Optimization of Extraction Process for Longan (Dimocarpus longan Lour.) Leaves Using Multi-indicator Comprehensive Evaluation Method

[Objectives] This study aimed to optimize the extraction process of longan(Dimocarpus longan Lour.) leaves by multi-indicator comprehensive evaluation method. [Methods] The contents of gallic acid ethyl ester, astragalin, quercetin, luteolin and kaempferol in longan leaves were determined simultaneously by HPLC. Using the multi-indicator comprehensive evaluation method, the methanol concentration, solid to liquid ratio and extraction time for extraction of longan leaves were optimized by orthogonal test. [Results] The optimal extraction process of longan leaves are as follows: methanol concentration of 100%, solid to liquid ratio of 1∶5, and extraction time of 50 min. [Conclusions] The optimized process is simple and feasible, and it can be used to determine the contents of different ingredients in longan leaves.