Investigation On Determination Methods Of Eleven Phenolic Compounds By High Performance Liquid Chromatography

The phenol compound, including phenol acid, flavonoid and other compound, widely exists in the natural plants, and is a kind of ubiquitous complex compound in the mankind foods. The phenol acid and flavonoid among the phenol compound possess the remarkable biological and pharmacological activity and can be used to treat some common or frequent disease. In this thesis, the HPLC method combined with off - line pre - column reaction or enhancive sensitivity by mobile phase addition agent was established to detect the eleven phenol compounds. The present studies hold very important significances in both the quality control of Chinese traditional medicine and the broadening application range of HPLC. This thesis consists of four chapters. The author's main works are as follows:1. The determination methods of two compounds (caffeic acid and baicalin) in Shuanghuanglian injection, three compounds (protocatechuic acid, p - coumaric acid and luteolin) in Scutellaria barbata, and five compounds (gallic acid, chlorogenic acid, p - coumaric acid, lutin and quercetin) in Folium Eucommiae leaves were established by HPLC, respectively. The experiment results showed that the recoveries of caffeic acid and baicalin in Shuanghuanglian injection were 108.0% (RSD=1.2%, n=5) and 99.7% (RSD = 1.6%, n = 5); the recoveries of three compounds in Scutellaria barbata ranged from 95.3% to 106.4% with RSDs of 1.5-5.6%; and the recoveries of five compounds in Folium Eucommiae leaves ranged from 97.8% to 106.4% with RSDs of 1.6-3.3%. The studies are reproducible and accurate, which can be used for the simultaneous determination of caffeic acid and baicalin in Shuanghuanglian injection, and provide both the scientific basis for the further exploitation and the quality control of Scutellaria barbata and Folium Eucommiae leaves.2. An HPLC - ECD-DAD method for simultaneous separation and determination of the contents of chlorogenic acid, caffeic acid, ferulic acid, lutin, quercetin and luteolin in Houttuynia cordata, Cirsium setosum, Portulaca Oleracea L and Taraxacum mongolicum was established. As a result, all calibration curves showed good linearity (r≥0.9996) and the average recoveries of six compounds ranged from 94.0% to 102.5% (RSD≤2.8%). Compared with HPLC - DAD, HPLC -ECD is more sensitive for determination of electrochemical active compounds. Compared with HPLC-DAD or HPLC - ECD, HPLC - ECD - DAD is a rapid, simple and performs simultaneous determination method of multi - components.3. A new method of HPLC - ECD - DAD using off- line pre - column reaction for the investigation of hydroxyl radical scavenging capacity of chlorogenic acid, ferulic acid and quercetin was established. Moreover, the method was utilized to investigate hydroxyl radical scavenging capacity of Eucommia ulmoides, Viola yedoensis, Mulberry leaf, Imperata eylindrica and Lonicera japonica thumb. As a result, the 50% inhibition concentration (IC₅₀) order of hydroxyl radical scavenging of three compounds was chlorogenic acid > ferulic acid > quercetin. The hydroxyl radical scavenging of Eucommia ulmoides, Viola yedoensis, Mulberry leaf, Imperata eylindrica and Lonicera japonica thumb was 58.3%, 6.5%, 10.2%, 8.6% and 37.3%, respectively. The method can be utilized to identify the components of the Chinese herb with antioxidation function.4. Using sodium dodecylsulfonate as sensitizer, a new HPLC - ECD method for determination of apigenin in three Chinese herbs and two vegetables was established. As a result, the linear range of apigenin was 0.14-177.27μg·mL^-1(r = 0.9999). The recoveries were 96.0 - 103.7% (RSD≤2.5%). Compared with HPLC - DAD, this new method is more sensitive.