ascorbic-acid and artemisinin

Susceptibility to oxidative stress is a well-established feature of the malarial parasite. Pharmacologists have taken advantage of this property to design highly effective pro-oxidant antimalarial drugs. Less well appreciated is the fact that nutritional manipulation of host oxidative stress status by dietary means can have a profound effect on the growth of the parasite. In particular, rapid induction of vitamin E deficiency in mice by feeding highly unsaturated fatty acids (fish oil) strongly suppresses plasmodial growth. Likewise, the status of other antioxidant nutrients (e.g., riboflavin or vitamin C) may also influence the course of malarial infection under certain conditions. A combined nutritional pharmacology approach may offer some promise in controlling malaria.

Topics: Animals; Antimalarials; Antioxidants; Artemisinins; Ascorbic Acid; Dietary Fats; Drug Interactions; Malaria; Male; Mice; Nutritional Status; Oxidation-Reduction; Plasmodium; Rats; Riboflavin; Sesquiterpenes; Vitamin E Deficiency

This study aims to optimize sodium iodide (NaI) derivatization headspace-GC/MS described in European Pharmacopoeia by using vitamin C as an alternative antioxidant for the determination of mutagenic alkyl toluenesulfonate impurities in an active pharmaceutical ingredient (API) of a candidate drug with an artemisinin derivative. Alkyl toluenesulfonates are transformed into their corresponding alkyl iodides (methyl iodide, ethyl iodide, propyl iodide, and isopropyl iodide) by utilizing the derivatization reagent NaI. Results show that the MS response of methyl iodide is a critical indicator of method robustness because of the deteriorating effects of methyl iodide on stability when sodium thiosulfate is used as an antioxidant originally described in the pharmacopoeia. With vitamin C as a newly developed antioxidant, the robustness of this method is improved significantly. The optimized method is further validated and applied successfully for the quality control and safety of the API of an artemisinin derivative.

Topics: Antioxidants; Artemisinins; Ascorbic Acid; Drug Contamination; Gas Chromatography-Mass Spectrometry; Iodides; Mutagens; Pharmaceutical Preparations; Tosyl Compounds

Topics: Artemisinins; Ascorbic Acid; Drug Combinations; Humans; Malaria, Falciparum

Impact of long-term salinity and subsequent oxidative stress was studied on cellular antioxidants, proline accumulation and lipid profile of Artemisia annua L. (Sweet Annie or Qinghao) which yields artemisinin (Qinghaosu), effective against cerebral malaria-causing strains of Plasmodium falciparum. Under salinity (0.0-160 mM NaCl), in A. annua, proline accumulation, contents of ascorbate and glutathione and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) increased, but the contents of reduced forms of glutathione (GSH) and ascorbate declined. The fatty-acid profiling revealed a major salinity-induced shift towards long-chain and mono-saturated fatty acids. Myristic acid (14:0), palmitoleic acid (16:1), linoleic acid (18:2) and erucic acid (22:1) increased by 141%, 186%, 34% and 908%, respectively, in comparison with the control. Contents of oleic acid (18:1), linolenic acid (18:3), arachidonic acid (22:0) and lignoceric acid (24:0) decreased by 50%, 17%, 44% and 78%, respectively. Thus, in A. annua, salinity declines ascorbate and GSH contents. However, increased levels of proline and total glutathione (GSH+GSSG), and activities of antioxidant enzymes might provide a certain level of tolerance. Modification in fatty-acid composition might be a membrane adaptation to long-term salinity and oxidative stress.

Topics: Antioxidants; Artemisia annua; Artemisinins; Ascorbic Acid; Catalase; Fatty Acids; Glutathione; Glutathione Reductase; Oxidative Stress; Proline; Salinity; Salt Tolerance; Sodium Chloride

The effects of different cadmium (Cd) concentrations (0, 20, 60, and 100 micromol/L) on hydroponically grown Artemisia annua L. were investigated. Cd treatments applied for 0, 4, 12, 24, 72, 144, 216, and 336 hr were assessed by measuring the changes in photosynthetic pigments, electrolyte leakage, malondialdehyde (MDA) and antioxidants (ascorbic acid and glutathione), while the artemisinin content was tested after 0, 12, 144, 216, and 336 hr. A significant decrease was observed in photosynthetic pigment levels over time with increasing Cd concentration. Chlorophyll b levels were more affected by Cd than were chlorophyll a or carotenoid levels. The cell membrane was sensitive to Cd stress, as MDA content in all treatment groups showed insignificant differences from the control group, except at 12 hr treatment time. Ascorbic acid (AsA) content changed slightly over time, while glutathione (GSH) content took less time to reach a maximum as Cd concentration increased. Cd was found to promote synthesis and accumulation of artemisinin, especially at concentrations of 20 and 100 micromol/L. In conclusion, Cd stress can damage to photosynthetic pigments, and vigorously growing A. annua showed a strong tolerance for Cd stress. Appropriate amounts of added Cd aided synthesis and accumulation of artemisinin.

