Figure 2

Principal component analysis (PCA) of LC-ESI(−)-MS chromatographic peaks. Scores plots are shown on the left, the corresponding loading plots on the right. The color and ellipses on the scores plots denote grouping obtained from k-NN with 3 specified clusters. The proportion of variance encompassed by each principal component is given in parentheses. (A) The scores plot (left panel) is based on the absolute amplitude of all 107 detected peaks, showing that the geographical origin of the extracts is primarily associated with the 3 specified groups (red = USA, extracts 1 to 7, blue = Europe, extracts 11 and 12 and China, extracts 8 to 10, green = India, extract 13). The loadings plot (right) highlights peaks that are representative of the grouping observed in the scores plot (3-hydroxyflavone for USA, methyl caffeoylquinic acid for Europe and China, dicaffeoyltartaric (chicoric) acid for India. (B) The scores plot (left panel) is of the 5,671 peak intensity ratios obtained from the 107 detected peaks using the rational of Tilton and colleagues [28] showing the geographical origin of the extracts is primarily associated with the 3 specified groups (red = USA, blue = Europe and China, green = India). The loadings plot (right) contained no significant information (C).