Parkinson's disease (PD) is a neurodegenerative pathology characterized by resting tremor, rigidity, bradykinesia, and loss of dopamine-producing neurons in the pars compacta of the substantia nigra in the central nervous system (CNS) that result in dopamine depletion in the striatum. Oxidative stress has been documented as a key pathological mechanism for PD. Epidemiological studies have shown that smokers have a lower incidence of PD. In this aspect, different studies have shown that nicotine, a chemical compound found in cigarette, is capable of exerting beneficial effects in PD patients, but it can hardly be used as a therapeutic agent because of its inherent toxicity. Several studies have suggested that the use of nicotine analogs can have the same benefits as nicotine but lack its toxicity. In this study, we assessed the effects of two nicotine analogs, (E)-nicotinaldehyde O-cinnamyloxime and 3-(pyridin-3-yl)-3a,4,5,6,7,7a-hexahidrobenzo[d]isoxazole, in an in vitro model of PD. Initially, we performed a computational prediction of the molecular interactions between the nicotine analogs with the α7 nicotinic acetylcholine receptor (nAChR). Furthermore, we evaluated the effect of nicotine, nicotine analogs and rotenone on cell viability and reactive oxygen species (ROS) production in the SH-SY5Y neuronal cell line to validate possible protective effects. We observed that pre-treatment with nicotine or (E)-nicotinaldehyde O-cinnamyloxime (10 μM) improved cell viability and diminished ROS production in SH-SY5Y cells insulted with rotenone. These findings suggest that nicotine analogs have a potential protective effect against oxidative damage in brain pathologies.
Herein we report the synthesis of a series of O-alkyl oximes of flavone and 6-hydroxyflavone using a simple experimental protocol under solvent free conditions with yields up to 87%. Cytotoxicity of all compounds was evaluated against MDA-MB-231, PC-3, A-549 and MRC-5 cells. IC 50 values for two compounds were determined to be in the range 28.7-47.8 μM against all tested cell lines. Oxime ethers derivatives showed IC 50 values between 28.7 and 49.5 μM against MDA-MB-231, while the best activity was obtained for 6-hydroxyflavone with an IC 50 of 3.4 μM against this cell line. Compounds containing the substituent hydroxyl at the position six of flavone system displayed the best antiproliferative activity over MDA-MB-231 cells, being necessary this group to improve the sensibility on this type of cells. The antiproliferative activity of 6-hydroxyflavone is drastically diminished when the carbonyl group of flavone is changed by an oxime ether.
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