Novel bio-renewable matrinium-based ionic liquids derived from Chinese herb medicine: Synthesis, physicochemical properties and biological activity

Bio-renewable ionic liquids (ILs) have been the focus of intensive research following the realization that commonly used ILs are not as environmentally and biologically friendly as first thought. Matrine, a reactive and bioactive alkaloid found in a Chinese herb medicine from the genus Sophora, was used to synthesize a novel family of matrinium-based room temperature ILs, featuring a series of long-chain fatty acid anions derived from vegetable oils. The prepared ILs exhibited superb physicochemical properties, including relatively low viscosities (325.5–489.5 m Pas), moderate densities (1.00–1.07 g cm−3), and wide liquid operating ranges (230–270 °C). Solvatochromic experiments showed that the dipolarity/polarizability (π*) values (0.67–0.78) of these ILs were far below those of most common ILs, suggesting promising application potential as solvents for lipophilic compounds. Furthermore, the prepared ILs were shown to have better antibacterial and anticancer activities than matrine, while elongation of the alkanoate anions strongly enhanced their bioactivities. Additionally, the prepared ILs demonstrated relatively lower cytotoxicity on normal cells (L929) compared to tumor cells (HeLa and A549). Consequently, the bio-renewable matrinium-based ILs should have potential applications as benign solvents for use in chemistry, biology, pharmacy, etc.