ABSTRACT
Object To observe the differences of Isodon amethystoides (Benth.) C. Y. Wu et Hsuan, I. nervosa (Hemsl) Kudo and I. macrocalyx (Dunn) Kudo from different regions in their UV spectra, to make the applicability of the method of Detrended Correspondence Analysis (DCA) clear in the comparison of Chinese medicinal materials based on the UV spectra. Methods The UV spectra of the 15 samples of I. amethystoides, I. nervosa and I. macrocalyx from different regions and organs were obtained, based on the indices of wavenumber absorbance, the differences of 15 UV spectra were compared by DCA. Results(1) the UV spectra of I. amthystoides from different regions were very different; (2) the samples of I. macrocalyx (or I. nervosa) from the same region were rather similar in their UV spectra; (3) there were resemblances among I. nervosa, I. macrocalyx and I. amethystoides in their UV spectra.; (4) the difference of UV spectra between the stems and leaves were obvious. Conclusion The above results indicate: (1) the medicinal effects of I. amethystoides from different regions may be very different; (2) the stems and leaves of I. amethystoides are of different medical effects; (3) I. macrocalyx and I. nervosa could be considered as the substitutes of I. amethystoides. It is practical to apply DCA on the basis of UV spectra to compare the chemical differences of plant samples.