Abstract: This study was to investigate the optimum extraction conditions of antioxidant components from Ledum palustre L.and antioxidation of the extraction.Based on the results of the single-factor tests,three factors,i.e.,extraction time,solid-liquid ratio and extraction temperature were screened out,which were then used as the factors in Box-Benhnken center composite design.Response surface methodology (RSM) analysis was carried out with the scavenging rates of the extracts toward 1,1-dipheny1-2-picrylhydrazyl(DPPH) radical as the response values.Besides,the antioxidant activity in vitro of Ledum palustre L.extraction was evaluated.Results showed that the optimum extraction conditions by RSM were as follows:extraction time of 3.3 h,extraction temperature of 69 ℃ and solid-liquid ratio of 1∶23.Under these conditions,the average DPPH radical scavenging rate was 84.37±0.17% which was close to the predicted results.The yield of the antioxidant components was 4.68±0.24 g/100 g,and content of the total flavonoid and polyphenol was 236.17±2.16 mg/g and 73.97±3.18 mg/g,respectively.The results of antioxidation experiment indicated that the Ledum palustre L.extracts showed good antioxidant activity.

Key words: Ledum palustre L., solvent extraction, response surface methodology, antioxidant activity