Induction of Apoptosis by Extracts of Edible Wild Plants in C6 Glioma Cells

Abstract

　Many edible wild plants have been consumed as food. It has been reported that these plants have antioxidants, antitumor and antibacterial activities. First, we examined the DPPH radical scavenging activity and total polyphenol contents in 14 species of edible wild plants, which were collected from the Yamanashi prefecture. A significant correlation between antioxidant activity and polyphenol content was observed. Moreover, Akebia quinata, Pteridium aquilinum, Adenophora triphylla, Cacalia delphiniifolia, Allium victorialis, Hosta sieboldiana, Vinca minor and Acer maximowiczianum were found to have significant antitumor effects against C6 glioma cells. The decrease of cell viability raises two possibilities-induction of cell death or growth retardation. We then subjected the extracts to propidium iodide (PI) and calcein-AM staining to distinguish between dead and live cells, respectively. The extracts from A. maximowiczianuminduced an increase in the number of PI-positive cells. Moreover, activation of caspase 3 and translocation of phosphatidylserine were observed in the extract-treated cells suggesting that apoptosis might be the reason for decreased cell viability. On the other hand, extracts of A. victorialis, H. sieboldiana, and V. minor induced abnormalities in the cell cycle in the G₂/M phase of cell cycle. Our data suggest that the antitumor effect of the edible wild plants might be through the induction of apoptosis and cell cycle abnormalities.