Arginin and nitrites kill plasmodium
avec arginine et nitrites contre le paludisme
The health benefits of nitrates, nitrites and nitric oxide are numerous: cardiovascular, vasodilating, immunity strengthening, bactericidal. The blood pressure lowering effect of potassium is much stronger for KNO³ than for KCl and the authors relate this to the formation od nitrite a known vasodilator. Kapil V, Milsom AB, Okorie M, Maleki-Toyserkani S, Akram F, Rehman F, Arghandawi S, Pearl V, Benjamin N, Loukogeorgakis S, Macallister R, Hobbs AJ, Webb AJ, Ahluwalia A Inorganic nitrate supplementation lowers blood pressure in humans: role for nitrite-derived NO. Hypertension. 2010 Aug;56(2):274-81. doi: 10.1161.110.153536. Nitric oxide (NO), a highly diffusible mediator is involved in a wide range of biological effects and is one of the cytotoxic agents released by leukocytes to counteract malaria infection. It was shown for the first time in 1995 that human red blood cells infected by Plasmodium falciparum synthsize NO. This production is very high when compared with normal endothelial cells and not measurable in normal red blood cells. NO and reactive nitrogen species were found in intraerythrocytic Plasmodium falciparum parasites and their food vacuoles. D Ghigo, R Todde, H Ginsburg, A Bosia, Erythrocyte stages of Plasmodium falciparum exhibit a high nitric oxide synthase NOS) activity. J Exp Med. 182, 1995, 677-688. Dietary nitrate has recently emerged as a potential modulator of muscle energy metabolism and a possible « natural » ergogenic aid to exercice performance. Lansley KE, Winyard PG, Bailey S, Vanhatalo A, Wilkerson DP, Blackwell JR, Gilchrist M, Benjamin N, Jones AM. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011 Jun;43(6):1125-31. doi: 10.1249/MSS.0b013e31821597b4. Nitric oxide decreases platelet stickiness. Riddell DR, Owen JS, Nitric oxide and platelet aggregation. Vitam Horm 1999, 57, 25-48 It is now fully recognized that health hazards of nitrates and nitrites have been overestimated. No study could confirm the risk of cancer or methemoglobina for normal dietary intakes. Nitrates and nitrites are produced endogenously in the human body but 80% come from the diet. Estimation of nitrate and nitrite concentrations of milk sources may provide a better insight. Let’s not forget that milk, espially mother’s milk especially colostrum is also rich in nitrite. This may contribute to the immunity of newborns against malaria in the first weeks or months. In colostrum (1-3 days postpartum) nitrite concentrations are much higher than in mature milk (0.08 mg/100mL versus 0.001). Norman G. Hord, Janine S. Ghannam, Harsha K. Garg, Pamela D. Berens, Nitrate and Nitrite Content of Human, Formula, Bovine, and Soy Milks: Implications for Dietary Nitrite and Nitrate Recommendations Breastfeed Med. 2011 Dec; 6(6): 393–399. doi: 10.1089/bfm.2010.0070 Medicinal herbs contain on the average higher amounts of nitrate and nitrite than fruits or vegetables: a mean nitrate concentration of 1.240 mg/kg fresh weight versus 336 mg/kg in fruits and vegetables Nitrate in vegetables. The EFSA Journal (2008) 689, 1-79 The nitrate-nitrite-nitrite oxide pathway has been shown to exist in many alternative herbal medicines or dietary supplements According to the authors this change is partly due to the changing intestinal microflora in the baby and the changing metabolic demands as the baby grows. The beneficial effects of NO in adult stomachs on gastroprotective and immunomodulatory functions is known. Therefore, it is reasonable to surmise that nitrite must be supplied to the newborn by colostrum. A recent thesis from Sweden C Jädert, Diet and inflammation The role of nitrate and conjugated linoleic acid. Akademisk afhandeling, thesis, Karolinska Institutet, 2014 confirms and documents well all these positive elements. Dietary nitrates have potent anti-inflammatory