Subchronic toxicological study of two artemisinin derivatives in dogs

Artesunate Exerts Organ- and Tissue-Protective Effects by Regulating Oxidative Stress, Inflammation, Autophagy, Apoptosis, and Fibrosis: A Review of Evidence and Mechanisms

The human body comprises numerous organs and tissues operating in synchrony, it facilitates metabolism, circulation, and overall organismal function. Consequently, the well-being of our organs and tissues significantly influences our overall health. In recent years, research on the protective effects of artesunate (AS) on various organ functions, including the heart, liver, brain, lungs, kidneys, gastrointestinal tract, bones, and others has witnessed significant advancements. Findings from in vivo and in vitro studies suggest that AS may emerge as a newfound guardian against organ damage. Its protective mechanisms primarily entail the inhibition of inflammatory factors and affect anti-fibrotic, anti-aging, immune-enhancing, modulation of stem cells, apoptosis, metabolic homeostasis, and autophagy properties. Moreover, AS is attracting a high level of interest because of its obvious antioxidant activities, including the activation of Nrf2 and HO-1 signaling pathways, inhibiting the release of reactive oxygen species, and interfering with the expression of genes and proteins associated with oxidative stress. This review comprehensively outlines the recent strides made by AS in alleviating organismal injuries stemming from various causes and protecting organs, aiming to serve as a reference for further in-depth research and utilization of AS.

Thrombocytopenia a predictor of malaria: how far?

Malaria is an acute febrile illness. It is a dangerous disease that contributes to millions of hospital visits and hundreds of thousands of deaths, especially in children residing in sub-Saharan Africa. In a non-immune individual, symptoms usually appear 10-15 days after the infective mosquito bite. The first symptoms-fever, headache, and chills-may be mild and difficult to recognize as malaria. If not treated within 24 h, P. falciparum malaria can progress to severe illness, often leading to death. Children with severe malaria frequently develop one or more of the following symptoms: severe anaemia, respiratory distress in relation to metabolic acidosis, or cerebral malaria. In adults, multi-organ involvement is also frequent. In malaria endemic areas, people may develop partial immunity, allowing asymptomatic infections to occur. Haematological changes are well-recognised with malarial infection however background haemoglobinopathy, nutritional status, demographic factors and malaria immunity play a major role in specific changes in that geographical region. Artemisinin derivatives are new generation antimalarial drugs they are used in the treatment of acute attacks of severe malaria including cerebral malaria. Information on the safety of these new antimalarial drugs on body function is still scanty. Haematological parameters are well studied in P. falciparum infection, but now recent studies have indicated that these changes do occur in P. vivax infection also. Hematological profile together with microscopy will enable rapid diagnosis, prompt treatment and further complications can be avoided. This current review is aimed at providing an up-to-date information on the role of malaria and anti-malarial drugs on haematological parameters especially thrombocytopenia.

Clinical Efficacy and Safety of Malarone®, Azithromycin and Artesunate Combination for Treatment of Babesia gibsoni in Naturally Infected Dogs

Babesia gibsoni is a tick-borne protozoal blood parasite that may cause hemolytic anemia, thrombocytopenia, lethargy, and/or splenomegaly in dogs. Many drugs have been used in management of canine babesiosis such as monotherapy or combined treatment, including diminazene aceturate, imidocarb dipropionate, atovaquone, and antibiotics. This report examines the effectiveness and safety of Malarone®, azithromycin (AZM) and artesunate (ART) combination for the treatment of babesiosis in dogs naturally infected with Babesia gibsoni. Twelve American Pit Bull Terriers were included in the experiment. Examined dogs underwent clinical and laboratory analysis including hematology and biochemistry profile and serum protein electrophoresis. After diagnosis, the dogs received combined therapy with Malarone® (13.5 mg/kg PO q24 h), azithromycin (10 mg/kg PO q24 h) and artesunate (12.5 mg/kg PO q24 h) for 10 days. The combined treatment improved hematology and biochemical parameters to the reference range gradually during the first 14 days already, resulting in the stable values until day 56 after treatment. No clinically apparent adverse effects were reported during treatment and monitoring. No relapses of parasitemia were detected in control days 180, 360, 540 and 720 in all dogs. Results of the study indicate that the combined treatment leads to successful elimination of parasitemia in chronically infected dogs with B. gibsoni.

