Synthesis and Antioxidant Activity of Polyhydroxylated trans-Restricted 2-Arylcinnamic Acids
作者:Mitko Miliovsky、Ivan Svinyarov、Elena Prokopova、Daniela Batovska、Simeon Stoyanov、Milen Bogdanov
DOI:10.3390/molecules20022555
日期:——
A series of sixteen polyhydroxylated trans-restricted 2-arylcinnamic acid analogues 3a–p were synthesized through a one-pot reaction between homophthalic anhydrides and various aromatic aldehydes, followed by treatment with BBr3. The structure of the newly synthesized compounds was confirmed by spectroscopic methods and the configuration around the double bond was unequivocally estimated by means of gated decoupling 13C-NMR spectra. It was shown that the trans-cinnamic acid fragment incorporated into the target compounds’ structure ensures the cis-configuration of the stilbene backbone and prevents further isomerization along the carbon–carbon double bond. The antioxidant activity of compounds 3a–p was measured against 1,1-diphenyl-2-picrylhydrazyl (DPPH●), hydroxyl (OH●) and superoxide (O2●▬) radicals. The results obtained showed that the tested compounds possess higher activities than natural antioxidants such as protocatechuic acid, caffeic acid and gallic acid. Moreover, it was shown that a combination of two different and independently acting fragments of well-known pharmacological profiles into one covalently bonded hybrid molecule evoke a synergistic effect resulting in higher than expected activity. To rationalize the apparent antioxidant activity and to establish the mechanism of action, a SAR analysis and DFT quantum chemical computations were also performed.
通过均苯二甲酸酐与各种芳香醛的一锅反应,然后用 BBr3 处理,合成了一系列多羟基反式限制性 2-芳基肉桂酸类似物 3a-p。新合成化合物的结构通过光谱方法得到了证实,双键周围的构型通过门控去耦 13C-NMR 光谱得到了明确的估计。结果表明,目标化合物结构中的反式肉桂酸片段确保了二苯乙烯骨架的顺式构型,并阻止了碳碳双键的进一步异构化。测定了化合物 3a-p 对 1,1-二苯基-2-苦基肼(DPPH●)、羟基(OH●)和超氧自由基(O2●▬)的抗氧化活性。结果表明,测试化合物的活性高于原儿茶酸、咖啡酸和没食子酸等天然抗氧化剂。此外,研究还表明,将两种不同的、独立作用的、具有著名药理特征的片段结合到一个共价键杂化分子中,会产生协同效应,从而产生比预期更高的活性。为了合理解释这种明显的抗氧化活性并确定其作用机制,还进行了 SAR 分析和 DFT 量子化学计算。