Synergistic combination of Cinnamomum verum and Syzygium aromaticum treatment for cutaneous leishmaniasis and investigation of their molecular mechanism of action.

Combination therapy at appropriately suitable doses presents a promising alternative to monotherapeutic drugs. In this study, Cinnamomum verum and Syzygium aromaticum essential oils and their major compounds have exhibited substantial leishmaniacidal potential against both promastigote and amastigote forms of Leishmania (L.) major. However, they displayed high cytotoxicity against Raw264.7 macrophage cells. Interestingly, when combined with each other or with amphotericin B, they demonstrated a synergistic effect (FIC<0.5) with low cytotoxicity. These combinations are able to modulate the production of nitric oxide (NO) by macrophages. Notably, the combination of S. aromaticum Essential oil with amphotericin B stimulates macrophage cells by increasing NO production to eliminate leishmanial parasites. Furthermore, investigation of the molecular mechanism of action of these synergistic combinations reveals potent inhibition of the sterol pathway through the inhibition of the CYP51 gene expression. The findings suggest that combination therapy may offer significant therapeutic benefits in both food and pharmaceutical fields.

In vitro Anti-Leishmanial Activities of Methanol Extract of Brucea antidysenterica J.F. Mill Seeds and Its Solvent Fractions.

Introduction: Leishmaniasis is one of the neglected tropical diseases, threatening lives of about 350 million people globally. Brucea antidysenterica seeds are used for the treatment of cutaneous leishmaniasis in the traditional medicine in Ethiopia. Objective: This study aimed to evaluate Brucea antidysenterica seeds' anti-leishmanial activity in vitro. Methods: The crude (80% methanol) extract of Brucea antidysenterica seeds and its fractions were evaluated for their anti-leishmanial activities against promastigotes and intracellular amastigotes of Leishmania donovani and Leishmania aethiopica, and for their cytotoxic effects against mammalian cells. The quantitative estimations of total phenolic compounds (TPCs), flavonoids (TFCs) and alkaloids (TACs) were determined, spectrophotometrically. Median inhibitory concentration (IC50) and median cytotoxic concentration (CC50) of the extract and its solvent fractions were calculated using GraphPad Prism 9.1.0 computer software. Data was presented as mean ± standard error of the mean (SEM). Results: The crude extract and its hexane, ethyl acetate and butanol fractions showed anti-leishmanial activities, with IC50 values of 4.14-60.12 µg/mL against promastigotes, and 6.16-40.12 µg/mL against amastigotes of both Leishmania species. They showed moderate cytotoxicity against Vero cell lines and peritoneal mice macrophages, with CC50 values of 100-500 µg/mL, but >1600 µg/mL against red blood cells. Selectivity indices ranged from 7.97 to 30.97. The crude extract, and its ethyl acetate and hexane fractions possessed 54.78-127.72 mg of gallic acid equivalent TPC, 18.30-79.21 mg of quercetin equivalent TFC, and 27.62-97.22 mg of atropine equivalent TAC per gram of extracts. Conclusion: The seeds of the plant possessed anti-leishmanial activities against L. aethiopica and L. donovani that might provide a scientific justification for its use in the treatment of leishmaniasis by traditional healers. Future works are recommended to isolate, purify and identify the possible secondary metabolites attributed to the anti-leishmanial activity.

In vitro Anti-Leishmanial Activity of Essential Oils Extracted from Plants Growing in Northern Cyprus Against Leishmania tropica

