Reaction of hydroxyl radical with phenylpropanoid glycoside and its derivatives by pulse radiolysis

The reaction of hydroxyl radical with 1 phenylpropanoid glycoside (PPG), cistanoside C, and its 3 derivatives: I-O-β-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-( E)-feruloyl-glucose and 6-O-( E)-p-hydroxy-cinnamoyl-glucose isolated from folk medicinal herbs was investigated by pulse radiolysis technique respectively. The reaction rate constants were determined by analysis of built-up trace of absorption at λmax of specific transient absorption spectra of PPG and its derivatives upon attacking ·OH. All four compounds react with ?OH at close to diffusion controlled rate (1. 03 x 109-19.139X 109L·mol-1·s-1), suggesting that they are effective ?OH scavengers. The results demonstrated that the numbers of phenolic hydroxyl groups of PPG and its derivatives are directly related to their scavenging activities. By comparing the reaction rates of ·OH with l-O-β-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-(E)-feruloyl-glucose or 6-O-(E)-p-hydroxy-cinnomoyl-glucose, it is evident that the phenylethyl group is more important than phenylacryloyl group for scavenging ?OH.

The reaction of hydroxyl radical with 1 phenylpropanoid glycoside （ PPG）, cistanoside C, and its 3 derivatives: 1-O-β-D-2-（p-hydroxyphenyl）-ethanyl-glucose, 6-O-（E）-feruloyl-glucose and 6-O-（E）-p-hydroxy-cinnamoylglucose isolated from folk medicinal herbs was investigated by pulse radiolysis technique respectively. The reaction rate constants were determined by analysis of built-up trace of absorption at λmax of specific transient absorption spectra of PPG and its derivatives upon attacking·OH. All four compounds react with·OH at close to diffusion controlled rate (1.03×109—19.139×109 L·mol-1·s-1), suggesting that they are effective·OH scavengers. The results demonstrated that the numbers of phenolic hydroxyl groups of PPG and its derivatives are directly related to their scavenging activities. By comparing the reaction rates of·OH with 1-O-β-D-2-（p-hydroxyphenyl）-ethanyl-glucose, 6-O-（E）-feruloyl-glueose or 6-O-（E）-p-hydroxy-cinnomoyl-glucose, it is evident that the phenylethyl