Antiplasmodial Activity Evaluation of a Bestatin-Related Aminopeptidase Inhibitor, Phebestin

Study of the naturally occurring lignan brachangobinan A as antiplasmodial agent: Synthesis, biological evaluation, and in silico prediction

This study focused on the synthesis, structural validation, and evaluation of the antiplasmodial efficacy of brachangobinan A (BA) and its enantiomers, (+)-BA and (-)-BA, as potential antimalarial agents. BA, (+)-BA, and (-)-BA were synthesized through chemical processes and validated via advanced spectroscopic techniques. In vitro studies were conducted to assess their efficacy against Plasmodium falciparum strains 3D7 and K1 by determining their half maximal inhibitory concentration (IC50) values, cytotoxicity profiles, and selectivity indices. Additional evaluations examined the impacts of exposure to these compounds on stage-specific effects, parasite morphology, and parasitemia levels, as well as potential mechanisms of action through in silico drug target prediction and molecular docking simulations. In vivo efficacy was tested in a mouse model of malaria caused by P. yoelii 17XNL. The results revealed that BA, (+)-BA, and (-)-BA exhibited promising in vitro antiplasmodial activity and selectivity, inducing morphological changes and demonstrating cidal effects. Drug-likeness predictions indicated favorable safety profiles but challenges in terms of bioavailability. In silico analyses identified Pf HSP90, Pf CDK2H, and Pf MAPK as key targets of (+)-BA and (-)-BA. In vivo studies confirmed the efficacy of BA in reducing parasitemia levels (trial 1: 19.72 %; trial 2: 15.00 %) compared with the untreated group (trial 1: 29.95 %; trial 2: 28.27 %) without adverse effects. These findings suggest that BA and its enantiomers have potential as seed compounds for development of antimalarial agents.

Evaluation of the antiplasmodial efficacy of synthetic 2,5-diphenyloxazole analogs of compounds naturally derived from Oxytropis lanata

The persistent prevalence and dissemination of drug-resistant malaria parasites continue to challenge the progress of malaria eradication efforts. As a result, there is an urgent need to search for and develop innovative therapies. In this study, we screened synthetic 2,5-diphenyloxazole analogs from Oxytropis lanata. Among 48 compounds, 14 potently inhibited the proliferation of P. falciparum strains 3D7 (chloroquine-sensitive) and K1 (multidrug-resistant) in vitro, exhibited IC50 values from 3.38 to 12.65 μM and 1.27-6.19 μM, respectively, and were toxic to human foreskin fibroblasts at 39.53-336.35 μM. Notably, Compounds 31 (2-(2',3'-dimethoxyphenyl)-5-(2″-hydroxyphenyl)oxazole) and 32 (2-(2',3'-dimethoxyphenyl)-5-(2″-benzyloxyphenyl)oxazole) exhibited the highest selectivity indices (SIs) against both P. falciparum strains (3D7/K1), with values > 40.20/>126.58 and > 41.27/> 59.06, respectively. In the IC50 speed and stage-specific assays, Compounds 31 and 32 showed slow action, along with distinct effects on the ring and trophozoite stages. Microscopy observations further revealed that both compounds impact the development and delay the progression of the trophozoite and schizont stages in P. falciparum 3D7, especially at concentrations 100 times their IC50 values. In a 72-h in vitro exposure experiment at their respective IC80 in P. falciparum 3D7, significant alterations in parasitemia levels were observed compared to the untreated group. In Compound 31-treated cultures, parasites shrank and were unable to reinvade red blood cells (RBCs) during an extended 144-h incubation period, even after compound removal from the culture. In vivo assessments were conducted on P. yoelii 17XNL-infected mice treated with Compounds 31 and 32 at 20 mg/kg administered once daily for ten days. The treated groups showed statistically significant lower peaks of parasitemia (Compound 31-treated: trial 1 12.7%, trial 2 15.8%; Compound 32-treated: trial 1 12.7%, trial 2 14.0%) compared to the untreated group (trial 1 21.7%, trial 2 28.3%). These results emphasize the potential of further developing 2,5-diphenyloxazoles as promising antimalarial agents.

