Archive for mai 2012

artemisia annua deux familles

mai 20, 2012

Il se confirme qu’il y a deux espèces d’artemisia annua. L’une riche en acide artemisinique qui ne se transforme pas en artemisinine dans la plante; l’autre riche en acide dihydroartemisinique, précurseur de l’artemisinine.
Il se confirme également que l’artemisinine ne se transforme pas par métabolisme naturel en dihydroartemisinine. Cette transformation peut uniquement se faire par procédé chimique pour produire l’artesunate ou l’artemether

Or are there two chemotypes of artemisia annua ?
Artemisinin was initially called arteannuin and sold under this name as qinghoasu.
Arteannuin-B without endoperoxide bridge is a precursor or competitor to artemisinin.
Arteannuin-B was detected by Efferth in Chinese samples but not in Anamed samples (T Efferth et al Phytomedicine, 18, 2011, 959-969). He finds also that it is as cytotoxic against cancer cells as artemisinin.
It is very difficult to detect any arteannuin-B in Brazilian artemisia annua from Campinas, at least by HPLC-ELSD. Very often the arteannuin-B peak overlaps with the peaks of degradation products of artemisinin (CA Peng et al., J of Chromatography, 1133, 2006, 254-8).
D Fulzele et al. ( Phytotherapy Research , 5, 1991, 149-153) find that plants from Europe produced the highest level of artemisin and those from Lucknow produced the highest level of arteannuin-B
L.Olofsonet al., ( BMC Plant biology, 11, 2011, 45) state that the conversion of dihydroartemisinic acid to artemisinin is believed to be a non enzymatic spontaneous reaction. In a similar way artemisinic acid is converted to arteannuin-B . The genetic variation within A. annua appears to be high. One chemotype shows high content of dihydroartemisinic acid and artemisinin, while the second chemotype shows high content of artemisinic acid and arteannuin-B.
This is confirmed by GD Brown (Molecules, 2010, 15, 7603-98) and by P Weathers (Phytochem Rev 19 Feb 2010).
Artemisinic acid even appears to inhibit the transformation of dihydroartemisinic acid into artemisinin, by inhibition of the CYP transcription. (PR Arsenault et al., Plant Pysiol 154 oct 2010).
Chenfei Ma et al., (J of Chromatography A 1186, 2008, 412-19) also studied two chemotypes and find that in one of the samples at the flowering stage artemisinin had no significant increase , but arteannuin-B increased significantly. High arteannuin-B creates a bottle-neck in the production of artemisinin.
It is possible however that a decoction of the artemisia annua herb might lead to an in vivo transformation of certain precursors into artemisinin
Artemisinin has an EC50 of 10ng/ml against plasmodium compared to 1000 for arteannuin-B (Nguyen Tien Ban 1999 http://www.proseanet.org).
Against human and plant pathogenic fungi only arteannuin B shows activity whereas artemisinin shows none ( HQ Tang et al., Planta Medic 66, 2000. 391-393)
J Ferreira (J Agric Food Chem 58, 2010, 1691-98) also finds d that during the drying process of artemisia annua herb only dihydtroartemisinic acid is transformed into artemisinin, artemisinic acid stays stable in the leaves. The same author also claims that the two different chemotypes of artemisia annua are very different in their polyphenol composition ( Molecules. 2010. 15)
In light of this the biosynthesis of artemisinic acid by many research groups for the production of artemisinin appears to be a mistake.

Research at Basel ( Molecules, 2010 November) has firmly confirmed this: dihydroartemisinic acid is a late-stage precursor to artemisinin and the closely related metabolite artemisinic acic is not. They have also found that some derivates from artemisinic acid, the arteannuin-B precursor, have shown 10-20 times more in vitro antimalarial activities against plasmodium falciparum than artemisinin.
A similar concept is developed by TE Wallart et al., ( Planta Med 66. 2000, 57-62
And by HJ Woerdenbag et al., (Flavour and Fragrance Journal 8, 1993, 131-137) distinguishing between a Chinese and a Vietnamese chemotype. The former containing 4.0% essential oil but only 0.17 artemisinin, the latter 1.0%.
The Chinese ( W Wu et al., Planta Med, 77, 2011, 1048-53 ) have recently detected considerable differences in artemisinic acid and dihydroartemisinic acid between two chemotypes within the species Artemisia annua.
Huge differences were also found in the work of L. Al-Soweimel , Worcester, 2009, between the content in artemisinin and arteannuin between strains from Yugoslavia and China. They relate this to differences in the precursors artemisinic acid and dihydroartemisinic acid
lutgenp@gms.lu

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artemisia annua: 2 different chemotypes

mai 20, 2012

Or are there two chemotypes of artemisia annua ?

