Atorvastatin as a potential antimalarial drug: in vitro synergy in combinational therapy with dihydroartemisinin

Antiplasmodial, Trypanocidal, and Genotoxicity In Vitro Assessment of New Hybrid α,α-Difluorophenylacetamide-statin Derivatives

BACKGROUND

Statins present a plethora of pleiotropic effects including anti-inflammatory and antimicrobial responses. A,α-difluorophenylacetamides, analogs of diclofenac, are potent pre-clinical anti-inflammatory non-steroidal drugs. Molecular hybridization based on the combination of pharmacophoric moieties has emerged as a strategy for the development of new candidates aiming to obtain multitarget ligands.

METHODS

Considering the anti-inflammatory activity of phenylacetamides and the potential microbicidal action of statins against obligate intracellular parasites, the objective of this work was to synthesize eight new hybrid compounds of α,α-difluorophenylacetamides with the moiety of statins and assess their phenotypic activity against in vitro models of Plasmodium falciparum and Trypanosoma cruzi infection besides exploring their genotoxicity safety profile.

RESULTS

None of the sodium salt compounds presented antiparasitic activity and two acetated compounds displayed mild anti-P. falciparum effect. Against T. cruzi, the acetate halogenated hybrids showed moderate effect against both parasite forms relevant for human infection. Despite the considerable trypanosomicidal activity, the brominated compound revealed a genotoxic profile impairing future in vivo testing.

CONCLUSIONS

However, the chlorinated derivative was the most promising compound with chemical and biological profitable characteristics, without presenting genotoxicity in vitro, being eligible for further in vivo experiments.

High-dose atorvastatin improves vascular endothelial function in patients with leukoaraiosis

Objective

Leukoaraiosis (LA), as an age‐related white matter degeneration, is mainly caused by chronic ischemia. Our study aims to explore the efficacy of different doses of atorvastatin (ATV) in the vascular endothelial function in patients with LA.

Methods

Our study enrolled 402 LA patients who were then randomly included as control or treated with ATV (10 mg), ATV (20 mg), or ATV (30 mg). The total cholesterol (TC), triglycerides (TG), high‐density lipoprotein cholesterol (HDL‐C), and low‐density lipoprotein cholesterol (LDL‐C) were detected by enzyme colorimetric assay. The high‐sensitivity C‐reactive protein (hs‐CRP) level, reactive hyperemia index (RHI), endothelin‐1 (ET‐1) content, and nitric oxide (NO) level were tested by latex agglutination test, peripheral arterial tonometry technology, radioimmunoassay, and nitrate reductase assay, respectively.

Results

After 8 weeks of ATV treatment, the levels of TC, LDL‐C, and HS‐CRP decreased significantly, and the trends were demonstrated in a more significant way with the increases of dose of ATV. The treatment with ATV at different doses elevated NO level and RHI and declined ET‐1 content. Gastrointestinal reaction, muscular pain, and increased aminopherase were observed after treatment with the ATV at different doses with more obvious symptoms detected accompanied by the increase of the dose. The RHI was in negative correlation with the ET‐1 and HS‐CRP while in positive correlation with NO.

Conclusion

Our study demonstrates that ATV can significantly improve the vascular endothelial function in LA patients with a dose‐dependent effect.

Primaquine derivatives: Modifications of the terminal amino group

Numerous modifications of the well-known antimalarial drug primaquine, both at the quinoline ring and at the primary amino group, have been reported, mostly to obtain antimalarial agents with improved bioavailability, reduced toxicity and/or prolonged activity. Modifications of the terminal amino group were made with the main idea to prevent the metabolic pathway leading to inactive and toxic carboxyprimaquine (follow-on strategy), but also to get compounds with different activity (repurposing strategy). The modifications undertaken until 2009 were included in a review published in the same year. The present review covers various classes of primaquine N-derivatives with diverse biological profiles, prepared in the last decade by our research group as well as the others. We have summarized the synthetic procedures applied for their preparation and discussed the main biological results. Several hits for the development of novel antiplasmodial, anticancer, antimycobacterial and antibiofilm agents were identified.

