Antimalarial Amodiaquine Research Articles

Electrochemical detection of antimalarial drug (Amodiaquine) using Dy-MOF@MWCNTs composites to prevent erythrocytic stages of plasmodium species in human bodies

Herein, we report on fabrication of dysprosium-based metal–organic framework (Dy-MOF)@multiwalled carbon nanotubes (MWCNT) composites modified with glassy carbon electrode (Dy-MOF@MWCNT/GC) as a working electrode for Antimalarial drug detection. Dy-MOF@MWCNT composites was prepared by sonochemical process along with ultrasonication. The composite structure, phase purity, morphology and composition of the composites were confirmed by X-ray diffraction, Scanning electron microscope, and X-ray photoelectron spectroscopy. Further, Dy@MWCNT composites were deposited on a glassy carbon electrode by drop casting method, and used as an electrode material to efficiently detect Amodiaquine (ADD) by electrochemical techniques such as CV and DPV. The as-prepared Dy@MWCNT composite material showed the oxidation peak current of ADD to be ∼ 60 % higher than other unmodified GC electrodes and showed a low charge transfer resistance (Rct) of 24 Ω. The Dy@MWCNT provided a broad linear range of 0.4 to 20 µM with a limit of detection of 0.377 μM and sensitivity of 1.817 μA.μM−1 for the detection of ADD. According to the pH study, the amount of electrons and protons involved in the electrochemical processes of ADD was calculated and a plausible mechanism for ADD electro-oxidation was proposed. Thus, the prepared sensor exhibited practical usefulness by determining the ADD drug in human urine samples. Hence, the results shows that the Dy@MWCNT- modified sensor has good electrocatalytic activity for the redox of ADD.

Meta-analysis of the global distribution of clinically relevant CYP2C8 alleles and their inferred functional consequences.

CYP2C8 is responsible for the metabolism of 5% of clinically prescribed drugs, including antimalarials, anti-cancer and anti-inflammatory drugs. Genetic variability is an important factor that influences CYP2C8 activity and modulates the pharmacokinetics, efficacy and safety of its substrates. We profiled the genetic landscape of CYP2C8 variability using data from 96 original studies and data repositories that included a total of 33,185 unrelated participants across 44 countries and 43 ethnic groups. The reduced function allele CYP2C8*2 was most common in West and Central Africa with frequencies of 16-36.9%, whereas it was rare in Europe and Asia (< 2%). In contrast, CYP2C8*3 and CYP2C8*4 were common throughout Europe and the Americas (6.9-19.8% for *3 and 2.3-7.5% for *4), but rare in African and East Asian populations. Importantly, we observe pronounced differences (> 2.3-fold) between neighboring countries and even between geographically overlapping populations. Overall, we found that 20-60% of individuals in Africa and Europe carry at least one CYP2C8 allele associated with reduced metabolism and increased adverse event risk of the anti-malarial amodiaquine. Furthermore, up to 60% of individuals of West African ancestry harbored variants that reduced the clearance of pioglitazone, repaglinide, paclitaxel and ibuprofen. In contrast, reduced function alleles are only found in < 2% of East Asian and 8.3-12.8% of South and West Asian individuals. Combined, the presented analyses mapped the genetic and inferred functional variability of CYP2C8 with high ethnogeographic resolution. These results can serve as a valuable resource for CYP2C8 allele frequencies and distribution estimates of CYP2C8 phenotypes that could help identify populations at risk upon treatment with CYP2C8 substrates. The high variability between ethnic groups incentivizes high-resolution pharmacogenetic profiling to guide precision medicine and maximize its socioeconomic benefits, particularly for understudied populations with distinct genetic profiles.

