Protective effects of Alaria esculenta and Palmaria palmata extracts on intestinal epithelial cells: insights from cell-based assays and transcriptomics

Seaweeds contain diverse bioactive compounds and are promising candidates for functional foods and nutraceuticals, though many studies lack in vivo relevance. This research used cell-based assays and transcriptomics to assess the effects of digested extracts from dried Alaria esculenta (Phaeophyceae), Palmaria palmata (Rhodophyta), and combinations of the two on human intestinal epithelium health. Caco-2 cells were exposed to seaweed extracts obtained through in vitro digestion and tested for viability, reactive oxygen species (ROS) production, wound healing, and IL-8 inflammatory response. At realistic intake concentrations (0.5–2 g), all extracts significantly inhibited ROS production induced by external stress. Cell viability was significantly increased by both species and their 1:1 mixture. No changes in anti-inflammatory or wound healing activities were recorded. Transcriptomics analysis revealed species-specific molecular response: A. esculenta activated cell defence pathways, while P. palmata enhanced nutrient transport and cellular functions. These differences suggest a potential complementary aspect of the two species for intestinal health, although analyses of the mixture effects suggest they may be antagonistic rather than synergistic. Small, significant differences between Norwegian and Faroese seaweed extracts suggest population and environmental effects on bioactive properties. Overall, both species showed protective properties against oxidative stress and may be good candidates as intestinal health supplements. • Both A. esculenta and P. palmata digests have positive effects on Caco-2 cells. • Protective antioxidant activity was strongest in both seaweeds and their mixtures. • Mild increases in cell viability were also observed at realistic concentrations. • Transcriptomics showed species-specific molecular and mechanistic responses. • Population and environmental effects may affect bioactive properties.