Optimization of extraction conditions for colchicine from Gloriosa superba tubers using response surface methodology

Gloriosa superba is a medicinal plant used in traditional medicine for the treatment of various diseases. The tuber of Gloriosa superba is a rich source of colchicine which is used for the treatment of gout, cirrhosis and also used in plant breeding studies to produce polyploidy. Optimization of various extraction parameters using response surface methodology (RSM) was performed to assess maximum yield of colchicine from Gloriosa superba tubers. PlackettBurman design criterion was applied to identify the significant effect of various extraction parameters such as temperature, time, mean particle size, solvent-solid ratio, solvent composition, pH and number of extraction steps on extraction of colchicine. Among the seven variables tested extraction time, mean particle size, solvent-solid ratio and solvent composition were found to have significant effect on colchicine extraction. Optimum levels of the significant variables were determined by using Box-Behnken Design (BBD). The most suitable condition for extraction of colchicine was found to be single step extraction at temperature 35C, pH 7, extraction time 70 minutes, solvent-solid ratio 50:1, mean particle size 0.5 mm and solvent composition 70% ethanol in ethanol-water mixture. At these optimum levels of extraction parameters, the maximum yield of colchicine obtained experimentally (0.91% dry weight of tubers) was found to be very closed to its predicted value of 0.97% dry weight of tubers. The mathematical model developed was found to fit well with the experimental data of colchicine extraction.