Objective To investigate the phase changes and component distribution patterns during the decoction process by performing phase separation and characterization of Baihe Dihuang Decoction (BDD, 百合地黄汤) at different decoction times, and provide a reference for elucidating the material basis of synergistic effects of components in traditional Chinese medicine formulas. Methods BDD was decocted for 20, 40, 60, 80, 100, and 120 min to obtain the decoctions. The sediment phase and nanophase solutions were separated using the “high-speed centrifugation-dialysis” method. The two phases were characterized by scanning electron microscope, laser particle size analyzer, ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy. The fingerprint spectra of BDD and its different phases were constructed using HPLC method, and chemometric methods were applied to screen key differential components among different phases, followed by content determination of the main differential components. Results The nanophase of BDD exhibited the smallest particle size, while the original decoction showed the largest particle size. The particle size of the nanophase initially increased and then decreased with prolonged decoction time, eventually stabilizing, and the stability of nanophase gradually enhanced. The contents of polysaccharides and proteins increased progressively with prolonged decoction time, and both the nano-sized fraction and the precipitated fraction were found to be rich in polysaccharides. Spectral analysis revealed that the chemical structures of components in the original decoction and each phase at different decoction times were generally similar, but differences in functional group contents were observed. Fingerprint analysis combined with hierarchical cluster analysis (HCA) and partial least squares-discriminant analysis (PLS-DA) showed that the types of chemical components in different phases of BDD were similar, but their contents differed significantly. The effect of decoction time on components was smaller than that of phase state. A total of 12 key differential components among different phases were screened. The average contents of five indicator components catalpol, regaloside C, regaloside A, regaloside B, isoverbascoside in the nanophase were higher than those in the sediment phase and the original decoction. Conclusion During the decoction process, BDD interacts with each other, resulting in significant differences in the content of active ingredients among various phases. The nanophase achieves enrichment of active components, suggesting that it may be the main effective phase of BDD.

Baihe Dihuang Decoction  /  phase state  /  nanophase  /  decoction time  /  catalpol  /  regaloside C  /  regaloside A  /  regaloside B  /  isoverbascoside