Abstract 4526: Inhibition of RNA Pol I transcription and induction of nucleolar stress in cancer cells treated with the experimental alpha-adrenergic receptor antagonist JP-1302

Abstract The inhibition of ribosome biogenesis through pharmacological means has drawn attention as a potential strategy in cancer therapy. In our previous study we highlighted a novel property of the FDA-approved antimalarial drug amodiaquine, demonstrating its ability to dose-dependently inhibit ribosomal RNA (rRNA) transcription, a critical step in ribosome biogenesis (Espinoza JA, et al Cell Death Diff, 2020). Amodiaquine was found to induce the degradation of the catalytic subunit of RNA polymerase I, known as POLR1A (RPA194), and resulting in nucleolar stress and the stabilization of p53. Notably, RNA Pol I shutdown occurred independently of DNA damage. Motivated by these findings, we sought to find additional inhibitors of ribosome biogenesis. Acridine derivatives display anti-cancer properties. The activity of acridines is mainly attributed to the planarity of these structures, which can intercalate within the DNA structure, and inhibition of chromatin associated protein targets including topoisomerases. JP-1302 is an experimental drug, on a 9-aminoacridine structural scaffold, acting as a selective alpha-2 adrenergic receptor antagonist. It was recently shown that JP-1302 inhibits transcription, blocking RNA Pol II phosphorylation and inhibiting p21 expression at a concentration of 10 μM (Mitchell DC, et al Nat Biotech, 2023). Given JP-1302's structural similarity to other acridine derivatives such as aminacrine, ethacridine, and the experimental compound BMH-21, all known to inhibit RNA Pol I transcription, we hypothesized that JP-1302 might share similar properties. The purpose of our new study was to evaluate JP-1302´s effect on ribosome biogenesis, p53, and cancer cell growth. We show here that JP-1302 acts as an inhibitor of RNA Pol I transcription. Treatment with JP-1302 induced a rapid decrease in the levels of POLR1A, cessation of rRNA synthesis and nucleolar stress already within six hours and at a concentration of 0.5 μM. JP-1302 treatment stabilized wild type p53 and enhanced p21 expression in the osteosarcoma line U2OS. RNA Pol I shutdown occurred in the absence of DNA damage response, as determined by gH2A.X staining. JP-1302 impaired the growth of both p53 wild type and p53 null HCT116 cells with GI50 values of around 0.6 μM, as well as in U2OS cells at 0.8 μM, as determined after 48 hours. Paradoxically, at very low concentrations JP-1302 appeared to transiently stimulate RNA synthesis, a phenomenon that will require further investigation. In conclusion, we identified JP-1302 as a novel inhibitor of ribosomal RNA synthesis, exerting this effect at concentrations that do not induce DNA damage, and independently of p53. Given that JP-1302 passes the blood-brain barrier in rodents, and accumulating in different brain regions, it is of future interest to evaluate this drug in brain tumor models. Citation Format: Sheetanshu Saproo, Styliani Papadaki, Jaime A. Espinoza, Jiri Bartek, Mikael S. Lindström. Inhibition of RNA Pol I transcription and induction of nucleolar stress in cancer cells treated with the experimental alpha-adrenergic receptor antagonist JP-1302 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4526.

Process Development for the Manufacture of the Antimalarial Amodiaquine Dihydrochloride Dihydrate.

A robust process for the manufacture of the active pharmaceutical ingredient (API) amodiaquine dihydrochloride dihydrate (ADQ, 3), an important antimalarial, is reported. The process consists of a three-step synthetic route that involves a Mannich reaction, substitution with 4,7-dichloroquinoline (4,7-DCQ, 5), and rehydration. Additionally, a cost-competitive process for the production of 4,7-DCQ (5) is also reported wherein 4,7-DCQ (5) was prepared in four steps from meta-chloroaniline (7). 4-Acetamido-2-(diethylaminomethyl)phenol (14), 4,7-DCQ (5), and ADQ (3) were obtained in yields of 92, 89, and 90%, respectively. Costing and process mass intensities of 4,7-DCQ and ADQ are also reported.

