Effect of fireweed (Chamerion angustifolium L.) leaf extract on mitochondrial functions in human colorectal Caco-2 cancer cells

Abstract

Extracts from various species of Epilobium display numerous therapeutic effects, including antiinflammatory, antiproliferative, antimicrobial, antioxidant and others. Giving the importance of mitochondrial energy metabolism in cancer, we investigated the effect of fireweed (Chamerion angustifolium L.) leaf aqueous extract on the cell viability and mitochondrial bioenergetics in human colorectal adenocarcinoma cancer cell line Caco-2.Caco-2 cells were incubated for 24 h in RPMI 1640 medium supplemented with 10% of fetalbovine serum and 1% penicillin/streptomycin at 37 °C in 5% CO2 humidity. Then cells were treated by fireweed leaf extract (IC50= 0.8085 mg/ml) for 48 hours. Mitochondrial respiration rate was measured using an Oxygraph-2k at 37 °C with glutamate/malate and succinate as substrates [2]. In fireweed extract four phenolic acids (p-coumaric, elagic, chlorogenic, neochlorogenic), flavonoids (hyperoside and isoquercitrin) and oenothein B were determined by HPLC. Treatment of Caco-2 cells with fireweed extract dose-dependently suppressed (by 53-91%) the viability. The mitochondrial function in Caco-2 cells exposed to fireweed extract decreased by 50% (glutamate/malate) and by 35 % (succinate) and the leak respiration rate increased by 73%, p<0.05, showing the damage of mitochondrial function. Mitochondrial respiratory control index in Caco-2 cells after pre-treatment decreased by 55% and 52%. Moreover, the cytochrome c effect was slightly increased after pre-treatment of cells with fireweed extract showing the damage of mitochondrial outer membrane in Caco -2 cells. In conclusion, fireweed leaf aqueous extract diminished significantly the viability of Caco-2 cells and mitochondrial function in Caco-2 cells and could be promising therapeutic agent in cancer cells.