Response Surface Optimized Ultrasonic Assisted Extraction of Total Flavonoids from Walnut Leaves and In Vitro Antibacterial Activities

摘要

In this paper, the optimum extraction conditions oftotal flavonoids extracted from walnut leaves subjected to Ultrasonic AssistedExtraction (UAE) were optimized by Response Surface Methodology (RSM). Themathematical model showed the high coefficient of measurement (R2 =0.9938) which indicated that this model could be used to guide the responsesurface methodology. The optimum extraction parameters for extractingflavonoids from walnut leaves determined in this study were extractiontemperature 47.73°C, extraction time 30.79 min, ethanol concentration 72.89% (v/v). Under the optimal extractionconditions, the flavonoids yield was about 3.5315%. Statistical analysis of theresults showed that extraction temperature, extraction time and ethanolconcentration significantly affected the extraction yield of total flavonoids.In addition, the antibacterial activity assays ofthe flavonoids were carried out and it wasdemonstrated that the total flavonoids extracted at the optimum conditions hadpronounced antibacterial effects against the four bacterial species. Therefore,this study suggested that walnut leaves are promisingresourceswith antibacterial properties for the development of phytomedicines.