Assessing the quality consistency of Rong'e Yishen oral liquid by five-wavelength maximization profilings and electrochemical fingerprints combined with antioxidant activity analyses

Highlights: • Assess the quality consistency of REYS using SQFM. • Establish five-wavelength maximization profiling (FWMP) to synthesize information at multi-wavelength. • Explore electrochemical fingerprint (ECFP) to characterize TCM liquid preparation for the first time. • First development of merged ECFPs and determination of antioxidant activity using both ABTS^+· scavenging test and ECFP. • Explore and compare two different efficacy relationships using PLS model and BCA. Quality consistency control of traditional Chinese medicine (TCM) is often essential for providing reference and procedure to guarantee the safety and effectiveness of TCM. Taking Rong'e Yishen oral liquid (REYS) as an example, five-wavelength maximization profilings (FWMPs) of 21 samples were constructed to fully manifest the maximum UV absorption characteristics at multi-wavelength. The preliminary analysis of FWMPs by principal component analysis (PCA) suggested us focusing on evaluating the quality consistency qualitatively and quantitatively by systematically quantified fingerprint method (SQFM). Meanwhile, electrochemical fingerprints (ECFPs) were established and the related characteristic parameters were deeply analyzed. All the samples had inhibitory effect on the electrochemical oscillation system, and the oscillation life (t_ol) was linear with the added volume and temperature in a certain range, respectively (r > 0.94). The merging point method was first introduced to process ECFP to facilitate its evaluation with SQFM. The evaluation results of FWMPs and the merged ECFPs were integrated in an equal weight for assessing the sample quality completely, and 21 samples were classified into two grades with good quality consistency. Furthermore, 2, 2-azino-bis (3 - ethyl - benzthiazoline - 6 - sulfonic acid) (ABTS) scavenging assay was applied to study the antioxidant activity of samples using vitamin C as a positive control. Partial least squares (PLS) model and bivariate correlation analysis (BCA) was used for FWMP-ABTS efficacy relationship and FWMP-merged ECFP efficacy relationship respectively. 15 of the 48 co-possessing peaks made important contributions to the two efficacy relationships simultaneously. This study suggested a comprehensive and reliable approach for quality consistency control of complex TCM or herbal medicine.