Effects of terpenes in the treatment of visceral leishmaniasis: a systematic review of preclinical evidence

Lupeol stimulates iNOS, TNF-α, and IL-10 expression in the U937 cell line infected with old-world Leishmania donovani

OBJECTIVE

Visceral leishmaniasis is a neglected tropical disease that can be lethal if not treated. The available medicines have severe side effects, such as toxicity and drug resistance. Various investigations are looking into new anti-leishmanial compounds from natural products that have little impact on host cells. Lupeol, a triterpenoid present in the flora of many edible plants, has been shown to have antimicrobial properties. The present study investigated the immunomodulatory effects of lupeol on U937 macrophages infected with Leishmania donovani, focusing on the expression of key cytokines and enzymes involved in the immune response.

METHODS

U937 macrophages were infected with Leishmania donovani amastigotes and treated with varying concentrations of lupeol throughout three days. The expression levels of inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-α), and interleukin-10 (IL-10) were measured using real-time polymerase chain reaction (RT-PCR). A positive simulation of gene expression was estimated using ΔΔCT to assess relative expression.

RESULTS

The results demonstrated that lupeol significantly upregulated iNOS and TNF-α expression, especially at higher concentrations, indicating enhanced pro-inflammatory and anti-leishmanial activity. Interestingly, IL-10 expression also increased, suggesting a complex immunomodulatory role of lupeol that involves both pro-inflammatory and anti-inflammatory pathways. Pearson correlation analysis revealed a strong association between iNOS and TNF-α (0.97692), as well as a moderate correlation between iNOS and IL-10 (0.51603).

CONCLUSION

These findings suggest that lupeol may promote a balanced immune response, enhancing the body's ability to combat L. donovani while potentially mitigating excessive inflammation. Lupeol can potentially serve as a novel therapeutic agent against visceral leishmaniasis.

Lantana camara L. induces a multi-targeted cell death process in Leishmania amazonensis

ETNOPHARMACOLOGICAL RELEVANCE

Lantana camara L. is a species known for its broad spectrum of bioactivities and is commonly used in folk therapy to address inflammatory, dermatological, gastrointestinal, intestinal worms and protozoan diseases. It boasts a diverse array of secondary metabolites such as terpenes, flavonoids, and saponins. However, despite its rich chemical profile, there remains a scarcity of studies investigating its antileishmanial properties.

AIM OF THE STUDY

This research aims to explore the antileishmanial potential of L. camara, focusing also on its mechanism of action against Leishmania amazonensis.

MATERIAL AND METHODS

The ethanolic extract of L. camara leaves (LCE) was obtained through static maceration, and its phytoconstituents were identified using UFLC-QTOF-MS. The colorimetric MTT method was conducted to determine the effect of LCE on promastigotes of L. amazonensis and murine macrophages. The anti-amastigote activity was evaluated by counting intracellular parasites in macrophages after Giemsa staining. Additionally, investigations into the mechanisms underlying its action were conducted using cellular and biochemical approaches.

RESULTS

LCE exhibited significant activity against both promastigotes and intracellular amastigotes of L. amazonensis, with IC50 values of 12.20 μg/mL ± 0.12 and 7.09 μg/mL ± 1.24, respectively. These IC50 values indicate very promising antileishmanial activity, comparable to those found for the positive control miltefosine (5.10 μg/mL ± 1.79 and 8.96 μg/mL ± 0.50, respectively). Notably, LCE exhibited negligible cytotoxicity on macrophages (IC50 = 223.40 μg/mL ± 47.02), demonstrating selectivity towards host cells (SI = 31.50). The antileishmanial activity of LCE involved a multi-targeted cell death process, characterized by morphological and ultrastructural alterations observed through SEM and TEM analyses, as well as oxidative effects evidenced by the inhibition of trypanothione reductase, elevation of ROS and lipid levels, and mitochondrial dysfunction evaluated using DTNB, H2DCFDA, Nile red, and JC-1 assays. Additionally, extraction of ergosterol and double labeling with annexin V and PI revealed modifications to the organization and permeability of the treated parasite's plasma membrane. LCE was found to consist predominantly of terpenes, with lantadenes A, B, and C being among the eleven compounds identified through UFLC-QTOF-MS analysis.

