Fluorescence Property And Analysis Of Mangiferin And Puerarin In Chinese Herbal Medicine

Fluorescence property of mangiferin and puerarin, active components of Chinese herbalmedicine Mangguoye and Gegen, respectively, were studied in this thesis. Influences ofexperimental conditions on fluorescence spectra were investigated. Molar fluorestivities,fluorescence quantum yields and ionization constants of mangiferin and puerarin weremeasured under the best conditions. Fluorometric methods were proposed for the analyses ofmangiferin in Mangguoye and puerarin in Gegen, respectively.Four parts were included in this thesis:1. Fluorescence spectra of mangiferin were studied. The influence of acidity, solvent andsurfactant on spectral properties, the stability, and the linear relationship between fluorescenceintensity and concentration were investigated. Molar fluorestivity of mangiferin wasmeasured to be6.84×10^-6L mol^-1with pH8.27.2. Fluorescence property of Mangguoye methanol extraction was studied, and it wassimilar with that of the mangiferin. Using a thin-layer fluorescence scanning method, weverified that the fluorescence of mangiferin was not disturbed by other ingredients ofMangguoye. Based on this fact, a fluorometric method for determination of mangiferin inMangguoye was proposed, and the content of mangiferin in Mangguoye was determined to be4.79%and4.62%, by a standard curve method and a standard addition method, respectively.3. Fluorescence spectra of puerarin were studied. The influence of acidity on spectralproperty, the stability, and the linear relationship between fluorescence intensity andconcentration were investigated. Using quinine sulfate as a reference, fluorescence quantumyield of puerarin in weakly alkaline solution （pH8.3） was measured to be0.069. By afluorescence method, the ionization constants of puerarin were measured to be pK_a1=6.96and pK_a2=9.93, respectively.4. Fluorescence property of Gegen methanol extraction was studied. The fluorescenceproperty of Gegen methanol extraction, puerarin and daidzein were similar with each other.Since the content of puerarin was much higher than that of daidzein in Gegen, a fluorometricmethod was proposed for the determination of total amount of puerarin and daidzein in Gegenmedicinal materials.