First approach of characterization of bioactive compound in pyropia orbicularis during the daily tidal cycle

Abstract

The red seaweed Pyropia orbicularis is an economic important species that occurs predominantly in the high intertidal zone along the chilean coast where it experiences extreme conditions under daily turning tides. Its gametophytic phase has been demonstrated to have a high desiccation tolerance, both at the genomic and proteomic levels, but studies at the metabolomic level are still lacking. This research aimed at characterizing compounds related to desiccation stress tolerance by performing several phase solid extractions with different solvents. Bioactivity-guided fractionation (antioxidant and antibacterial activities) was made for a more specific characterization. Compounds identification was done using LC-MS/MS. Results showed that P. orbicularis produces different compounds depending on the state of hydration during the tidal cycle. For example, minoxidil was only found under hydration, while vincamine only during desiccation. It was also found that the main antioxidant activity was most likely due to lutein and the antibacterial activity could be mainly attributed to compounds of lipid nature such as phosphatidylethanolamine (PE), phosphatidylserine (PS) and monogalactosyldiacylglycerol (MGDG). These results help to get a better understanding of the stress tolerance mechanisms in P. orbicularis and place it like a potential source of bioactive compounds.