounds are promising because they yield considerable synthesis, have low cytotoxicity to mammalian cells and act as leishmanicidal agents.

Piperine-A Major Principle of Black Pepper: A Review of Its Bioactivity and Studies

Piperine is the main compound present in black pepper, and is the carrier of its specific pungent taste, which is responsible for centuries of human dietary utilization and worldwide popularity as a food ingredient. Along with the application as a food ingredient and food preservative, it is used in traditional medicine for many purposes, which has in most cases been justified by modern scientific studies on its biological effects. It has been confirmed that piperine has many bioactive effects, such as antimicrobial action, as well as many physiological effects that can contribute to general human health, including immunomodulatory, hepatoprotective, antioxidant, antimetastatic, antitumor, and many other activities. Clinical studies demonstrated remarkable antioxidant, antitumor, and drug availability-enhancing characteristics of this compound, together with immunomodulatory potential. All these facts point to the therapeutic potential of piperine and the need to incorporate this compound into general health-enhancing medical formulations, as well as into those that would be used as adjunctive therapy in order to enhance the bioavailability of various (chemo)therapeutic drugs.

Cinnamomum cassia exhibits antileishmanial activity against Leishmania donovani infection in vitro and in vivo

BACKGROUND

There is a pressing need for drug discovery against visceral leishmaniasis, a life-threatening protozoal infection, as the available chemotherapy is antiquated and not bereft of side effects. Plants as alternate drug resources has rewarded mankind in the past and aimed in this direction, we investigated the antileishmanial potential of Cinnamomum cassia.

METHODOLOGY

Dichloromethane, ethanolic and aqueous fractions of C. cassia bark, prepared by sequential extraction, were appraised for their anti-promastigote activity along with apoptosis-inducing potential. The most potent, C. cassia dichloromethane fraction (CBD) was evaluated for anti-amastigote efficacy in infected macrophages and nitric oxide (NO) production studied. The in vivo antileishmanial efficacy was assessed in L. donovani infected BALB/c mice and hamsters and various correlates of host protective immunity ascertained. Toxicity profile of CBD was investigated in vitro against peritoneal macrophages and in vivo via alterations in liver and kidney functions. The plant secondary metabolites present in CBD were identified by gas chromatography-mass spectroscopy (GC-MS).

PRINCIPAL FINDINGS

CBD displayed significant anti-promastigote activity with 50% inhibitory concentration (IC50) of 33.6 μg ml-1 that was mediated via apoptosis. This was evidenced by mitochondrial membrane depolarization, increased proportion of cells in sub-G0-G1 phase, ROS production, PS externalization and DNA fragmentation (TUNEL assay). CBD also inhibited intracellular amastigote proliferation (IC50 14.06 μg ml-1) independent of NO production. The in vivo protection achieved was 80.91% (liver) and 82.92% (spleen) in mice and 75.61% (liver) and 78.93% (spleen) in hamsters indicating its profound therapeutic efficacy. CBD exhibited direct antileishmanial activity, as it did not specifically induce a T helper type (Th)-1-polarized mileu in cured hosts. This was evidenced by insignificant modulation of NO production, lymphoproliferation, DTH (delayed type hypersensitivity), serum IgG2a and IgG1 levels and production of Th2 cytokines (IL-4 and IL-10) along with restoration of pro-inflammatory Th1 cytokines (INF-γ, IL-12p70) to the normal range. CBD was devoid of any toxicity in vitro as well as in vivo. The chemical constituents, cinnamaldehyde and its derivatives present in CBD may have imparted the observed antileishmanial effect.

CONCLUSIONS

Our study highlights the profound antileishmanial efficacy of C. cassia bark DCM fraction and merits its further exploration as a source of safe and effective antieishmanial compounds.