Atorvastatin: In-Vivo Synergy with Metronidazole as Anti-Blastocystis Therapy

Blastocystis is an enteric Straminopile in tropical, subtropical and developing countries. Metronidazole has been a chemotheraputic for blastocystosis. Failures in its regimens were reported and necessitate new studies searching for alternative therapeutic agents. Aim of current study is to investigate potential effects of Atorvastatin (AVA) compared to the conventional chemotherapeutic MTZ in experimentally Blastocystis-infected mice. Anti-Blastocystis efficacy of AVA was evaluated parasitologically, histopathologically and by transmission electron microscopy using MTZ (10 mg/kg) as a control. Therapeutic efficacy of AVA was apparently dose-dependent. Regimens of AVA (20 and 40 mg/kg) proved effective against Blastocystis infections with high reduction in Blastocystis shedding (93.4–97.9%) compared to MTZ (79.3%). The highest reductions (98.1% and 99.4%) were recorded in groups of combination treatments AVA 20–40 mg/kg and MTZ 10 mg/kg. Blastocystis was nearly eradicated by the 20th day post infection. Genotype analysis revealed that genotype I was most susceptible, genotype III was less. Histopathologic and ultrastructural studies revealed apoptotic changes in Blastocystis and significant improvement of intestinal histopathological changes more remarkable in combinational therapy groups. Thus, the present study offers AVA as a potential candidate for Blastocystis therapy combined with MTZ.

In vitro interaction of lumefantrine and piperaquine by atorvastatin against Plasmodium falciparum

Background

There is an urgent need for the discovery of new anti-malarial drugs and combination therapy. A combinatorial approach protects each drug from the development of resistance and reduces generally the overall transmission rate of malaria. Statins, the inhibitors of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase and a family of lipid-lowering drugs, have in vitro anti-malarial properties, and more specially atorvastatin. However, atorvastatin has a short elimination half-life (14 hours) and an efficient combination of anti-malarial drugs must associate a drug with a short elimination half-life and a drug with a long elimination half-life. The objective of the present work was to identify new potential partners among standard new anti-malarial drugs with long elimination half-life, such as lumefantrine, piperaquine, pyronaridine and atovaquone, to improve the in vitro activity of atorvastatin against different Plasmodium falciparum strains to treat uncomplicated malaria.

Methods

In vitro interaction of atorvastatin in combination with lumefantrine, piperaquine, pyronaridine and atovaquone was assessed against 13 P. falciparum strains by isotopic test.

Results

Atorvastatin showed additive effects with pyronaridine, piperaquine and lumefantrine. Atorvastatin increased the in vitro activity of lumefantrine and piperaquine at concentrations expected in clinical observations. The average IC₅₀ values of lumefantrine decreased significantly from 31.9 nM to 20.5 nM (a decrease of 35.7%) in combination with 1 μM of atorvastatin.

Conclusions

Even though in vitro data indicate that atorvastatin improved the activity of lumefantrine and piperaquine, the same may not necessarily be true in vivo. Piperaquine, a new drug with long terminal elimination half-life, is currently a very promising anti-malarial drug.

Improvement of the efficacy of dihydroartemisinin with atorvastatin in an experimental cerebral malaria murine model

Background

The medical care of malaria is a clinical emergency because it may develop into severe malaria, which has a high risk of complications and death. One of the major complications of Plasmodium falciparum infections is cerebral malaria (CM), which is responsible for at least 175,000 deaths worldwide each year and has long-term neurological sequelae. Moreover, treatment for CM is only partially effective. Statins are now known to have anti-inflammatory action, to attenuate sepsis and to have neuroprotective effects. In vitro, atorvastatin (AVA) has an anti-malarial activity and has improved the activity of quinine (QN), mefloquine (MQ), and dihydroartemisinin (DHA).

Objectives

This study had two objectives. First, the ability of AVA to enhance DHA efficacy by improving the survival rate for CM and also decreasing signs of CM was evaluated in a murine model of experimental cerebral malaria (ECM), which was designed in C57BL6/N mice. Second, the inflammatory biomarkers were assessed at D6 and D10 in mice treated by DHA and in untreated mice in which clinical signs of CM appear rapidly and death occurs before D12. Both experiments were designed with seven days of treatment with 40 mg/kg AVA combined with five days of 3 mg/kg DHA administered intraperitoneally.

Results

AVA in combination with DHA in a therapeutic scheme leads to a significant delay in mouse death, and it has an effect on the onset of CM symptoms and on the level of parasitaemia. Evaluation of the biomarkers highlights the significant difference between treated and control mice for five cytokines and chemokines (Eotaxin-CCL11, IL-13, LIX-CXCL5, MIP1b-CCL4 and MIP2) that are known to have a role in chemotaxis.

Conclusions

The combination of DHA and AVA seems to be effective as a therapeutic scheme for improving mouse survival but less effective for cytokine modulation, which is associated with protection against CM. These results call for clinical trials of AVA as an adjuvant with anti-malarial therapy, especially with artemisinin-based combination therapy, in CM treatment or prevention.