The immunosuppressive activity of artemisinin-type drugs towards inflammatory and autoimmune diseases

The sesquiterpene lactone artemisinin from Artemisia annua L. is well established for malaria therapy, but its bioactivity spectrum is much broader. In this review, we give a comprehensive and timely overview of the literature regarding the immunosuppressive activity of artemisinin-type compounds toward inflammatory and autoimmune diseases. Numerous receptor-coupled signaling pathways are inhibited by artemisinins, including the receptors for interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), β3-integrin, or RANKL, toll-like receptors and growth factor receptors. Among the receptor-coupled signal transducers are extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), AKT serine/threonine kinase (AKT), mitogen-activated protein kinase (MAPK)/extracellular signal regulated kinase (ERK) kinase (MEK), phospholipase C γ1 (PLCγ), and others. All these receptors and signal transduction molecules are known to contribute to the inhibition of the transcription factor nuclear factor κ B (NF-κB). Artemisinins may inhibit NF-κB by silencing these upstream pathways and/or by direct binding to NF-κB. Numerous NF-κB-regulated downstream genes are downregulated by artemisinin and its derivatives, for example, cytokines, chemokines, and immune receptors, which regulate immune cell differentiation, apoptosis genes, proliferation-regulating genes, signal transducers, and genes involved in antioxidant stress response. In addition to the prominent role of NF-κB, other transcription factors are also inhibited by artemisinins (mammalian target of rapamycin [mTOR], activating protein 1 [AP1]/FBJ murine osteosarcoma viral oncogene homologue [FOS]/JUN oncogenic transcription factor [JUN]), hypoxia-induced factor 1α (HIF-1α), nuclear factor of activated T cells c1 (NF-ATC1), Signal transducers and activators of transcription (STAT), NF E2-related factor-2 (NRF-2), retinoic-acid-receptor-related orphan nuclear receptor γ (ROR-γt), and forkhead box P-3 (FOXP-3). Many in vivo experiments in disease-relevant animal models demonstrate therapeutic efficacy of artemisinin-type drugs against rheumatic diseases (rheumatoid arthritis, osteoarthritis, lupus erythematosus, arthrosis, and gout), lung diseases (asthma, acute lung injury, and pulmonary fibrosis), neurological diseases (autoimmune encephalitis, Alzheimer's disease, and myasthenia gravis), skin diseases (dermatitis, rosacea, and psoriasis), inflammatory bowel disease, and other inflammatory and autoimmune diseases. Randomized clinical trials should be conducted in the future to translate the plethora of preclinical results into clinical practice.

Selection of safe artemisinin derivatives using a machine learning-based cardiotoxicity platform and in vitro and in vivo validation

The majority of drug candidates fails the approval phase due to unwanted toxicities and side effects. Establishment of an effective toxicity prediction platform is of utmost importance, to increase the efficiency of the drug discovery process. For this purpose, we developed a toxicity prediction platform with machine-learning strategies. Cardiotoxicity prediction was performed by establishing a model with five parameters (arrhythmia, cardiac failure, heart block, hypertension, myocardial infarction) and additional toxicity predictions such as hepatotoxicity, reproductive toxicity, mutagenicity, and tumorigenicity are performed by using Data Warrior and Pro-Tox-II software. As a case study, we selected artemisinin derivatives to evaluate the platform and to provide a list of safe artemisinin derivatives. Artemisinin from Artemisia annua was described first as an anti-malarial compound and later its anticancer properties were discovered. Here, random forest feature selection algorithm was used for the establishment of cardiotoxicity models. High AUC scores above 0.830 were achieved for all five cardiotoxicity indications. Using a chemical library of 374 artemisinin derivatives as a case study, 7 compounds (deoxydihydro-artemisinin, 3-hydroxy-deoxy-dihydroartemisinin, 3-desoxy-dihydroartemisinin, dihydroartemisinin-furano acetate-d3, deoxyartemisinin, artemisinin G, artemisinin B) passed the toxicity filtering process for hepatotoxicity, mutagenicity, tumorigenicity, and reproductive toxicity in addition to cardiotoxicity. Experimental validation with the cardiomyocyte cell line AC16 supported the findings from the in silico cardiotoxicity model predictions. Transcriptomic profiling of AC16 cells upon artemisinin B treatment revealed a similar gene expression profile as that of the control compound, dexrazoxane. In vivo experiments with a Zebrafish model further substantiated the in silico and in vitro data, as only slight cardiotoxicity in picomolar range was observed. In conclusion, our machine-learning approach combined with in vitro and in vivo experimentation represents a suitable method to predict cardiotoxicity of drug candidates.