Artemisinin was initially called arteannuin and sold under this name as qinghoasu.
Arteannuin-B without endoperoxide bridge is a precursor or competitor to artemisinin.
Arteannuin-B was detected by Efferth in Chinese samples but not in Anamed samples (T Efferth et al Phytomedicine, 18, 2011, 959-969). He finds also that it is as cytotoxic against cancer cells as artemisinin.
It is very difficult to detect any arteannuin-B in Brazilian artemisia annua from Campinas, at least by HPLC-ELSD. Very often the arteannuin-B peak overlaps with the peaks of degradation products of artemisinin (CA Peng et al., J of Chromatography, 1133, 2006, 254-8).
D Fulzele et al. ( Phytotherapy Research , 5, 1991, 149-153) find that plants from Europe produced the highest level of artemisin and those from Lucknow produced the highest level of arteannuin-B
L.Olofsonet al., ( BMC Plant biology, 11, 2011, 45) state that the conversion of dihydroartemisinic acid to artemisinin is believed to be a non enzymatic spontaneous reaction. In a similar way artemisinic acid is converted to arteannuin-B . The genetic variation within A. annua appears to be high. One chemotype shows high content of dihydroartemisinic acid and artemisinin, while the second chemotype shows high content of artemisinic acid and arteannuin-B.
This is confirmed by GD Brown (Molecules, 2010, 15, 7603-98) and by P Weathers (Phytochem Rev 19 Feb 2010).
Artemisinic acid even appears to inhibit the transformation of dihydroartemisinic acid into artemisinin, by inhibition of the CYP transcription. (PR Arsenault et al., Plant Pysiol 154 oct 2010).
Chenfei Ma et al., (J of Chromatography A 1186, 2008, 412-19) also studied two chemotypes and find that in one of the samples at the flowering stage artemisinin had no significant increase , but arteannuin-B increased significantly. High arteannuin-B creates a bottle-neck in the production of artemisinin.
It is possible however that a decoction of the artemisia annua herb might lead to an in vivo transformation of certain precursors into artemisinin
Artemisinin has an EC50 of 10ng/ml against plasmodium compared to 1000 for arteannuin-B (Nguyen Tien Ban 1999 http://www.proseanet.org).
Against human and plant pathogenic fungi only arteannuin B shows activity whereas artemisinin shows none ( HQ Tang et al., Planta Medic 66, 2000. 391-393)
J Ferreira (J Agric Food Chem 58, 2010, 1691-98) also finds d that during the drying process of artemisia annua herb only dihydtroartemisinic acid is transformed into artemisinin, artemisinic acid stays stable in the leaves. The same author also claims that the two different chemotypes of artemisia annua are very different in their polyphenol composition ( Molecules. 2010. 15)
In light of this the biosynthesis of artemisinic acid by many research groups for the production of artemisinin appears to be a mistake.

Research at Basel ( Molecules, 2010 November) has firmly confirmed this: dihydroartemisinic acid is a late-stage precursor to artemisinin and the closely related metabolite artemisinic acic is not. They have also found that some derivates from artemisinic acid, the arteannuin-B precursor, have shown 10-20 times more in vitro antimalarial activities against plasmodium falciparum than artemisinin.
A similar concept is developed by TE Wallart et al., ( Planta Med 66. 2000, 57-62
And by HJ Woerdenbag et al., (Flavour and Fragrance Journal 8, 1993, 131-137) distinguishing between a Chinese and a Vietnamese chemotype. The former containing 4.0% essential oil but only 0.17 artemisinin, the latter 1.0%.
The Chinese ( W Wu et al., Planta Med, 77, 2011, 1048-53 ) have recently detected considerable differences in artemisinic acid and dihydroartemisinic acid between two chemotypes within the species Artemisia annua.
Huge differences were also found in the work of L. Al-Soweimel , Worcester, 2009, between the content in artemisinin and arteannuin between strains from Yugoslavia and China. They relate this to differences in the precursors artemisinic acid and dihydroartemisinic acid