Voltammetric determination of anti-malarial drug amodiaquine at a boron-doped diamond electrode surface in an anionic surfactant media

In this study, the electrochemical determination of the amodiaquine (ADQ) drug was evaluated using an electrochemically pretreated boron-doped diamond (BDD) electrode due to the enhanced surface activity. The cyclic voltammogram results of ADQ were given as single reversible and diffusion-controlled peaks at +0.48 V for the oxidation peak and +0.05 V for the reduction peak (vs. Ag/AgCl) in Britton-Robinson (BR) buffer at pH 8.0. The peak potential and current signals of ADQ were evaluated at the surface of the BDD electrode using instrumental parameters to develop a simple method for ADQ detection. Also, the effect of an anionic surfactant, sodium dodecyl sulfate (SDS), on the adsorption applicability of the BDD electrode significantly increased the stripping voltammetric determination of ADQ. Under the optimal conditions chosen and employing square-wave adsorptive stripping voltammetry at the BDD electrode, ADQ was determined at + 0.34 V (vs. Ag/AgCl) at the open-circuit condition in BR buffer at pH 8.0 in the presence of 2·10–4 mol l–1 SDS. Furthermore, analytical parameters showed the linear relationship for ADQ determination in the concentration range of 0.1–20.0 μg ml–1 (2.2·10–7 – 4.3·10–5 mol l–1), with a detection limit of 0.03 μg ml–1 (6.5·10–8 mol l–1). The proposed approach can be applied to determine ADQ in water samples.

Plasmodium falciparum merozoite invasion ligands, linked antimalarial resistance loci and ex vivo responses to antimalarials in The Gambia.

Artemether/lumefantrine is the most commonly used artemisinin-based combination treatment (ACT) for malaria in sub-Saharan Africa. Drug resistance to ACT components is a major threat to malaria elimination efforts. Therefore, rigorous monitoring of drug efficacy is required for adequate management of malaria and to sustain the effectiveness of ACTs. This study identified and described genomic loci that correlate with differences in ex vivo responses of natural Plasmodium falciparum isolates from The Gambia to antimalarial drugs. Natural P. falciparum isolates from The Gambia were assayed for IC50 responses to four antimalarial drugs (artemether, dihydroartemisinin, amodiaquine and lumefantrine). Genome-wide SNPs from 56 of these P. falciparum isolates were applied to mixed-model regression and network analyses to determine linked loci correlating with drug responses. Genomic regions of shared haplotypes and positive selection within and between Gambian and Cambodian P. falciparum isolates were mapped by identity-by-descent (IBD) analysis of 209 genomes. SNPs in 71 genes, mostly involved in stress and drug resistance mechanisms correlated with drug responses. Additionally, erythrocyte invasion and permeability loci, including merozoite surface proteins (Pfdblmsp, Pfsurfin), and high-molecular-weight rhoptry protein 2 (Pfrhops2) were correlated with responses to multiple drugs. Haplotypes of pfdblmsp2 and known drug resistance loci (pfaat1, pfcrt and pfdhfr) from The Gambia showed high IBD with those from Cambodia, indicating co-ancestry, with significant linkage disequilibrium between their alleles. Multiple linked genic loci correlating with drug response phenotypes suggest a genomic backbone may be under selection by antimalarials. This calls for further analysis of molecular pathways to drug resistance in African P. falciparum.

In Vivo Activity of Repurposed Amodiaquine as a Host-Targeting Therapy for the Treatment of Anthrax.

Anthrax is caused by Bacillus anthracis and can result in nearly 100% mortality due in part to anthrax toxin. Antimalarial amodiaquine (AQ) acts as a host-oriented inhibitor of anthrax toxin endocytosis. Here, we determined the pharmacokinetics and safety of AQ in mice, rabbits, and humans as well as the efficacy in the fly, mouse, and rabbit models of anthrax infection. In the therapeutic-intervention studies, AQ nearly doubled the survival of mice infected subcutaneously with a B. anthracis dose lethal to 60% of the animals (LD60). In rabbits challenged with 200 LD50 of aerosolized B. anthracis, AQ as a monotherapy delayed death, doubled the survival rate of infected animals that received a suboptimal amount of antibacterial levofloxacin, and reduced bacteremia and toxemia in tissues. Surprisingly, the anthrax efficacy of AQ relies on an additional host macrophage-directed antibacterial mechanism, which was validated in the toxin-independent Drosophila model of Bacillus infection. Lastly, a systematic literature review of the safety and pharmacokinetics of AQ in humans from over 2 000 published articles revealed that AQ is likely safe when taken as prescribed, and its pharmacokinetics predicts anthrax efficacy in humans. Our results support the future examination of AQ as adjunctive therapy for the prophylactic anthrax treatment.

