厚朴酚和厚朴酚的抗氧化活性：与过氧自由基反应的动力学和机理研究,The Journal of Organic Chemistry

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厚朴酚和厚朴酚的抗氧化活性：与过氧自由基反应的动力学和机理研究
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2015-10-16 00:00:00 , DOI: 10.1021/acs.joc.5b01772
Riccardo Amorati ₁ , Julija Zotova ₁ , Andrea Baschieri ₁ , Luca Valgimigli ₁

Affiliation

木兰和厚朴酚是厚朴中含有的生物活性植物化学物质，是罕见的抗氧化剂，带有被烯丙基官能团取代的同分异构双酚核心。我们已经通过实验和计算方法阐明了其抗氧化活性背后的化学作用。在枯烯和苯乙烯的为303K的抑制自氧化，厚朴被困4个过氧自由基，具有ķ _INH的6.1×10 ⁴中号^-1小号^-1在氯苯和6.0×10 ³中号^-1小号^-1在乙腈中，并厚朴酚在氯苯中捕获了两个过氧自由基（k _inh = 3.8×10 ⁴ M^–1 s ^–1）和乙腈中的四个过氧自由基（k _inh = 9.5×10 ³ M ^–1 s ^–1）。它们的不同行为是由反应性OH基团（在厚朴酚中）和OH基团与芳香族和烯丙基π系统的分子内氢键结合所引起的，这已通过FT-IR光谱法和DFT计算得到证实。与结构相关的3,3'，5,5'-四甲基联苯-4,4'-二醇，2-烯丙基苯酚和2-烯丙基茴香醚的比较使我们可以排除厚朴酚和厚朴酚的抗氧化性能是由于烯丙基的缘故。烯丙基与过氧自由基的反应（C–H夺氢）以1.1 M ^–1 s的速率常数进行在303 K时为^–1。厚木酚和厚朴酚基团不会与分子氧反应，并且在典型的自氧化抑制条件下不会产生超氧化物基团。

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Antioxidant Activity of Magnolol and Honokiol: Kinetic and Mechanistic Investigations of Their Reaction with Peroxyl Radicals

Magnolol and honokiol, the bioactive phytochemicals contained in Magnolia officinalis, are uncommon antioxidants bearing isomeric bisphenol cores substituted with allyl functions. We have elucidated the chemistry behind their antioxidant activity by experimental and computational methods. In the inhibited autoxidation of cumene and styrene at 303 K, magnolol trapped four peroxyl radicals, with a k_inh of 6.1 × 10⁴ M^–1 s^–1 in chlorobenzene and 6.0 × 10³ M^–1 s^–1 in acetonitrile, and honokiol trapped two peroxyl radicals in chlorobenzene (k_inh = 3.8 × 10⁴ M^–1 s^–1) and four peroxyl radicals in acetonitrile (k_inh = 9.5 × 10³ M^–1 s^–1). Their different behavior arises from a combination of intramolecular hydrogen bonding among the reactive OH groups (in magnolol) and of the OH groups with the aromatic and allyl π-systems, as confirmed by FT-IR spectroscopy and DFT calculations. Comparison with structurally related 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol, 2-allylphenol, and 2-allylanisole allowed us to exclude that the antioxidant behavior of magnolol and honokiol is due to the allyl groups. The reaction of the allyl group with a peroxyl radical (C–H hydrogen abstraction) proceeds with rate constant of 1.1 M^–1 s^–1 at 303 K. Magnolol and honokiol radicals do not react with molecular oxygen and produce no superoxide radical under the typical settings of inhibited autoxidations.

更新日期：2015-10-16

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