Fluorescence Properties Of Some Flavonoids And Fluorometric Analysis Of Total Isoflavones In Fermented Soybean

Fluorescence properties of 10 kinds of flavonoids?including flavonoids,isoflavones and anthocyanins?were studied.The new fluorometric method for the determination of total isoflavones in Chinese traditional medicine fermented soybean was established.The paper mainly includes the following four parts:1.The fluorescent properties of three isoflavone compounds?including7-methoxy-4'-hydroxyisoflavone,7,4'-dimethoxyisoflavone and 7-hydroxyisoflavone?were investigated.7-Methoxy-4'-hydroxyisoflavone has no fluorescence and is cleaved by heating under strong alkali conditions to produce fluorescence.The maximum excitation and emission wavelengths(?_ex/?_em)are 249/389 nm,and the fluorescence quantum yield is Y=0.006.The aqueous solution of 7,4'-dimethoxyisoflavone has weak fluorescence,?_em/?_ex=255 nm/490nm;in water-methanol solution with 70%methanol,Y=0.016;under strong alkaline conditions after heating,the product has fluorescence with?_em/?_ex=288 nm/390 nm,Y=0.0086.The acidic and near-neutral aqueous solution of 7-hydroxyisoflavone had weak fluorescence,and the fluorescence was enhanced under strong alkali conditions,?_ex/?_em=335/465 nm,Y=0.055;but,the fluorescence is quenched when pH>12.4.2.The fluorescent properties of four flavonoids?5-methoxyflavone,6-chloroflavonoid,7,8,3',4'-tetramethoxyflavone and 5-hydroxyflavone?were investigated.The aqueous solution of 5-methoxyflavone has fluorescence,?_em/?_ex=325 nm/464 nm,Y=0.008.6-chloroflavonoid aqueous solution has fluorescence,?_em/?_ex=305 nm/395 nm;heated under strong alkaline conditions,the fluorescence greatly enhanced,Y=0.49.The aqueous solution of 7,8,3',4'-tetramethoxyflavone has fluorescence,?_em/?_ex=340 nm/445 nm,Y=0.018.The aqueous solution of 5-hydroxyflavone has no fluorescence,and can not produce sensitized fluorescence under various experimental conditions.3.The fluorescence properties of three anthocyanin compounds?malvidin chloride,cyanidin chloride,cyanidin-3-O-glucoside chloride?were studied.The experimental results show that the malvidin chloride and the cyanidin chloride can produce fluorescence by heated under strong alkaline conditions;but the cyanidin-3-O-glucoside chloride is basically no fluorescence,and can not produce sensitized fluorescence.4.New fluorometric method for the determination of total isoflavones in Chinese traditional medicine fermented soybean was studied,and the experiment was carried out respectively by the routine fluorometric method,the three-dimensional fluorescence coupled with second-order correction method,and the three-dimensional fluorescence coupled with second-order correction method with correcting the inner filter effects.The results of the last method is the best.