Applying Multi-Component Quantitative Analyses Combined with Chemometric Analyses to Evaluate the Quality of Ponkan Chenpi with Different Aging Durations

Objective: In order to establish a high performance liquid chromatographic (HPLC) fingerprint and multi-component content determination methods of Ponkan Chenpi, the effects of different aging durations on 8 kinds of flavonoid components of Ponkan Chenpi were investigated by chemometric analysis. Methods: The injection volume was 10 μL and gradient elution was applied with acetonitrile (A)-0.1% phosphoric acid aqueous solution (B) as the mobile phase. The detection wavelengths were 283 nm for hesperidin, neohesperidin, naringin, and narirutin, 310 nm for fingerprint, and 330 nm for nobiletin, 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF), tangeretin, 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone (5-HPMF). The fingerprint profiles of 10 batches of Ponkan Chenpi with different aging periods (0~126 d) were established by HPLC and their similarities were evaluated. The variability of 8 flavonoid components was analyzed by combined chemometric methods, including hierarchical cluster analysis (HCA), principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Results: The similarities of fingerprint profiles of 10 batches of Ponkan Chenpi samples were all greater than 0.995, and 32 common peaks were marked. The result indicated that the quality of Ponkan Chenpi was relatively stable during different aging periods and the established fingerprint profiles were reliable and credible. The contents of five components, including naringin, hesperidin, nobiletin, tangeretin and 5-HPMF, showed a fluctuating decreasing trend, and neohesperidin showed a fluctuating upward and then downward trend, while those of narirutin and HMF showed a fluctuating increasing one during the aging. The result of HCA indicated that 10 batches of Ponkan Chenpi samples could be divided into two categories. The samples with accelerated aging time of 56 d, 70 d and 0 d were clustered into one category, while the rest were clustered into another one. The PCA result revealed that three principal components with a cumulative variance contribution of 85.740% could be extracted. Four flavonoid components, including hesperidin, neohesperidin, 5-HPMF and tangeretin, were identified as the differential markers to distinguish between different aging periods of Ponkan Chenpi samples. Conclusion: The fingerprint profile and multi-component content determination methods constructed in this study were highly stable and reproducible. Combined with HCA, PCA and OPLS-DA, the methods could be applied to monitor and evaluate the changes in chemical components and quality of Ponkan Chenpi with different aging periods. The study provided a theoretical and methodology basis for the development and utilization of Ponkan Chenpi.