Quantum Chemical Study on the Antioxidation Mechanism of Piceatannol and Isorhapontigenin toward Hydroxyl and Hydroperoxyl Radicals

Abstract

A systematic study of the antioxidation mechanisms behind hydroxyl (•OH) and hydroperoxyl (•OOH) radical scavenging activity of piceatannol (PIC) and isorhapontigenin (ISO) was carried out using density functional theory (DFT) method. Two reaction mechanisms, abstraction (ABS) and radical adduct formation (RAF), were discussed. A total of 24 reaction pathways of scavenging •OH and •OOH with PIC and ISO were investigated in the gas phase and solution. The thermodynamic and kinetic properties of all pathways were calculated. Based on these results, we evaluated the antioxidant activity of every active site of PIC and ISO and compared the abilities of PIC and ISO to scavenge radicals. According to our results, PIC and ISO may act as effective •OH and •OOH scavengers in organism. A4-hydroxyl group is a very important active site for PIC and ISO to scavenge radicals. The introducing of -OH or -OCH3 group to the ortho-position of A4-hydroxyl group would increase its antioxidant activity. Meanwhile, the conformational effect was researched, the results suggest that the presence and pattern of intramolecular hydrogen bond (IHB) are considerable in determining the antioxidant activity of PIC and ISO.

A Theoretical Study on the Antioxidant Activity of Piceatannol and Isorhapontigenin Scavenging Nitric Oxide and Nitrogen Dioxide Radicals

“…While among the conformers of isorhapontigenin, ISO and ISO-I have relative lower and similar energies. According to the bond dissociation energy (BDE) obtained by Lu etc., PIC and ISO have lower BDE values and thus have higher reactivity than PIC-I and ISO-I, respectively [32]. Therefore, in this work, PIC and ISO were chosen out from their conformers.…”

“…In the previous study, the radical scavenging activity of PIC and ISO toward ·OH and ·OOH were theoretically investigated using the same method of M05-2X/6-311++G(d,p), and the reaction energy barriers with ZPE corrections for HAT and RAF mechanisms were also obtained [32]. We gathered Δ G ≠ sol values of the major channels in water solution of PIC and ISO scavenging ·OH, ·OOH, NO and NO 2 in Table 5, in order to research the features of PIC and ISO scavenging radicals in vivo.…”

“…It is can be found that these research are concerned only with ROS, however RNS as another kind of harmful radical in vivo were ignored. As for as ISO, in previous our team theoretically investigated the antioxidant mechanisms of ISO and PIC scavenging two ROS (·OH and ·OOH) [32], no studies addressed the scavenging activity of ISO toward some specific radicals until quite recently.…”

A theoretical study of the radical scavenging activity of natural stilbenes

“…Natural stilbenes are also good antioxidants 5 and thus the radical scavenging activity of this class of compounds is an active area of research. [6][7][8][9][10][11][12][13][14][15][16] As one of the antioxidant polyphenols found in red wine, resveratrol and its derivatives gained much attention. 6,8,9,11,12,15,17,18 Several studies demonstrated that the radical scavenging abilities of resveratrol and its metabolite piceatannol are higher than that of Trolox, the universally accepted benchmark.…”

Isorhapontigenin induced cell growth inhibition and apoptosis by targeting EGFR‐related pathways in prostate cancer

“…Isorhapontigenin (ISO), a natural compound extracted from Chinese herb Belamacanda Chinensis , Gnetum Cleistostachyum , and grapes, is a resveratrol analogue which is widespread in plants and belongs to the group of naturally occurring polyhydroxy stilbenes (Lu, Wang, Shi, Zhang, & Li, ; Wang, Lin, & Liu, ). It has been reported that ISO plays an important role in anti‐oxidative and anti‐inflammatory (Kawakami et al, ; Xu et al, ), and it has also been revealed that ISO exhibits anti‐proliferation effect in multiple human cancers (Fang et al, , ; Siddiqui, Ahad, & Ahsan, ).…”