Fluorimetric Analysis Of Methyl Salicylate, Daidzin And Daidzein In Chinese Herbal Medicine

Fluorescence spectra of methyl salicylate, daidzin and daidzein, active components of Chinese herbal medicine, were studied in this thesis. Fluorimetric method for determination of methyl salicylate in Speranskia Tuberculata (Bge.) Baill (Tougucao in Chinese), daidzin in Puerariae Lobatae Radix (Gegen in Chinese) and Puerariae Thomsonii Radix (Fenge in Chinese) were eatablished, and the reliability of the new methods was verified by thin-layer scanning method.Four parts were included in this thesis:1. Fluorescence spectra of methyl salicylate and its hydrosis product were studied. The fluorescence of methyl salicylate was wery weak, but the fluorescence of its hydrosis product was very strong, with maxmum emission wavelength at 405 nm and excitation wavelengths at 230 nm and 295 nm. Influence of acidity, temperature and heating time on hydrolysis was investegatied. Using L-tryptophan as a reference, fluorescence quantum yield of hydrolyzed methyl salicylate were measured to be 0.224. The hydrolysis product of methyl salicylate was proved to be salicylic acid by comparation of fluorescence spectra.2. A new fluorimetric method, without preseperation, for determination of methyl salicylate in Chinese medicine Tougucao was established, the content of methyl salicylate in a Tougucao sample was deternined to be 0.262%. A thin-layer scanning method for determination of methyl salicylate in Tougucao was also proposed, the obtained result was essentially the same as that of the fluorimetric method.3. Fluorescence spectra of daidzin and daidzein were studied. The fluorescence of daidzin was wery weak, but the fluorescence of its hydrosis product was very strong, with maxmum emission wavelength at 394 nm and excitation wavelengths at 248 nm and 292 nm. Influence of experimental conditions on hydrosis was investigated. Using L-tryptophan as a reference, fluorescence quantum yield of hydrolyzed daidzin was measured to be 0.017. Fluorescence of daidzein was closely related to pH, the strongest fluorescence was observed at about pH9.4, with emission wavelength at 466 nm and excitation wavelengths at 260 nm and 339 nm, and fluorescence quantum yields was measured to be 0.022. The hydrosis product of daidzin was not daidzein.4. New fluorimetric methods, without preseperation, for determination of daidzin in Chinese herbal medicine Gegen and Fenge were established. The contents of daidzin in Gegen and Fenge commercial drugs were deternined to be 0.984% and 0.138%, respectively. Thin-layer scanning methods for determination of daidzin and daidzein in Gegen and Fenge were also established, the obtained results were essentially the same as that of the fluorimetric methods.