Topics: Artemisia annua; Artemisinins; Ascorbic Acid; Cadmium; Electric Conductivity; Glutathione; Hydroponics; Lipid Peroxidation; Malondialdehyde; Photosynthesis

The antimalarial sesquiterpene, artemisinin, is in short supply; demand is not being met, and the role of artemisinin in the plant is not well established. Prior work showed that addition of dimethyl sulfoxide (DMSO) to seedlings increased artemisinin in their shoots and this study further investigated that serendipitous observation. When in vitro-cultured Artemisia annua rooted shoots were fed different amounts of DMSO (0-2.0% v/v), artemisinin levels doubled and showed biphasic optima at 0.25 and 2.0% DMSO. Both artemisinin and its precursor, dihydroartemisinic acid, increased with the former continuing 7 days after DMSO treatment. There was no stimulation of artemisinin production in DMSO-treated unrooted shoots. The first gene in the artemisinin biosynthetic pathway, amorphadiene synthase, showed no increase in transcript level in response to DMSO compared to controls. In contrast, the second gene in the pathway, CYP71AV1, did respond to DMSO but at a level of transcripts inverse to artemisinin levels. When rooted shoots were stained for the reactive oxygen species (ROS), H2O2, ROS increased with increasing DMSO concentration; unrooted shoots produced no ROS in response to DMSO. Both the increases in DMSO-induced ROS response and corresponding artemisinin levels were inhibited by addition of vitamin C. Together these data show that at least in response to DMSO, artemisinin production and ROS increase and that when ROS is reduced, so also is artemisinin suggesting that ROS may play a role in artemisinin production in A. annua.

Topics: Artemisia annua; Artemisinins; Ascorbic Acid; Culture Media; Dimethyl Sulfoxide; Gene Expression Regulation, Plant; Plant Roots; Plant Shoots; Reactive Oxygen Species; RNA, Messenger; RNA, Plant

Artemisinin (QHS) is a natural drug with a very low solubility in water. To improve its availability in hydrophilic media, it was solubilized in micellar dispersions of octanoyl-6-O-ascorbic acid (ASC8), a relatively novel surfactant that combines surface activity with powerful performance as radical scavenger. In this article we report a study based on diffusion-ordered NMR spectroscopy (DOSY) measurements carried out on QHS/ASC8 micellar dispersions. QHS is efficiently solubilized by ASC8 micelles, with no significant perturbation of the micellisation.

Topics: Algorithms; Artemisinins; Ascorbic Acid; Chemical Phenomena; Chemistry, Physical; Diffusion; Light; Magnetic Resonance Spectroscopy; Micelles; Neutrons; Scattering, Radiation; Sesquiterpenes; Solubility

Artemisinin is an effective antimalarial agent, and its action on the malarial parasite is suggested to be mediated by oxidative processes. Since malarial parasites contain a high concentration of hemin, and hemin may induce the formation of reactive oxygen species, we investigated the interaction of artemisinin, iron and hemin. We used erythrocyte membrane-bound Ca2+ pump ATPase (basal) and calmodulin (CaM)-activated Ca2+ pump ATPase as our model. Membranes were incubated with artemisinin in the presence or absence of iron-ascorbate or hemin at 37 degrees for 1 hr. Following incubation, ATPase activity was measured. Our results showed that artemisinin (500 microM) had no effect on ATPase activities. However, artemisinin enhanced the inhibitory effect of iron (50 microM)-ascorbate (500 microM) on ATPase activity (46.3 +/- 3.9 vs 63 +/- 2.1% for basal; 57.2 +/- 2.5 vs 74.8 +/- 2.1% for CaM-activated). Desferrioxamine (DFO, 200 microM) blocked significantly the effect of iron-ascorbate-artemisinin on ATPases (P < 0.01). Hemin inhibited ATPase activity in a concentration-dependent fashion. Artemisinin enhanced hemin (10 microM)-induced inhibition of basal (36.0 +/- 6.0 vs 73.7 +/- 3.0%) and CaM-activated Ca2+ pump ATPase (31.6 +/- 2.8 vs 70.0 +/- 1.5%). Iron chelators (DFO, ferene, 8-hydroxyquinoline, 1,10-phenanthroline, and 1,2-dimethyl-3-hydroxypyrid-4-one) had no effect on artemisinin plus hemin-induced enzyme inhibition. Catalase (2000 U/mL) had a minor effect on the artemisinin-hemin or hemin-mediated effect. Thiourea (1 mM) had no effect. However, superoxide dismutase (500 U/mL) and dithiothreitol blocked artemisinin-hemin or hemin-mediated ATPase inhibition significantly (P < 0.001). In conclusion, these results suggest that, in our model, artemisinin enhances the damage of hemin-induced ATPases via oxidation of thiol groups on the enzymes. Free iron or hydroxyl radical does not seem to be involved. This interaction between artemisinin and hemin may contribute to the antimalarial action of artemisinin against malarial parasites.

Topics: Antimalarials; Artemisinins; Ascorbic Acid; Calcium; Calcium-Transporting ATPases; Calmodulin; Enzyme Activation; Erythrocyte Membrane; Ferrous Compounds; Hemin; Humans; Iron Chelating Agents; Sesquiterpenes

Topics: Animals; Antimalarials; Artemisinins; Artesunate; Ascorbic Acid; Chemical Phenomena; Chemistry; Erythrocytes; Free Radicals; Glutathione; Humans; In Vitro Techniques; Lipid Peroxidation; Plasmodium falciparum; Sesquiterpenes