Thein vitroantileishmanial activity of essential oil fromAloysia gratissimaand guaiol, its major sesquiterpene againstLeishmania amazonensis

Leishmaniases is a tropical disease caused by protozoa of the genusLeishmaniafor which the current treatment is expensive, besides increasing reports of parasite resistance. This study investigated the anti-Leishmania amazonensisactivity of the essential oil fromAloysia gratissima(AgEO) and guaiol, the major sesquiterpene constituent in the oil. Our results showed that AgEO killed promastigotes and intracellular amastigotes at an IC50of 25 and 0·16µg mL−1, respectively, while guaiol killed amastigotes at an IC50of 0·01µg mL−1. Both AgEO and guaiol were safe for macrophages up to 100µg mL−1, as evaluated by the dehydrogenase activity, membrane integrity and phagocytic capacity. AgEO and guaiol did not induce nitrite oxide (NO) in resting macrophages and inhibited the production of NO in lipopolysaccharide-stimulated macrophages. The ultrastructural analysis suggested that AgEO and guaiol act directly on parasites, affecting promastigotes kinetoplast, mitochondrial matrix and plasma membrane. Together, these results pointed out that AgEO and guaiol could be promising candidates to develop anti-Leishmaniadrugs.

Inhibitory effects of (+)-spectaline and iso-6-spectaline from Senna spectabilis on the growth and ultrastructure of human-infective species Trypanosoma brucei rhodesiense bloodstream form

In our ongoing work searching for new trypanocidal lead compounds from Malaysian plants, two known piperidine alkaloids (+)-spectaline (1) and iso-6-spectaline (2) were isolated from the leaves of Senna spectabilis (sin. Cassia spectabilis). Analysis of the ¹H and ¹³C NMR spectra showed that 1 and 2 presented analytical and spectroscopic data in full agreement with those published in the literature. All compounds were screened in vitro against Trypanosoma brucei rhodesiense in comparison to the standard drug pentamidine. Compound 1 and 2 inhibited growth of T. b. rhodesiense with an IC₅₀ value of 0.41 ± 0.01 μM and 0.71 ± 0.01 μM, without toxic effect on L6 cells with associated a selectivity index of 134.92 and 123.74, respectively. These data show that piperidine alkaloids constitute a class of natural products that feature a broad spectrum of biological activities, and are potential templates for the development of new trypanocidal drugs. To our knowledge, the compounds are being reported for the first time to have inhibitory effects on T. b. rhodesiense. The ultrastructural alterations in the trypanosome induced by 1 and 2, leading to programmed cell death were characterized using electron microscopy. These alterations include wrinkling of the trypanosome surface, formation of autophagic vacuoles, disorganization of kinetoplast, and swelling of the mitochondria. These findings evidence a possible autophagic cell death.

In Vitro Evaluation of Essential Oils Derived from Piper nigrum (Piperaceae) and Citrus limonum (Rutaceae) against the Tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The present research aimed to study the chemical composition and acaricidal activity of Citrus limonum and Piper nigrum essential oils against the cattle tick Rhipicephalus microplus. GC-MS analysis of C. limonum essential oil showed limonene (50.3%), β-pinene (14.4%), and γ-terpinene (11.7%) as the major components; P. nigrum oil was mainly composed of β-caryophyllene (26.2%), σ-ocymene (5.8%), and α-pinene (5.5%). Acaricide activity was evaluated at concentrations of 2.5, 5.0, and 10.0% (v/v) of each plant oil, as well as 1 : 1 combination of both oils (5% : 5%, 2.5% : 2.5%, and 1.25% : 1.25% each), by immersing engorged R. microplus females for one minute. The LC90 of oils from C. limonum, P. nigrum, and the combination were 4.9%, 14.8%, and 5.1%, respectively. C. limonum essential oil caused 100% mortality of engorged females at the highest concentration (10%). P. nigrum essential oil inhibited egg-laying by up to 96% in a concentration-dependent manner, suggesting it reduces tick fecundity. When combined, the oils presented toxicity as to C. limonum oil alone, but with stronger inhibition of oviposition (5% : 5%), indicating a possible additive effect against R. microplus. The present data provide support for further investigation of novel natural products to control bovine tick infestations.

