In search of promising antimalarial drugs: Detection of heme-based adducts induced in complex matrixes from Brazilian plants using HPLC-DAD

The development of fast and efficient detection and HPLC separation methods on a bioprospection program is crucial for speeding-up the selection of natural matrixes. Based on this goal, the induction of an in situ heme adduct in crude plant extracts from Brazilian Cerrado and Atlantic Forest turned out to be a powerful tool, foretelling if a crude extract contains promising molecules that may have antimalarial or antileishmanial properties. Studies of heme adducts were reported using known drugs such as quinine and artemisinin. We initially selected 75 plants from our bank of extracts based on chemosystematics, reported antimalarial activities as well as ethnopharmacological data. Species such as Arrabidaea samydoides (Cham.) Sandwith (Bignoniaceae), Strychnos pseudoquina St. Hil. (Loganiaceae), Garcinia gardineriana Miers ex Planch. Et Triana (Clusiaceae), Zanthoxyllum rhoifolium Lam. (Rutaceae), Sorocea bonplandii Baill. Burg. (Moraceae) and Bidens segetum Mart. ex Colla (Asteraceae) were some of the matrixes that showed adduct formation when incubated with hemine. Through the observation of retention time shifts and comparison of UV spectra after adduct induction, we were able to pin-point the responsible molecules and thus select plant extracts for further specific studies. C-glucosylxanthones isolated from A. samydoides were the metabolites responsible for adduct formation.

Acknowledgements: To Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), CAPES and CNPq for research funding.