Fig. 7

Soluble polyphenol content in leaves from selected plant species. A The measured polyphenol content of the extract was normalized by the total chlorophyll content of freeze-dried leaf material. Different letters indicate significant differences at P < 0.05, as determined using the Shapiro–Wilk normality test followed by the student’s t-distribution analysis. Data are represented as the median, quartiles, and border values of 4 technical replicates. Data and calculations are presented in Additional file 1: Data S1. B Phenolic compounds profiling. Heatmap of the major phenolic compounds (identified with available standards (a) or annotated from literature (b: [45], c: [47], d: [48]) in the five species (Q. pubescens, O. basilicum, P. oceanica, A. thaliana, V. vinifera). Common logarithm of the peak area means (area/mL) for each condition (five technical replicates) and each metabolite is expressed per one microliter of the extract solution injected (one mg of the starting plant dry material per mL). Colors in the heatmap are related to the sequential logarithmic scale presented in the right panel (0: not detected)