@misc{oai:repo.qst.go.jp:00084368,
 author = {Ikuo, Nakanishi and Yoshimi, Shoji and Kei, Ohkubo and Megumi, Ueno and Matsumoto, Ken-ichiro and Kiyoshi, Fukuhara and Hiroki, Hamada and Ikuo, Nakanishi and Yoshimi, Shoji and Kei, Ohkubo and Megumi, Ueno and Kenichiro, Matsumoto},
 month = {Dec},
 note = {Resveratrol (1), 3,5,4'-trihydroxy-trans-stilbene, found in grapes is one of the representative antioxidants that shows a plethora of remarkable biological properties. On the other hand, pterostilbene (2), a methylated analog of 1, has attracted much attention due to its enhanced bioavailability as compared to that of 1. However, little is known about the radical-scavenging mechanism of 2. There are two mechanisms in the radical-scavenging reaction of phenolic antioxidants: a one-step hydrogen-atom transfer from the phenolic OH group; and an electron transfer followed by proton transfer. Redox inactive metal ions, such as magnesium ion (Mg2+), are a powerful tool to distinguish between these two mechanisms, because electron-transfer reactions are known to be accelerated by their presence. In fact, a significant acceleration in the radical-scavenging reaction of 1 was observed in the presence of Mg2+ in acetonitrile (MeCN), suggesting that the reaction may proceed via the electron-transfer mechanism (Chem. Lett. 2007, 36, 1276). We report herein the effect of Mg2+ on the scavenging reaction of galvinoxyl radical (GO) by 2 in MeCN. GO has been frequently used as a reactivity model of reactive oxygen radicals to estimate the activity of antioxidants.
Upon mixing of 2 with GO on a UNISOKU RSP-1000-02NM stopped-flow spectrophotometer in MeCN at 298 K, a gradual decrease in the absorption band at 428 nm due to GO was observed, indicating that 2 efficiently scavenged GO. From the time course change in the absorbance at 428 nm, the second-order rate constant (k) for the reaction between 2and GO was determined to be 1.3 × 10 M−1 s−1, which is about 3-fold larger than that of 1 (4.1 M−1 s−1). When Mg(ClO4)2 (0.1−0.3 M) was added to the 2−GO system, no effect of Mg2+ on the k values was observed. Thus, the GO-scavenging reaction by 2 may proceed via the one-step hydrogen-atom transfer rather than the electron transfer followed by proton transfer., PACIFICHEM 2021},
 title = {Effect of Magnesium Ion on the Radical-Scavenging Reaction of Pterostilbene and the Mechanism},
 year = {2021}
}