effects, without impairing the ability to clear an infection. They are able to restore the gastric and colonic mucus layer in case of colitis. Many anecdotical or scientific results indicate that leaves and stems of Artemisia annua have different therapeutical properties, often higher for leaves, sometimes lower. Astonishing is the fact that Artemisia annua from China sold in European and African pharmacies contains some 80% of stems. There appears to be one major difference between stems (stalks, twigs, petioles) and leaves: a 2-3x lower concentration of nitrate in leaves. Nitrate assimilation in plants mainly occurs in leaves by nitrate reductase activity (NRA), and more even in young leaves. Leaves show NRA levels two to three times higher than stems. BL Black, LH Fuchigami, GD Coleman. Partitioning of nitrate assimilation among leaves, stems and roots of poplar Tree physiology 22 (10), 717-724 Medicinal herbs contain on the avarage higher amounts than fruits or vegetables: a mean nitrate concentration of 1.240 mg/kg fresh weight versus 336 mg/kg in fruits and vegetables. Nitrate in vegetables. Scientific Opinion of the Panel on Contaminants in the Food chain. The EFSA Journal (2008) 689, 1-79 The nitrate-nitrite-nitrite oxide pathway has been shown to exist in many alternative herbal medicines or dietary supplements. The nitrate concentration in plants varies with solar radiation. In spinach leaves it decreases from 1670 mg/kg in the morning to 1390 mg/kg in the afternoon. In the stem it stays constant around 3800 mg/kg during the day. Dr. Joji Muramoto. Comparison of Nitrate Content in Leafy Vegetables from Organic and Conventional Farms in California, Thesis, June, 1999 University of California, Santa Cruz The plant Artemisia is an accumulator for many minerals: potassium, selenium, nitrate, iron Traore Alassane, Diallo Mouhamadou, Gueye Papa El Hadji Omar, Wague Ahmadou, Lutgen Pierre, Sarr Ousmane and Mboup Souleymane. Characterization of element and mineral content in Artemisia annua and Camellia sinensis leaves by handheld X-ray fluorescence. African Journal of Biotechnology Vol. 12(26), pp. 4179-4186, 26 June, 2013 Artemisia thrives on nitrate rich soils. In dried, desiccated herbs or plants these concentrations are multiplied by ten. 100 grams of Artemisia annua tea contain 3 grams of nitrate (30 000 mg/kg). The amino acid arginine is the only molecule in our food known to generate nitric oxide NO via NOS enzymes. It plays a key role in malaria therapy and cerebral malaria. NO derived from arginine is not only lethal for merozoites but also for gametocytes. NO is efficient against other diseases like leishmaniasis or filariasis. Richard A. O'Connor, Jessica S. Jenson and Eileen Devaney. NO Contributes to Proliferative Suppression in a Murine Model of Filariasis. Infection and Immunity, 2000, 68, 6101-6107 Naotunne, T. de S., K aranuweeua, N. D., M endis, K. N. & C arter, R. (1993). Cytokine-mediated inactivation of malarial gametocytes is dependent on the presence of white bloodcells and involves reactive nitrogen intermediates. Immunology, 78, 555-562. Immunology, 1993, 78, 555-562 Nitric oxide is a known mediator of parasite killing by WBC as was shown when the production of NO by arginine is blocked by an inhibitor. Nitric oxide (NO), a highly diffusible cellular mediator involved in a wide range of biological effects, has been indicated as one of the cytotoxic agents released by leukocytes to counteract malaria infection. Human red blood cells infected by Plasmodium falciparum synthesize NO. The synthesis of NO measured as citrulline and nitrate production appeared to be very high in comparison with no detectable citrulline and nitrate production in noninfected red blood cells. Ghigo D, Todde R, Ginsburg H, Costamagna C, Gautret P, Bussolino F, Ulliers D, Giribaldi G, Deharo E, Gabrielli G, Pescarmona