Integrated chemometric approach combining morphology, stable isotopes, and quantitative markers for quality control and origin discrimination of Lonicerae japonicae flos

Lonicerae japonicae flos (LJF) is a significant food and traditional Chinese medicine with diverse pharmacological effects and extensive prescription compatibility. However, systematic quality evaluation of LJF remains limited. Accurate identification of geographical origin is crucial for quality control and clinical efficacy. For the first time, this study integrates morphological quality assessment, environmental factors, and intrinsic quality characteristics by analyzing stable carbon (δ13C) and nitrogen (δ15N) isotope ratios alongside quantification of marker compounds to systematically evaluate LJF quality and discriminate its geographical origin. Stable isotope ratios (δ13C and δ15N) and relative contents of the marker compounds in LJF from eight geographical regions (n = 40) were determined. Multivariate statistical analysis revealed significant original differences. Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA), and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) identified δ15N, luteoloside, chlorogenic acid, and cryptochlorogenic acid as key markers responsible for these geographical variations. Furthermore, a classification model for discriminating LJF geographical origin was developed using Linear Discriminant Analysis (LDA), and this model achieved 97.5% accuracy. This analysis elucidates the variations in stable isotopes and marker compounds, providing a valuable reference for the origin authentication, selection, and quality assessment of LJF.