Response surface methodology was used to optimize extraction conditions, including ethanol concentration (X1) and extraction time (X2), to obtain the maximal antioxidant activity of Elsholtzia splendens extract. The optimized values of X1 and X2 were found to be 54.61% and 116.8 min, respectively. Experimental results obtained for the optimum extraction conditions agreed favorably with the predicted results, indicating the usefulness of prediction models for antioxidant extractions. This potent antioxidant activity had good correlation with total flavonoid content. The E. splendens extract prepared according to optimal conditions demonstrated a concentration-dependent α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging activity and lipid peroxidation inhibitory activity. In conclusion, E. splendens extract prepared by optimal conditions may be useful as a natural functional food ingredient with antioxidant activity.


Natural antioxidant compounds have received much attention because of their potential protective effects against free radical damage preventing cardiovascular diseases and tumor formation. Elsholtzia splendens, a subclass of the family Labiatae, is used as an ingredient of traditional medicinal food in eastern Asia. Although many health-promoting properties of E. splendens were demonstrated by recent studies, in order to develop a functional food derived from new bioactive compounds, such as E. splendens, the extraction steps should be well characterized for the quality of extracts and the efficiency of extraction. In this paper, response surface methodology was used to optimize extraction conditions to obtain the maximal antioxidant activity of E. splendens extract. The optimized E. splendens extract demonstrated a potent radical-scavenging and lipid peroxidation inhibitory activity. It is expected that the E. splendens extract could be used in a wide range of foods as a potential functional food ingredient.