Comparison of the Reactivity of Antimalarial 1,2,4,5-Tetraoxanes with 1,2,4-Trioxolanes in the Presence of Ferrous Iron Salts, Heme, and Ferrous Iron Salts/Phosphatidylcholine

详细信息    查看全文

• 作者：Fatima Bousejra-El Garah ; Michael He-Long Wong ; Richard K. Amewu ; Sant Muangnoicharoen ; James L. Maggs ; Jean-Luc Stigliani ; B. Kevin Park ; James Chadwick ; Stephen A. Ward ; Paul M. O鈥橬eill
• 刊名：Journal of Medicinal Chemistry
• 出版年：2011
• 出版时间：October 13, 2011
• 年：2011
• 卷：54
• 期：19
• 页码：6443-6455
• 全文大小：1205K
• 年卷期：v.54,no.19(October 13, 2011)
• ISSN：1520-4804

文摘

Dispiro-1,2,4,5-tetraoxanes and 1,2,4-trioxolanes represent attractive classes of synthetic antimalarial peroxides due to their structural simplicity, good stability, and impressive antimalarial activity. We investigated the reactivity of a series of potent amide functionalized tetraoxanes with Fe(II)gluconate, FeSO₄, FeSO₄/TEMPO, FeSO₄/phosphatidylcholine, and heme to gain knowledge of their potential mechanism of bioactivation and to compare the results with the corresponding 1,2,4-trioxolanes. Spin-trapping experiments demonstrate that Fe(II)-mediated peroxide activation of tetraoxanes produces primary and secondary C-radical intermediates. Reaction of tetraoxanes and trioxolanes with phosphatidylcholine, a predominant unsaturated lipid present in the parasite digestive vacuole membrane, under Fenton reaction conditions showed that both endoperoxides share a common reactivity in terms of phospholipid oxidation that differs with that of artemisinin. Significantly, when tetraoxanes undergo bioactivation in the presence of heme, only the secondary C-centered radical is observed, which smoothly produces regioisomeric drug derived-heme adducts. The ability of these tetraoxanes to alkylate the porphyrin ring was also confirmed with Fe^IITPP and Mn^IITPP, and docking studies were performed to rationalize the regioselectivity observed in the alkylation process. The efficient process of heme alkylation and extensive lipid peroxidation observed here may play a role in the mechanism of action of these two important classes of synthetic endoperoxide antimalarial.