Anti-Plasmodial Polyvalent Interactions in Artemisia annua L. Aqueous Extract – Possible Synergistic and Resistance MechanismsReportar como inadecuado




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Artemisia annua hot water infusion tea has been used in in vitro experiments against P. falciparum malaria parasites to test potency relative to equivalent pure artemisinin. High performance liquid chromatography HPLC and mass spectrometric analyses were employed to determine the metabolite profile of tea including the concentrations of artemisinin 47.5±0.8 mg L-1, dihydroartemisinic acid 70.0±0.3 mg L-1, arteannuin B 1.3±0.0 mg L-1, isovitexin 105.0±7.2 mg L-1 and a range of polyphenolic acids. The tea extract, purified compounds from the extract, and the combination of artemisinin with the purified compounds were tested against chloroquine sensitive and chloroquine resistant strains of P. falciparum using the DNA-intercalative SYBR Green I assay. The results of these in vitro tests and of isobologram analyses of combination effects showed mild to strong antagonistic interactions between artemisinin and the compounds 9-epi-artemisinin and artemisitene extracted from A. annua with significant IC50 <1 μM anti-plasmodial activities for the combination range evaluated. Mono-caffeoylquinic acids, tri-caffeoylquinic acid, artemisinic acid and arteannuin B showed additive interaction while rosmarinic acid showed synergistic interaction with artemisinin in the chloroquine sensitive strain at a combination ratio of 1:3 artemisinin to purified compound. In the chloroquine resistant parasite, using the same ratio, these compounds strongly antagonised artemisinin anti-plasmodial activity with the exception of arteannuin B, which was synergistic. This result would suggest a mechanism targeting parasite resistance defenses for arteannuin B’s potentiation of artemisinin.



Autor: John O. Suberu, Alexander P. Gorka, Lauren Jacobs, Paul D. Roepe, Neil Sullivan, Guy C. Barker , Alexei A. Lapkin

Fuente: http://plos.srce.hr/



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