A human-airway-on-a-chip for the rapid identification of candidate antiviral therapeutics and prophylactics.

The rapid repurposing of antivirals is particularly pressing during pandemics. However, rapid assays for assessing candidate drugs typically involve in vitro screens and cell lines that do not recapitulate human physiology at the tissue and organ levels. Here, we show that a microfluidic bronchial-airway-on-a-chip lined by highly differentiated human bronchial-airway epithelium and pulmonary endothelium can model viral infection, strain-dependent virulence, cytokine production, and the recruitment of circulating immune cells. In airway chips infected with influenza A, the co-administration of nafamostat with oseltamivir doubled the treatment-time window for oseltamivir. In chips infected with pseudotyped SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), clinically relevant doses of the antimalarial drug amodiaquine inhibited infection, but clinical doses of hydroxychloroquine and other antiviral drugs that inhibit the entry of pseudotyped SARS-CoV-2 in cell lines under static conditions did not. We also show that amodiaquine showed substantial prophylactic and therapeutic activities in hamsters challenged with native SARS-CoV-2. The human airway-on-a-chip may accelerate the identification of therapeutics and prophylactics with repurposing potential.

Artemisia annua L. extracts inhibit the in vitro replication of SARS-CoV-2 and two of its variants

Ethnopharmacological relevanceArtemisia annua L. has been used for millennia in Southeast Asia to treat “fever”. Many infectious microbial and viral diseases have been shown to respond to A. annua and communities around the world use the plant as a medicinal tea, especially for treating malaria. Aim of the studySARS-CoV-2 (the cause of Covid-19) globally has infected and killed millions of people. Because of the broad-spectrum antiviral activity of artemisinin that includes blockade of SARS-CoV-1, we queried whether A. annua suppressed SARS-CoV-2. Materials and methodsUsing Vero E6 and Calu-3 cells, we measured anti SARS-CoV-2 activity against fully infectious virus of dried leaf extracts of seven cultivars of A. annua sourced from four continents. IC50s were calculated and defined as the concentrations that inhibited viral replication by 50%; CC50s were also calculated and defined as the concentrations that kill 50% of cells. ResultsHot-water leaf extracts based on artemisinin, total flavonoids, or dry leaf mass showed antiviral activity with IC50 values of 0.1–8.7 μM, 0.01–0.14 μg, and 23.4–57.4 μg, respectively. Antiviral efficacy did not correlate with artemisinin or total flavonoid contents of the extracts. One dried leaf sample was >12 years old, yet its hot-water extract was still found to be active. The UK and South African variants, B1.1.7 and B1.351, were similarly inhibited. While all hot water extracts were effective, concentrations of artemisinin and total flavonoids varied by nearly 100-fold in the extracts. Artemisinin alone showed an estimated IC50 of about 70 μM, and the clinically used artemisinin derivatives artesunate, artemether, and dihydroartemisinin were ineffective or cytotoxic at elevated micromolar concentrations. In contrast, the antimalarial drug amodiaquine had an IC50 = 5.8 μM. Extracts had minimal effects on infection of Vero E6 or Calu-3 cells by a reporter virus pseudotyped by the SARS-CoV-2 spike protein. There was no cytotoxicity within an order of magnitude above the antiviral IC90 values. ConclusionsA. annua extracts inhibit SARS-CoV-2 infection, and the active component(s) in the extracts is likely something besides artemisinin or a combination of components that block virus infection at a step downstream of virus entry. Further studies will determine in vivo efficacy to assess whether A. annua might provide a cost-effective therapeutic to treat SARS-CoV-2 infections.

Evaluating Novel RXR Agonists That Induce ApoE and Tyrosine Hydroxylase in Cultured Human Glioblastoma Cells.

