Not ordinary antimalarial drugs: Madagascar plant decoctionspotentiating the chloroquine action against Plasmodium parasites

Malaria mortality rates have fallen by 47% globally since 2000 and by 54% in the African region, but theyare still a major problem. Malaria is caused by Plasmodium parasites, vectored to people through Anophe-les mosquitoes, which mainly bite between dusk and dawn. Currently, a growing number of Plasmodiumspecies and strains developed resistance to the most commonly used anti-malarial drugs. Chloroquine(CQ), the most commonly used anti-malarial drug, actually is not effective in a number of cases, and grow-ing Plasmodium resistance has been already observed to artemisinin. New approaches are necessary toface this challenge. One of the strategies to overcome the drug resistance in different Plasmodium speciesis the search for compounds known as resistance-modifiers or chemosensitizers. These compounds mayrestore the CQ sensitivity in CQ-resistant strains of Plasmodium. The studies started from the knowledgethat some Madagascar populations use decoctions of some local plants in association with low dosesof CQ to complement the CQ action against chronic malaria. In such way, resistance insurgence is low-ered, as well as collateral effects. Phytochemical analyses on twelve plant species commonly used bylocal populations to treat malaria evidenced the presence of complex alkaloids, which showed in vitroand/or in vivo efficacy against CQ-resistant Plasmodium strains, attesting the potential use of the mix ofCQ and medicinal plant preparations or compounds therein present. The approach, in accordance withrecent tendencies on multidrug resistance control, is based on mixtures of natural products and classicantimalarial drugs, with a relevant coincidence between the ethnobotanical reports and the scientificevidence.