Treatment with bestatin (the exogenous synthetic inhibitor of metalloproteinases) reduces the activity of metalloproteinase 2 and 12 in the spleen and lung tissues of rats in a model of lipopolysaccharide-induced sepsis

Sepsis is caused by an inadequate or dysregulated host response to infection. Enzymes causing cellular degradation are matrix metalloproteinases (MMPs). Lipopolysaccharide (LPS) is used in models of sepsis in laboratory settings The aim of the study was to measure MMP 2 and 12 concentrations in spleen and lungs in rats in which septic shock was induced by LPS. The experiment was carried out on 40 male Wistar rats (5 groups of 8): 0. controls 1. administered LPS 2. administered bestatin 3. LPS and bestatin 4.bestatin and after 6 hours LPS Animals were decapitated. Lungs and spleens were collected. Concentrations of MMP-2 and MMP-12 were determined using immunoenzymatic methods. Mean (±SD) MMP-2 in the controls was 43.57 ± 20.53 ng/ml in the lungs and 1.7 ± 0.72 ng/ml in the spleen; Group 1: 31.28 ± 13.13 ng/ml, 0.83 ± 0.8 ng/ml; Group 2: 44.24 ± 22.75 ng /ml, 1.01 ± 0.32 ng/ml; Group 3: 35.94 ± 15.13 ng/ml, 0.41 ± 0.03 ng/ml; Group 4:79.42 ± 44.70 ng/ml, 0.45 ± 0.15, respectively. Mean MMP-12 in controls was 19.79 ± 10.01 ng/ml in lungs and 41.13 ± 15.99 ng/ml in the spleen; Group 1:27.97 ± 15.1 ng/ml; 40.44 ± 11.2 ng/ml; Group 2: 37.93 ± 25.38 ng/ml 41.05 ± 18.08 ng/ml; Group 3: 40.59 ± 11.46 ng/ml, 35.16 ± 12.89 ng/ml; Group 4: 39.4 ± 17.83 ng/ml, 42.04 ± 12.35 ng/ml, respectively. CONCLUSIONS: 1. Bestatin reduces MMP 2 and 12 levels in spleen and lungs. 2. Treatment with bestatin minimizes the effect of LPS.

Ubenimex combined with Albendazole for the treatment of Echinococcus multilocularis-induced alveolar echinococcosis in mice

Introduction

Alveolar echinococcosis (AE) is a parasitic disease caused by E. multilocularis metacestodes and it is highly prevalent in the northern hemisphere. We have previously found that vaccination with E. multilocularis-Leucine aminopeptidase (EM-LAP) could inhibit the growth and invasion of E. multilocularis in host liver, and Ubenimex, a broad-spectrum inhibitor of LAP, could also inhibit E. multilocularis invasion but had a limited effect on the growth and development of E. multilocularis.

Methods

In this study, the therapeutic effect of Ubenimex combined with Albendazole on AE was evaluated. Mice were intraperitoneally injected with protoscoleces and imaging examination was performed at week 8 and week 16 to detect cyst change. During this period, mice were intraperitoneally injected with Ubenimex and intragastrically administered with Albendazole suspension. At last, the therapeutic effect was evaluated by morphological and pathological examination and liver function.

Results

The results revealed that the combined treatment could inhibit the growth and infiltration of cysts in BALB/c mice infected with E. multilocularis protoscoleces. The weight, number, invasion and fibrosis of cysts were reduced in mice treated with Ubenimex in combination with Albendazole. The same effect was achieved by the single Ubenimex treatment because of its inhibitory effect on LAP activity, but it was less effective in inhibiting the growth of cysts. The levels of ALT, AST, TBIL, DBIL, ALP, and γ-GT were reduced after the combined treatment, indicating that treatment with both Ubenimex and Albendazole could alleviate liver damage.

Discussion

This study suggests that the combined treatment with Ubenimex and Albendazole could be a potential therapeutic strategy for E. multilocularis infections.