[Comparison on material basis between single and co-decoctions of Rhei Radix et Rhizoma and Coptidis Rhizoma by supramolecular chemistry]

This study employed supramolecular chemistry of traditional Chinese medicine to compare the material basis between different decocting methods(co-decocting and single decocting) and explained the chemical basis of Rhei Radix et Rhizoma-Coptidis Rhizoma in alleviating the disadvantage of bitter and cold medicines damaging the stomach. The spectroscopic differences between the co-decoction and single decoctions were characterized by ultraviolet-visible absorption spectrum, infrared spectrum, and circular dichroism spectrum. Five characteristic alkaloids, such as berberine, were selected as the indicators to compare the sample solubility and dissolution of medicinal components between the co-decoction and single decoctions by high performance liquid chromatography. The chemical components and their total content were similar between the co-decoction and single decoctions of Rhei Radix et Rhizoma and Coptidis Rhizoma. The medicinal components in the co-decoction interacted with each other to form supramolecular parts. The dissolution and release of supramolecular parts in the aqueous solution was slow, which explained the lower component content in the co-decoction than that in single decoctions. In addition, the adsorption of medicinal components by the residue of decoction pieces during decocting was also a factor causing the difference of material basis between different decocting methods. This study compared the material basis between the co-decoction and single decoctions of Rhei Radix et Rhizoma and Coptidis Rhizoma from the dynamic changes of components, which provided a basis further explaining the scientific connotation of the compatibility of the two medicines in reducing the bitter and cold medicinal natures.