(A) Flowchart illustrating the bioactivity-guided fractionation of the Viola extract. Three initial subfractions were generated from the extract applying preparative HPLC, and the most active one was chosen for further fractionation yielding five subfractions by semi-preparative HPLC. Subsequently, the most abundant peaks of the most active subfractions were purified using semi-preparative HPLC in isocratic elution mode to yield active fractions VT3.1F and VT3.1 G. (B, C) Base peak chromatograms from LC–MS analysis of the Viola extract (B, left panel) and the subfractions VT 3.1F and G obtained from manual peak collection are presented (C, left panel). The subfractions showed an inhibition of proliferation as measured by flow cytometry (B, C; right panels). Cyclotides were identified by LC–MS reconstruct and database search as described in Section 2. A corresponding list of cyclotides identified in the active fractions is given in Table 1. Phytochemical and anti-proliferative data of all tested extracts and fractions are provided as Supplementary Material (Supplementary Figs. S1 and S2).