CONCLUSIONS

The extract of L. camara presents a diverse array of chemical constituents, prominently featuring high terpene content, which may underlie its antileishmanial properties through a combination of apoptotic and non-apoptotic mechanisms of cell death induced by LCE. This study underscores the therapeutic potential of L. camara as a candidate for antileishmanial treatment, pending further validation.

The ethnomedicine, phytochemistry, and pharmacological properties of the genus Bersama: current review and future perspectives

Bersama (Melianthaceae) has been used in traditional medicine for a wide range of ailments, including blood purifier, immune booster, psychotropic medication, and treatment for malaria, hepatitis, infertility, diabetes, impotency, meningitis, and stroke. This review gathers fragmented information from the literature on ethnomedicinal applications, phytochemistry, pharmacology, and toxicology of the Bersama genus. It also explores the therapeutic potential of the Bersama genus in ethnophytopharmacology, allowing for further investigation. All the available information published in the English language on Bersama genus was compiled from electronic databases such as Academic Journals, Ethnobotany, Google Scholar, PubMed, Science Direct, Web of Science, and library search using the following keywords: "Bersama genus," "traditional use," "phytochemistry," "pharmacological effects," and "toxicology". The ethnomedical applications of the Bersama genus have been recorded, and it has been used traditionally for more than 30 different types of ailments. Thus far, more than 50 compounds have been isolated from the genus. Cardiac glycosides and terpenoids are the main compounds isolated from the Bersama genus. Different plant parts of Bersama genus extracts demonstrated a wide range of pharmacological properties, including antioxidant, antimalarial, antidiabetic, antiviral, anti-inflammatory, and cytotoxic activity. Exemplary drug leads from the genus include mangiferin and quercetin-3-O-arabinopyranoside, both of which have antioxidant activities. Bersama genus has long been used to cure a wide range of ailments. Bersama genus extracts and phytochemicals have been found to have promising pharmacological activities. Further study on promising crude extracts and compounds is required to develop innovative therapeutic candidates.

Comparison of cytotoxicity of Miltefosine and its niosomal form on chick embryo model

Various drugs have been used for the treatment of leishmaniasis, but they often have adverse effects on the body's organs. In this study, we aimed to explore the effects of one type of drug, Miltefosine (MIL), and its analogue or modifier, liposomal Miltefosine (NMIL), on several fetal organs using both in silico analysis and practical tests on chicken embryos. Our in silico approach involved predicting the affinities of MIL and NMIL to critical proteins involved in leishmaniasis, including Vascular Endothelial Growth Factor A (VEGF-A), the Kinase insert domain receptor (KDR1), and apoptotic-regulator proteins (Bcl-2-associate). We then validated and supported these predictions through in vivo investigations, analyzing gene expression and pathological changes in angiogenesis and apoptotic mediators in MIL- and NMIL-treated chicken embryos. The results showed that NMIL had a more effective action towards VEGF-A and KDR1 in leishmaniasis, making it a better candidate for potential operative treatment during pregnancy than MIL alone. In vivo, studies also showed that chicken embryos under MIL treatment displayed less vascular mass and more degenerative and apoptotic changes than those treated with NMIL. These results suggest that NMIL could be a better treatment option for leishmaniasis during pregnancy.

Synergistic antileishmanial activity of erythrodiol, uvaol, and oleanolic acid isolated from olive leaves of cv. Chemlali

This study aimed to assess the antileishmanial activity of biomolecules obtained from Olea europaea L. leaves and twigs recovered from eight Tunisian cultivars. The extraction was first carried out with 80% methanol, and then the obtained extract was fractionated using three solvents of increasing polarity: cyclohexane (CHX), dichloromethane (DCM) and ethyl acetate (EtOAc). The antileishmanial activity was determined against leishmanial strains responsible for cutaneous, visceral, and mucocutaneous leishmaniasis. The cyclohexane fraction of the leaves of cv. Chemlali from the region of Sidi-Bouzid exhibited the strongest leishmanicidal activity against all the tested leishmanial strains. The inhibition concentrations (IC50) were 16.5, 14.5, and 7.4 μg mL-1 for Leishmania mexicana (cutaneous), Leishmania braziliensis (mucocutaneous), and Leishmania donovani (visceral), respectively. Interestingly, low cytotoxicity was observed on THP-1 cells with selective indexes (SI) ranging from 22.8 to 50.5. HPLC-HRMS and full-house NMR analysis allowed the identification of three triterpenic compounds, oleanolic acid (IC50 = 64.1 μg mL-1), erythrodiol (IC50 = 52.0 µg mL-1), and uvaol (IC50 = 53.8 μg mL-1). Antileishmanial activity of uvaol and oleanolic acid has been previously reported. However, this work constitutes the first report of the antileishmanial activity of erythrodiol which showed combinatorial interaction with uvaol (IC50 = 26.1 μg mL-1) against Leishmania tropica. The mixture of the three compounds, as major ones, exhibited an enhanced activity against Leishmania tropica (IC50 = 16.3 µg mL-1) compared to erythrodiol alone or the combination of uvaol and erythrodiol. This finding is of great importance and needs further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03825-3.

