Spectral Properties And Fluorimetric Analysis Of Active Components Of Chinese Medicine Caodoukou And Huangqin

Fluorescence spectra and absorption spectra of Chinese herbal medicine Alpinia katsumadai Hayata (AKH, Caodoukou), Scutellaria baicalensis Gcorgi (SBG, Huangqin) and their active components alpinetin, cardamonin, baicalin, baicalein and scutellarein had been studied. Based on their spectral properties, fluorimetric methods for the analysis of alpinetin and cardamonin in AKH as well as baicalin in SBG had been developed. By comparing the fluorescence spectra of ten flavonoids, relationship between fluorescence and molecular structure was discussed.The main contents of the thesis were as follows:1. Spectral properties of AKH and its active component, and fluorimetric analysis of alpinetin and cardamonin in AKH sampleFluorescence and absorption spectra of alpinetin were studied. Influences of pH and solvent on fluorescence were investigated. Using L-Trp as a reference, fluorescence quantum yield of alpinetin was determined to be 0.033 at excitation wavelength 290 nm under pH 5.3. The ionization constant was determined to be pKa= 6.96 by an absorption method.Cardamonin had basically no fluorescence. After heating 3 hours at 100oC under pH 5.3, cardamonin could be completely transformed into alpinetin. The ionization constants were measured to be pKa1=7.06 and pKa2=9.84, by an absorption method.A fluorimetric method for the determination of alpinetin and cardamonin in AKH was proposed. The content of alpinetin and cardamonin in AKH sample were determined to be 0.59% and 0.44%, respectively.2. Spectral properties of SBG and its active component, and fluorimetric analysis of baicalin in SBG sampleBaicalin had very weak fluorescence. After addition of borax, fluorescence peaks were found at 325/420 nm and 270/420 nm. Using quinine bisulfate as a reference and the concentration of borax was 0.01 mol l-1, fluorescence quantum yield of baicalin was measured to be 0.018 at excitation wavelength 330 nm. When the concentration of borax was 0.01 mol l^-1, a linear relationship between fluorescence intensity and baicalin concentration was found. The content of baicalin in SBG sample was determined to be in the range of 8.02%～8.95 %. The fluorescence of baicalein and scutellarein were very week before and after addition of borax, so they should not interfere with the analysis of baicalin in SBG.3 Relationship between fluorescence and molecular structure of flavonoid was discussed, by comparing three-dimensional fluorescence spectra of ten flavonoids.