New qualities control strategy of Scutellaria baicalensis by isothermal titration calorimetry

Abstract

It has been focused on that there will be precipitates when decoction of Scutellariat Radix mixed with Coptidis Rhizoma. Precipitation was derived from interaction between acidic and basic compounds. This study was based on the interaction between active ingredients after compatibility, strived to explore whether it was feasible to judge the qualities of different Scutellariat Radix by isothermal titration calorimetry (ITC), build a new method established to characterize the qualities of traditional Chinese medicine by taking a series of active ingredients as index. We selected Scutellariat Radix (including three batches of different Scutellariat Radix bought from market and immature Scutellariat Radix which usually was used as adulterant) in different batches as the samples. First, we used ITC to determine the binding heat of the reactions between berberine and the decoctions of different Scutellariat Radix. The test showed that the binding heat of berberine titrated Scutellariat Radix was Scutellariat Radix A (－317.20 μJ), Scutellariat Radix B (－292.83 μJ), Scutellariat Radix C (－208.95 μJ) and immature Scutellariat Radix (－21.53 μJ), respectively. We chose deionized water titrated by berberine (2.51 μJ) as control. The heat change of berberine titrated immature Scutellariat Radix was much less than berberine titrated Scutellariat Radix. Then we determined the absorbance of different decoctions of Scutellariat Radix by UV Spectrophotometry on the maximum absorption wavelength, and the result is： Scutellariat Radix A (0.372), Scutellariat Radix B (0.333), Scutellariat Radix C (0.272), immature Scutellariat Radix (0.124). The absorbance of immature Scutellariat Radix was also less than Scutellariat Radix. The result of ITC assay was corresponded to UV spectrophotometry test. In conclusion, ITC could be used to characterize the quality of Scutellariat Radix. The new method to characterize the qualities of traditional Chinese medicine by taking a kind of active ingredients as index building by ITC was simple, scientific and feasible.