G, Bosia A. Erythrocyte stages of Plasmodium falciparum exhibit a high nitric oxide synthase (NOS) activity and release an NOS-inducing soluble factor. J Exp Med. 1995 Sep 1;182(3):677-88. The digestion of hemoglobin by Plasmodium falciparum leads to an excess of amino acids which rise to high extracellular levels during the trophozoite stage. Alanine, valine, histidine are excreted as waste from the infected erythrocyte. The concentration of other amino acids like isoleucine and proline however increases in the infected erythrocytes. The most dramatic relative change in extracellular levels occur for ornithine and citrulline which accumulate and are derived from arginine, via the arginase pathway or the NOS pathway respectively. Arginine levels are depleted to almost undetectable levels over 40 hours during the trophozoite stage. The ornithine produced accounts for the majority of depleted arginine. Endothelial dysfunction in malaria is nearly universal in malaria disease, symptomatic and asymptomatic. It is reversible with arginine. TW Yeo, D Lampah, R Gitwati, NM Anstey. Impaired nitric oxide bioavailability and L-arginine-reversible endothelial dysfunction in adults with falciparum malaria. JEM, 2007, 204, 11, 2693-2704. Kellen L. Olszewski, Joanne M. Morrisey, Daniel Wilinski, James M. Burns, Akhil B. Vaidya, Joshua D. Rabinowitz, and Manuel Llinás. Host-parasite Interactions Revealed by Plasmodium falciparum Metabolomics. Cell Host Microbe. 2009 Feb 19; 5(2): 191–199.. doi: 10.1016/j.chom.2009.01.004 This is intriguing because several studies have demonstrated a strong correlation between reduced arginine levels and advanced malaria in both child and adult malaria patients. The model proposed by the authors is that the parasite modulates the activity of the host enzymes iNOS and arginase. iNOS is used by the host immune system to generate antimicrobial NO radicals from arginine. Depletion of the plasma arginine pool may suppress this immune response by removing the substrate for NO production. The parasite does almost everything it can to eliminate arginine which is going to kill it. Free heme can significantly impair arginine uptake by the erythrocytes and enhances arginine consumption through arginase (F Omodo-Salè et al., Am J Phys Cell Physiol 2010, 299 C148-154). Heme also easily forms a complex with arginine and by this way inhibits NO synthesis Wang J, Stuehr DJ, Rousseau DL. Interactions between substrate analogues and heme ligands in nitric oxide synthase. Biochemistry. 1997 Apr 15;36(15):4595-606. and hemozoin crystallization. Hemozoin by itself induces a dose dependent inhibition of macrophage NO production. Taramelli D, Basilico N, Pagani E, Grande R, Monti D, Ghione M, Olliaro P. The heme moiety of malaria pigment (beta-hematin) mediates the inhibition of nitric oxide and tumor necrosis factor-alpha production by lipopolysaccharide-stimulated macrophages. Exp Parasitol. 1995 Dec;81(4):501-11. NO down-regulates endothelial inflammation, reduces IL-6 and has a vasodilatory capacity and in this way reduces the adhesion of infected erythrocytes in small vessels which is leading to severe and cerebral malaria and further development into gametocytes by escaping their renal destruction. It also binds to hemoglobinto prevent the generation of free heme. Gramaglia, Sobolewski P, Meays D, Contreras R, Nolan JP, Frangos JA, Intaglietta M, van der Heyde HC. Low nitric oxide bioavailability contributes to the genesis of experimental cerebral malaria. Nat Med. 2006 Dec;12(12):1417-22. There is substantial evidence linking hypoargininemia to malarial infection and progression to cerebral malaria. A study measured concentrations of arginine in cryopreserved plasma samples from Tanzanian children. The concentrations were low in individuals with cerebral malaria, intermediate in those with uncomplicated malaria and within the normal