Natural deep eutectic solvents (NADES): dual functionality in the extraction and stabilization of polyphenols, terpenoids and nitrogen compounds.

Bioactive compounds from plants are highly valued due to their functional properties and health benefits; however, their chemical labile often results in significant degradation after extraction and during storage. While natural deep eutectic solvents (NADES) have been widely investigated as green extraction media, increasing evidence indicates that their role extends beyond solubilization, as they can act as stabilizing matrices that modulate degradation pathways. In this context, this review critically examines the dual functionality of NADES as both extraction and stabilization systems, with emphasis on the relationship between their physicochemical properties and the preservation of bioactive compounds. A comparative and mechanistic analysis of current literature is presented, focusing on how hydrogen-bond networks, microviscosity, polarity, and microenvironmental factors influence degradation processes such as oxidation, hydrolysis, and isomerization under thermal, photonic, and oxidative stress conditions. Across different classes of bioactive compounds, emerging trends are identified to establish structure-property-stability relationships and to highlight key factors governing stabilization performance relative to conventional solvents. To the best of our knowledge, few reviews have systematically addressed this emerging protective role across different classes of bioactive compounds, highlighting the need for integrative and comparative analyses to establish actionable criteria for NADES selection according to compound stability, physicochemical compatibility, and stress conditions.