Optimization of Microwave Assisted Extraction of Total Triterpenoid in Diospyros kaki Leaves Using Response Surface Methodology

The tnterpenoid in Diospyms kaki leaf has multiple pharmacological activities Thus a fast and efficient method for preparation of triterpenoid from Diospyros kaki is very important In this study, several extraction methods (Soxhlet exti action, reflux extraction, ultrasound assisted extraction, microwave assisted extraction) were compared Microwave assisted extraction was found to be the most effective method and then the extraction conditions were further optimized using central composits, design. The results showed extraction time and solvent to solid ratio were statistically most significant factors on total tnterpenoid extraction The optimal conditions were calculated as extraction under microwave power 365 3 W for 13.05 min, with 60 27 % ethonal as solvent at a solvent to solid ratio 22 26 Under the optimal conditions, the yield of total tnterpenoid obtained experimentally (61 82 mg/g dry leaves) was close to its predicted value of 71 43 mg/g dry leaves, which suggested the mathematical model was fit well with the experimental data of total tnterpenoid extraction In addition, the HPLC assay implied that live tnterpene acids (ursolic acid. oleamc acid, barbmervic acid, rotungemc acid and 24-hydroxy ursolic acid) were abundant in the extracts