range in healthy controls Lopansri BK, Anstey N, Weinberg J, Stoddard G, Hobbs M, Levesque M, Mwaikambo E, Granger D. Low plasma arginine concentrations in children with cerebral malaria and decreased nitric oxide production. Lancet 2003; 361: 676-78. Replenishment of arginine and restoration of nitric oxide production in clinical malaria diminishes parasitized red blood cell adherence to endothelium and reduces the sequelae of these interactions. JB Weinberg, BK Lopansri, E Mwaikambo. Arginine, nitric oxide, ccarbon monoxide and endthelial function in severe malaria. Curr Opin Infect Dis, 2008, 21(5), 468-75. It was also found that reduced erythrocyte deformability is associated with hypoargininemia and low nitric oxide ; it starts on day zero of infection and returns to normal values only at full convalescence on day 28. Deformability can be restored by arginine supplementation. Juliana Rey, Pierre A. Buffet, Liliane Ciceron, Geneviève Milon, Odile Mercereau-Puijalon & Innocent Safeukui. Reduced erythrocyte deformability associated with hypoargininemia during Plasmodium falciparum malaria. Scientific Reports 4, Article number: 3767 (2014) doi:10.1038/srep03767 Potassium increases NO release. A large body of evidence supports the view of a strong relation between sodium intake and the development of hypertension. In contrast potassium intake has been shown to have a beneficial effect on the cardiovascular system. Increased potassium swells endothelial cells and modifies endothelial cell stiffness. Artemisia plants are very rich in potassium and contain virtually no sodium. H. Oberleithner, C Callies, HE de Wardener. Potassium softens vascular endothelium and increases nitric oxide release, PNAS, 2009, 106,8, 2829-2834 K Sudhir, T Kurtz, P Yock, C Morris. Potassium preserves endothelial function and enhances aortic compliance in Dahl rats. Hypertension, 1993, 22, 315-322. Potassium depletion even leads to an accumulation of arginine in muscles and other tissues. J Arnauld, P Lachance, Basic amino acid accumulation in potasssium-depleted rat muscle. J Nutrit 1980, 110, 2480-2489. Potassium shows a toxicity at lower concentrations for Paramecium than sodium. Potassium reduces the survival of Paramecium at concentrations of 11 mg/L and sodium only at 249 mg/L. Changing the potassium concentrations changes their swimming behavior and membrane potential. Freitas E Efeitos de sodio e potassio sobre parametros da historia de vida do cladocero de agua doce Pseudosida ramose. J. Braz. Soc. Ecotoxicol., v. 7, n. 2, 2012, 85-91doi: 10.5132/jbse.2012.02.013 T Oka, Y Nakaoka, F Oosawa, Changes in membrane potential during adaptation to external potassium ions in Paramecium caudatum. J Exp Biolog 1986, 126, 111-117. Arginine is also a crucial amino acid for macrophage activation, and influences other arms of host immune responses, including T and B cells. It increases the CD4 count. In Leishmania infection the parasite desactivates macrophages. Arginine however will trigger iNOS activity and promote parasite killing in macrophages. This highlights the importance of arginine in iNOS mediated control of leishmaniasis Wanasen N, Soong L. L-arginine metabolism and its impact on host immunity against Leishmania infection. Immunol Res. 2008;41(1):15-25. NO also kills the trophozoites of Giardia lamblia. In schistosomiasis serum arginine levels are also severily depleted. Senft AW. Studies in arginine metabolism by schistosomes. II. Arginine depletion in mammals and snails infected with S. mansoni or S. hematobium. Comp Biochem Physiol. 