Structure-activity relationship of piperine and its synthetic amide analogs for therapeutic potential to prevent experimentally induced ER stress in vitro

Endoplasmic reticulum (ER) is the key organelle involved in protein folding and maturation. Emerging studies implicate the role of ER stress in the development of chronic kidney disease. Thus, there is an urgent need for compounds that could ameliorate ER stress and prevent CKD. Piperine and its analogs have been reported to exhibit multiple pharmacological activities; however, their efficacy against ER stress in kidney cells has not been studied yet. Hence, the goal of this study was to synthesize amide-substituted piperine analogs and screen them for pharmacological activity to relieve ER stress using an in vitro model of tunicamycin-induced ER stress using normal rat kidney (NRK-52E) cells. Five amide-substituted piperine analogs were synthesized and their chemical structures were elucidated by pertinent spectroscopic techniques. An in vitro model of ER stress was developed using tunicamycin, and the compounds of interest were screened for their effect on cell viability, and the expression of ER chaperone GRP78, the pro-apoptotic ER stress marker CHOP, and apoptotic caspases 3 and 12 (via western blotting). Our findings indicate that exposure to tunicamycin (0.5 μg/mL) for 2 h induces the expression of GRP78 and CHOP, and apoptotic markers (caspase-3 and caspase-12) and causes a significant reduction in renal cell viability. Pre-treatment of cells with piperine and its cyclohexylamino analog decreased the tunicamycin-induced upregulation of GRP78 and CHOP and cell death. Taken together, our findings demonstrate that piperine and its analogs differentially regulate ER stress, and thus represent potential therapeutic agents to treat ER stress-related renal disorders. Graphical Abstract Piperine (PIP) reduces the expression of ER stress markers (GRP78 and CHOP) induced by pathologic stimuli and consequently decreases the activation of apoptotic caspase-12 and caspase-3; all of which contributes to its chemical chaperone and cytoprotective properties to protect renal cells against ER stress and ER stress-induced cell death, and would ultimately prevent the development of chronic kidney disease.

Evidences for Piperine inhibiting cancer by targeting human G-quadruplex DNA sequences

Piperine, a naturally occurring alkaloid, is well known as anti-oxidant, anti-mutagenic, anti-tumor and anti-proliferative agent. Piperine exerts such pharmacological activities by binding or interacting with various cellular targets. Recently, the first report for Piperine interaction with duplex DNA has been published last year but its interaction with G-quadruplex structures has not been studied yet. Herein, we report for the first time the interaction of Piperine with various DNA G-quadruplex structures. Comprehensive biophysical techniques were employed to determine the basis of interaction for the complex formed between Piperine and G-quadruplex DNA sequences. Piperine showed specificity for G-quadruplex DNA over double stranded DNA, with highest affinity for G-quadruplex structure formed at c-myc promoter region. Further, in-vitro studies show that Piperine causes apoptosis-mediated cell death that further emphasizes the potential of this natural product, Piperine, as a promising candidate for targeting G-quadruplex structure and thus, acts as a potent anti-cancer agent.

Anti-Leishmania amazonensis activity of Serjania lethalis A. St.-Hil

Extracts of Serjania lethalis A. St.-Hil leaves and stems were tested in order to identify potential agents against Leishmania amazonensis. The hexane fraction (HF) and dichloromethane subfractions (DDF and MDF) showed leishmanicidal effect. The anti-promastigote IC₅₀ values were 10.29 (HF), 11.41 (DDF) and 28.33μg⁄mL (MDF); whereas those against amastigote were 7.2 (HF), 8.1 (DDF) and 6.5μg⁄mL (MDF). Among the fractions and subfractions assayed, only HF altered the cell cycle of the parasite, increasing 3-fold the number of cells in the sub-G0/G1 phase. HF also changed the parasite mitochondrial membrane potential (ΔΨm) and the percentage of annexin-V-propidium iodide positive promastigotes. Our evaluations of the IC₅₀ values showed that HF, DDF and MDF decreased NO production in infected macrophages stimulated with IFN-γ and LPS. Moreover, HF increased the production of TNF-α in Leishmania infected macrophages. This paper reports for the first time the leishmanicidal activity of extracts and fractions of Serjania lethalis leaves and also characterizes its leishmanicidal and immunomodulatory properties.

