Optimization of ultrasonic-stimulated solvent extraction of sinigrin from Indian mustard seed (Brassica Juncea L.) using response surface methodology.

Sinigrin, a major glucosinolate present in Indian mustard (Brassica juncea L.) seeds as the precursor of the anticancer compound allyl isothiocyanate, shows a wide range of biological activities. It's necessary to optimize the extraction methods and conditions, in order to improve the extraction productivity and save raw material. To systemically investigate and optimize the most important factors affected the productivity of sinigrin in the process of extraction using response surface methodology. The ranges of three main factors including the ethanol concentration, extraction time and extraction temperature were selected by the one-factor-at-a-time method. The conditions of ultrasonic-stimulated extraction of sinigrin from defatted Indian mustard seed powder were optimized by Box-Behnken design to obtain the maximum productivity. The predicted productivity (3.81%) was obtained using 57% ethanol concentration at 81 °C for 60 min, with the coefficient of the model R² > 0.96 (n = 17). The actual productivity (3.84 ± 0.02%) of sinigrin under the optimized condition was increased by 70.67% compared with the result of conventional extraction. Meanwhile, HPLC, UV and IR were applied to examine if there is a difference between the ultrasonic-stimulated solvent extraction and conventional extraction, and the improvement of productivity of sinigrin depended on the destruction of cell wall caused by the elimination of outer pectinous material was explained by SEM and composition content analysis. The ultrasonic-stimulated solvent extraction was suggested to be a promising method to improve the productivity of sinigrin. And the results demonstrated that sinigrin productivity may be related to pectinous materials existed in the seeds.