Mechanisms of artemether toxicity on single cardiomyocytes and protective effect of nanoencapsulation

BACKGROUND AND PURPOSE

The artemisinin derivative, artemether, has antimalarial activity with potential neurotoxic and cardiotoxic effects. Artemether in nanocapsules (NC-ATM) is more efficient than free artemether for reducing parasitaemia and increasing survival of Plasmodium berghei-infected mice. NCs also prevent prolongation of the QT interval of the ECG. Here, we assessed cellular cardiotoxicity of artemether and how this toxicity was prevented by nanoencapsulation.

EXPERIMENTAL APPROACH

Mice were treated with NC-ATM orally (120 mg·kg^-1 twice daily) for 4 days. Other mice received free artemether, blank NCs, and vehicle for comparison. We measured single-cell contraction, intracellular Ca²⁺ transient using fluorescent Indo-1AM Ca²⁺ dye, and electrical activity using the patch-clamp technique in freshly isolated left ventricular myocytes. The acute effect of free artemether was also tested on cardiomyocytes of untreated animals.

KEY RESULTS

Artemether prolonged action potentials (AP) upon acute exposure (at 0.1, 1, and 10 μM) of cardiomyocytes from untreated mice or after in vivo treatment. This prolongation was unrelated to blockade of K⁺ currents, increased Ca²⁺ currents or promotion of a sustained Na⁺ current. AP lengthening was abolished by the NCX inhibitor SEA-0400. Artemether promoted irregular Ca²⁺ transients during pacing and spontaneous Ca²⁺ events during resting periods. NC-ATM prevented all effects. Blank NCs had no effects compared with vehicle.

CONCLUSION AND IMPLICATIONS

Artemether induced NCX-dependent AP lengthening (explaining QTc prolongation) and disrupted Ca²⁺ handling, both effects increasing pro-arrhythmogenic risks. NCs prevented these adverse effects, providing a safe alternative to the use of artemether alone, especially to treat malaria.

The osteoprotective effects of artemisinin compounds and the possible mechanisms associated with intracellular iron: A review of in vivo and in vitro studies

Osteoporosis is a progressive systemic disease characterized by low bone mineral density and deterioration of bone microarchitecture. The current therapies are effective to prevent further bone loss and fractures but they are accompanied by undesirable side effects and cost issues. The discovery of Chinese herbal medicines with osteoprotective effects provides alternative treatments to prevent bone loss without causing severe side effects. Artemisinin (ARS) and its related compounds have been clinically used as antimalarial agents. Interestingly, their bioactivity is not limited to antimalarial treatment. Experimental evidences indicate that ARS compounds are a potential type of therapeutic alternative medicine for bone loss induced by accelerated osteoclastic bone resorption. The present review intends to summarize the current understandings of ARS compounds and their molecular mechanisms of actions in preventing bone loss. ARS compounds selectively inhibit osteoclast differentiation by downregulation of pathways involved in receptor activator of nuclear factor kappa-B ligand (RANKL) -induced osteoclastogenesis, and have no effect on osteogenic differentiation of osteoblasts. The exact mechanism of activation and action of these anti-resorption effects are not fully elucidated. Considering the characteristic of high levels of intracellular iron in osteoclasts, ARS compounds may inhibit osteoclast differentiation via mechanisms associated with intracellular iron, including the cleavage of endoperoxide bridge, oxidative damage and ferroptosis. The anti-resorptive effects of ARS compounds need to be further investigated in bone loss models caused by different factors, and to be under clinical development.

