灵芝子实体中三萜酸的提取及其稳定性

Optimization of Triterpenoid Acid Extraction from Ganoderma lingzhi Fruit Bodies and Stability Under Different Temperature-Time Regimes

研究不同提取方法对灵芝（Ganodermalingzhi）子实体中三萜酸提取率的影响，结果表明，采用乙醇回流法所得三萜酸的提取得率最大，影响提取的关键因素为液料比、提取时间和提取次数；采用Box．Behnken设计及响应面分析法对这3个因素进行优化，并通过回归拟合，建立了预测灵芝三萜酸提取的多项式模型，可预测灵芝子实体中三萜酸提取率的回归模型如下：Y=0．335-0．003125X1＋0．021X2—0．014X3＋0．0005X1 X2—0．019X1X3—0．005X2X3—0．044X12—0．040X2^2-0．032X3^2经响应面最优分析，获得3个因素的最佳水平为：液料比25：1，提取时间2h，提取次数3次。经实际试验验证，在该条件下，灵芝子实体三萜酸提取率可达0．335mg／g，与预测值相比，实测值低1．18％。稳定性试验结果表明，在较低温度下（25℃以下），三萜酸化合物较稳定；但在50℃及以上温度条件下，三萜酸存在明显的降解现象，三萜酸的稳定性与温度及保藏时间呈负相关。

Four methods （ultrasonic, soaking, shaking bed, reflux） for extracting triterpenoid acids from Ganoderma lingzhi fruit bodies were compared reflux extraction with absolute ethanol was most effective and the key parameters affecting the yield of triterpenoid acids were the ethanol：fruit body ratio （X1）, extraction time （X2） and extraction frequency （X3）. Application of Box-Benhnken testing and response surface methodology using the polynomial model YExtraction yield = 0. 33 ＋ 0. 003125X1 ＋ 0. 021X2 - 0. 014X3 ＋ 0.0005X1 X2 - 0. 019X1 X3 - 0. 005X2 X3 - 0. 044Xlz - 0. 040X22 - 0. 032X32 predicted that maximal triterpenoid acid yields would be achieved with three two-hour extractions using an ethanol： fruit body ratio of 25：1 （v/w）. When tested experimentally, an extraction yield of 0. 335 mg/g was attained under the optimized conditions, which was 1. 18% lower compared with the predicted maximum value. Extracted triterpenoid acids were stable at low temperatures （4, 25 ℃） but significant degradation occurred when exposed to 50 ℃ and above.