Hepatotoxic, cytotoxic, neurotoxic, genotoxic, embryotoxic, hemolytic, immunodepressive effects of chemical artemisinine derivatives (ACTs) at high doses.

mai 17, 2012

Hepatotoxic, cytotoxic, neurotoxic, genotoxic, embryotoxic, hemolytic, immunodepressive effects of chemical artemisinine derivatives (ACTs) at high doses.

Some recent research, mostly in relation with the resistance to ACT pills and/or artesunate injections, has highlighted serious secundary health effects at the doses prescribed by WHO.
Fears of emerging artemisin resistance in western Cambodia have promoted a series of clinical trials investigating if resistance can be overcome by increasing doses of drug. After 3 to 5 doses neutrophil counts were reduced in all groups and several patients required artesunate to be discontinued because of neutropenia. This study demonstrates that the dosing limit may have been reached (D Bethell et al., Clin Infect Dis, Nov 2010). A high risk of neutropenia in HIV-infected children following treatment with artesunate was also noticed in Uganda (AF Gasasira et al., Clin Infect Dis 1. 2008, 992-993)
One of the side effects of the higher doses is the dormancy effect induced in plasmodium. The parasite encapsulates itself against the aggressive peroxide artesunate and reawakens at the end of the treatment. This may be one of the causes of resistance .
In Nigeria (O Omotuyi et al, Afr J Biochem Res, 2, 2008, 107-110) in a study on rats it was found that hepatoxicity and hemolysis were clearly associated with artesunate. The hepatoxicity effect was monitored in the rats as a function of aspartase transaminase (ASAT), alanine transaminase (ASAT) which both increased dratically. The hemolytic effect was monitored by the packed cell volume, bilirubin, hematocrit and serum albumin. Acute hepototoxicty following administration of artesunate in guinea pigs was also noticed in other trials in Nigeria ( HU Nwanjo et al., The International J of Toxicol., 4, 2007, 1-5). In humans hepatotoxicity can be particularly severe if artesunate is used in combination with HIV antiretroviral drugs ( P.German et al., Clin Inf Diseases44, 2007, 889-891) The document WHOPAR 06/2011 MA058 recognizes that artesunate/amodiaquine 100/270 mg tablets may result in severe hepatotoxicity.
Derivatives of artemisinin exhibit potent immunosuppressive activity (JX Wang et al., Br J Pharmacol150, 2007, 652-661). Artesunate concentrations between 0.1-1.5 microg/ml reduced lymphocyte production in a generally dose dependant manner ( P Veerusubramanian et al., Southeast Asian J Trop Med , 37, 2006, 838-847). The authors claim that further work is warranted to define the mechanisms involved and wether this affects malaria treatment. Another research work confirmed the genotoxic and cytotoxic effect of artesunate in cultured human lymphocytes ( TC Mota et al., Env Mol Mutagen 52, 2011, 590-594.) But the mechanism of inhibitory effect on lymphoproliferation is unknown. In the same work a reduction of CD4+ and CD8+ T cells was noticed which could be detrimental in HIV infections. TNF-α levels were also reduced in patient treated with artesunate (W Ittarat et al., Southeast Asian J Trop Med, 30, 1999, 7-10) which obviously has an effect on the inflammatory process. In normal mice artemisinin and artether affect the immune response ( AF Tawfik et al., Int J Immunopharmacol 12, 1990, 385-389). Artesunate suppressed phagocytosis of peritoneal macrophage in mice ( PY LIN et al, Acta Pharmacol Sin. 16, 1995, 441-444).
The haemolytic effect is well described in the following paper ( A Corpolongo et al., Malaria Journal, 11-91, 2012) The patient described in their article presented with fever, headache after returning from Central African Republic. He had been treated with oral artemether and lumefantrine. The blood analysis revealed acute renal failure Hereditary or auto-inmune disorders were excluded .There are a few other cases described in the same paper of haemolytic anaemia during or after treatment with i.v. artesunate alone or combined with mefloquine: the case of a Nigerian male with severe P. falciparum malaria initially treated with mefloquine. After one day of treatment, because