Scutellariae Radix-Coptidis Rhizoma(SR-CR) herbal pair is commonly used in many compound prescriptions for their synergistic heat-clearing and dampness-drying properties. During the decoction process, a substantial amount of precipitate is generated. However, there have been no explicit reports on the composition, morphology, and potential effects of this precipitate on the in vivo behavior of SR-CR decoction. This study employed high-performance liquid chromatography(HPLC), high-resolution mass spectrometry, and other techniques to analyze the composition of the co-precipitate in the decoction of SR-CR. Scanning electron microscopy and mass spectrometry imaging were used to analyze its appearance and morphology. Additionally, rats were used to investigate the effects of the co-precipitate on the in vivo behavior of the main components in the SR-CR decoction. The research findings indicated that eight components, including coptisine, berberine, epiberberine, palmatine, baicalin, oroxylin A-7-O-β-D-glucuronide, wogonoside and baicalein, constituted the primary composition of the co-precipitate. Among these, baicalin and berberine hydrochloride were the most abundant, accounting for about 60% of the total weight. Moreover, the co-precipitate contained 18% tannins. Morphological analysis revealed that the particles in the SR-CR decoction precipitate were spherical microparticles with an average diameter of around 600 nm. Pharmacokinetic research demonstrated that there were significant differences in the AUC, C_(max), t_(1/2), and T_(max) of baicalin, a major component, in rats administered with lyophilized powders of the combined decoction and single decoctions of SR-CR orally, suggesting that the precipitate generated during the decoction process can affect the in vivo behavior of the main components of the SR-CR decoction. It can reduce the absorption of baicalin in the body, decrease the extent of rapid drug release, and to a certain extent, prevent adverse reactions or side effects.
Keywords: Scutellariae Radix-Coptidis Rhizoma; co-precipitate; composition; morphology; pharmacokinetic.