A review on the pharmacokinetic properties and toxicity considerations for chloroquine and hydroxychloroquine to potentially treat coronavirus patients

Chloroquine and hydroxychloroquine: Immunomodulatory effects in autoimmune diseases

Chloroquine (CQ) and hydroxychloroquine (HCQ), originally developed as antimalarial drugs, have found a new purpose in treating various autoimmune diseases due to their immunomodulatory properties. These drugs work through multiple mechanisms, including inhibiting Toll-like receptor signaling, suppressing antigen presentation, and modulating autophagy. This review article provides a comprehensive analysis of the immunomodulatory effects of CQ and HCQ in several autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, and others. We delve into the intricate mechanisms of action, highlighting the key immune cells involved and discussing the clinical implications of these drugs in managing autoimmune conditions. Our review covers the latest research and clinical trials, offering a comprehensive understanding of the therapeutic potential of CQ and HCQ in autoimmune diseases. We also discuss the challenges and controversies surrounding the use of these drugs, such as their long-term side effects and the need for personalized treatment approaches. By synthesizing current knowledge and identifying areas for future research, this review aims to provide a valuable resource for healthcare professionals and researchers involved in the management of autoimmune diseases.

Effects of chloroquine and hydroxychloroquine on bone health (Review)

Chloroquine (CQ) and hydroxychloroquine (HCQ), which were initially used to treat malaria, are now also used to treat autoimmune and inflammatory diseases, which have gained notoriety during the coronavirus‑19 pandemic. The emerging uses of CQ and HCQ in cancer therapy, metabolic syndrome and bone disorders highlight their broad clinical potential. Patients with autoimmune and inflammatory conditions have a higher risk of suboptimal bone health because of chronic inflammation, immune dysregulation and medication use. In the present review, the use of CQ and HCQ in bone research was explored, particularly in terms of their effectiveness and mechanism in modulating bone homeostasis. CQ and HCQ inhibit osteoblastic activity by suppressing autophagy, inducing oxidative stress and promoting osteoblast apoptosis. CQ suppresses osteoclastic activity by blocking the receptor activator of nuclear factor κ‑β/receptor activator of nuclear factor κ‑β ligand interaction, autophagy and inflammation. HCQ inhibits osteoclastogenesis by increasing the expression levels of osteoprotegerin, inducing osteoclast apoptosis and reducing cytokines without affecting autophagy. With regard to the molecular machineries, CQ and HCQ inhibit bone formation and bone resorption. Variations in dose, frequency and duration of CQ and HCQ treatment result in heterogenous outcomes. Further research is necessary to clarify the net effects of CQ and HCQ on bone through studies specifically designed to explore their direct impact as the primary objective. The use of these medications is broadening particularly in patients with autoimmune diseases who are at risk of skeletal disorders. However, their safety profiles, adverse effects and contraindications must be carefully monitored when administered for long‑term use and in combination.

New reverse sum Revan indices for physicochemical and pharmacokinetic properties of anti-filovirus drugs

Ebola and Marburg viruses, biosafety level 4 pathogens, cause severe hemorrhaging and organ failure with high mortality. Although some FDA-approved vaccines or therapeutics like Ervebo for Zaire Ebola virus exist, still there is a lack of effective therapeutics that cover all filoviruses, including both Ebola and Marburg viruses. Therefore, some anti-filovirus drugs such as Pinocembrin, Favipiravir, Remdesivir and others are used to manage infections. In theoretical chemistry, a chemical molecule is converted into an isomorphic molecular graph, G ( V , E ) by considering atom set V as vertices and bond set E as edges. A topological index is a molecular descriptor derived from the molecular graph of a chemical compound that characterizes its topology. The relationship between a compound's chemical structure and its properties is investigated through the quantitative structure-property relationship (QSPR). This article introduces new reverse sum Revan degree based indices to explore the physicochemical and pharmacokinetic properties of anti-filovirus drugs via multilinear regression. The findings reveal a strong correlation between these proposed indices and the properties of anti-filovirus drugs when compared to reverse and Revan degree-based indices. Thus, reverse sum Revan indices offer valuable insights for analyzing the drugs properties used to treat Ebola and Marburg virus infections. Moreover, the multilinear regression (MLR) results through reverse sum Revan indices are compared with Artificial Neural Network (ANN) modelling technique and it provides the better prediction of the physicochemical and pharmacokinetic properties of anti-filovirus drugs.

Toxicological effects of hydroxychloroquine sulfate and chloroquine diphosphate substances on the early-life stages of fish in the COVID-19 pandemic context

Hydroxychloroquine sulfate (HCQ) and chloroquine diphosphate (CQ) have been used at increased rates to treat COVID-19 but can constitute a potential environmental risk. The objective was to evaluate the toxicity of sublethal concentrations of HCQ and CQ in zebrafish embryos/larvae. The 50% lethal concentrations (LC50) of HCQ and CQ at 96 h post-fertilization (hpf) were calculated by testing various concentrations on 2,160 embryos. The LC50 obtained were 560 and 800 µM for HCQ and CQ, respectively. Next, the embryotoxicity assay was performed, where 1,200 embryos were subjected to sublethal concentrations of HCQ and CQ. The hatching and heart rates were recorded. After euthanasia, photomicrographs of all larvae were taken to measure the total length, pericardial and yolk sac areas. The embryos exposed to sublethal concentrations of HCQ and CQ showed delayed hatching at 72 hpf, as well as an increase in the heart rate, larger pericardial and yolk sac areas, and body malformations at 96 hpf. The findings show that HCQ and CQ are toxic to fish in the early development phases. Understanding the mechanisms of toxicity will help extrapolate the effects of 4-aminoquinoline derivatives when they reach the aquatic environment in the context of the COVID-19 pandemic.

