Qualea grandiflora Mart. (“pau-terra”) is a medicinal plant symbolic from Cerrado biome. Qualea species reportedly have antiparasitic properties, but their active compounds have yet to be identified. In this study, we investigated the antiplasmodial activity of Q. grandiflora fruit and stem extracts against Plasmodium falciparum. The polar extracts of both fruits and stems showed promising in vitro antiplasmodial activity against sensitive and resistant P. falciparum strains (half-maximal inhibitory concentration (IC50) = 1.2 and 4.2 ng mL-1, respectively), low cytotoxicity against human hepatic cells (IC50HepG2 ≥ 400 ng mL-1), and a noteworthy selectivity index (SI ≥ 322 and ≥ 96, respectively). The fruit ethanolic extract revealed significant oral efficacy at 100 mg kg-1 in a mouse model of P. berghei malaria (100% reduction in parasitemia on day 5 post-infection). To investigate the chemical composition of the extracts, we developed a method involving liquid chromatography-high resolution quadrupole-time of flight mass spectrometer. The chemical profiling of active extracts indicated 32 compounds, including gallotannins, ellagic acid derivatives and flavonoids. The common component in the active polar extracts was found to be ellagic acid (EA), which may contribute favorably to the in vitro and in vivo inhibitory activity observed in this study.

A chemical investigation of two specimens of Byrsonima coccolobifolia collected in the southeast cerrado and from central Brazil was performed. A new degraded diterpenoid, byrsonimaquinone, was isolated from the stems along with known compounds. This is the first study on the roots of B. coccolobifolia, and several triterpenes, such as α-amyrin, β-amyrin, oleanolic acid, and glochidonol, along with a mixture of stigmasterol, β-sitosterol and campesterol, were identified. These compounds were identified by spectroscopic analysis techniques, including 1D and 2D NMR, GC-MS and high-resolution mass spectrometry.

Cathepsins represent a class of enzymes that has the primary function of randomly degrading proteins in the lysosomes, although are also involved in different pathologies. The aim of this paper was to evaluate the capacity of acridone alkaloids isolated from Swinglea glutinosa (Rutaceae) to inhibit cathepsin L in vitro . The IC50 values found were in the 0.8-57 µM range and the most promising compounds were alkaloids 1 and 2, with IC50 of 0.9 and 0.8 µM, respectively. Enzyme kinetics revealed that they are reversible competitive inhibitors with respect to the substrate Z-FR-MCA. This small series of acridone alkaloids showed low selectivity for both cathepsins, but represent promising lead candidates for the further development of competitive cathepsin L and V inhibitors.