There is considerable interest in identifying effective and safe drugs for neurodegenerative disorders. Cell culture and animal model work have demonstrated that modulating gene expression through RXR-mediated pathways may mitigate or reverse cognitive decline. However, because RXR is a dimeric partner for several transcription factors, activating off-target transcription is a concern with RXR ligands (rexinoids). This off-target gene modulation leads to unwanted side effects that can include low thyroid function and significant hyperlipidemia. There is a need to develop rexinoids that have binding specificity for subsets of RXR heterodimers, to drive desired gene modulation, but that do not induce spurious effects. Herein, we describe experiments in which we analyze a series of novel and previously reported rexinoids for their ability to modulate specific gene pathways implicated in neurodegenerative disorders employing a U87 cell culture model. We demonstrate that, compared to the FDA-approved rexinoid bexarotene (1), several of these compounds are equally or more effective at stimulating gene expression via LXREs or Nurr1/NBREs and are superior at inducing ApoE and/or tyrosine hydroxylase (TH) gene and protein expression, including analogs 8, 9, 13, 14, 20, 23, and 24, suggesting a possible therapeutic role for these compounds in Alzheimer's or Parkinson's disease (PD). A subset of these potent RXR agonists can synergize with a presumed Nurr1 ligand and antimalarial drug (amodiaquine) to further enhance Nurr1/NBREs-directed transcription. This novel discovery has potential clinical implications for treatment of PD since it suggests that the combination of an RXR agonist and a Nurr1 ligand can significantly enhance RXR-Nurr1 heterodimer activity and drive enhanced therapeutic expression of the TH gene to increase endogenous synthesis of dopamine. These data indicate that is it possible and prudent to develop novel rexinoids for testing of gene expression and side effect profiles for use in potential treatment of neurodegenerative disorders, as individual rexinoids can have markedly different gene expression profiles but similar structures.

High-energy ionizing radiation-induced degradation of amodiaquine in dilute aqueous solution: radical reactions and kinetics

The widely used antimalarial drug amodiaquine (AQ) contains a 7-Cl-quinoline unit, a substituted 4-aminophenol part connected through the amino group and a tertiary amine part. The 4-aminophenol unit can be easily oxidized through radical intermediates to iminoquinone. This reaction also takes place in vitro and in vivo enzymatic reactions. The reaction is expected to have an important role in degradation of AQ in surface waters and also during degradation in advanced oxidation processes. In this paper by means of radiation chemical techniques the one-electron oxidation and reduction of AQ were studied using transient kinetics, kinetics of AQ degradation, formation and decay of end-products of radical reactions. The hydroxyl radicals were shown to add both to the quinoline (∼ 38%) and aminophenol (∼ 50%) parts via formation of hydroxycyclohexadienyl radicals and by H-abstraction or by an electron removal from the tertiary amine part of the molecule (∼ 12%). The dihydroxycyclohexadienyl radical formed on the aminophenol part is suggested to transform to aminophenoxy radical. The hydrated electrons can also effectively contribute to AQ degradation. Chemical oxygen demand and total organic carbon content investigations were also made in order to characterize the ionizing radiation-induced oxidation and mineralization. In aerated 0.1 mmol dm−3 solution, at 2.5 kGy absorbed dose AQ and its higher molecular mass degradation products demolished completely. Ionizing irradiation is a capable technique for degradation of AQ under both oxidative and reductive circumstances.

The antimalarial drug amodiaquine stabilizes p53 through ribosome biogenesis stress, independently of its autophagy-inhibitory activity

Pharmacological inhibition of ribosome biogenesis is a promising avenue for cancer therapy. Herein, we report a novel activity of the FDA-approved antimalarial drug amodiaquine which inhibits rRNA transcription, a rate-limiting step for ribosome biogenesis, in a dose-dependent manner. Amodiaquine triggers degradation of the catalytic subunit of RNA polymerase I (Pol I), with ensuing RPL5/RPL11-dependent stabilization of p53. Pol I shutdown occurs in the absence of DNA damage and without the subsequent ATM-dependent inhibition of rRNA transcription. RNAseq analysis revealed mechanistic similarities of amodiaquine with BMH-21, the first-in-class Pol I inhibitor, and with chloroquine, the antimalarial analog of amodiaquine, with well-established autophagy-inhibitory activity. Interestingly, autophagy inhibition caused by amodiaquine is not involved in the inhibition of rRNA transcription, suggesting two independent anticancer mechanisms. In vitro, amodiaquine is more efficient than chloroquine in restraining the proliferation of human cell lines derived from colorectal carcinomas, a cancer type with predicted susceptibility to ribosome biogenesis stress. Taken together, our data reveal an unsuspected activity of a drug approved and used in the clinics for over 30 years, and provide rationale for repurposing amodiaquine in cancer therapy.