Dibenzylideneacetones Are Potent Trypanocidal Compounds That Affect the Trypanosoma cruzi Redox System

Despite ongoing efforts, the available treatments for Chagas' disease are still unsatisfactory, especially in the chronic phase of the disease. Our previous study reported the strong trypanocidal activity of the dibenzylideneacetones A3K2A1 and A3K2A3 against Trypanosoma cruzi (Z. Ud Din, T. P. Fill, F. F. de Assis, D. Lazarin-Bidóia, V. Kaplum, F. P. Garcia, C. V. Nakamura, K. T. de Oliveira, and E. Rodrigues-Filho, Bioorg Med Chem 22:1121-1127, 2014, http://dx.doi.org/10.1016/j.bmc.2013.12.020). In the present study, we investigated the mechanisms of action of these compounds that are involved in parasite death. We showed that A3K2A1 and A3K2A3 induced oxidative stress in the three parasitic forms, especially trypomastigotes, reflected by an increase in oxidant species production and depletion of the endogenous antioxidant system. This oxidative imbalance culminated in damage in essential cell structures of T. cruzi, reflected by lipid peroxidation and DNA fragmentation. Consequently, A3K2A1 and A3K2A3 induced vital alterations in T. cruzi, leading to parasite death through the three pathways, apoptosis, autophagy, and necrosis.

Oleanolic acid (OA) as an antileishmanial agent: Biological evaluation and in silico mechanistic insights

Although a worldwide health problem, leishmaniasis is considered a highly neglected disease, lacking efficient and low toxic treatment. The efforts for new drug development are based on alternatives such as new uses for well-known drugs, in silico and synthetic studies and naturally derived compounds. Oleanolic acid (OA) is a pentacyclic triterpenoid widely distributed throughout the Plantae kingdom that displays several pharmacological activities. OA showed potent leishmancidal effects in different Leishmania species, both against promastigotes (IC(50 L. braziliensis) 30.47 ± 6.35 μM; IC(50 L. amazonensis) 40.46 ± 14.21 μM; IC(50 L. infantum) 65.93 ± 15.12 μM) and amastigotes (IC(50 L. braziliensis) 68.75 ± 16.55 μM; IC(50 L. amazonensis) 38.45 ± 12.05 μM; IC(50 L. infantum) 64.08 ± 23.52 μM), with low cytotoxicity against mouse peritoneal macrophages (CC(50) 235.80 ± 36.95 μM). Moreover, in silico studies performed to evaluate OA molecular properties and to elucidate the possible mechanism of action over the Leishmania enzyme sterol 14α-demethylase (CYP51) suggested that OA interacts efficiently with CYP51 and could inhibit the ergosterol synthesis pathway. Collectively, these data indicate that OA is a good candidate as leading compound for the development of a new leishmaniasis treatment.

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

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

Lessons from black pepper: piperine and derivatives thereof

INTRODUCTION

Piperine is a simple and pungent alkaloid found in the seeds of black pepper (Piper nigrum). Following its isolation and full characterization, the biological properties of piperine have been extensively studied, and piperine-like derivatives have shown an interesting range of pharmacological activities. In this context, significant advances have been made in the discovery of new chemical entities based on the piperine scaffold endowed with therapeutic potential.

AREAS COVERED

The aim of this review is to provide a thorough inquiry on the therapeutic potential of piperine and related derivatives. It provides an overview of recent developments in patented processes and applications thereof between 2000 and 2015.