Objective: Natural plant products are considered as a source of novel and effective compounds for the treatment of leishmaniasis. In this study, the in vitro activities of essential oils obtained from Origanum dubium (OD), Origanum majorana (OM), Salvia fruticosa (SF) and Laurus nobilis (LN) plants in Northern Cyprus were investigated against Leishmania tropica. Methods: Leishmania tropica strain (MHOM/TR/2012/CBCL-LT) was obtained. RPMI-1640 was added to 96-well plates in 100 µL aliquots, 100 µg/mL essential oil was added to the first well of each row and serial 2-fold dilutions were performed. A promastigote suspension was pipetted into all wells, and the plates were incubated. The promastigotes were enumerated using a haemocytometer. Results: OD essential oil was effective at killing all promastigotes at a minimum inhibitor height (MIC)=0.2 µg/mL and had high activity at the lowest concentrations. Both SF and LN oils had MIC=1.56 µg/mL and LD50=0.78 µg/mL. SF was observed to impair promastigote morphology at the lowest concentrations, while LN did not exert any effect at concentrations <0.2 µg/mL. OM essential oil was found to have a MIC=3.13 µg/mL and a LD50=1.56 µg/mL. Conclusion: All tested essential oils inhibited promastigotes of Leishmania tropica. OD essential oil demonstrated the highest anti-leishmanial activity. Amaç: Bitkilerden elde edilen dogal ürünlerin leishmaniasis tedavisi için yeni ve etkili bilesiklerin üretilmesine öncülük edecegi düsünülmektedir. Çalismamizda, Kuzey Kibris'ta yetisen Origanum dubium (OD), Origanum majorana (OM), Salvia fruticosa (SF) ve Laurus nobilis (LN) bitkilerinden elde edilen uçucu yaglarin Leishmania tropica'ya karsi in vitro etkinlikleri arastirilmistir. Yöntemler: Çalismamizda, Leishmania tropica susu (MHOM/TR/2012/CBCL-LT) kullanildi. Düz tabanli 96'lik plaklarda, tüm kuyucuklara 100 µL RPMI-1640 ve ilk kuyucuklara 100 µg/mL uçucu yaglar eklenerek, seri dilüsyonlari yapildi. Ardindan tüm kuyucuklara Leishmania tropica promastigot süspansiyonundan pipetlendi ve inkübe edildi. Hemositometre yöntemiyle promastigotlarin sayisi incelendi. Bulgular: OD yaginin minimum inhibitör konsantrasyonu (MIK)=0,2 µg/mL'de tüm promastigotlari öldürürken, en düsük konsantrasyonlarda bile etkili oldugu görülmüstür. SF ve LN uçucu yaglarinin ikisinde de MIK=1,56 µg/mL, LD50=0,78 µg/mL olarak saptanmistir. SF'nin en düsük konsantrasyonlarinin bile promastigot morfolojisini bozdugu görülürken, Laurus nobilis'in ise 0,2 µg/mL'den sonraki konsantrasyonlarda etkisini kaybettigi belirlenmistir. OM uçucu yaginin MIK=3,13 µg/mL, LD50=1,56 µg/mL oldugu görülmüstür. Sonuç: Kullanilan tüm uçucu yaglarin Leishmania tropica promastigotlarini inhibe ettigi görülürken, en yüksek anti-leishmanial etkinlik Origanum dubium uçucu yaginda bulunmustur.

Computational Identification of Chemical Compounds with Potential Activity against Leishmania amazonensis using Nonlinear Machine Learning Techniques.

Leishmaniasis is a poverty-related disease endemic in 98 countries worldwide, with morbidity and mortality increasing daily. All currently used first-line and second-line drugs for the treatment of leishmaniasis exhibit several drawbacks including toxicity, high costs and route of administration. Consequently, the development of new treatments for leishmaniasis is a priority in the field of neglected tropical diseases. The aim of this work is to develop computational models those allow the identification of new chemical compounds with potential anti-leishmanial activity. A data set of 116 organic chemicals, assayed against promastigotes of Leishmania amazonensis, is used to develop the theoretical models. The cutoff value to consider a compound as active one was IC50≤1.5µM. For this study, we employed Dragon software to calculate the molecular descriptors and WEKA to obtain machine learning (ML) models. All ML models showed accuracy values between 82% and 91%, for the training set. The models developed with k-nearest neighbors and classification trees showed sensitivity values of 97% and 100%, respectively; while the models developed with artificial neural networks and support vector machine showed specificity values of 94% and 92%, respectively. In order to validate our models, an external test-set was evaluated with good behavior for all models. A virtual screening was performed and 156 compounds were identified as potential anti-leishmanial by all the ML models. This investigation highlights the merits of ML-based techniques as an alternative to other more traditional methods to find new chemical compounds with anti-leishmanial activity.

Pharmacological activities of cinnamaldehyde and eugenol: antioxidant, cytotoxic and anti-leishmanial studies.

