Speisky Hernán, Arias-Santé María Fernanda, Fuentes Jocelyn
Laboratory of Antioxidants, Nutrition and Food Technology Institute, University of Chile, El Líbano 5524, Macul, Santiago 7810000, Chile.
Antioxidants (Basel). 2023 Jan 9;12(1):155. doi: 10.3390/antiox12010155.
The contention that flavonoids' oxidation would necessarily lead to a loss of their antioxidant properties was recently challenged by the demonstration that quercetin oxidation leads to the formation of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (Que-BZF), a metabolite whose antioxidant potency was notably higher than that of its precursor. Here, we compared and expanded the former observation to that of the quercetin analogue kaempferol. Oxidation of kaempferol led to the formation of a mixture of metabolites that included the 2-(4-hydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (Kae-BZF). Following the chromatographic isolation of Kae-BZF from such a mixture, its antioxidant, mitochondria- and cell-protecting, and NF-kB-inhibiting effects were assessed, and compared with those of Que-BZF, in Caco-2 cells exposed to indomethacin as a source of ROS. The concentrations of Que-BZF (100 nm) and Kae-BZF (1 nm) needed to attain their maximal protection effects were 50- and 5000-fold lower than those of their respective precursors. The former differences in concentrations were also seen when the abilities of Que-BZF and Kae-BZF to inhibit the indomethacin-induced activation of NF-kB were compared. These data not only reveal that the oxidative conversion of quercetin and kaempferol into their respective 2-benzoyl-2-hydroxy-3(2H)-benzofuranones (BZF) results in a considerable amplification of their original antioxidant properties, but also that the in the case of kaempferol, such amplification is 100-fold greater than that of quercetin.
黄酮类化合物的氧化必然会导致其抗氧化性能丧失的观点，最近受到了挑战。有证据表明，槲皮素氧化会生成2-(3,4-二羟基苯甲酰基)-2,4,6-三羟基-3(2H)-苯并呋喃酮（Que-BZF），该代谢产物的抗氧化能力明显高于其前体。在此，我们将之前的观察结果进行了比较，并扩展至槲皮素类似物山奈酚。山奈酚氧化生成了一种代谢产物混合物，其中包括2-(4-羟基苯甲酰基)-2,4,6-三羟基-3(2H)-苯并呋喃酮（Kae-BZF）。从该混合物中通过色谱法分离出Kae-BZF后，在暴露于作为活性氧来源的吲哚美辛的Caco-2细胞中，评估了其抗氧化、保护线粒体和细胞以及抑制核因子-κB的作用，并与Que-BZF的作用进行了比较。达到最大保护效果所需的Que-BZF（100 nM）和Kae-BZF（1 nM）的浓度分别比其各自前体的浓度低50倍和5000倍。在比较Que-BZF和Kae-BZF抑制吲哚美辛诱导的核因子-κB激活的能力时，也发现了上述浓度差异。这些数据不仅表明槲皮素和山奈酚氧化转化为各自的2-苯甲酰基-2-羟基-3(2H)-苯并呋喃酮（BZF）会使其原始抗氧化性能大幅增强，而且还表明，就山奈酚而言，这种增强幅度比槲皮素大100倍。