EXPERT OPINION

Cumulative evidence shows that piperine is currently paving its way to become a privileged scaffold for the development of bioactive compounds with therapeutic application in multiple human diseases. In particular, piperine derivatives were shown to modulate the activity of several targets related to neurological disorders, including epilepsy, Parkinson's disease, depression and pain related disorders. Moreover, the efflux pump inhibitory ability of piperine and its analogues tackles important drug resistance mechanisms and may improve the clinical efficacy of antibiotic and anticancer drugs. Although the use of piperine as a scaffold for bioactive compounds is still in its early stages, the continuous exploration of this structure may lead to remarkable advances in drug discovery programs.

Leishmanicidal Effect of Synthetic trans-Resveratrol Analogs

Background

Stilbene-based compounds show antitumoral, antioxidant, antihistaminic, anti-inflammatory and antimicrobial activities. Here, we evaluated the effect of the trans-resveratrol analogs, pterostilbene, piceatannol, polydatin and oxyresveratrol, against Leishmania amazonensis.

Methodology/Principal Findings

Our results demonstrated a low murine macrophage cytotoxicity of all four analogs. Moreover, pterostilbene, piceatannol, polydatin and oxyresveratrol showed an anti-L. amazonensis activity with IC₅₀ values of 18 μM, 65 μM, 95 μM and 65 μM for promastigotes, respectively. For intracellular amastigotes, the IC₅₀ values of the analogs were 33.2 μM, 45 μM, 29 μM and 30.5 μM, respectively. Among the analogs assayed only piceatannol altered the cell cycle of the parasite, increasing 5-fold the cells in the Sub-G0 phase and decreasing 1.7-fold the cells in the G0-G1 phase. Piceatannol also changed the parasite mitochondrial membrane potential (ΔΨm) and increased the number of annexin-V positive promastigotes, which suggests incidental death.

Conclusion/Significance

Among the analogs tested, piceatannol, which is a metabolite of resveratrol, was the more promising candidate for future studies regarding treatment of leishmaniasis.

Natural Products: Insights into Leishmaniasis Inflammatory Response

Leishmaniasis is a vector-borne disease that affects several populations worldwide, against which there are no vaccines available and the chemotherapy is highly toxic. Depending on the species causing the infection, the disease is characterized by commitment of tissues, including the skin, mucous membranes, and internal organs. Despite the relevance of host inflammatory mediators on parasite burden control, Leishmania and host immune cells interaction may generate an exacerbated proinflammatory response that plays an important role in the development of leishmaniasis clinical manifestations. Plant-derived natural products have been recognized as bioactive agents with several properties, including anti-protozoal and anti-inflammatory activities. The present review focuses on the antileishmanial activity of plant-derived natural products that are able to modulate the inflammatory response in vitro and in vivo. The capability of crude extracts and some isolated substances in promoting an anti-inflammatory response during Leishmania infection may be used as part of an effective strategy to fight the disease.

Resveratrol is active against Leishmania amazonensis: in vitro effect of its association with Amphotericin B

Resveratrol is a polyphenol found in black grapes and red wine and has many biological activities. In this study, we evaluated the effect of resveratrol alone and in association with amphotericin B (AMB) against Leishmania amazonensis. Our results demonstrate that resveratrol possesses both antipromastigote and antiamastigote effects, with 50% inhibitory concentrations (IC50s) of 27 and 42 μM, respectively. The association of resveratrol with AMB showed synergy for L. amazonensis amastigotes, as demonstrated by the mean sums of fractional inhibitory index concentration (mean ΣFIC) of 0.483, although for promastigotes, this association was indifferent. Treatment with resveratrol increased the percentage of promastigotes in the sub-G0/G1 phase of the cell cycle, reduced the mitochondrial potential, and showed an elevated choline peak and CH2-to-CH3 ratio in the nuclear magnetic resonance (NMR) spectroscopy analysis; all these features indicate parasite death. Resveratrol also decreased the activity of the enzyme arginase in uninfected and infected macrophages with and without stimulation with interleukin-4 (IL-4), also implicating arginase inhibition in parasite death. The anti-Leishmania effect of resveratrol and its potential synergistic association with AMB indicate that these compounds should be subjected to further studies of drug association therapy in vivo.