Theoretical Study of the Adsorption Process of Antimalarial Drugs into Acrylamide-Base Hydrogel Model Using DFT Methods: The First Approach to the Rational Design of a Controlled Drug Delivery System

The interaction between three widely used antimalarial drugs chloroquine, primaquine and amodiaquine with acrylamide dimer and trimer as a hydrogel model, were studied by means of density functional theory calculation in both vacuum and water environments, using the functional wb97xd with 6-31++G(d,p) basis set and polarizable continuum model (C-PCM) of solvent. According to binding energy, around −3.15 to −11.91 kJ/mol, the interaction between antimalarial compounds and hydrogel model are exothermic in nature. The extent of interaction found is primaquine &gt; amodiaquine &gt; chloroquine. The natural bond orbital (NBO) calculation and application of second-order perturbation theory show strong charge transfer between the antimalarial and hydrogel model. In addition, the results suggest these interactions are polar in nature, where hydrogen bonds play a principal role in stabilization of the complex. Comparing with the gas-phase, the complexes in the water environment are also stable, with suitable values of Log P (Partition coefficient), and dipolar momentum. Consequently, these results encourage to test acrylamide hydrogels as antimalarial delivery systems.

Stability Profiling of Amodiaquine under stress Degradation Conditions

Degradation Product is an impurity which results from a chemical change in the drug substance during storage and/or manufacture of the new drug product due to some environmental changes or by reaction with an excipient and/or the immediate container closure system. Impurity development may be either during formulation or upon aging of both API’S and formulated API’S in medicines. The objective of the current investigation was to study the stress degradation behaviour of Amodiaquine under different ICH recommended stress conditions by HPLC method. The anti-malarial drug Amodiaquine, when subjected to stress degradation conditions of hydrolysis, oxidation, photolysis and thermal decomposition prescribed by ICH guideline Q1A (R2), it is found that, the drug Amodiaquine (API) was stable. The method was established using column C18 Hypersyl BDS (250* 4.6) mm, 5µ, mobile phase as monobasic potassium phosphate PH 2.5 with orthophosphoric acid and methanol. Method was isocratic and composition 22: 78 (A: B), at a flow rate of 1.2ml/ min. To facilitate the development of analytical methodology, in order to obtain a better understanding of active pharmaceutical ingredient (API) and drug product (DP) stability, and also to provide information about degradation pathways and degradation products, this process is very useful. These types of studies will provide information about the degradation products that could form during storage and transportation.

Heterogeneity in the in vitro susceptibility of Loa loa microfilariae to drugs commonly used in parasitological infections