The present study reports the antioxidant, cytotoxic and anti-leishmanial activities of cinnamaldehyde and eugenol. Both the compounds are naturally present in cinnamon and bay leaf. Eugenol is abundantly present in clove. The antioxidant potential was measured in terms of reducing power (FRAP assay), nitric oxide (NO) radical scavenging ability and anti-lipid peroxidative activities. MTT assay was used to evaluate the effect of test compounds on cell viability of prostate cancer cell line (PC-3) as well as for the assessment of in vitro growth inhibition of promastigotes as a measure of anti-leishmanial activity.  Eugenol exhibited considerable NO radical scavenging (63%) and reducing abilities (FRAP value 127×104 µM/mM) while cinnamaldehyde showed comparatively better protective efficacy against lipid peroxidation in rat brain and kidney homogenates (up to 40%). Cinnamaldehyde also displayed substantial cytotoxic activity (75%) against PC-3 cell line. Both the compounds exhibited moderate anti-leishmanial activity and IC50 values for eugenol and cinnamaldehyde were found to be 0.681 g/ml and 1.426g/ml, respectively. The study revealed that both the test compounds have noticeable antioxidant and cytotoxic activities.

In vitro and in vivo antileishmanial activity of Artemisia annua L. leaf powder and its potential usefulness in the treatment of uncomplicated cutaneous leishmaniasis in humans

ABSTRACT INTRODUCTION: Cutaneous leishmaniasis (CL) is a tropical disease that affects millions of individuals worldwide. The current drugs for CL may be effective but have serious side effects; hence, alternatives are urgently needed. Although plant-derived materials are used for the treatment of various diseases in 80% of the global population, the validation of these products is essential. Gelatin capsules containing dried Artemisia annua leaf powder were recently developed as a new herbal formulation (totum) for the oral treatment of malaria and other parasitic diseases. Here, we aimed to determine the usefulness of A. annua gel capsules in CL. METHODS: The antileishmanial activity and cytotoxicity of A. annua L. capsules was determined via in vitro and in vivo studies. Moreover, a preliminary evaluation of its therapeutic potential as antileishmanial treatment in humans was conducted in 2 patients with uncomplicated CL. RESULTS: Artemisia annua capsules showed moderate in vitro activity in amastigotes of Leishmania (Viannia) panamensis; no cytotoxicity in U-937 macrophages or genotoxicity in human lymphocytes was observed. Five of 6 (83.3%) hamsters treated with A. annua capsules (500mg/kg/day) for 30 days were cured, and the 2 examined patients were cured 45 days after initiation of treatment with 30g of A. annua capsules, without any adverse reactions. Both patients remained disease-free 26 and 24 months after treatment completion. CONCLUSION: Capsules of A. annua L. represent an effective treatment for uncomplicated CL, although further randomized controlled trials are needed to validate its efficacy and safety.

Physicochemical characterization by AFM, FT-IR and DSC and biological assays of a promising antileishmania delivery system loaded with a natural Brazilian product.

The control and treatment of Leishmaniasis, a neglected and infectious disease affecting approximately 12 million people worldwide, are challenging. Leishmania parasites multiply intracellularly within macrophages located in deep skin and in visceral tissues, and the currently employed treatments for this disease are subject to significant drawbacks, such as resistance and toxicity. Thus, the search for new Leishmaniasis treatments is compulsory, and Ocotea duckei Vattimo, a plant-derived product from the biodiverse Brazilian flora, may be a promising new treatment for this disease. In this regard, the aim of this work was to develop and characterize a delivery system based on solid lipid nanoparticles (SLN) that contain the liposoluble lignan fraction (LF) of Ocotea duckei Vattimo, which targets the Leishmania phagolysosome of infected macrophages. LF-loaded SLNs were obtained via the hot microemulsion method, and their physical and chemical properties were comprehensively assessed using PCS, AFM, SEM, FT-IR, DSC, HPLC, kinetic drug release studies, and biological assays. The size of the developed delivery system was 218.85±14.2 nm, its zeta potential was -30 mV and its entrapment efficiency (EE%) was high (the EEs% of YAN [yangambin] and EPI-YAN [epi-yangambin] markers were 94.21±0.40% and 94.20±0.00%, respectively). Microscopy, FT-IR and DSC assays confirmed that the delivery system was nanosized and indicated a core-shell encapsulation model, which corroborated the measured kinetics of drug release. The total in vitro release rates of YAN and EPI-YAN in buffer (with sink conditions attained) were 29.6±8.3% and 34.3±8.9%, respectively, via diffusion through the cellulose acetate membrane of the SLN over a period of 4 h. After 24 h, the release rates of both markers reached approximately 45%, suggesting a sustained pattern of release. Mathematical modeling indicated that both markers, YAN and EPI-YAN, followed matrix diffusion-based release kinetics (Higuchi's model) with an estimated diffusion coefficient (D) of 1.3.10(-6) cm(2)/s. The LF-loaded SLNs were non-toxic to murine macrophages (20-80 µg mL(-1) range) and exerted a prominent anti-leishmanial effect (20 µg mL(-1)). These data suggest this new and well-characterized lipid nanoparticle delivery system safely and effectively kills Leishmania and warrants further clinical investigation.

