The ethanol precipitation process of Nauclea officinalis extract was optimized based on the concept of quality by design(QbD). Single factor tests were carried out to determine the levels of test factors. The ethanol volume fraction, pre-ethanol precipitation drug concentration, and ethanol precipitation time were taken as critical process parameters(CPPs). With the comprehensive scores of strictosamide transfer rate and solid removal rate as the critical quality attributes(CQAs), Box-Behnken design was employed to establish the mathematical models and space design between CPPs and CQAs, and the obtained optimal operating space was validated. The optimal operating space included ethanol volume fraction of 65%-70%, pre-ethanol precipitation drug concentration of 22-27 mg·mL~(-1), and ethanol precipitation time of 12 h. Based on the concept of QbD, this study adopted the design space to optimize the ethanol precipitation process of N. officinalis extract, which provided a reliable theoretical basis for the quality control in the production process of N. officinalis preparations. Moroever, this study provided a reference value for guiding the research and industrial production of traditional Chinese medicines.
Keywords: Box-Behnken design; Nauclea officinalis extract; critical process parameters; critical quality attributes; ethanol precipitation process; quality by design.