In Vitro Antileishmanial and Antischistosomal Activities of Anemonin Isolated from the Fresh Leaves of Ranunculus multifidus Forsk

Leishmaniasis and schistosomiasis are neglected tropical diseases (NTDs) infecting the world’s poorest populations. Effectiveness of the current antileishmanial and antischistosomal therapies are significantly declining, which calls for an urgent need of new effective and safe drugs. In Ethiopia fresh leaves of Ranunculus multifidus Forsk. are traditionally used for the treatment of various ailments including leishmaniasis and eradication of intestinal worms. In the current study, anemonin isolated from the fresh leaves of R. multifidus was assessed for its in vitro antileishmanial and antischistosomal activities. Anemonin was isolated from the hydro-distilled extract of the leaves of R. multifidus. Antileishmanial activity was assessed on clinical isolates of the promastigote and amastigote forms of Leishmania aethiopica and L. donovani clinical isolates. Resazurin reduction assay was used to determine antipromastigote activity, while macrophages were employed for antiamastigote and cytotoxicity assays. Antischistosomal assays were performed against adult Schistosoma mansoni and newly transformed schistosomules (NTS). Anemonin displayed significant antileishmanial activity with IC50 values of 1.33 nM and 1.58 nM against promastigotes and 1.24 nM and 1.91 nM against amastigotes of L. aethiopica and L. donovani, respectively. It also showed moderate activity against adult S. mansoni and NTS (49% activity against adult S. mansoni at 10 µM and 41% activity against NTS at 1 µM). The results obtained in this investigation indicate that anemonin has the potential to be used as a template for designing novel antileishmanial and antischistosomal pharmacophores.

Identification of Suitable Agents against Adenine Phosphoribosyl Transferase for the Management of Leishmaniasis: Synthesis, Characterization and Computational Studies

A leishmaniasis is a group of diseases attributable to protozoan parasites of the genus Leishmania. It is a potential disease mostly occurring in developing nations. Various quinoline substituted derivatives (11a-f, 12a-f, and 13a-f) were synthesized by refluxing amino quinolines with an equivalent number of different alkylaminoethyl chlorides and evaluated for their in vitro antileishmanial activity against promastigotes forms of Leishmania donovani by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] reduction assay. Compounds 11f (IC50 = 13.61μg/mL), 12f (IC50 = 11.92 μg/mL) and 13f (IC50 =10.41 μg/mL) have shown significant antileishmanial activity when compared with standard sitamaquine (IC50= 10.09 μg/mL). Furthermore, the molecular docking analysis targeting adenine phosphoribosyltransferase of Leishmania donovani exhibits significant binding interactions. In silico, ADMET predictions revealed that these compounds, i.e., 11f, 12f, and 13f, demonstrated good absorption as well as solubility characteristics with good drug-likeness and drug score values compared to the standard drug.

Novel Dual Acting Antimalarial Antileishmanial Agents Derived from Pyrazole Moiety

Malaria and leishmaniasis are two highly detrimental parasitic diseases with a global impact. Attempts to eradicate malaria and control leishmaniasis are generally unsuccessful due to the rapidly developing resistance to currently used drug therapy. The pyrazole ring is a key moiety reported to have a variety of biological activities. The current study aimed to design, synthesize and evaluate an array of pyrazole derivatives for potential antimalarial antileishmanial activity. The scheme for the synthesis of the pyrazole derivatives is presented. The antimalarial activity was assessed in-vivo on P. berghei ANKA infected mice to determine % parasitemia and mean survival time. The antileishmanial activity was assessed in-vitro, and IC50 for each compound was calculated. In-vivo acute toxicity and molecular docking on putative antimalarial and antileishmanial drug targets were performed using the most active compounds. All the derivatives exhibited significant antimalarial activity, the highest being 95% suppression of parasitemia with compounds 9a and 9b. The mean survival time of mice treated with these two compounds was also the highest (16-17 days) but was lower than chloroquine, the standard agent. Compounds 9a and 9b exhibited superior antileishmanial activity as compared to miltefosine. However, they were less potent than amphotericin. The compounds were safe and well-tolerated at toxic, oral and intraperitoneal, doses of 150mg/kg and 75mg/kg, respectively. Molecular docking of compound 9a revealed a good fitting pose with plasmodial Pf-DHFR enzyme and Lm-PTR1 enzyme, which explains the biological activity noted with this compound. Pyrazole derivatives 9a and 9b exhibited substantial dual antimalarial antileishmanial activity and may be a valuable scaffold for the design of further derivatives with antiprotozoal potential.

Design, synthesis and biological evaluation of N-oxide derivatives with potent in vivo antileishmanial activity

Leishmaniasis is a neglected disease that affects 12 million people living mainly in developing countries. Herein, 24 new N-oxide-containing compounds were synthesized followed by in vitro and in vivo evaluation of their antileishmanial activity. Compound 4f, a furoxan derivative, was particularly remarkable in this regard, with EC50 value of 3.6 μM against L. infantum amastigote forms and CC50 value superior to 500 μM against murine peritoneal macrophages. In vitro studies suggested that 4f may act by a dual effect, by releasing nitric oxide after biotransformation and by inhibiting cysteine protease CPB (IC50: 4.5 μM). In vivo studies using an acute model of infection showed that compound 4f at 7.7 mg/Kg reduced ~90% of parasite burden in the liver and spleen of L. infantum-infected BALB/c mice. Altogether, these outcomes highlight furoxan 4f as a promising compound for further evaluation as an antileishmanial agent.

Antileishmanial Activity of Cassia fistula L., Morus nigra L. and Ziziphus jujuba Mill., Plant Extracts

Aim: To investigate the different antileishmanial activities of extracts of Cassia Fistula L., Morus Nigra L. and Ziziphus Jujuba Mill. Methodology: In this method, three (03) plants having concentrations between 500 – 2000 µg/mL were subjected to KWH23 strains of L. tropica in which Standard drug was Amphotericin B and have negative control for 24 – 48 hours. To check the in-vivo studies, plant extract was tested on BALB/c mice (Iqbal et al., 2016). Results: It showed that inhibition (mean) of KWH23 strains at 500, 1000, 1500, 2000 µg/mL after 48 hours were 92.1 ± 0.02, 95.00 ± 0.05, 97.09 ± 0.07 and 98.05 ± 0.05 % respectively. It decreased the lesion size (mean) from 0.8 ± 0.1 mm to 0.40 ± 0.2 mm having significance value p < 0.01 after 8th week, and cure at 200 mg/Kg against intracellular amastigotes in BALB/c mice was 90.00% (95% Cl = 80.05 – 97.00). Conclusion: The result shows that Ziziphus jujuba Mill. leaves possess significant antileishmanial activity.