Box-Behnken design for optimizing extraction of luteolin from celery leaves

A 17-run Box-Behnken design (BBD) was applied to statistically optimize the extraction of luteolin from celery leaves by varying three factors: extraction time (h), extraction temperature (°C), and ratio of water to raw material. The analysis was performed on a high-performance liquid chromatography (HPLC) system with a C18 column (150 x 4.6 mm, i.d.), and the optimum mobile phase was acetonitrile-water (30/70, v/v). The flow rate was 0.7 mL min-1, and the chromatogram was monitored at a wavelength of 347 nm. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and were examined using the appropriate statistical methods. The adjusted coefficient of determination (R2Adj) for the model was 0.9555, and the probability value (p < 0.0001) demonstrated a high significance for the regression model. The optimum extraction conditions were an optimized extraction time of 4.2 hr, an extraction temperature of 72.0°C, and a ratio of water to raw material of 26.0. Under these conditions, the mean extraction yield of luteolin was 69.1 mg g-1, which was in good agreement with the predicted model value.