Neurotoxic Mode of Action of Artemisinin

Abstract

We recently described a screening system designed to detect neurotoxicity of artemisinin derivatives based on primary neuronal brain stem cell cultures (G. Schmuck and R. K. Haynes, Neurotoxicity Res. 2:37-49, 2000). Here, we probe possible mechanisms of this brain stem-specific neurodegeneration, in which artemisinin-sensitive neuronal brain stem cell cultures are compared with nonsensitive cultures (cortical neurons, astrocytes). Effects on the cytoskeleton of brain stem cell cultures, but not that of cortical cell cultures, were visible after 7 days. However, after a recovery period of 7 days, this effect also became visible in cortical cells and more severe in brain stem cell cultures. Neurodegeneration appears to be induced by effects on intracellular targets such as the cytoskeleton, modulation of the energy status by mitochondrial or metabolic defects, oxidative stress or excitotoxic events. Artemisinin reduces intracellular ATP levels and the potential of the inner mitochondrial membrane below the cytotoxic concentration range in all three cell cultures, with these effects being most dominant in the brain stem cultures. Surprisingly, there were substantial effects on cortical neurons after 7 days and on astrocytes after 1 day. Artemisinin additionally induces oxidative stress, as observed as an increase of reactive oxygen species and of lipid peroxidation in both neuronal cell types. Interestingly, an induction of expression of AOE was only seen in astrocytes. Here, manganese superoxide dismutase (MnSOD) expression was increased more than 3-fold and catalase expression was increased more than 1.5-fold. In brain stem neurons, MnSOD expression was dose dependently decreased. Copper-zinc superoxide dismutase and glutathione peroxidase, two other antioxidant enzymes that were investigated, did not show any changes in their mRNA expression in all three cell types after exposure to artemisinin.Chemically induced neurodegeneration is characterized by different patterns of neuronal cell death, gliosis, swollen or destroyed axons, or destruction of the myelin sheet. Effects on biochemical targets possibly precede manifestation of these morphologic endpoints. Therefore, not only cell viability but also integrity of the cytoskeleton and neuronal energy state should be considered (6). Primary neuronal cell cultures derived from the embryonal rat cortex have been used as a model for neuron-specific toxicity of various neurotoxicants, whose neurotoxic mode of action has been well characterized (36). The neurotoxicants include chemicals that primarily target the cytoskeleton, such as the organophosphate mipafox and ␤,␤-iminodipropionitrile, and substances that primarily impair the cellular energy supply, such as potassium cyanide and 3-nitropropionic acid. Also included were compounds such as acrylamide and 2,5-hexanedione, which act on both cytoskeleton and cellular energy production, and the well-known excitotoxin N-methyl-D-aspartate, which indirectly affects mitochondria.Artemisinin, isolated from the traditional C...

Levels of two oxidative stress indicators of human sickle erythrocytes incubated in aqueous extracts of Anacardium occidentale, Psidium guajava and Terminalia catappa.

“…The values of absorbance of the samples were converted to MDA concentrations using the MDA standard curve. [55] Determination of methaemoglobin content of erythrocyte haemolysate was by modification of the method of Evelyn and Malloy, [56] as described by Akomopong et al [57] A total of 0.4 ml of 0.5 M phosphate buffer (pH = 6.5) was added to 0.6 ml of the cell lysate, and the mixture was centrifuged at 16,000 x g for 5 min to sediment debris. A 0.7 ml aliquot of the supernatant fraction was used to measure the absorbance at λ max = 630 nm (the absorbance maximum for methaemoglobin), and the measurement was recorded as first reading (S1).…”

Hypoxia modulates the effect of dihydroartemisinin on endothelial cells

“…In this study, lipid damage, measured as TBARS production, occurred only with high doses (50μM DHA), and this both in normoxia and hypoxia. So far, artemisinin-induced lipid peroxidation had been demonstrated only on red blood cells and neurons [47,48]. For comparison, on malaria parasites in vitro, DHA at nanomolar concentrations was more effective in normoxia than hypoxia, a finding which was explained by oxidative stress occurring in normoxic conditions [27].…”

Pengaruh Artemisin dan Moringa terhadap Derajat Parasitemia, Kadar Malondialdehyde serta Histopatologi Otak Mencit Malaria

“…Penelitian ini telah mendapatkan persetujuan dari yang terbentuk selama infeksi malaria dapat Komisi Etik Fakultas Kedokteran Universitas Brawijaya menyebabkan kerusakan jaringan (2 (4,5). Obat ini bekerja dengan menghambat enzim ATPase dan menghasilkan radikal bebas untuk mengeliminasi parasit penyebab malaria sehingga penggunaan obat ini dapat menyebabkan penumpukan radikal bebas dalam tubuh (6,7). Artemisin saat ini digunakan untuk pengobatan malaria berat (8) dan penggunaan obat ini dianjurkan dalam bentuk kombinasi yang dikenal dengan artemisin-based combination therapies (ACT) (1).…”