Antimalarial xanthones from Calophyllum caledonicum and Garcinia vieillardii

The antimalarial activity of 22 xanthones against chloroquino-resistant strains of Plasmodium falciparum was evaluated. Natural caloxanthone C, demethylcalabaxanthone, calothwaitesixanthone, calozeyloxanthone, dombakinaxanthone, macluraxanthone, and 6-deoxy-γ-mangostin were isolated from Calophyllum caledonicum. 1,6-dihydroxyxanthone, pancixanthone A, isocudraniaxanthone B, isocudraniaxanthone A, 2-deprenylrheediaxanthone B and 1,4,5-trihydroxyxanthone were isolated from Garcinia vieillardii. Moreover, synthetic compounds are analogues or intermediates of xanthones purified from Calophyllum caledonicum (Oger J.M., Morel C., Hélesbeux J.J., Litaudon M., Séraphin D., Dartiguelongue C., Larcher G., Richomme P., Duval O. 2003. First 2-Hydroxy-3-Methylbut-3-Enyl substituted xanthones isolated from Plants: structure elucidation, synthesis and antifungal activity. Natural Product Research 17(3), 195–199; Hélesbeux J.J., Duval O., Dartiguelongue C., Séraphin D., Oger J.M., Richomme P., 2004. Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors. Tetrahedron 60(10), 2293–2300). The relationship between antimalarial activity and molecular structure of xanthones has also been explored. The most potent xanthones and (IC50 = c.a. 1.0 μg/mL) are 1,3,7 trioxygenated and prenylated on the positions 2 and 8

Photochemical inactivation with amotosalen and long-wavelength ultraviolet light of Plasmodium and Babesia in platelet and plasma components

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