In Vitro Anticancer Potential of and Its Main Components against Human Amelanotic Melanoma Cells.

L. (Campanulaceae) is used in traditional Belarusian herbal medicine for sleep disorders in children, but the chemical composition and biological activity have not been investigated. In this study, the activities of extracts, their fractions and main compounds were evaluated in amelanotic melanoma C32 (CRL-1585) cells and normal fibroblasts (PCS-201-012). The extracts and fractions were analyzed using liquid chromatography-photodiode array detection-electrospray ionization-mass spectrometry (LC-PDA-ESI-MS/TOF) to characterize 25 compounds. Further, three major and known constituents, luteolin () and its derivatives such as 7--glucoside () and 7--sambubioside () were isolated and identified. The cytotoxic activities against fibroblasts and the amelanotic melanoma cell line were determined using the fixable viability stain (FVS) assay. The influence of diethyl ether (EtO) fraction () and on apoptosis induction was investigated using an annexin V binding assay. The obtained results showed significant cytotoxicity of and with IC values of 119.7 ± 3.2 and 95.1 ± 7.2 μg/mL, respectively. The proapoptotic potential after treatment in the C32 human amelanotic melanoma cell line was comparable to that of vinblastine sulfate (VLB), detecting 29.2 ± 3.0% apoptotic cells. Moreover, displayed less necrotic potential against melanoma cells than VLB. In addition, the influences of and on the dysfunction of the mitochondrial membrane potential (MMP), cell cycle and activity of caspases 3, 8, 9, and 10 were established. The effects of on MMP change (74.5 ± 3.0% of the cells showed a reduced MMP) corresponded to the results obtained from the annexin V binding assay and activation of caspase-9. and displayed a significant impact on caspase-9 (40.9 ± 2.4% of the cells contained active caspase-9 after treatment and 16.6 ± 0.8% after incubation with ) and the intrinsic (mitochondrial) apoptotic pathway. Moreover, studies have shown that and affect the activation of external apoptosis pathways by inducing the caspase-8 and caspase-10 cascades. Thus, activation of caspase-3 and DNA damage via external and internal apoptotic pathways were observed after treatment with and . The obtained results suggest that extracts could be developed as new topical preparations with potential anticancer properties due to their promising cytotoxic and proapoptotic potential.