Purification process of total triterpenic acids from Lycopus lucidus Turcz. by Box-Behnken design-response surface methodology

【Objective】 A response surface model was established to optimize the purification process of total triterpenic acids from Lycopus lucidus Turcz. with suitable resin， so as to provide technical reference for further study on the activity of total triterpenic acids from L. lucidus.【Method】Using the Box-Behnken design method，the total triterpenic acids of L. lucidus was purified by macroporous resin adsorption. The purification effects of macroporous resins（AB-8 type， D101 type，HPD600 type，DA201 type and S-8 type）on total triterpenic acids of L. lucidus were determined by using the adsorption rate and desorption rate as indexes. The sample concentration， sample loading speed，eluent concentration and eluentvelocity were the independent variables，and recovery rate was the dependent variable. The purification process parameters of total triterpenic acids from L. lucidus were optimized by response surface methodology.【Result】 Optimum color development conditions were：color development temperature of 60 ℃，5% vanillin-glacial acetic acid of 0.2 mL，perchloric acid of 0.4 mL，and detection wavelength of 545 nm. The results showed that AB-8 type macroporous resin had the best adsorption and desorption effectsontotal triterpenic acids of L. lucidus，withthe desorption rate of 88.61% and the adsorption rate of 70.54%. The loading volume was 40 mL，and 80% ethanol 100 mL was the best eluent volume. A regression equation was set up： Y=0.6887+0.0196A-0.0085B-0.0287C+0.0052D+0.0299AB-0.0107AC-0.0122AD+0.0128BC+ 0.0211BD+0.026A²-0.0765B²-0.0877C²-0.0932D² （A： sample concentration， B： sample loading speed， C： eluent concentration， D： eluent velocity， Y： recovery rate of total triterpenic acids）. According to Box-Behnken variance analysis， sample concentration，eluent concentration， the interaction between sample concentration and sample loading speed， and the interaction between eluent concentration and eluent velocity had extremely significant effects on the recovery rate of total triterpenic acids from L. lucidus （P＜0.01），while the interaction between sample loading speed and eluent velocity had significant effects on the recovery rate of total triterpenic acids from L. lucidus（P＜0.05）. The four single factors affected the recovery rate of total triterpenic acids of L. lucidus in the order of eluent concentration＞sample concentration＞sample loading speed＞eluent velocity from L. lucidus. The optimized purification process for total triterpenic acids of L. lucidus was：sample concentration of 0.66 mg/mL，sample loading speed of 2 BV/h，eluent concentration of 80% and from L. lucidus of 2 BV/h. Under these conditions，the average recovery rate of total triterpenic acids was 67.37%.【Conclusion】The established regression model can be used to predict the purification process of total triterpenic acids from L. lucidus；the AB-8 type macroporous resin has a relatively good effect on the separation and purification of total triterpenic acids from L. lucidus，which is suitable for the purification of total triterpenic acids.