Impact of methylene blue and atorvastatin combination therapy on the apparition of cerebral malaria in a murine model

Background

Proveblue®, a methylene blue dye that complies with European Pharmacopoeia and contains limited organic impurities and heavy metals of recognized toxicity, showed in vitro synergy against Plasmodium falciparum when combined with atorvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase. The objective of this study was to evaluate the in vivo efficacy of Proveblue® when combined with atorvastatin in a murine model of experimental cerebral malaria.

Methods

Forty female C57Bl6/N mice were divided into four groups (control, atorvastatin 40 mg/kg for seven days, Proveblue® 10 mg/kg for five days and atorvastatin combined with Proveblue®), infected with Plasmodium berghei ANKA parasites by intraperitoneal inoculation and observed for 45 days.

Results

Treatment with atorvastatin alone did not demonstrate an effect significantly different from no treatment (p = 0.0573). All the mice treated by atorvastatin alone died. Treatment with Proveblue® or a combination of Proveblue® and atorvastatin was significantly increased survival of cerebral malaria (p = 0.0011 and 0.0002, respectively). Although there was only one death in the atorvastatin and Proveblue® combination treatment group (10%) versus two deaths (22%) with Proveblue® treatment, the effect on cerebral malaria was not significant (p = 0.283).

Conclusions

The present work demonstrated, for the first time, the high efficacy of Proveblue® in preventing cerebral malaria. Atorvastatin alone or in combination appears to possess limited use for preventing cerebral malaria. Combination of atorvastatin with lower doses of Proveblue® (<10 mg/kg/day) should be evaluated to show potential synergistic effects in cerebral malaria prevention.

Early treatment failure during treatment of Plasmodium falciparum malaria with atovaquone-proguanil in the Republic of Ivory Coast

The increased spread of drug-resistant malaria highlights the need for alternative drugs for treatment and chemoprophylaxis. The combination of atovaquone‐proguanil (Malarone®) has shown high efficacy against Plasmodium falciparum with only mild side-effects. Treatment failures have been attributed to suboptimal dosages or to parasite resistance resulting from a point mutation in the cytochrome b gene. In this paper, a case of early treatment failure was reported in a patient treated with atovaquone-proguanil; this failure was not associated with a mutation in the parasite cytochrome b gene, with impaired drug bioavailability, or with re-infection.

Atorvastatin treatment is effective when used in combination with mefloquine in an experimental cerebral malaria murine model

BACKGROUND

One of the major complications of Plasmodium falciparum infection is cerebral malaria (CM), which causes one million deaths worldwide each year, results in long-term neurological sequelae and the treatment for which is only partially effective. Statins are recognized to have an immunomodulatory action, attenuate sepsis and have a neuroprotective effect. Atorvastatin (AVA) has shown in vitro anti-malarial activity and has improved the activity of mefloquine (MQ) and quinine.

METHODS

The efficiency of 40 mg/kg intraperitoneal AVA, alone or in association with MQ, was assessed in an experimental Plasmodium berghei ANKA rodent parasite model of CM and performed according to different therapeutic schemes. The effects on experimental CM were assessed through the evaluation of brain histopathological changes and neuronal apoptosis by TUNEL staining.

RESULTS

AVA alone in the therapeutic scheme show no effect on survival, but the prophylactic scheme employing AVA associated with MQ, rather than MQ alone, led to a significant delay in mouse death and had an effect on the onset of CM symptoms and on the level of parasitaemia. Histopathological findings show a correlation between brain lesions and CM onset. A neuronal anti-apoptotic effect of AVA in the AVA + MQ combination was not shown.

CONCLUSIONS

The combination of AVA and MQ therapy led to a significant delay in mouse mortality. There were differences in the incidence, time to cerebral malaria and the level of parasitaemia when the drug combination was administered to mice. When used in combination with MQ, AVA had a relevant effect on the in vivo growth inhibition and clinical outcome of P. berghei ANKA-infected mice.

Atorvastatin prevents Plasmodium falciparum cytoadherence and endothelial damage

Background

The adhesion of Plasmodium falciparum parasitized red blood cell (PRBC) to human endothelial cells (EC) induces inflammatory processes, coagulation cascades, oxidative stress and apoptosis. These pathological processes are suspected to be responsible for the blood-brain-barrier and other organs' endothelial dysfunctions observed in fatal cases of malaria. Atorvastatin, a drug that belongs to the lowering cholesterol molecule family of statins, has been shown to ameliorate endothelial functions and is widely used in patients with cardiovascular disorders.

Methods

The effect of this compound on PRBC induced endothelial impairments was assessed using endothelial co-culture models.

