Betulin derivatives impair Leishmania braziliensis viability and host–parasite interaction

Anti-Leishmania amazonensis Activity of Morolic Acid, a Pentacyclic Triterpene with Effects on Innate Immune Response during Macrophage Infection

Leishmaniasis is a group of infectious diseases transmitted to humans during vector bites and caused by protozoans of the genus Leishmania. Conventional therapies face challenges due to their serious side effects, prompting research into new anti-leishmania agents. In this context, we investigated the effectiveness of morolic acid, a pentacyclic triterpene, on L. amazonensis promastigotes and amastigotes. The present study employed the MTT assay, cytokine analysis using optEIATM kits, an H2DCFDA test, and nitric oxide dosage involving nitrite production and Griess reagent. Morolic acid inhibited promastigote and axenic amastigote growth forms at IC50 values of 1.13 µM and 2.74 µM, respectively. For cytotoxicity to macrophages and VERO cells, morolic acid obtained respective CC50 values of 68.61 µM and 82.94 µM. The compound causes damage to the parasite membrane, leading to cellular leakage. In the infection assay, there was a decrease in parasite load, resulting in a CI50 of 2.56 µM. This effect was associated with immunomodulatory activity, altering macrophage structural and cellular parasite elimination mechanisms. Morolic acid proved to be an effective and selective natural compound, making it a strong candidate for future in vivo studies in cutaneous leishmaniasis.

Novel triterpenoid pyrones, phthalimides and phthalates are selectively cytotoxic in CCRF-CEM cancer cells - Synthesis, potency, and mitochondrial mechanism of action

A series of triterpenoid pyrones was synthesized and subsequently modified to introduce phthalimide or phthalate moieties into the triterpenoid skeleton. These compounds underwent in vitro cytotoxicity screening, revealing that a subset of six compounds exhibited potent activity, with IC50 values in the low micromolar range. Further biological evaluations, including Annexin V and propidium iodide staining experiment revealed, that all compounds induce selective apoptosis in cancer cells. Measurements of mitochondrial potential, cell cycle analysis, and the expression of pro- and anti-apoptotic proteins confirmed, that apoptosis was mediated via the mitochondrial pathway. These findings were further supported by cell cycle modulation and DNA/RNA synthesis studies, which indicated a significant increase in cell accumulation in the G0/G1 phase and a marked reduction in S-phase cells, alongside a substantial inhibition of DNA synthesis. The activation of caspase-3 and the cleavage of PARP, coupled with a decrease in the expression of Bcl-2 and Bcl-XL proteins, underscored the induction of apoptosis through the mitochondrial pathway. Given their high activity and pronounced effect on mitochondria function, trifluoromethyl pyrones 1f and 2f, and dihydrophthalimide 2h have been selected for further development.

Leishmanicidal Activity of Betulin Derivatives in Leishmania amazonensis; Effect on Plasma and Mitochondrial Membrane Potential, and Macrophage Nitric Oxide and Superoxide Production

Herein, we evaluated in vitro the anti-leishmanial activity of betulin derivatives in Venezuelan isolates of Leishmania amazonensis, isolated from patients with therapeutic failure.

METHODS

We analyzed promastigote in vitro susceptibility as well as the cytotoxicity and selectivity of the evaluated compounds. Additionally, the activity of selected compounds was determined in intracellular amastigotes. Finally, to gain hints on their potential mechanism of action, the effect of the most promising compounds on plasma and mitochondrial membrane potential, and nitric oxide and superoxide production by infected macrophages was determined.

RESULTS

From the tested 28 compounds, those numbered 18 and 22 were chosen for additional studies. Both 18 and 22 were active (GI50 ≤ 2 µM, cytotoxic CC50 > 45 µM, SI > 20) for the reference strain LTB0016 and for patient isolates. The results suggest that 18 significantly depolarized the plasma membrane potential (p < 0.05) and the mitochondrial membrane potential (p < 0.05) when compared to untreated cells. Although neither 18 nor 22 induced nitric oxide production in infected macrophages, 18 induced superoxide production in infected macrophages.

CONCLUSION

Our results suggest that due to their efficacy and selectivity against intracellular parasites and the potential mechanisms underlying their leishmanicidal effect, the compounds 18 and 22 could be used as tools for designing new chemotherapies against leishmaniasis.

Promastigotes of Leishmania donovani exhibited sensitivity towards the high altitudinal plant Cicer microphyllum

In this study, we explored Cicer microphyllum (CM), a Trans-Himalayan plant for its chemical components by GC-MS, phytochemical quantitation, and anti-leishmanial efficacy against sensitive strain (SS) and resistant strain (RS) promastigotes of L. donovani in vitro. The hydroethanolic extract of aerial parts of CM was screened for the presence of chemical compounds and phytochemical estimation. The antileishmanial activity of CM was assessed against the promastigotes of L. donovani. The cell volume and cell viability were analyzed by flow cytometry. The generation of reactive oxygen species (ROS) and lipid bodies was determined after treatment with reference and test drug. The extract of CM is complemented with major plant secondary metabolites and the quantitative assessment for phytoconstituents showed the highest concentration of phenols followed by flavonoids and terpenoids. Different biologically active chemical compounds were identified by the GC-MS analysis. The 50% inhibitory concentrations against L. donovani sensitive strain were 14.40 μg/ml and 23.03 μg/ml whereas for resistant promastigotes these were 49.84 μg/ml and 26.77 μg/ml after SAG (sodium stibogluconate) and CM exposure, respectively. CM treatment reduced cell viability induced by loss in plasma membrane integrity. Drug treatment resulted in higher ROS generation and production of lipid bodies. GC-MS screening of the extract revealed the richness of active chemical components in CM. The presence of diverse phytochemicals, no cytotoxicity to human macrophages, and the antileishmanial action of CM depicted its potential as an alternative future drug.

