Silybum marianum L. (milk thistle): A review of phytochemical and bioactive compound extraction, food applications, and safety considerations

Abstract

Silybum marianum (milk thistle) is a major source of flavonolignans, particularly silymarin, with well-documented antioxidant and hepatoprotective properties; however, its effective utilization in food systems is limited by challenges in extraction efficiency, selectivity, and process scalability. Accordingly, this review aims to critically evaluate conventional and emerging extraction strategies for milk thistle bioactive compounds in relation to their efficiency, sustainability, and applicability in food systems. Comparative analysis indicates that green extraction technologies significantly enhance mass transfer, reduce solvent consumption, and better preservation of bioactive integrity compared to conventional methods. Emerging systems such as natural deep eutectic solvents (NaDES) and gas expanded liquid extraction (GELE) further improve recovery of polar compounds, although limitations related to viscosity, downstream processing, and regulatory acceptance remain. Process optimization, integration of green solvents, and hybrid extraction strategies are identified as key approaches to enhance yield, selectivity, and industrial feasibility. Despite these advances, challenges including compound degradation, impurity formation, and lack of standardization highlight the need for comprehensive safety assessment and regulatory alignment to support the development of safe and functional food applications.