Effects of fireweed (Chamerion angustifolium L.) leaf extract on mitochondrial function in gastric cancer cells

Introduction. Fireweed (Chamerion angustifolium L.) is a medicinal plant that is effective in treating gastrointestinal inflammation, irritation, gastric and duodenal ulcers, gastritis and colitis, acid reflux [1]. Fireweed is included in a European Medicines Agency (EMA) monograph stating that it can be used to relieve lower urinary tract symptoms associated with benign prostatic hyperplasia [2]. Fireweed contains abundant polyphenolic compounds (tannins, flavonoids, phenolic acids, etc.) and has anti-cancer, anti-inflammatory and antibacterial properties [3, 4]. All living cells, whether healthy or cancer, require energy that is synthesized in the mitochondria. Currently there is no scientific research on fireweed leaf extract effect on cancer cell mitochondrial function. Aim. The aim of the study was to determine the effect of fireweed (Chamerion angustifolium L.) leaf extracts, derived from plants grown under different conditions, on mitochondrial function in gastric cancer (AGS) cells. Methods. The fireweed leaves were collected in Jonava district, Šafarka village (55°00′22″ N; 24°12′22″ E) in 2023 July. The aqueous extracts from unfermented leaves were prepared from plants grown under natural, organic and biodynamic farming conditions. Gastric cancer cells (AGS) were treated with the determined IC50 doses for 48 hours. The IC50 values were calculated as follows: 0.457 mg/ml for natural, 0.508 mg/ml for organic farming, and 0.590 mg/ml for biodynamic farming conditions. The impact of the extracts on mitochondrial function was evaluated using high-resolution respirometry Oxygraph-2k at 37 °C with glutamate/malate and succinate as substrates [5]. Results. The mitochondrial functions of the AGS gastric cancer cell line were most significantly affected by the fireweed leaf extract obtained from ecologically grown plants. The respiratory rate in leak state (L) with glutamate/malate increased by 168% and in leak state (L+CAT) with succinate by 318% (p<0.05), suggesting potential damage to the inner mitochondrial membrane. The respiration rate in the uncoupled state (E, induced by DNP) decreased by 30% (p<0.05), indicating impairment of the mitochondrial respiratory chain. Additionally, the cytochrome c effect increased 1.3-fold (p<0.05), pointing to damage to the outer mitochondrial membrane. Respiratory control ratio decreased by 62% with glutamate/malate and by 72% with succinate (p<0.05) in cells treated with fireweed leaf extract. Conclusions. The aqueous extract from unfermented leaves of fireweed (Chamerion angustifolium L.) noticeably supresses mitochondrial function in gastric cancer cells (AGS). The extract derived from ecologically grown fireweed had the most significant effect. Treatment with the fireweed extract increased the permeability of both, the inner and outer mitochondrial membranes, thus inhibiting the ability to synthesize ATP, underscoring the potential as a therapeutic agent against gastric cancer.