Multiple wavelengths maximization fusion fingerprint profiling for quality evaluation of compound liquorice tablets and related antioxidant activity analysis

With natural plant entering a worldwide new arena in clinical medicine and pharmaceutical, herbal preparation are becoming popular all over the world. Compound liquorice tablets (CLQTs) have been widely applied as effective and typical antitussive, expectorant and antiasthma. It is worth noting that quality determines effectiveness and safety, which make it essential for quality control of CLQTs. Considering the different UV absorption characteristics of various components, high-performance liquid chromatography fingerprint of 156 batches of CLQTs were determined at four wavelengths. Additionally, multi-wavelength maximization fusion profiling was developed to digest and synthesize the valuable fingerprint information of each sample for its holistic quality evaluation. Quantitative determination of five major ingredients was performed and no significant differences were found in five-compound content among 156 samples (p > 0.05). All samples were clarified into six quality grades using systematic quantified fingerprint method from qualitative and quantitative perspective and showed significant difference among nine manufactures (p < 0.05). A well established 2,2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and diphenyl-1-picrylhydrazyl (DPPH) scavenging assay was applied to study the in vitro antioxidant activity of CLQTs samples using L-ascorbic acid as positive control. Furthermore, OPLS was established for the fingerprint-efficacy relationship analysis and demonstrated the significant contribution of peaks 15-liquiritin and 30-glycyrrhizic acid (VIP > 0.5). The study suggested that this quantitative fingerprint approach is reliable and beneficial for quality control of complex herbal medicine or herbal preparation.