In vitro evaluation of traditionally used Surinamese medicinal plants for their potential anti-leishmanial efficacy.

ETHNOPHARMACOLOGICAL RELEVANCE: Plant-based preparations are extensively used in Surinamese folk medicine for treating leishmaniasis, but often without a scientific rationale. AIM OF THE STUDY: To evaluate 25 Surinamese medicinal plants for their potential efficacy against leishmaniasis. MATERIALS AND METHODS: Concentrated plant extracts were evaluated for their effect on the viability of L. (V.) guyanensis AMC, L. (L.) major NADIM5, and L. (L.) donovani GEDII promastigotes, as well as intracellular amastigotes of L. (L.) donovani BHU814 in infected THP-1 cells. Selectivity was assessed by cytotoxicity against THP-1 cells. RESULTS: The only plant extract that showed potentially meaningful anti-leishmanial activity was that from Solanum lycocarpum that displayed mean IC50 values of about 51, 61, and <16 µg/mL against L. (V) guyanensis, L. (L) major, and L. (L) donovani promastigotes, respectively; about 374 µg/mL against L. (L) donovani amastigotes; and >500 µg/mL against THP-1 cells. The Bryophyllum pinnatum, Inga alba, and Quassia amara extracts displayed moderate to high IC50 values against promastigotes (about 51 to >500 µg/mL) and/or amastigotes (about 224 to >500 µg/mL) but were relatively toxic to THP-1 cells (IC50 values <16 to about 42 µg/mL). The remaining plant extracts exhibited in many cases IC50 values close to, around, or above 500µg/mL against promastigotes, amastigotes, and THP-1 cells. CONCLUSIONS: The S. lycocarpum preparation may be useful against leishmaniasis and may have a good safety index, warranting further investigations into its active constituents and mechanism(s) of action.

In vitro and in vivo evaluation of anti-leishmanial and immunomodulatory activity of Neem leaf extract in Leishmania donovani infection.

The toxicity and emergence of resistance to available chemical drugs against visceral leishmaniasis is evoking to explore herbal treatment. One such attempt with the Neem is being reported here. The current study is primarily focused to evaluate the anti-leishmanial effects of Neem leaf extracts. Among which, ethyl acetate fraction (EAF) alone was found to exhibit leishmanicidal effect validated through cytotoxicity assay and estimated its IC50 to be 52.4 µg/ml on the promastigote stage. Propidium iodide (PI) staining of dead cells substantiated the aforementioned activity. Carboxy fluorescein-diaceate succinimidyl ester (CFSE) staining of promastigotes has affirmed its anti-proliferation activity. The characteristic features such as DNA fragmentation, reduced mitochondrial membrane potential, increased sub G0/G1 phase parasites and increased reactive oxygen species (ROS) production in EAF treated promastigotes indicate the apoptosis like death. In addition, the reduced parasite burden both in vitro (viz. ~45% in human monocytic leukemia cell line (THP-1) and ~50% in peripheral blood mononuclear cells) and in vivo (spleen and liver) provides the evidence for its anti-leishmanial activity on amastigote stage. The increase of ROS levels in THP-1 and nitric oxide (NO) production from J774.1 cell line (mouse macrophages) upon EAF treatment was evidenced for oxidative killing of intracellular amastigotes. Active immunomodulatory activity at m-RNA level (viz. upregulation of Th1 cytokines, and downregulation of Th2 cytokines) both in vitro and in vivo was also shown to be exhibited by EAF. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of EAF revealed the presence of 14 compounds.

Anti-leishmanial activities of extracts and isolated compounds from Drechslera rostrata and Eurotium tonpholium.

