Evaluating the cytotoxic potential of phytochemicals isolated from Veronica incana against DU-145 prostate cancer cells.

Veronica incana L. (Plantaginaceae), commonly known as silver speedwell, is a flowering plant native to eastern Europe and parts of Russia, Siberia, Mongolia, and northern China. This study aimed to isolate various iridoid glycosides and other phytochemicals from the n-BuOH fraction of V. incana, resulting in the identification of one new phenolic compound (1) along with three known phenolic compounds (2: 1-O-β-d-vanillyl-glucose, 3: isopungenin, and 4: pungenin), one tyrosol (5: salidroside), one flavonoid (6: apigenin), two megastigmane glucosides (7: [6R,9R] 3-oxo-α-ionol-β-d-glucoside and 8: [6R,9S] 3-oxo-α-ionol-β-d-glucoside), and ten iridoid glycosides (9: veronicoside, 10: catalposide, 11: 4'-methoxycatalposide, 12: verproside, 13: 6-O-veratroylcatalpol, 14: 6-vanilloylcatalpol, 15: 6-O-isovanilloylcatalpol, 16: verminoside, 17: longifolioside A, and 18: dolicocymboside D). The isolation of these compounds was achieved through solvent partitioning, open-column chromatography, and semi-preparative high-performance liquid chromatography. Their structures, including absolute configurations, were determined by 1D and 2D NMR spectroscopy, optical rotation [α]D, and electronic circular dichroism (ECD), and confirmed by comparison with reported data. Among the isolates, compounds 2-5, 7-9, 11, 13, and 16-18 were reported for the first time from this species, while compounds 2, 7, and 8 were newly reported from the genus Veronica. Notably, compound 3 was isolated for the first time from this plant family. To evaluate their potential anticancer activity, all isolated compounds except 3, 4, and 5 were tested for antiproliferative effects against DU-145 prostate cancer cells using the MTT assay. Compounds 10 and 11 demonstrated notable inhibitory activity in this assay.