BackgroundCo-infection with loiasis remains a potential problem in control programs targeting filarial infections. The effects of many anti-parasitic drugs often administered to Loa loa infected people are not well documented. This study compared the in vitro activity of several of these drugs on the viability of L. loa microfilariae (mf).MethodsHuman strain L. loa mf were isolated from baboon blood using iso-osmotic Percoll gradient, and cultured in RPMI 1640/10% FBS with antimalarial drugs (mefloquine, amodiaquine, artesunate, chloroquine and quinine), anthelmintics (ivermectin, praziquantel, flubendazole and its reduced and hydrolyzed metabolites), two potential trypanocidal agents (fexinidazole and Scynexis-7158) and the anticancer drug imatinib. The drug concentrations used varied between 0.156 μg/ml and 10 μg/ml. Mf motility (CR50 = 50% immotility) and a metabolic viability assay (MTT) were used to assess the effects of these drugs on the parasites.ResultsMf in control cultures showed only a slight reduction in motility after 5 days of culture. Active inhibition of Loa loa motility was seen with mefloquine and amodiaquine (CR50 values of 3.87 and 4.05 μg/ml, respectively), immobilizing > 90% mf within the first 24 hours: mefloquine killed the mf after 24 hours of culture at concentrations ≥ 5 μg/ml. SCYX-7158 also induced a concentration-dependent reduction in mf motility, with > 50% reduction in mf motility seen after 5 days at 10 μg/ml. The anticancer drug imatinib reduced mf motility at 10 μg/ml from the first day of incubation to 55% by day 5, and the reduction in motility was concentration-dependent. Praziquantel and fexinidazole were inactive, and FLBZ and its metabolites, as well as ivermectin at concentrations > 5 μg/ml, had very minimal effects on mf motility over the first 4 days of culture.ConclusionsThe considerable action of the anti-malarial drugs mefloquine and amodiaquine on Loa mf in vitro highlights the possibility of repurposing the existing anti-infectious agents for the development of drugs against loiasis. The heterogeneity in the activity of anti-parasitic agents on Loa loa mf supports the need for further investigation using animal models of loiasis.

The antimalarial drug amodiaquine possesses anti-ZIKA virus activities.

Zika virus (ZIKV) outbreak has emerged as a global health threat, particularly in tropical areas, over the past few years. No antiviral therapy or vaccine is available at present. For these reasons, repurposing clinically approved drugs against ZIKV infection may provide rapid and cost-effective global health benefits. Here, we explored this strategy and screened eight FDA-approved drugs for antiviral activity against ZIKV using a cell-based assay. Our results show that the antimalarial drug amodiaquine has anti-ZIKV activity with EC50 at low micromolar concentrations in cell culture. We further characterized amodiaquine antiviral activity against ZIKV and found that it targets early events of the viral replication cycle. Altogether, our results suggest that amodiaquine may be efficacious for the treatment of ZIKV infection.

Novel anti-adipogenic activity of anti-malarial amodiaquine through suppression of PPARγ activity.

Amodiaquine (AQ) was developed as a selective drug against Plasmodium falciparum malaria infection and has received increasing attention as a therapeutic agent for the treatment of rheumatoid arthritis, Parkinson's disease, and cancer due to its anti-inflammatory, anti-proliferative, and autophagic-lysosomal blockade properties. As autophagy activation is involved in promoting adipogenic differentiation, we examined whether anti-autophagic AQ affected adipocyte differentiation of 3T3-L1 pre-adipocytes. AQ dose-dependently and significantly suppressed adipocyte differentiation in conjunction with decreases in lipid droplet formation and expression of adipogenic markers including adiponectin, adipocyte fatty acid-binding protein 2 (aP2), resistin, and leptin. Although peroxisome proliferator-activated receptor γ (PPARγ) decreases by inhibition of autophagy, AQ treatment did not induce PPARγ degradation despite the suppression of autophagolysosomal degradation. Instead, AQ suppressed the PPARγ activity to transcriptionally activate the aP2 gene transcription through the selective prevention of nuclear localization of PPARγ. These results demonstrated the novel anti-adipogenic activity of AQ and identified its underlying mechanism that AQ suppressed adipogenic gene expression and lipid formation by inhibiting nuclear localization of PPARγ in an autophagy-independent manner. AQ is recommended as a safe and effective anti-obesity drug for controlling overweight and obesity.

The Effects of Quinoline and Non-Quinoline Inhibitors on the Kinetics of Lipid-Mediated β-Hematin Crystallization.

