Optimization of the extraction of curcumin from turmeric (Curcuma longa L.) using carbamate ionic liquid as green solvent

Emerging new technologies have attracted considerable interest for extraction of bioactive compounds from medicinal plants. Carbamate ionic liquids have shown great solubility towards organic compounds; they are considered as green solvents for extraction of bioactive compounds. In this study, N, N-dipropyl ammonium N′, N′-dipropylcarbamate (DPCARB) and N, N-diethyl ammonium N′, N′-diethycarbamate (DECARB) were synthesized using solid carbon dioxide and a secondary amine which were dipropyl amine and diethyl amine, respectively. The synthesized carbamate ionic liquids were used for the extraction of curcumin from turmeric. Curcumin extraction yield was investigated at different extraction temperatures (15, 25, 35, 45 °C) and times (1, 3, 6 and 8 h). Results showed that the maximum curcumin extraction yields were 3.86 and 3.18%, obtained using the synthesized DPCARB and DECARB at 25 °C and 3 h, respectively. Also, the purity of the extracted curcumin using DPCARB was 85%, as determined by HPLC analysis. Results showed that the carbamate ionic liquids resulted in high extraction yield at room temperature and relatively short extraction time. The high purity of the extracted curcumin verifies the high selectivity of carbamate ionic liquids toward curcumin compared to other organic compounds available in the turmeric structure.