Attribution and identification of absorbed components by HPLC-DAD-ESI-MS after oral administration of Erhuang decoction

Supramolecular interaction between berberine hydrochloride and baicalin in aqueous solution: Reaction kinetics, spectral analysis and dynamic simulation

The current study presents a comprehensive investigation on the precipitation reaction and supramolecular interactions between berberine hydrochloride (BBR) and baicalin (BA) in an aqueous system. Utilizing a combination of multi-spectral analytical techniques and molecular dynamic simulations, we elucidated the mechanism of the complexion process. The precipitate formation was observed within a drug concentration range of 0.1-1.0 mM, and a 1:1 stoichiometry ratio of BBR to BA was established by the Job's plot method. Morphological and structural characterizations of the precipitates were conducted using DSC, FTIR and PXRD. Additionally, UV-Vis absorption and 1H NMR spectroscopy were employed to compare the spectral characteristics of the precipitates with those of individual drug solution. Molecular dynamic simulations further dissected the intermolecular interactions and self-assembly mechanisms. The precipitates formed were amorphous microparticles with an average diameter of approximately 20 μm, primarily stabilized by hydrogen bonding and π-π stacking. This study contributes foundational insights into the supramolecular interactions between BBR and BA, therefore facilitated a better understanding of the precipitation process involving flavonoid-alkaloid pairs in mixed aqueous solutions.

Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures

The Scutellaria baicalensis—Coptis chinensis pair is an herbal combination used for the treatment of various heat-related diseases. During the extraction process, two herbs can mutually influence the extraction efficiency of the chemical constituents contained in each herb. The concentrations of five flavonoids from S. baicalensis and seven alkaloids from C. chinensis were compared in paired or single hot-water extracts at different temperatures (80, 90, and 100 °C) and extraction times (60, 90, and 120 min). Temperature- and time-dependent increases in marker compound concentrations were observed in both paired and single extracts, with the exception of baicalin, berberine, and coptisine in the paired extracts at 100 °C. However, the extractions of the compounds in the paired and single extracts were affected differently by the extraction conditions. Furthermore, the concentrations of most marker compounds in single extracts were 1.09–44.13 times those in paired extracts. The contents of baicalin, wogonoside, coptisine, and berberine, known to be easily aggregated by the flavonoid–alkaloid complex, were changed by 0.024–0.764-fold in the paired extract. The effect of extraction temperature and time on the formation of the flavonoid–alkaloid complex was not significant. The extraction efficiency of the flavonoids and alkaloids can be affected by the pair of S. baicalensis—C. chinensis, which is a primary factor in the chemical modification of two herb-containing herbal extracts.

Correction to: Attribution and identification of absorbed components by HPLC-DAD-ESI-MS after oral administration of Erhuang decoction

An amendment to this paper has been published and can be accessed via the original article.