Chloroquine reduces neutrophil extracellular trap (NET) formation through inhibition of peptidyl arginine deiminase 4 (PAD4)

Neutrophil extracellular traps (NETs) occur when chromatin is decondensed and extruded from the cell, generating a web-like structure. NETs have been implicated in the pathogenesis of several sterile disease states and thus are a potential therapeutic target. Various pathways have been shown to induce NETs, including autophagy, with several key enzymes being activated like peptidyl arginine deiminase 4 (PAD4), an enzyme responsible for citrullination of histones, allowing for DNA unwinding and subsequent release from the cell. Pre-clinical studies have already demonstrated that chloroquine (CQ) and hydroxychloroquine (HCQ) are able to reduce NETs and slow disease progression. The exact mechanism as to how these drugs reduce NETs has yet to be elucidated. CQ and HCQ decrease NET formation from various NET activators, independent of their autophagy inhibitory function. CQ and HCQ were found to inhibit PAD4 exclusively, in a dose-dependent manner, confirmed with reduced CitH3+ NETs after CQ or HCQ treatment. Circulating CitH3 levels were reduced in pancreatic cancer patients after HCQ treatment. In silico screening of PAD4 protein structure identified a likely binding site interaction at Arg639 for CQ and Trp347, Ser468, and Glu580 for HCQ. SPR analysis confirmed the binding of HCQ and CQ with PAD4 with KD values of 54.1 µM (CQ) and 88.1 µM (HCQ). This data provide evidence of direct PAD4 inhibition as a mechanism for CQ/HCQ inhibition of NETs. We propose that these drugs likely reduce NET formation through multiple mechanisms; the previously established TLR9 and autophagy inhibitory mechanism and the novel PAD4 inhibitory mechanism.

The marine natural product, dicitrinone B, induces apoptosis through autophagy blockade in breast cancer

Being a highly conserved catabolic process, autophagy is induced by various forms of cellular stress, and its modulation has considerable potential as a cancer therapeutic approach. In the present study, it was demonstrated that dicitrinone B (DB), a rare carbon-bridged citrinin dimer, may exert anticancer effects by blocking autophagy at a late stage, without disrupting lysosomal function in MCF7 breast cancer and MDA-MB-231 triple-negative breast cancer cells. Furthermore, it was discovered that DB significantly enhanced intracellular reactive oxygen species (ROS) production and that the removal of ROS was followed by the attenuation of autophagy inhibition. In addition, DB exerted notable inhibitory effects on the proliferation and promoting effects on the apoptosis of MCF7 and MDA-MB-231 cells. In combination with conventional chemotherapeutic drugs, DB exhibited a further enhanced synergistic effect than when used as a single agent. Overall, the data of the present study demonstrate that DB may prove to be a promising autophagy inhibitor with anticancer activity against breast cancer.

CHIKV strains Brazil (wt) and Ross (lab-adapted) differ with regard to cell host range and antiviral sensitivity and show CPE in human glioblastoma cell lines U138 and U251

Chikungunya virus (CHIKV), a (re)emerging arbovirus, is the causative agent of chikungunya fever. To date, no approved vaccine or specific antiviral therapy are available. CHIKV has repeatedly been responsible for serious economic and public health impacts in countries where CHIKV epidemics occurred. Antiviral tests in vitro are generally performed in Vero-B4 cells, a well characterised cell line derived from the kidney of an African green monkey. In this work we characterised a CHIKV patient isolate from Brazil (CHIKV^Brazil) with regard to cell affinity, infectivity, propagation and cell damage and compared it with a high-passage lab strain (CHIKV^Ross). Infecting various cell lines (Vero-B4, A549, Huh-7, DBTRG, U251, and U138) with both virus strains, we found distinct differences between the two viruses. CHIKV^Brazil does not cause cytopathic effects (CPE) in the human hepatocarcinoma cell line Huh-7. Neither CHIKV^Brazil nor CHIKV^Ross caused CPE on A549 human lung epithelial cells. The human astrocyte derived glioblastoma cell lines U138 and U251 were found to be effective models for lytic infection with both virus strains and we discuss their predictive potential for neurogenic CHIKV disease. We also detected significant differences in antiviral efficacies regarding the two CHIKV strains. Generally, the antivirals ribavirin, hydroxychloroquine (HCQ) and T-1105 seem to work better against CHIKV^Brazil in glioblastoma cells than in Vero-B4. Finally, full genome analyses of the CHIKV isolates were done in order to determine their lineage and possibly explain differences in tissue range and antiviral compound efficacies.