Effects of Alternanthera sessilis Red leaf extracts on hydrogen peroxide-induced oxidative stress in HepG2 cells and identification of phytochemicals using HPLC-QToF-MS/MS

Alternanthera sessilis Red (ASR) is an edible medicinal plant that receives little attention in Asia. This study aimed to investigate the ability of ASR ethanolic (EtOHASR) and ethyl acetate (EtACASR) leaf extracts in protecting HepG2 cells against oxidative damage. To determine the effect of both extracts on the cellular antioxidant status and preventive activities against hydrogen peroxide (H2O2)-induced oxidative stress, HepG2 cells were treated with both extracts at concentration ≤ 20 µg/mL as the extracts were shown low toxicity. With increasing concentrations, both extracts improved cellular antioxidant status where cells treated with EtACASR showed a higher ferric reducing activity than the EtOHASR. Both extracts also reduced the levels of reactive oxygen species and inhibited lipid peroxidation in the cells. The highest cytoprotective activity against H2O2-induced cell damage was exhibited by EtACASR at 5 µg/mL. HPLC-QToF-MS/MS analysis tentatively identified the presence of 30 phytochemicals in both extracts with 28 of them comprising of polyphenols, whereas two carotenoids were found only in the EtOHASR. These may be responsible for the cytoprotective properties of the ASR leaf. The current findings highlight the potential of ASR leaf as a source of natural antioxidants for protecting cells from oxidative damage. Furthermore, newly discovered phytochemical compounds in ASR, particularly polyphenols, which are mostly flavonoids, could be useful for future research into its potential as a functional food or nutraceutical against oxidative stress-related diseases.