In vitro antioxidant, anticancer and in silico studies of polyphenol enriched leaf extract of Asystasia gangetica

Polyphenols are natural biomolecules known for circumventing several diseases including cancer with little adverse effects. This study aimed to investigate the polyphenol enriched fractions from the leaf extract of Asystasia gangetica for their composition, biological activities such as antioxidant activity, haemolytic effects, and in vitro cytotoxicity against cancer cell lines. LC–MS/MS analysis of the enriched fractions identified a total of 35 distinct polyphenols with caffeic acid, luteolin, apigenin, and protocatechuic acid at higher concentrations. Fractions AG-3 and AG-4 exhibited the highest total antioxidant activity with higher concentration of phenolics and flavonoids. The AG-4 fraction had the highest levels of DPPH radical scavenging (IC50 = 32.74 µg mL-1) and ABTS radical scavenging (IC50 = 29.45 µg mL–1) activity, in addition to a modest iron chelating activity and reducing power. The fractions exhibited the least haemolytic activity. The cytotoxic potential of enriched fractions against the HCT-116, HeLa, PC-3, and HDF cell lines was further examined. While the extract showed no inhibitory effect on normal HDF cells, the cytotoxic activity of fractions on cell lines varied, with HCT-116 cells having the strongest anticancer activity with an IC50 of 43.82 µg mL–1. Additionally, fractions induced apoptotic activity in HCT-116 cells, resulting in cell cycle arrest at the G2M phase and an increase in sub-G0/G1 cells, with an IC50 of 13.54 µg mL–1 after 48 h of incubation. The in silico molecular docking of the active compounds against the TNIK receptor protein and ADMET (Absorption–Distribution–Metabolism–Excretion–Toxicity) characteristics are described. Overall, the study highlights the enhanced biological and antiproliferative activities of polyphenols in Asystasia gangetica leaf extract, which could be further utilized as a potential cancer treatment strategy.