Quercetin (Qu), a noted polyphenolic flavonol molecule, exhibits remarkable antioxidant properties against bioenzymes like peroxidase and tyrosinase. However, it was found that under pH = 3.5–5.5 and room temperature, Qu cannot reduce hydrogen peroxide (HP) which is a well-perceived reactive oxygen species (ROS) responsible for oxidative stress. We found that in presence of noble-metal nano-particles, such redox interactions can be accomplished. We thus synthesized homogenous PVP-coated nano-platinum particles (PNP) to catalyze the oxidation of Qu by HP. On reaction, Qu is oxidized by HP to ortho-quinone (QQ) following the first-order kinetics. The observed rate constant, k_o, gradually increases and tends to saturate with increasing [HP]_T where T represents the analytical concentrations of the reactant. The saturation kinetics indicates that the activities of PNP resemble to that of bioenzymes and similarly, the nano-particles host the reactants on its active surface during the redox interactions. The estimated value of the k_cat reveals that the extent of catalysis of even 10⁻¹⁰ M PNP is nearly comparable with the rate constants of oxidation of Qu in presence of enzymes like horseradish peroxidase and tyrosinase.

Quercetin (Qu) is a ubiquitous natural antioxidant. However, in acidic buffer media (pH = 3.5–5.5), hydrogen peroxide (HP) cannot oxidize Qu. Strikingly, in presence of nano-platinum particles (PNP), Qu is promptly oxidized by HP to ortho-quinone following the first-order kinetics. PNP hosts the reactants on its active surface during the redox interactions. The saturation kinetics with respect to HP resembles to enzyme-like activities of PNP, and indeed, the calculated value of the rate constant, k_cat, is comparable with those of the rate constants of enzyme-mediated oxidation of Qu.

槲皮素（Qu）是一种著名的多酚类黄酮醇分子，对过氧化物酶和酪氨酸酶等生物酶表现出显着的抗氧化性能。但是，发现在pH = 3.5-5.5和室温下，Qu不能还原过氧化氢（HP），过氧化氢是引起氧化应激的公认的活性氧（ROS）。我们发现，在存在贵金属纳米颗粒的情况下，可以实现这种氧化还原相互作用。因此，我们合成均质PVP涂覆纳米铂粒子（PNP）催化的氧化曲由HP。反应时，Qu被HP氧化为邻醌（QQ）遵循一级动力学。观察到的速率常数k _o随着[ HP ] _T的增加而逐渐增加并趋于饱和，其中T表示反应物的分析浓度。饱和动力学表明PNP的活性类似于生物酶的活性，并且类似地，在氧化还原相互作用期间，纳米颗粒在其活性表面上容纳反应物。k _cat的估计值表明，即使10 ^-10 M PNP的催化程度也几乎与Qu的氧化速率常数相当 存在诸如辣根过氧化物酶和酪氨酸酶之类的酶。

槲皮素（Quercetin（Qu））是一种普遍存在的天然抗氧化剂。但是，在酸性缓冲液（pH = 3.5–5.5）中，过氧化氢（HP）不能氧化Qu。令人惊讶的是，在存在纳米铂粒子（PNP）的情况下，Qu会按照一级动力学迅速被HP氧化为邻醌。在氧化还原相互作用期间，PNP将反应物承载在其活性表面上。关于HP的饱和动力学类似于PNP的酶样活性，实际上是速率常数k _cat的计算值与酶介导的Qu的氧化速率常数相当。