The fungal extract of Drechslera rostrata and Eurotium tonpholium showed a significant anti-leishmanial activity against Leishmania major; IC50 was 28.8 and 28.2 µg/mL, respectively. Seven compounds, five from D. rostrata (H1-H5) and two from E. tonpholium (H6 and H7), were isolated and identified using different spectroscopic analysis including (1) HNMR, (13) CNMR, Hetero-nuclear multiple bond connectivity (HMBC), Hetero-nuclear Multiple Quantum Correlation (HMQC), and EI-MS. The isolated compounds are: di-2-ethylhexyl phthalate (1), (22E)-5α,8α-epidioxyergosta-6,22-diene-3ß-ol (2),1,3,8-trihydroxy-6-methyl-nthraquinone (3), aloe-emodine 8-O-glucopyranoside(4), 2R, 3R,4R,5R hexane 1, 2, 3, 4, 5, 6 hexole (Mannitol) (5), 1,8-dihydroxy-3-methoxy-6-methyl-anthraquinone (6) and 1, 4, 5-trihydroxy-7-methoxy-2-methyl-anthraquinone (7). However, compounds (1) and (6) showed activity against L. major with IC50 of 3.2 and 10.38 µg/mL, respectively. On the other hand, oral administration of the two extracts (100 mg/kg) and compounds 1 and 6 (50 mg/kg) showed very good activity when compared with the anti-leishmanial drug Pentostam (125 mg/kg). Interestingly, the complete heeling activity of the extracts and compounds (1) and (6) was obtained after 13-17 days of treatment, while complete healing activity of Pentostam was obtained after 28 days. No alteration on liver and kidney functions was recorded on animals treated with the two extracts for 15 consecutive days.

Antileishmanial activity of some plants growing in Algeria: Juglans regia, Lawsonia inermis and Salvia officinalis.

The current study was undertaken to evaluate in vitro the antileishmanial activity of three plants growing wild in Algeria : Juglans regia, Lawsonia inermis and Salvia officinalis. The hydroalcoholic extracts of these plants were tested on the growth of the promastigotes of Leishmania major. The plant extract effects were compared with three controls : CRL1 composed of 1 ml RPMI inoculated with 10(6) of promastigotes, CRL2 composed of 1 ml RPMI inoculated with 10(6) of promastigotes and 100 µl of hydroalcoholic solvent, CRL3 composed of 1 ml RPMI inoculated with 10(6) of promastigotes and 100 µl of Glucantim as a reference drug in the management of leishmaniasis. The results showed that both J. regia and L. inermis extracts reduced the promastigotes number significantly (P<0.01). however, S. officinalis showed a total inhibition of the Leishmania major growth.

In vitro effects of Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens on Leishmania major promastigotes.

Plant extracts from Warburgia ugandensis Sprague (Family: Canellaceae), Psiadia punctulata Vatke (Family: Compositae) and Chasmanthera dependens Hoschst (Family: Menispermaceae) were tested for activity on Leishmania major promastigotes (Strain IDU/KE/83 = NLB-144) and infected macrophages in vitro. Plants were collected from Baringo district, dried, extracted, weighed and tested for antileishmanial activity. Serial dilutions of the crude extracts were assayed for their activity against Leishmania major in cell free cultures and in infected macrophages in vitro. Inhibitory concentrations and levels of cytotoxicity were determined. Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens had an IC(50) of 1.114 mg/ml, 2.216 mg/ml and 4.648 mg/ml, respectively. The cytotoxicity of the drugs on BALB/c peritoneal macrophage cells was insignificant as compared to the highly toxic drug of choice Pentostam(®). The supernatants from control and Leishmania infected macrophages were analyzed for their nitrite contents by Griess reaction and nitrite absorbance measured at 540 nm. Warburgia ugandensis (stem bark water extract), Chasmanthera dependens (stem bark water extract) and Psiadia punctulata (stem bark methanol extract) produced 112.3%, 94% and 88.5% more nitric oxide than the untreated infected macrophages respectively. Plant crude extracts had significant (p<0.05) anti-leishmanial and immunomodulative effects but insignificant cytotoxic effects at 1mg/ml concentration. All experiments were performed in triplicate. Statistical analysis of the differences between mean values obtained from the experimental group compared to the controls was done by students't test. ANOVA was used to determine the differences between the various treatment groups. The analysis program Probit was used to determine IC(50)s.