[Study on traditional Chinese medicine extracts of rhizoma coptidis by FTIR spectroscopy]

In the present paper, we applied Fourier transform infrared spectroscopy (FTIR) and second derivative infrared spectroscopy to establish a rapid and efficient analytical method for a preliminary quality control of medicinal herb extracts. The commonly used Chinese herb medicine, Rhizoma coptidis, was taken as an example. The main component-berberine in rhizoma coptidis was analyzed as target compound. The results indicated that the IR spectra of rhizoma coptidis herb, its water and alcohol extracts, exhibit their macroscopic fingerprint characters with fine repeatability, and the corresponding secondary derivative spectra further confirmed the spectral characteristics of the original IR spectra by enhancing spectral resolution. The typical and strongest absorption band of IR spectrum of berberine is at 1,505 cm(-1), which is assigned to aromatic skeleton vibration band, and its intensities in spectra of rhizoma coptidis herb and its different extracts become the main identification standard of the contents of berberine in those samples. In addition, comparing the IR spectra of the medicinal herb and its extracts, it was shown that the main bioactive components, alkaloids in rhizoma coptidis herb, are enriched by extraction, and the contents of berberine in alcohol extracts of rhizoma coptidis are higher than those in water extracts. The spectroscopic technique described is a simple and rapid analytical technique, which could provide valuable information about chemical constituents of medicinal extracts for guiding further chromatographic analysis and separation improvement.