Effect of extraction solvents on cytotoxicity and high-resolution LC-MS profiling of red yeast rice extracts

With increasing public interest in health-promoting foods, appropriate safety assessment of functional food ingredients is essential. In vitro toxicity testing typically requires extraction of food materials, and the choice of solvent can substantially influence the resulting chemical composition and toxicological profile. This study investigated the effects of solvent polarity on extraction yield, cytotoxicity, and also the chemical composition of red yeast rice (RYR) extracts. Using ten solvents with varying physicochemical properties, extracts were evaluated for cytotoxicity in an NCTC clone 1469 cells via WST-1 assay. Methanol extract exhibited the highest cytotoxicity, while aqueous and non-polar extracts showed minimal effects. LC-MS profiling of RYR extracts revealed distinct chemical compositions among solvents, and eight candidate compounds associated with cytotoxic fractions were identified from methanol extract by Q-TOF-MS/MS. These included known Monascus pigments and two putatively novel constituents. While structural confirmation and mechanism studies are needed, these results emphasise that cytotoxicity outcomes can vary significantly depending on extraction strategy. Therefore, multi-solvent approaches should be considered when evaluating the in vitro toxicity of complex food materials.