Optimization of the extraction process for the seven bioactive compounds in Yukmijihwang‑tang, an herbal formula, using response surface methodology

Background: Yukmijihwang‑tang (YJT) contains multiple bioactive compounds. Heat‑reflux extraction was employed and optimized for the extraction of the bioactive compounds in YJT. Objective: The determination of optimal conditions with maximum yields of bioactive compounds, gallic acid, 5‑hydroxymethylfurfural, morroniside, loganin, paeoniflorin, benzoic acid and paeonol, in YJT. Materials and Methods: The extraction ratio (ratio of water to herbal formula), extraction time and extraction number were set as individual values and the yields of the seven compounds were the response values that were optimized with a Box–Behnken design. Results: The optimal conditions obtained from response surface methodology (RSM) were 1:11.99 for the extraction ratio, 94.53 min for the extraction time and 2.21 for the extraction number. Under the optimal conditions, the response value of the experiment closely agreed with the predicted response value. Conclusions: The result suggests that RSM is successfully applied for optimizing the extraction of the marker compounds in YJT.