1967 May;21(2):299–306 Hypoargininemia is a hallmark of pathogenic inflammations, bacterial sepsis or traumatic insult. A strong relation with inflammation was found for plasma arginine and citrulline concentrations in critically ill children. van Waardenburg DA1, de Betue CT, Luiking YC, Engel M, Deutz NE. Plasma arginine and citrulline concentrations in critically ill children: strong relation with inflammation. Am J Clin Nutr. 2007 Nov;86(5):1438-44. iNOS mediated production of NO occurs also in human tuberculosis and leprosy ; NO can kill mycobacteria, and arginine leads to clinical improvement in TB patients. Th Schön, Nitric oxide in Tuberculosis and Leprosy,Thesis, Linköping University, 2002, No 749 Adequate tissue arginine appears to be essential for efficient wound repair and immune function. Arginine supplementation will restore and increase NO levels. Arginine capsules can be found in drugstores but it is probably easier for most people in Africa to rely on nutrition rich in arginine ; meat, fishes, eggs, some vegetables like garlic, and nuts like avocados. Peanuts (Arachis hypogeia) are a common staple in many countries and are very rich in in arginine. This may explain why Artemisia annua powder in peanut butter has shown excellent therapeutic results in several of our trials. But even at the higher levels of supplementation in these combinations we are far from toxic levels. The safety profile of arginine IV-infusion in moderately severe malaria was studied in Australia. 12 g over 30 minutes are well tolerated and no clinically important changes in hemodynamic or biochemical factors were noticed Yeo TW , Lampah DA , Gitawati R , Tjitra E , Kenangalem E , Granger DL , Weinberg JB , Lopansri BK , Price RN , Celermajer DS , Duffull SB , Anstey NM Safety profile of L-arginine infusion in moderately severe falciparum malaria. PLoS One. 2008 Jun 11;3(6):e2347. doi: 10.1371/journal.pone.0002347. At DUKE US a clinical trial was also run studying the arginine kinetics and metabolism in children with severe falciparum malaria Haoyue Zhang. Donald L Granger, Matthew P Rubach, J Brice Weinberg, Nicholas M. UPLC-MSMS analysis of arginine kinetics and metabolism in children with severe falciparum malaria, poster, Duke Medicine Biochemical Genetics Laboratory, Durham, North Carolina, United States It confirmed a significative inverse association between malaria severity and NO production in the NOS pathway. Further research is necessary to improve our understanding of the complex mechanisms that regulate NO’s role and further clinical trials are recommended to study the impact of arginine. For that reason the sales of arginine capsules on drugstore shelves with indiscriminate dosage appears inappropriate in our eyes. Arginine, iNOS and NO indeed have a Janus face and at excessive levels may cause more harm than good and even cancer. Arginine in Artemisia plants, the role of sulfur starvation in fertilizers Artemisia plants are very rich in arginine. A recent study from Ukraine Ochkur, O. Amino acids composition of Artemisia L. genus species subgenus Dracunculus Bess. from Ukrainian flora / O. Ochkur, A. Kovalyova, N. Sydora // The Pharma Innovation Journal. – 2013. – Vol. 2, № 3. – P. 64–67. has analyzed the amino acid content in some 8 plants of this subgenus and found that they are all 5 to 10 times richer in arginine than other herbs or vegetables, with A annua topranking. This confirms the result of J Ferreira quoted in the introduction of this document. A team from the university of Benghazi analyzed several medicinal plants and found that arginine is only present in stems and not in leaves. Hamad M. Idres Hasan, Mariea Farage El-Mehdawy and Eman K. Saad. Amino Acid Contents of Leaves and Stems for Three Types of Herbal Plants at Al-Gabal Al-Akhder Region World Journal of Chemistry 9 (1): 15-19, 2014 DOI: 10.5829/idosi.wjc.2014.9.1.1113 Sulfur deficiency in soil or fertilizers also sharply increases the arginine content in plants. RG Coleman. The effect of sulfur deficiency on the free amino acids of some plants. Australian J Biol Sci 1957 10 50-60. Henning Hu, D Sparks. Sulfur deficiency influences vegetative growth and amino acids in