ascorbic-acid and artenimol

The objective of the present study was to investigate how oxidative status influences the effectiveness of cytotoxicity of artemisinin towards cancer cells. It is hypothesized that antioxidants would reduce, whereas pro-oxidants would enhance, cytotoxicity.. Molt-4 human leukemia cells were incubated with vitamins C, E, D3, dexamethasone, or hydrogen peroxide alone or in combination with dihydroartemisinin (DHA). Concentrations of these compounds studied were similar to those achievable by oral administration. Viable cell counts were performed before (0 h) and at, 24 and 48 h after treatment.. Vitamin C, vitamin D3, dexamethasone, and H2O2 caused significant Molt-4 cell death. Vitamin E caused an increase in Molt-4 cell growth. Vitamin C and vitamin D3 significantly interacted with DHA at the 48-h time point and with H2O2 at both 24-h and 48-h time points.. Cellular oxidative status could alter the potency of artemisinin in killing cancer cells.

Topics: Antioxidants; Apoptosis; Artemisinins; Ascorbic Acid; Cell Line, Tumor; Cholecalciferol; Chromans; Dexamethasone; Humans; Hydrogen Peroxide; Leukemia; Oxidation-Reduction; Reactive Oxygen Species

Artemisinins are peroxidic antimalarial drugs known to be very potent but highly chemically unstable; they degrade in the presence of ferrous iron, Fe(II)-heme, or biological reductants. Less documented is how this translates into chemical stability and antimalarial activity across a range of conditions applying to in vitro testing and clinical situations. Dihydroartemisinin (DHA) is studied here because it is an antimalarial drug on its own and the main metabolite of other artemisinins. The behaviors of DHA in phosphate-buffered saline, plasma, or erythrocyte lysate at different temperatures and pH ranges were examined. The antimalarial activity of the residual drug was evaluated using the chemosensitivity assay on Plasmodium falciparum, and the extent of decomposition of DHA was established through use of high-performance liquid chromatography with electrochemical detection analysis. The role of the Fe(II)-heme was investigated by blocking its reactivity using carbon monoxide (CO). A significant reduction in the antimalarial activity of DHA was seen after incubation in plasma and to a lesser extent in erythrocyte lysate. Activity was reduced by half after 3 h and almost completely abolished after 24 h. Serum-enriched media also affected DHA activity. Effects were temperature and pH dependent and paralleled the increased rate of decomposition of DHA from pH 7 upwards and in plasma. These results suggest that particular care should be taken in conducting and interpreting in vitro studies, prone as their results are to experimental and drug storage conditions. Disorders such as fever, hemolysis, or acidosis associated with malaria severity may contribute to artemisinin instability and reduce their clinical efficacy.

Topics: Animals; Antimalarials; Artemisinins; Ascorbic Acid; Carbon Monoxide; Chromatography, High Pressure Liquid; Drug Stability; Electrochemical Techniques; Erythrocytes; Half-Life; Heme; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Plasmodium falciparum; Temperature

Artemisinin derivatives, the current cornerstone of malaria treatment, possess also anti-angiogenic and anti-tumor activity. Hypoxia plays a crucial role both in severe malaria (as a consequence of the cytoadherence of infected erythrocytes to the microvasculature) and in cancer (due to the restricted blood supply in the growing tumor mass). However, the consequences of hypoxia onto the effects of artemisinins is under-researched. This study aimed at assessing how the inhibition of microvascular endothelial cell (HMEC-1) growth induced by dihydroartemisinin (DHA, an antimalarial drug and the active metabolite of currently in-use artemisinins) is affected by oxygen tension. Low doses of DHA (achieved in the patients' plasma when treating malaria) were more inhibitory in hypoxia, whereas high doses (required for anti-angiogenic or anti-tumor activity) were more effective in normoxia. The peroxide bridge is essential for cellular toxicity (deoxyDHA was inactive). High doses of DHA caused HMEC-1 apoptosis and G2 cell cycle arrest. Effects were mediated by the generation of oxidative stress as demonstrated by DCF-DA fluorescence and membrane lipid peroxidation analysis. Overall, these results suggest that DHA inhibition of endothelial cell growth is related to the level of tissue oxygenation and drug concentration. This should be considered when studying both the effects of artemisinin derivatives as antimalarials and the potential therapeutic applications of these drugs as anti-tumor agents.

Topics: Antimalarials; Apoptosis; Artemisinins; Ascorbic Acid; Cell Cycle; Cell Hypoxia; Cell Proliferation; Cells, Cultured; Endothelial Cells; Humans; Lipid Peroxidation; Oxidative Stress; Reactive Oxygen Species