Phytochemical profiling of saline cultivated Tetragonia decumbens Mill: In vitro cytotoxicity, acetylcholinesterase inhibitory activity, anti-cancer and anti-inflammatory potential

Abstract

Cancer, Alzheimer's disease and chronic inflammation present considerable health issues for individuals worldwide. Current treatment with synthetic drugs has been associated with adverse side effects. Thus, the search for plant-based options that are affordable, reliable, and safe is highly imperative. This study explored the phytochemical profiling of ethanolic extracts of Tetragonia decumbens, their cytotoxicity, as well as their acetylcholinesterase inhibitory activity, anti-cancer and anti-inflammatory potential. Phenolic compounds in leaf extracts collected from samples cultivated in saline (0, 50, 100, 150, 200 and 250 mM NaCl) were identified with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Cytotoxicity of the extracts against cancerous and non-cancerous cell lines was evaluated with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) cell viability assay. Lastly, the anti-inflammatory potency of the extracts against lipopolysaccharide induced macrophage cell line (RAW 264.7) was determined by monitoring the reduction of nitrites, while acetylcholinesterase inhibitory activity of the extract on H4IIE-luc cells was evaluated with the Ellman colorimetric method. For the first time, the UPLC-MS analysis identified 98 compounds in T. decumbens, most of which were flavonoids, flavonols, amino acids, hydroxybenzoic acid derivatives, and organic and fatty acids. A potent anti-inflammatory activity (27 μM) was observed at a dose of 100 μg/mL in the crude extract of plants grown in 100 mM NaCl, which was substantially higher than that of cells treated with aminoguanidine (35 μM) a positive control. There was also a significant inhibitory activity on acetylcholinesterase in cells treated with crude extracts of 0 mM NaCl (0.00031 mg/protein), followed by 50 mM NaCl (0.0016 mg/protein) and 100 mM NaCl (0.0031 mg/protein), respectively, compared with untreated cells (0.022 mg/protein). Additionally, the extract of 150 mM NaCl treatment showed a cytotoxic effect against cancer (34.3 %) and non-cancer (9.2 %) cells at a concentration of 1 mg/mL, and was not remmended for use due to toxicity concern on non-cancer cells. These findings suggest that the identified compounds in T. decumbens extracts could have potential anti-inflammatory and acetylcholinesterase inhibitory activities. Consequently, these compounds can be further explored as promising therapeutic agents for the dual treatment of inflammation and Alzheimer’s disease.