In vitro effect of alpha-bisabolol and its synthetic derivatives on macrophages, promastigotes, and amastigotes of Leishmania amazonensis and Leishmania infantum

Cutaneous and visceral leishmaniasis are public health problems in Africa, Asia, Europe, and America. The treatment has a high cost and toxicity. Thus, this work aims to evaluate the leishmanicidal activity of alpha-bisabolol and its three synthetic derivatives, P1, P2, and P3, on the promastigotes and amastigotes Leishmania infantum and L. amazonensis forms. Alpha-bisabolol showed the lowest IC50 with 3.43 for L. amazonensis promastigotes, while P1 was the most toxic for L. infantum with an IC50 of 9.10. The derivative P3 was better for the amastigote form, with an IC50 of 3.39 for L. amazonensis. All the compounds effectively decreased the intracellular load of amastigote and its ability to turn promastigote again. Thus, alpha-bisabolol and its three synthetic derivatives were effective in their leishmanicidal activity. Therefore, it can be an option for developing new treatments against leishmaniasis.

Neurotrophic basis to the pathogenesis of depression and phytotherapy

Depression is a major neuropsychiatric disease that considerably impacts individuals’ psychosocial function and life quality. Neurotrophic factors are now connected to the pathogenesis of depression, while the definitive neurotrophic basis remains elusive. Besides, phytotherapy is alternative to conventional antidepressants that may minimize undesirable adverse reactions. Thus, further research into the interaction between neurotrophic factors and depression and phytochemicals that repair neurotrophic factors deficit is highly required. This review highlighted the implication of neurotrophic factors in depression, with a focus on the brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), and nerve growth factor (NGF), and detailed the antidepressant activities of various phytochemicals targeting neurotrophic factors. Additionally, we presented future opportunities for novel diagnostic and therapeutic strategies for depression and provided solutions to challenges in this area to accelerate the clinical translation of neurotrophic factors for the treatment of depression.

Antileishmanial Activity and In Silico Molecular Docking Studies of Malachra alceifolia Jacq. Fractions against Leishmania mexicana Amastigotes

Malachra alceifolia Jacq. (family Malvaceae), known as "malva," is a medicinal plant used as a traditional therapy in many regions of America, Africa and Asia. Traditionally, this plant is used in the form of extracts, powder and paste by populations for treating fever, stomachache, inflammation, and parasites. However, the ethnopharmacological validation of M. alceifolia has been scarcely researched. This study showed that the chloroform fraction (MA-IC) and subfraction (MA-24F) of the leaves of M. alceifolia exhibited a potential antileishmanial activity against axenic amastigotes of Leishmania mexicana pifanoi (MHOM/VE/60/Ltrod) and had high and moderate cytotoxic effects on the viability and morphology of macrophages RAW 264.7. This study reports, for the first time, possible terpenoid metabolites and derivatives present in M. alceifolia with activity against some biosynthetic pathways in L. mexicana amastigotes. The compounds from the subfractions MA-24F were highly active and were analyzed by gas chromatography-mass spectrometry (GC-MS) and by a molecular docking study in L. mexicana target protein. This study demonstrates the potential modes of interaction and the theoretical affinity energy of the metabolites episwertenol, α-amyrin and methyl commate A, which are present in the active fraction MA-24F, at allosteric sites of the pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase, triose phosphate isomerase, aldolase, phosphoglucose isomerase, transketolase, arginase and cysteine peptidases A, target proteins in some vital biosynthetic pathways were responsible for the survival of L. mexicana. Some phytoconstituents of M. alceifolia can be used for the search for potential new drugs and molecular targets for treating leishmaniases and infectious diseases. Furthermore, contributions to research and the validation and conservation of traditional knowledge of medicinal plants are needed globally.