•

First report of in vitro leishmanial activity of Cicer microphyllum (CM) against SAG-resistant and SAG-sensitive strain.

•

Chemical characterization of CM by GC-MS revealed biologically active components.

•

CM augmented ROS production and lipid bodiesʼ formation in Leishmania parasites.

•

Parasitic cells exhibited loss of membrane integrity upon drug treatment.

•

No significant toxicity on THP-1 cell line was observed.

Chemotactic activities of vasoactive intestinal peptide, neuropeptide Y and substance P in Leishmania braziliensis

Cell-cell interaction and active migration (and invasion) of parasites into skin host-cell(s) are key steps for successful infection by Leishmania. Chemotaxis constitutes a primordial chapter of Leishmania-host cell interaction, potentially modulated by neuropeptides released into the skin due, for example, to the noxious stimuli represented by the insect bite. Herein we have evaluated in vitro the effect of sensory (Substance P, SP) and autonomic (Vasoactive Intestinal Peptide, VIP, and Neuropeptide Y, NPY) neuropeptides on parasite taxis, and investigated the potential modulatory effect of SP on Leishmania (Viannia) braziliensis-macrophage interaction. We demonstrated that VIP (10^-10 M) and NPY (10^-9 M) are chemorepellent to the parasites, while SP (10^-8 M) produces a chemoattractant response. SP did not affect macrophage viability but seems to impair parasite-macrophage interaction as it decreased promastigote adherence to macrophages. As this effect is blocked by ([D-Pro 2, D-Trp7,9]-Substance P (10^-6 M), the observed action may be mediated by neurokinin-1 (NK₁) transmembrane receptors. VIP and NPY repellent chemotactic effect is impaired by their corresponding receptor antagonists. Additionally, they suggest that SP may be a key molecule to guide promastigote migration towards, and interaction, with dendritic cells and macrophage host cells.

Neuroprotective Effects of Betulin in Pharmacological and Transgenic Caenorhabditis elegans Models of Parkinson's Disease

Parkinson’s disease (PD) is the second most common degenerative disorder of the central nervous system in the elderly. It is characterized by progressive loss of dopaminergic neurons in the substantia nigra pars compacta, as well as by motor dysfunction. Although the causes of PD are not well understood, aggregation of α-synuclein (α-syn) in neurons contributes to this disease. Current therapeutics for PD provides satisfactory symptom relief but not a cure. Treatment strategies include attempts to identify new drugs that will prevent or arrest the progressive course of PD by correcting disease-specific pathogenic process. Betulin is derived from the bark of birch trees and possesses anticancer, antimicrobial, and anti-inflammatory properties. The aim of the present study was to evaluate the potential for betulin to ameliorate PD features in Caenorhabditis elegans (C. elegans) models. We demonstrated that betulin diminished α-syn accumulation in the transgenic C. elegans model. Betulin also reduced 6-hydroxydopamine-induced dopaminergic neuron degeneration, reduced food-sensing behavioral abnormalities, and reversed life-span decreases in a pharmacological C. elegans model. Moreover, we found that the enhancement of proteasomes activity by promoting rpn1 expression and downregulation of the apoptosis pathway gene, egl-1, may be the molecular mechanism for betulin-mediated protection against PD pathology. Together, these findings support betulin as a possible treatment for PD and encourage further investigations of betulin as an antineurodegenerative agent.

Triterpenic azines, a new class of compounds with selective cytotoxicity to leukemia cells CCRF-CEM

Aim: From betulinic acid (1a), we synthesized 30-oxobetulinic acid (2a) that is highly cytotoxic against many cancer cell lines; however, its generic toxicity is the main obstacle in further development as cytostatic. Methodology & results: From 2a, we prepared a new class of compounds – nonsymmetrical azines and tested their in vitro cytotoxicity. All new azines with a free 28-COOH group (4a–4e) were highly and selectively cytotoxic against the T-lymphoblastic leukemia cell line CCRF-CEM and exhibited dose-dependent inhibition of RNA and DNA synthesis and other cell-cycle alterations, including the M-phase block. Conclusion: The potential use of azines (4a–4e) in drug development focused on hematological cancers is significantly higher than that of previously studied acids 1a and 2a.

Phytochemical and Biological Investigations of Conradina Canescens

Conradina canescens (Lamiaceae) is an endemic evergreen shrub native to Florida, Mississippi and Alabama, with no phytochemical or biological studies registered in the literature. Thus, a phytochemical study and a toxicity analysis of the chloroform extract obtained from the leaves of C. canescens were performed for the first time. In our preliminary screening, the crude extract and its fractions were subjected to cytotoxicity, antimicrobial and antileishmanial bioassays. The crude extract showed substantial cytotoxic, antimicrobial and antileishmanial activities. A total of six compounds, namely ursolic acid (62.4%), betulin (8.4%), β-amyrin (4.6%), myrtenic acid (2.9%), n-tetracosane (1.4%), and oleanolic acid (1.1%), were isolated. The structures of the isolated compounds were established by spectroscopic studies using NMR and IR spectroscopy.