Antiproliferative Activity of Phenylpropanoids Isolated from Lagotis brevituba Maxim

The aim of the present study was to evaluate the antiproliferative effect of phenylpropanoids isolated from the n ‐BuOH‐soluble fraction of an ethanolic extract of Lagotis brevituba Maxim. The phenylpropanoids were identified as echinacoside, lagotioside, glucopyranosyl(1–6)martynoside, plantamoside, and verbascoside. Three of the compounds, lagotioside, glucopyranosyl(1–6)martynoside, and plantamoside, were isolated from L. brevituba for the first time. The antiproliferative activity of the isolates was evaluated in human gastric carcinoma (MGC‐803), human colorectal carcinoma (HCT116), human hepatocellar carcinoma (HepG2), and human lung cancer (HCT116) cells using an 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Plantamoside showed promising activity against MGC‐803 cells, with a half maximal inhibitory concentration value of 37.09 μM. The mechanism of the pro‐apoptosis effect of plantamoside was then evaluated in MGC‐803 cells. Changes in cell morphology, including disorganization of the architecture of actin microfilaments and formation of apoptotic bodies, together with cell cycle arrest in G2/M phases, were observed after treatment of plantamoside. The antiproliferative and pro‐apoptotic effects were associated with a decrease in the ratio of Bcl‐2/Bax and reduced mitochondrial membrane potential, which was accompanied by the release of reactive oxygen species and Ca 2+ into the cytoplasm. Taken together, the results indicated that plantamoside promotes apoptosis via a mitochondria‐dependent mechanism. Copyright © 2017 John Wiley & Sons, Ltd.