[Fluorescence spectra of Dichroa febrifuga aqueous extraction].

Fluorescence spectra of chang shan (Dichroa febrifuga Lour) aqueous extraction were studied. In the three-dimensional fluorescence contour spectrum, three fluorescence peaks of quinazoline alkaloids, which are the active components of chang shan, were observed. The excitation wavelengths of the peaks were 235, 270 and 320 nm, respectively, and the emission wavelength of all the peaks was 430 nm. Three-dimensional fluorescence contour spectrum is the very image of fingerprint, suitable for qualitative identification of traditional Chinese medicine. In the range of pH 3 to pH 6, the fluorescence spectrum of chang shan aqueous extractions changes with the variation in pH value. The reason for this spectral change might be the protonation of N-1 in quinazolone ring of beta-dichroine (febrifugine) molecule. There is an excellent linear relationship between the fluorescence intensity and the concentration of chang shan under nearly neutral conditions, thereby a quantitative method for the determination of quinazoline alkaloids may be established.