The throughput of a biomimetic lipid-mediated assay used to investigate the effects of inhibitors on the kinetics of β-hematin formation has been optimized through the use of 24-well microplates. The rate constant for β-hematin formation mediated by monopalmitoyl-rac-glycerol was reduced from 0.17 ± 0.04 min-1 previously measured in Falcon tubes to 0.019 ± 0.002 min-1 in the optimized assay. While this necessitated longer incubation times, transferring aliquots from multiple 24-well plates to a single 96-well plate for final absorbance measurements actually improved the overall turnaround time per inhibitor. This assay has been applied to investigate the effects of four clinically relevant antimalarial drugs (chloroquine, amodiaquine, quinidine, and quinine) as well as several short-chain 4-aminoquinoline derivatives and non-quinoline (benzamide) compounds on the kinetics of β-hematin formation. The adsorption strength of these inhibitors to crystalline β-hematin (Kads) was quantified using a theoretical kinetic model that is based on the Avrami equation and the Langmuir isotherm. Statistically significant linear correlations between lipid-mediated β-hematin inhibitory activity and Kads values for quinoline (r2 = 0.76, P-value = 0.0046) and non-quinoline compounds (r2 = 0.99, P-stat = 0.0006), as well as between parasite inhibitory activity (D10) and Kads values for quinoline antimalarial drugs and short-chain chloroquine derivatives (r2 = 0.64, P-value = 0.0098), provide a strong indication that drug action involves adsorption to the surface of β-hematin crystals. Independent support in this regard is provided by experiments that spectrophotometrically monitor the direct adsorption of antimalarial drugs to preformed β-hematin.

Kinetic analysis of interactions of amodiaquine with human cholinesterases and organophosphorus compounds.

Standard therapy of poisoning by organophosphorus compounds (OP) is a combined administration of an anti-muscarinic drug (e.g. atropine) and an oxime as reactivator of inhibited acetylcholinesterase (AChE). Limited efficacy of clinically used oximes against a variety of OPs was shown in numerous studies, calling for research on novel reactivators of OP-inhibited AChE. Recently, reactivation of OP-inhibited AChE by the antimalarial drug amodiaquine was reported. In the present study, amodiaquine and its interactions with human cholinesterases in presence or absence of OP nerve agents was investigated in vitro. Thereby, reversible inhibition of human cholinesterases by amodiaquine (AChE ≫ BChE) was observed. Additionally, a mixed competitive-non-competitive inhibition type of amodiaquine with human AChE was determined. Slow and partial reactivation of sarin-, cyclosarin- and VX-inhibited cholinesterases by amodiaquine was recorded, amodiaquine failed to reactivate tabun-inhibited human cholinesterases. Amodiaquine, being a potent, reversible AChE inhibitor, was tested for its potential benefit as a pretreatment to prevent complete irreversible AChE inhibition by the nerve agent soman. Hereby, amodiaquine failed to prevent phosphonylation and resulted only in a slight increase of AChE activity after removal of amodiaquine and soman. At present the molecular mechanism of amodiaquine-induced reactivation of OP-inhibited AChE is not known, nevertheless amodiaquine could be considered as a template for the design of more potent non-oxime reactivators.

Interactions of the antimalarial amodiaquine with lipid model membranes

A detailed molecular description of the mechanism of action of the antimalarial drug amodiaquine (AQ) is still an open issue. To gain further insights on that, we studied the interactions of AQ with lipid model membranes composed of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylserine (DPPS) by spin labeling electron spin resonance (ESR) and differential scanning calorimetry (DSC). Both techniques indicate a coexistence of an ordered DPPS-rich domain with a disordered DPPC-rich domain in the binary DPPC/DPPS system. We found that AQ slightly lowered the melting transition temperatures associated to both domains and significantly increased the enthalpy change of the whole DPPC/DPPS phase transition. DSC and ESR data also suggest that AQ increases the number of DPPC molecules in the DPPC-rich domains. AQ also causes opposing ordering effects on different regions of the bilayer: while the drug increases the ordering of the lipid acyl chains from carbon 7 to 16, it decreases the order parameter of the lipid head group and of carbon 5. The gel phase was mostly affected by the presence of AQ, suggesting that AQ is able to influence more organized lipid domains. Moreover, the effects of AQ and cholesterol on lipid acyl chain ordering and mobility were compared at physiological temperature and, in a general way, they are similar. Our results suggest that the quinoline ring of AQ is located completely inside the lipid bilayers with its phenol ring and the tertiary amine directed towards the head group region. The nonspecific interaction between AQ and DPPC/DPPS bilayers is a combination of electrostatic and hydrophobic interactions.