Valorization of halophyte Mesembryanthemum nodiflorum for nutraceutical application: in vitro digestion and bioaccessibility of phenolic compounds

Halophytic plants, such as Mesembryanthemum nodiflorum, have the capacity to survive in extreme conditions of water scarcity and soil salinity, producing protective secondary metabolites such as polyphenols, well known for their pro-healthy activities. The aim of this work was to valorize Mesembryanthemum nodiflorum for nutraceutical application by studying the effects of in vitro gastrointestinal digestion on the bioaccessibility and bioactivity of polyphenols present in the extract prepared by ultrasound-assisted extraction using GRAS solvents (water and ethanol).

The simulated in vitro digestion revealed an increase in the Total Phenolic Content (TPC) (21.2 mg of gallic acid equivalent (GAE)/g on dry weight (dw)), antioxidant (33.84 of ferrous sulphate equivalent (FSE)/g dw) and antiradical capacities (23.72 mg of ascorbic acid equivalent (AAE)/g dw) in the following order: oral < gastric < intestinal digestion. The phenolic and flavonoid compounds became more bioaccessible upon the in vitro digestion action of enzymes and pH changes, with recovery rates exceeding 150% and 50%, respectively, corroborating the TPC and TFC results. The extract also demonstrated neuroprotective properties (<40%) after in vitro digestion, as well as upmodulating effects on antioxidant enzyme activities (catalase (130.46 nmol/min/g dw), glutathione peroxidase (178,46 µmol/min/g dw) and superoxide dismutase (65.8 µmol/min/g dw)). Moreover, the extract was safe on Caco-2 and HT29-MTX cells up to 500 µg/mL.

These findings suggest that Mesembryanthemum nodiflorum extracts could be explored as potential nutraceutical ingredient.