Isolation, identification and determination of methyl caffeate, ethyl caffeate and other phenolic compounds from Polygonum amplexicaule var. sinense

Polygonum amplexicaule D. Don (Polygonaceae) (Chinese name: Xuesanqi) is a widely distributed medicinal plant in China. It has been used in folk medicine to treat many common and frequently-occurring diseases, such as cardiovascular and cerebrovascular diseases, fractures, pain, etc. Thus, this plant has been of interest to researchers. However, the chemical constituents of Xuesanqi have not been investigated systematically. This study isolated and identified some effective compounds in this plant. The structure of important active chemicals of Xuesanqi from different regions was determined for the first time. Twelve phenolic compounds were isolated from this plant. Vanillin, isovanillic acid, p-hydroxyphenethyl alcohol, dihydro-kaempferol, and 5,7-dihydroxychromone were determined for the first time fromPolygonum. As markers for quality standard of this herb, the content of methyl caffeate and ethyl caffeate was determined by HPLC. It was found that Xuesanqi from Wufeng, Lichuan, Badong Counties in Hubei Province and Jiujiang City of Jiangxi Province had higher content of both chemicals. The results suggest that the herb might be a potential source of phenolic compounds of an agent for improving blood circulation, treating various fractures, muscle and tissue swelling, and pain.   Key words: Chemical constituents, Xuesanqi, analysis, high-performance liquid chromatography (HPLC).