Structure-activity relationship of coptis alkaloid bitterness inhibited by mPEG-PLLA / 中国中药杂志

Inhibition of bitterness is a significant measure to improve the compliance and clinical efficacy of traditional Chinese medicine(TCM) decoction. According to the characteristics of TCM decoction, such as high dispersion of bitterness components, multi-component bitterness superposition and strong instantaneous stimulation, the research group put forward a new strategy to inhibit bitterness in the early stage based on the self-assembly characteristics of amphiphilic substances in aqueous solution, in order to reduce the distribution of bitterness components in real solution and achieve the purpose of bitter-masking. It was found that the bitter-masking effect of amphiphilic substances was different on the bitter compounds of various structures. Therefore, it was speculated that there might be a certain relationship between the bitter inhibition effect and the substrate structure. In this paper, the interaction between mPEG-PLLA and five bitter alkaloids(bamatine, jatrorrhizine, berberine, epiberberine and coptisine) in Coptidis Rhizoma was studied to explore the effect of substrate structure on the inhibition of bitterness. The sensory test of volunteers was used to determine the bitter-masking effect of mPEG-PLLA on the decoction of Coptidis Rhizoma and its main bitter alkaloids. The molecular docking and molecular force field were applied to locate the bitter groups and the bitter-masking parts. The relationship between the bitter strength and the structure was analyzed by the surface electrostatic potential of the bitter alkaloids, and the correlation between the bitter-masking effect and the structural parameters of the bitter components was explored by factor analysis, so as to clarify the structure-activity relationship of mPEG-PLLA in masking the bitterness of coptis alkaloids. It was found that mPEG-PLLA had significant taste masking effect on the decoction of Coptidis Rhizoma and five alkaloids. The masking effect was obviously related to the structure of different alkaloids: the effect increased with the increase of the number of hydrogen donors, rotatable bonds, molecular weight, and hydrophobicity, and decreased with the increase of surface electrostatic potential, electrophilicity and binding energy with bitter receptors. In this study, the influence of alkaloid structure of Coptidis Rhizoma on the butter-masking effect of mPEG-PLLA was preliminarily elucidated, providing a scientific basis for better exerting the bitter-masking effect of amphiphilic block copolymers.

Summary of Small Molecular Bitter Quenchers are Applied to Oral Liquid Preparations / 中国药学杂志

Bitter drugs in oral liquid preparations are mostly in the form of molecule or colloid, which can instantly form a broad and strong stimulation with the large dispersion. Therefore, it makes the traditional bitter-masking method difficult to completely mask the bitterness, and greatly restrict the compliance of patients. In recent years, the discovery of small molecular bitter quenchers (SMBQ)has provided a new choice for improving the taste of oral liquid and has gradually become a hotspot in the research of bitter-masking technology. Based on these reasons, the paper explained the concept and characteristics of SMBQ, summarized the mechanism and influencing factors of bitterness quenching, and introduced the commonly-used small bitter quench quencher and its characteristics and applications. This study was aimed to promote the development and application of SMBQ in oral liquid preparations, and provide scientific theoretical guidance and technical support for bitter masking of oral liquid preparations. It may be of great theoretical and practical significance to promote the solution of the practical problems of oral liquid, the optimization of prescription design, and the improvement of product quality.