of the worsening clinical condition of the patient and the increase of the parasitaemia, therapy with i.v. artesunate was initiated. Parasite clearance was obtained within 20 hours after the first administration of artesunate, but fever persisted for a further seven days and haemolytic anaemia was observed, requiring blood transfusion; the case of a young woman with P. falciparum malaria who was successfully treated with i.v. artesunate, but showed worsening anaemia after artesunate administration ; severe haemolytic anaemia and jaundice on day 11 after i.v. artesunate administration in a 68-year-old Japanese woman affected by severe malaria; a series of 25 travellers with severe malaria treated with i.v. artesunate. Among them, six patients developed haemolytic anaemia week after treatment possibily related to artesunate or had persistent signs of haemolytic activity until six weeks after the first dose of i.v. artesunate. In this case series, patients with post-treatment haemolysis had received a higher cumulative dose of i.v. artesunate and were treated for longer periods.
The derivatives of artemisinin are strong peroxides. They create radicals and reactive oxygen species which at high doses might damage cortical and brain stem neurons (G Schmuck et al., Antimicrob Agents and Chemother. 46, 2002, 821-827) and are cytotoxic to many other cells. The genotoxicity of artesunate was was studies in Brazil on mice ( I Aquino et al., Food Chem Toxicol. 2011 Jun;49(6):1335-9.) The artesunate was administered by oral gavage at doses of 5, 50 and 100 mg/kg. Artesunate showed weak genotoxic effects at low doses and severe (clastogenic effects) at high doses. The authors claim that the data obtained suggest caution about either continuous or high-dose use of artesunate by humans. Similar results were obtained by another research team in Brazil. Their results showed that artesunate is a genotoxic and cytotoxic compound in cultured human lymphocytes. A significant increase in the frequency of apoptotic and necrotic cells was observed. (T Mota et al., Environ. Mol. Mutagen., 2011)
Artesunate and artemether rapidly degrade into dihydroartemisinin which is claimed by pharmaceutical companies to be 10 times more effective against malaria than artemisinin. Artemisinin itself does not metabolize into dihydroartemisinin and stays much longer in the plasma. This might be one of the reasons why artemisia annua tea infusions, despite the fact that they contain much less active molecules than ACTs, might be as effective.
All these findings are especially worrisome for the use of higher doses of artesunate required for pregnant women because immunity is temporarely disrupted in pregnancy. Nonimmune or immunodepressed patients require higher doses for an adequate therapeutic response. Artesunate also causes embryo death in animals by causing severe anemia with higher drug concentrations ( RL Clark et al., Birth Defect Res B Dev Rproduc Toxicol 92, 2011, 52-68). Embryotoxicity is due to dihydroartemisinin, the main metabolite of artesunate and artemether, but not of artemisinin ( S D’Alessandro et al., Toxicology 241, 2007, 66-74)
But none of these hepatotoxic, haemolytic, cytotoxic, immunodepressive effects has ever been observed by drinking Artemisia annua tea.
Several studies ( A Muzemil, PhD thesis, AddisAbeba 2009; JT Mukinda, Thesis, University of Western Cape, 2005; G Chuipet, Thesis, Université des Montagnes, 2012) have confirmed that Artemisia annua tea is completely innocuous up to 5000 mg/kg of dried plant extracts and although it administers doses of artemisinin 100 x lower than those of the ACT pills, it cures >95% of the malaria infections.
Many studies have shown that Artemisia annua stimulates the immune system, increasing for example the monocyte count. ( PE Ogwang et al., Brit J Phar Res., 1, 2011, 124-132) This effect is probably due to other constituents than artemisinin: essential oils, flavonoids, coumarins, polysaccharides, saponins. The research work from the University des Montagnes in Cameroon even indicates that Artemisia annua tea lowers the alanine aminotransferase (ALAT) and could be hepatoprotective.
Pierre Lutgen
13 May 2012