Unified Mechanistic Framework for the Fe(II)-Induced Cleavage of Qinghaosu and Derivatives/Analogues. The First Spin-Trapping Evidence for the Previously Postulated Secondary C-4 Radical
Qinghaosu and derivatives were easily reduced by ferrous sulfate in aqueous acetonitrile to give results different from those reported for other reducing systems. The unstable epoxide 7, a compound that was postulated earlier as a species responsible for the antimalarial activity, now has been isolated and characterized. The earlier speculative secondary C-4 radical has also been trapped with 2-me
Study on the mechanism of action of artemether against schistosomes: the identification of cysteine adducts of both carbon-centred free radicals derived from artemether
Reaction of the antimalarial and anti-schistosome drug artemether (1) and catalytic amount of ferrous ion in the presence of excess cysteine gave two adducts of cysteine and previous postulated primary and secondary carbon-centred free radicals besides their other rearrangement products. This piece of further evidence for the presence of carbon-centred radicals, especially the secondary carbon-centred free radical for the first time by the isolation of its coupling adduct, will be help to understand the mechanism of action of artemether and other qinghaosu derivatives against parasites. (C) 2003 Elsevier Science Ltd. All rights reserved.