Abstract: Reflux extraction method was used to extract the polyphenols from Clerodendranthus spicatus in this study.Single factor experiments and the L₉(3⁴) orthogonal experiment was applied to optimize the extraction conditions.In addition,the antioxidant activities of the extract were evaluated by DPPH· and ·OH scavenging assays.The optimal extraction conditions for extracting polyphenols were as follows:liquid/solid ratio of 10:1 mL/g,ethanol concentration of 50%,2 h per time,and extract 3 times.Under the optimized conditions,the extraction yield of total polyphenol was up to 3.60%.In vitro antioxidant activity of total polyphenols increased with the increasing of concentration,the scavenging abilities against DPPH· and ·OH were stronger than vitamin C within the range of 1-10 μg/mL and within the range of 100-1250 μg/mL,respectively.The IC₅₀ values were 5.78 and 6.31 μg/mL toward DPPH·,and 851.1 and 940.1 μg/mL toward ·OH,respectively.

Key words: Clerodendranthus spicatus (Thunb.) C.Y.Wu, polyphenols, extraction technology, antioxidant activity