Pesquisa | SciELO

Natural α,β-amyrins were isolated from endemic Brazilian Esenbeckia grandiflora Mart., and eight synthetic derivatives were obtained by esterification reactions with bromo acetate, followed by amine treatment. The structures of the all compounds were confirmed by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and high-resolution mass spectrometry (HRMS) data analysis. The derivatives were screened for cytotoxic activity against human tumor cell-lines PC3 (prostate carcinoma), HCT-116 (colon carcinoma) and HL60 (leukemia). HCT-116 and PC3 cell-lines showed weak tumor growth inhibition (range of 13.9-25.4 and 10.3-28.8%, respectively), but the derivatives presented moderate activity against HL60 (range of 13.6-59.0%). Diethyl, aniline, morpholine and imidazole moieties presented higher activities (range of 45.9-59.0%).

This work describes the mechanism of action of some reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the oxidative stress of the human body, and their consequences on damage to DNA, RNA, proteins and lipids. It also illustrates the defense system of our organism against these ROS and RNS species. The action of nonenzymatic protection systems is reported, with emphasis on micromolecules like Q10 coenzyme, vitamin C, alpha-tocopherol, carotenoids and flavonoids. The importance of flavonoids is also emphasized, and their body protection mechanism is detailed.

This work describes the evaluation of the antioxidant activity in the system b-carotene / linoleic acid and radical scavenging effects of the substances epicatechin-(2β→7,4β→8)-epicatechin, epicatechin, epigalocatechin-(2β→7,4β→8)-epicatechin, luteolin 3-β-Dglicopiranoside and crisoeriol 7-β-D-glicopiranoside isolated of the extract AcOEt of the stem of Dioclea lasiophylla, in comparison with the standards n-propyl gallate, BHT and a-tocopherol.

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