A high-performance liquid chromatography method for quality control of complex substances: analysis of marker alkaloids and flavonoids of the herb Herba leonuri (Yimucao)

Abstract

Standard chemical methods of analysis for marker alkaloids and flavonoids such as rutin, apigenin, quercetin, kaempferol, and leonurine were insufficient to discriminate the geographical origins of the complex Herba leonuri (HL) samples. This led to the research and development of a novel, quantitative HPLC fingerprint method for the simultaneous analysis of the content of important markers present in the HL samples. Seven HPLC peaks were selected and a structure was assigned to five. Fifty-six HL samples collected from three provinces, Anhui, Hubei, and Jiangxi, were analyzed by the above HPLC method and the resulting 56 × 7 matrix of the HPLC fingerprints and the seven marker compounds was submitted to principal component analysis (PCA) with consequent discrimination of the HL samples according to their geographical origins; interestingly, it was found that the highly correlated L6 (kaempferol) and L7 (apigenin) loadings were independent of the other five marker compound loadings (L1–L5). In addition, the L6 and L7 variables were related only to the Jiangxi group, while the L1–L5 loadings were associated with Jiangxi and Anhui; the Hubei cluster was not directly related to any loading. For quantitative analysis, the least squares-support vector machine (LS-SVM) calibration model was able to predict 94.4% of the samples correctly.