Studies On Fluorescent Properties And Analytical Methods Of Several Kinds Of Flavonoids

Fluorescent properties of 4 kinds of flavonoids, including flavonoid(2-phenylchromone),7-hydroxyflavone, tangeretin and lysionotin, were studied. UV absorption spectra of7-hydroxyflavone and lysionotin were also studied, and the dissociation constants of7-hydroxyflavone and lysionotin were measured. The feasibility of analysis of lysionotin in traditional Chinese medicine Fewflower Lysionotus(Shidiaolan) by fluorometric method was probed. A HPLC method for the determination of lysionotin in Shidiaolan was established.Two parts were included in the thesis:1. Fluorescent properties of flavonoid and its hydrolysate were studied. Flavonoid has no fluorescence, but it can hydrolyze in strong alkaline solutions, and therefore produce strong fluorescence. Influences of experimental conditions on the fluorescence of the hydrolysate were tested. The fluorescence quantum yield of the hydrolysate was measured to be 0.39.Fluorescence spectra and UV absorption spectra of 7-hydroxyflavone were studied. Influences of experimental conditions on the fluorescence of 7-hydroxyflavone were tested. It was found that the fluorescence of 7-hydroxyflavone can be sensitized by addition of CTAB.Fluorescence quantum yields of 7-hydroxyflavone before and after addition of CTAB were measured to be 0.0035 and 0.0099, respectively. The dissociation constant of7-hydroxyflavone was determined to be p Ka = 7.30 by a p H-absorption method. Fluorescent properties of tangeretin were studied. It was found that tangeretin can produce weak fluorescence, and the fluorescence can not be sensitized by changing experiment conditions.2. Fluorescence spectra and UV absorption spectra of lysionotin, a medicinal component of Chinese herbal medicine Shidiaolan, were studied. Influences of experimental conditions on the fluorescence of lysionotin were tested. Fluorescence quantum yield of lysionotin was measured to be 0.014. The dissociation constants of lysionotin were determined to be p Ka1 =6.08, p Ka2 = 9.22, by a p H-absorption method. It was found that the fluorescence of lysionotin in Shidiaolan was quenched by coexisting components, so the content of lysionotin in Shidiaolan can not be determined by fluorometric method. A HPLC method was established for the determination of the content of lysionotin in a Shidiaolan sample, and the result obtained was 0.307 %.