Colchicum autumnale L. also known as the autumn crocus, contains colchicine alkaloid having antifungal properties. The tuber of this plant is rich in terms of colchicine. In this research an ultrasound-assisted extraction (UAE) method was optimized for the extraction of colchicine from Colchicum autumnale L. bulbs before high-performance liquid chromatography with UV detection (HPLC-UV). Optimization of various extraction parameters was performed using response surface methodology (RSM) to evaluate the maximum colchicine yield from Colchicum autumnale L. bulbs. The Box-Behnken design (BBD) and RSM were used to investigate the effect of three key parameters (extraction time (20-60 min), extraction temperature (40-80 °C) and ultrasound power (500-700 W) on extraction efficiency. The variance analysis suggested that the dependent response variable of yield of colchicine may be expressed by a quadratic polynomial model. The optimal theoretical extraction conditions were found to be an ultrasonication power of 602.4 W, an extraction time of 42 min and a temperature of 64 °C. Under these conditions, the optimum foreseen yield was 0.237%. The experimental colchicine yield obtained by following the optimized conditions was found to be 0.238%. These values are very well compatible with each other.
Keywords: Colchicine; Colchicum autumnale; HPLC; Response surface methodology; Ultrasound-assisted extraction (UAE).