Discovery of Plasmodium falciparum inhibitors from Cerrado plants as lead compounds candidates for malaria: integrated studies of ultra-efficient chromatography, spectroscopy, and biological assays

Abstract

Malaria is a lethal parasitosis, worldwide prevalent, and despite investments in the search for new drugs, a high mortality rate is still observed. In the search for new candidates for antimalarial drug discovery, glycolytic pathway modulation has been explored as target to inhibit parasite development and fight infection. Enolase (Pfeno) is an attractive target of the parasite glycolytic pathway, which catalyzes the conversion of 2-phosphoglycerate (2PG) to phosphoenolpyruvate (PEP). Moreover, the enzyme is associated with other important cellular functions (moonlighting functions, non-glycolytic functions) due to the different biological compartments in which Pfeno is found. Recently our group (CIBFaR-CEPID) determined the 3D crystallographic structure of Pfeno along with its enzymatic complexes. The 3D structures indicated differences related to the homologous human enzyme that allow the search for new selective inhibitors. Given the success of antimalarial drugs from natural products (PNs) and that the Cerrado is a hotspot of world biodiversity, this proposal aims to investigate bioactive compounds against malaria from plants of this biome. Some plant species were selected for screening based on reported antiplasmodial activities of the species or genus of these plants. Among these, the fractions of fruits and bark of Qualea grandiflora stem (Vochysiaceae) were previously investigated, in collaboration between CIBFar-CEPID and LaBiOrg - UFG / RC, with promising in vitro activity against Plasmodium falciparum cultures (IC50 values between 1.2 ng / mL and 7.0 ng / mL), in vivo (100% reduction in parasitemia after the fifth day of P. berghei infection), and the identification of 32 compounds. LaBiOrg - UFG / RC has a significant collection of Cerrado plant extracts that will be investigated in this proposal. The extracts will be evaluated against Pfeno and the most promising extracts will be submitted to experiments in hyphenated analytical techniques including high resolution mass spectrometry (CLUE-MS / MS). The CLUE-MS / MS detection limit allows the identification of minor compounds that may be related to the biological activity. The phytochemical investigation will be performed using 1H NMR-guided HPLC-DAD. The isolated compounds will be investigated against Pfeno and P. falciparum strains (3D7 and K1), as well as cytotoxicity and selectivity assessed. Compounds with significant inhibition of enzyme and parasite growth will be selected as lead compounds candidates. (AU)