The ultrasonic-assisted extraction of polysaccharide from Dendrobium officinale at a 250 W low power was optimized by response surface methodology based on central combination design.Extraction temperature,solvent-to-solid ratio,and ultrasonic treatment time were considered as independent variables.The optimum extraction conditions were determined as follows:extraction temperature 41.74 ℃2,solvent-to-solid ratio 50.26∶1 (mL/g),and ultrasonic treatment time 28.65 min.Under these conditions,the maximum extraction yield of 25.39％ was obtained,which was increased by 18％ compared with the value obtained using conventional hot water extraction with a simultaneous reduction in extraction time of 75％.Moreover,the DPPH and hydroxyl radical scavenging activities of polysaecharide from D.officinale were not reduced during ultrasonic-assisted extraction.Drosophila melanogaster were fed with different doses of the extracted polysaecharide,and the results showed that the polysaccharide at moderate dose provided the best antioxidant activity as evidenced by a 30％ increase in superoxide dismutase (SOD) and catalase (CAT) activity and a 46％ decrease in malondialdehyde (MDA) content of male D.melanogaster,as well as an increase of 60％ in CAT activity and 6％ in SOD activity and a 20％ decrease in MDA content of female D.melanogaster,extending the lifespan by an average of 20％.%在低超声波功率250 W条件下,利用响应面法优化铁皮石斛多糖提取工艺.根据Box-Behnken设计原理对提取温度、液料比、超声波处理时间进行中心组合试验,结果表明最佳提取条件为提取温度41.74℃、液料比50.26∶1 (mL/g)、超声波处理时间28.65 min,此条件下铁皮石斛多糖得率为25.39％.比文献报道传统热水浸提最佳条件下多糖得率提高了18％,提取时间为传统热水浸提的1/4,且超声波辅助法并没有造成多糖清除1,1-二苯基-2-三硝基苯肼自由基能力、清除羟自由基能力的降低.利用不同剂量铁皮石斛多糖喂食果蝇,结果表明中剂量组为最佳剂量组,雄果蝇超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)活力提高了30％,丙二醛(malondialdehyde,MDA)含量降低了46％;雌果蝇CAT活力提高了60％,SOD活力提高了6％,MDA含量降低了20％,雌、雄果蝇的平均最高寿命提高了20％.
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