Results

Atorvastatin pre-treatment of EC was found to reduce the expression of adhesion molecules and P. falciparum cytoadherence, to protect cells against PRBC-induced apoptosis and to enhance endothelial monolayer integrity during co-incubation with parasites.

Conclusions

These results might suggest a potential interest use of atorvastatin as a protective treatment to interfere with the pathophysiological cascades leading to severe malaria.

Synergy of mefloquine activity with atorvastatin, but not chloroquine and monodesethylamodiaquine, and association with the pfmdr1 gene

OBJECTIVES

The aim of the study was to assess the in vitro potentiating effects of atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, in combination with mefloquine, chloroquine or monodesethylamodiaquine against Plasmodium falciparum and to evaluate whether the effects of atorvastatin could be associated with mutations or gene copy number in multidrug resistance (MDR)-like protein genes.

METHODS

The susceptibilities of 21 parasite strains to combinations of atorvastatin with mefloquine, chloroquine or monodesethylamodiaquine were assessed using the in vitro isotopic microtest. Genotypes and gene copy number were assessed for pfmdr1, pfmdr2 and pfmrp genes.

RESULTS

Atorvastatin demonstrated synergistic effects in combination with mefloquine. The mefloquine IC(50) (50% inhibitory concentration) was reduced by 7%, 24% and 37% in the presence of atorvastatin at concentrations of 0.1, 0.5 and 1.0 microM, respectively. The synergistic effect of atorvastatin on the response to mefloquine was significantly associated with pfmdr1 copy number. The concentration of atorvastatin that could reduce the IC(50) of mefloquine by 50% was 2.4 +/- 1.3 microM for the 12 strains that contained one copy of pfmdr1 and 5.8 +/- 2.1 microM for the 9 strains that contained two copies or more. The synergistic effect of atorvastatin in combination with mefloquine was found to be significantly unrelated to mutations in pfmdr1, pfmdr2 or pfmrp genes.

CONCLUSIONS

The synergy of the effect of mefloquine at concentrations relevant to its achievable plasma concentrations in patients taking 80 mg of atorvastatin daily suggests that atorvastatin will be a good candidate in combination with mefloquine for malaria treatment.

Atorvastatin as a potential anti-malarial drug: in vitro synergy in combinational therapy with quinine against Plasmodium falciparum

Background

Quinine (QN) remains the first line anti-malarial drug for the treatment of complicated malaria in Europe and Africa. The emergence of QN resistance has been documented. QN resistance is not yet a significant problem, but there is an urgent need to discover partners for use in combination with QN. The aim of the study was to assess the in vitro potentiating effects of atorvastatin (AVA), a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, in combination with QN against Plasmodium falciparum and to evaluate whether the effects of AVA could be associated with gene copy number or mutations in genes involved in QN resistance, such as pfcrt, pfmdr1, pfmrp and pfnhe.

Methods

The susceptibilities to combination of AVA with QN were assessed against 21 parasite strains using the in vitro isotopic microtest. Genotypes and gene copy number were assessed for pfcrt, pfmdr1, pfmdr2, pfmrp genes. In addition, the number of DNNND, DDNHNDNHNN repeats in pfnhe-1 ms4760 and the ms4760 profile were determined for each strains of P. falciparum.

Results

AVA demonstrated synergistic effects in combination with QN against 21 P. falciparum strains. The QN IC₅₀ was reduced by 5% (0% to 15%; 95%CI: 1%-8%), 10% (3% to 23%; 95%CI: 7%-14%) and 22% (14% to 40%; 95%CI: 19%-25%) in presence of AVA at concentrations of 0.1, 0.5 and 1.0 μM, respectively. These reductions were all significant (p < 0.009). The reduction in the QN IC₅₀ in presence of AVA was not significantly correlated with the QN IC₅₀ (r = 0.22, P = 0.3288) or the AVA IC₅₀ (r = 0.03, P = 0.8946). The synergistic effect of AVA in combination with QN was not significantly associated with polymorphisms in the pfcrt, pfmdr1, pfmrp, and pfnhe-1 genes that could be involved in QN resistance. The synergistic effect of AVA on QN responses was not significantly associated with pfmdr1 copy number (P = 0.0428).

Conclusion

The synergistic effect of AVA in combination with QN was found to be unrelated to mutations occurring in transport protein genes involved in QN drug resistance. The different mechanisms of drug uptake and/or mode of action for AVA compared to the other anti-malarial drugs, as well as the AVA-mediated synergy of the anti-malarial effect of QN, suggests that AVA will be a good candidate for combinatorial malaria treatment. All of these observations support calls for both an in vivo evaluation with pharmacokinetic component and clinical trials of AVA as an anti-malarial therapy.