| The flavonoids of three medicinal plants (Leontopodium haplophylloides Hand.Mazz.; Elsholitzia bodinieri Vaniot.; Centaurea picris)were studied in this thesis, which consists of three parts as follows:1. Studies on the chemical constituents of Leontopodium haplophylloides Hand.Mazz.The recent development of the chemical constituents and bioactive study on Leontopodium haplophylloides Hand.Mazz. were briefly reviewed. The chemical constituents of the ethanol extracts from Leontopodium haplophylloides Hand.Mazz. were systematically investigated and twelve compounds were isolated and purified by means of column chromatography. These compounds were identified by their spectral data as: 5,7,4'-trihydroxy-3'- methoxyflavone, 7- hydroxy-5- methoxyflavone, pinocembrin, galangin, 5,7,4'- trihydroxy-3',5'-dimethoxyflavone, luteolin, luteolin-4'-O-β-D-glucoside, luteolin-7-O-β-D-glucoside, cosmosiin,β-sitosterol, daucosterol.2. Determination of total flavonoids in Leontopodium haplophylloides Hand. Mazz. by three-wavelength spectrophotometryQuantitative determination of flavonoids in Leontopodium haplophylloides Hand. Mazz. by three-wavelength spectrophotometry method were developed. It can eliminate the absorbance error caused by interfering components in turbid solution and the scattering effect.Background changed with the concentration changed and asymmetric absorption peak problems can also be eliminated by three wavelength method. The flavonoids in Leontopodium haplophylloides Hand. Mazz. with aluminate to produce stable complex which absorption there was red shift of longer wavelength. The content of total flavonoids in Leontopodium haplophylloides Hand. Mazz. is 2.46%. The regression equation of concentration(X) ?A(Y) was obationed: Y=0.00419+0.03315X, correlation coefficient R=0.9998. The experimental results demonstrate the total flavonoids concentrations in 2.0012.00μg·mL-1 with ?A obeying linear relation results measured the absorbance at wavelengthλ1=310 nm,λ2=350 nm,λ3=460 nm. The average recovery is 97.6% and the coefficient of variation is 2.4%(n=5). The method is accurate, precise and feasible for the determination of the contents of total flavonoids in plants3. Study on Determination of luteolin-7-O-β-D-glucoside by HPLC and UVHPLC and UV methods were used to determine the content of luteolin-7-O-β-D -glucoside obtained from Elsholitzia bodinieri Vaniot. Results showed that no distinct difference exists between the two methods. The contents of luteolin-7-O-β-D -glucoside determinated by the two methods were 98.39% and 98.38%. The corresponding average recoveries of these methods were 99.5%(n=5) and 99.3%(n=5),respectively. Both of the methods can be used for the determination of the content of luteolin-7-O-β-D-glucoside for quality control of the product .4. Study on Method for Determination of luteolin in Centaurea picris by Reverse Phase High Performance Liquid ChromatographyA method of HPLC analysis of luteolin was developed for the determination in Centaurea picris. The Agilent Zorbax C18 (21 mm×150 mm,5μm) column was used at 30℃with methanol-4‰phosphoric acid (50:50) as the mobile phase. The flow rate was 0.3 mL·min-1. The detection wavelength was 360 nm. Luteolin and its primary impurity can be separated obviously. The content of luteolin in Centaurea picris was 9.3×10-5g·g-1. The linearity of the calibration cure was good in the range of 2.0×10-9～1.8×10-7 g for luteolin with the correlation coefficient 0.9999. The average recovery of luteolin was 100.6%. The method is reliable, sensitive and highly reproducible ; Luteolin in Centaurea picris exists almost in the form of free aglycone.
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