Antitumor Research on Artemisinin and Its Bioactive Derivatives

Cancer is the leading cause of human death which seriously threatens human life. The antimalarial drug artemisinin and its derivatives have been discovered with considerable anticancer properties. Simultaneously, a variety of target-selective artemisinin-related compounds with high efficiency have been discovered. Many researches indicated that artemisinin-related compounds have cytotoxic effects against a variety of cancer cells through pleiotropic effects, including inhibiting the proliferation of tumor cells, promoting apoptosis, inducing cell cycle arrest, disrupting cancer invasion and metastasis, preventing angiogenesis, mediating the tumor-related signaling pathways, and regulating tumor microenvironment. More importantly, artemisinins demonstrated minor side effects to normal cells and manifested the ability to overcome multidrug-resistance which is widely observed in cancer patients. Therefore, we concentrated on the new advances and development of artemisinin and its derivatives as potential antitumor agents in recent 5 years. It is our hope that this review could be helpful for further exploration of novel artemisinin-related antitumor agents.

Nanoparticle Delivery of Artesunate Enhances the Anti-tumor Efficiency by Activating Mitochondria-Mediated Cell Apoptosis

Artemisinin and its derivatives were considered to exert a broad spectrum of anti-cancer activities, and they induced significant anti-cancer effects in tumor cells. Artemisinin and its derivatives could be absorbed quickly, and they were widely distributed, selectively killing tumor cells. Since low concentrations of artesunate primarily depended on oncosis to induce cell death in tumor cells, its anti-tumor effects were undesirable and limited. To obtain better anti-tumor effects, in this study, we took advantage of a new nanotechnology to design novel artesunate-loaded bovine serum albumin nanoparticles to achieve the mitochondrial accumulation of artesunate and induce mitochondrial-mediated apoptosis. The results showed that when compared with free artesunate's reliance on oncotic death, artesunate-loaded bovine serum albumin nanoparticles showed higher cytotoxicity and their significant apoptotic effects were induced through the distribution of artesunate in the mitochondria. This finding indicated that artesunate-loaded bovine serum albumin nanoparticles damaged the mitochondrial integrity and activated mitochondrial-mediated cell apoptosis by upregulating apoptosis-related proteins and facilitating the rapid release of cytochrome C.

Artemether-lumefantrine and liver enzyme abnormalities in non-severe Plasmodium falciparum malaria in returned travellers: a retrospective comparative study with quinine-doxycycline in a Portuguese centre

Background

Artemisinin-based therapy is the current standard treatment for non-severe malaria due to Plasmodium falciparum. The potential for asymptomatic liver toxicity of this therapy and its implication in clinical practice is currently unknown. The aim of this study is to assess the hepatic function in patients treated with a standard three-day artemisinin-based regimen and to compare it with the quinine-doxycycline regimen.

Methods

Retrospective and comparative study of returned adult travellers admitted with non-severe P. falciparum malaria. Fifty-seven patients were included: 19 treated with artemisinin-based therapy and 38 with quinine-doxycycline therapy.

Results

During treatment, when compared with quinine-doxycycline group, the artemisinin-lumefantrine group presented a higher proportion of significant liver enzyme abnormalities (42 vs. 5%, p < 0.01) and a higher peak value of aspartate aminotransferase (131 vs. 64 U/L, p < 0.01) and alanine aminotransferase (99 vs. 75 U/L, p = 0.05). None of the patients was symptomatic, there were no treatment interruptions and all patients achieved clinical cure.

Conclusions

Treatment of uncomplicated falciparum malaria with artemisinin-based therapy might cause asymptomatic liver enzyme abnormalities in the first days of treatment. Nevertheless, these liver enzyme abnormalities seem to be harmless, asymptomatic and self-limited.