pecan leaves. J Am Soc Hortic Sci 1991, 116, 974-980. Based on scarce data available in the literature it can be assumed that argininine content in plants is not affected by the drying process or temperatures. The inducible nitric oxide synthase (iNOS) is NF-kB-regulated. Many botanical medicinal herbs and drugs derived from these herbs have been shown to have effects on the NO signaling pathway. Polysaccharides may enhance this production, through a potent macrophage/monocyte activation. This has been demonstrated for acidic polysaccharides from Artemisia tripartita. Gang Xie, Igor A. Schepetkin, Daniel W. Siemsen, Liliya N. Kirpotina, James A. Wiley, and Mark T. Quinn Fractionation and Characterization of Biologically-active Polysaccharides from Artemisia tripartita. Photochemistry, 2008, 69, 1359-71 from Tanacetum vulgare and from mushrooms. Gang Xie, Igor A. Schepetkin, and Mark T. Quinn. Immunomodulatory Activity of Acidic Polysaccharides Isolated from Tanacetum vulgare L Int Immunopharmacol 2007, 7, 1639-50 Volman JJ, Helsper JP, Wei S, Baars JJ, van Griensven LJ, Sonnenberg AS, Mensink RP, Plat J. Effects of mushroom-derived beta-glucan-rich polysaccharide extracts on nitric oxide production by bone marrow-derived But the polysaccharide with the strongest stimulation of NO synthesis is inulin Koo HN, Hong SH, Seo HG, Yoo TS, Lee KN, Kim NS, Kim CH, Kim HM. Inulin stimulates NO synthesis via activation of PKC-alpha and protein tyrosine kinase, resulting in the activation of NF-kappaB by IFN-gamma-primed RAW 264.7 cells. J Nutr Biochem. 2003 Oct;14(10):598-605. The production of NO and activation of NF-kB by inulin plays a key role. Bahmani F, Tajadadi-Ebrahimi M, Kolahdooz F, Mazouchi M, Hadaegh H, Jamal AS, Mazroii N, Asemi S, Asemi Z. The Consumption of Synbiotic Bread Containing Lactobacillus sporogenes and Inulin Affects Nitric Oxide and Malondialdehyde in Patients with Type 2 Diabetes Mellitus: Randomized, Double-Blind, Placebo-Controlled Trial. J Am Coll Nutr. 2016 Aug;35(6):506-513. Epub 2015 Oct 2. and may explain the antimicrobial and tumoricidal activity. This explains why current research is directed to develop inulin as an adjuvant for influenza vaccines, hepatitis B vaccines, malaria vaccines and anti-tumour drugs. Inulin can induce better humoral response against several antigens than alum adjuvant. Gamma-inulin has been shown to be a potent activator of the alternative pathway of complement and thus can cause direct activation of B cells. N. Mahalaksmi, R Aparnaa, P Kaliraj. Evaluaation of immune response eleicited by inulin as an adjuvant with filarial antigens in mice model. Experimental Immunology 2014, doi : 10.1111/sji.12208 Cooper PD, McComb, Steele EJ. The adjuvanticity of Algammulin, a new vaccine adjuvant. Vaccine, 1991, 9, 408-15. Inulin induces NO release to specific parasite antigens in proximity to the parasite Rajan TV, Porte P, Keefer L, Role of nitric oxide in host defense against an extracellular metazoan parasite. Brujia Malayi Infect Immun. 1996 64, 3351-3 On the opposite, vitamins, particularly vitamin E and C inhibit iNOS and are detrimental for this reason during a malaria infection. NO reacts with superoxide O₂¯ to generate the potent peroxinitrite ONOO¯. McCall T, Vallance P. Nitric oxide takes center stage with newly defined rules. Trends PharmacolSci 13, 1-6 Artemisia plants are rich in polysaccharides and these strongly enhance the production of NO and ROS by macrophages, up to 10fold for some fractions. G Xie, I Schepetkin, D Siemsen, MT Quinn. Fractionation and characterizationof biologically-active polysaccharides from Artemisia tripartita. Phytochemistry, 2008, 69, 1359-1371. Anwei Chenga, Fachun Wanb, Zhengyu Jina, Jiaqi Wangc, Xueming Xua. Nitrite oxide and inducible nitric oxide synthase were regulated by polysaccharides isolated from Glycyrrhiza uralensis Fisch. Journal of Ethnopharmacology Volume 118, Issue 1, 19 June 2008, Pages 59–64 K I Kim, K S Shin, W J Jun, H C Yang. Effect of polysaccharides from rhizomes of Curcuma zedoaria on macrophage functions. Biosc Biotechol, Biochem, 2001, 65, 2369-2377. Coumarins, particularly scopoletin, strongly inhibit iNOS. Tien-Ning Chang, Jeng-Shyan Deng, Yi-Chih Chang, Chao-Ying Lee, Liao Jung-Chun, Ameliorative Effects of Scopoletin from Crossostephium chinensis against Inflammation Pain and Its Mechanisms in Mice. Evid Based Complement Alternat Med. 2012; 2012: 595603. doi: 10.1155/2012/595603 RD Chougouo, Y Nguekeu, J Kouamouo, J Eloff. Anti-inflammatory activity of extract, fractions of Artemisia annua. SpringerPlus, 2016, 5 :1525 But sesquiterpene lactones even appear to be stronger NO inhibitors. This was first evidenced in 1997 for Artemisia ludoviciana in Mexico. Peter M. Borka, M. Lienhard Schmitz, Michaela Kuhnt, Claudia Escherb, Michael Heinricha.Sesquiterpene lactone containing Mexican Indian medicinal plants and pure sesquiterpene lactones as potent inhibitors of transcription factor NF-KB. FEBS 18108 FEBS Letters 402 (1997) 85-90 The sesquiterpene lactones parthenolide and isohelenin prevented NF-kB activation completely as low as 5 microM. A similar effect was confirmed for the sesquiterpene lactone helenalin. Lyss G, Knorre A, Schmidt TJ, Pahl HL, Merfort I The anti-inflammatory sesquiterpene lactone helenalin inhibits the transcription factor NF-kappaB. J Biol Chem. 1998 Dec 11;273(50):33508-16. Ergolide, a sesquiterpene lactone from Inula britannica inhibits iNOS in macrophages. Whan Han J, Gon Lee B, Kee Kim Y, Woo Yoon J, Kyoung Jin H, Hong S, Young Lee H, Ro Lee K, Woo Lee H. Ergolide, sesquiterpene lactone from Inula britannica, inhibits inducible nitric oxide synthase and cyclo-oxygenase-2 expression in RAW 264.7 macrophages through the inactivation of NF-kappaB. Br J Pharmacol. 2001 Jun;133(4):503-12. A similar effect for artemisinin was found in Italy. Elisabetta Aldieri, Daniela Atragene, Loredana Bergandi, Chiara Riganti, Artemisinin inhibits inducible nitric oxide synthase and nuclear factor NF-kB activation . FEBS Letters Volume 552, Issues 2–3, 25 September 2003, Pages 141–144 A more extensive study on 5 artemisin derivatives at the University of Heidelberg showed that among the five in a mouse macrophage model artesunate revealed the highest ability to inhibit generation of NO Konkimalla VB , Blunder M , Korn B , Soomro SA , Jansen H , Chang W , Posner GH , Bauer R , Efferth T Effect of artemisinins and other endoperoxides on nitric oxide-related signaling pathway in RAW 264.7 mouse macrophage cells. Nitric Oxide : Biology and Chemistry [2008, 19(2):184-191] DOI: 10.1016/j.niox.2008.04.008 In our own research we had found that in vitro pure artemisinin pretreatment strongly inhibited NF-kB activation (Dr Mario Dicato, personal communication 2008). By inhibiting NO artemisinin leads to the proliferation of gametocytes, artemisinin derivatives are strong immunosuppressors opening a wide angle door for recrudescence and reinfection. Tawfik AF , Bishop SJ , Ayalp A , el-Feraly FS. Effects of artemisinin, dihydroartemisinin and arteether on immune responses of normal mice. International Journal of Immunopharmacology [1990, 12(4):385-389] DOI: 10.1016/0192-0561(90)90019-J But the role of NO in malaria therapy however is complex. Its concentration remains approximately constant during infection. An Australian team investigated the in vitro susceptibility of Plasmodium falciparum to killing by nitric oxide and related molecules. A saturated solution of nitric oxide did not inhibit parasitic growth, but nitrite and nitrate ions were toxic to the parasite in millimolar concentrations KA Rocket, M Awburn, W Cowden, I Clark. Killing of Plasmodium falciparum In Vitro by Nitric Oxide Derivatives Infection and Immunity, 1991, vol 59-9 3280-3283).