Optimum extraction of polysaccharides from motherwort leaf and its antioxidant and antimicrobial activities

Box–Behnken design was employed to optimize the extraction conditions for polysaccharides from the leaves of motherwort (Leonurus cardiaca L.). Three independent variables including extraction temperature (60–100 °C), extraction time (60–120 min), and the ratio of water to raw material (20–60) were investigated. The results revealed that the quadratic and linear terms of three factors had strong effects on the extraction yield of polysaccharides from motherwort leaf. The best extraction conditions for the yield of polysaccharide (LCLP) was extraction temperature of 81.4 °C, time of 106.6 min and the ratio of water to raw material of 45.2. Under the optimal conditions, the extraction yield of LCLP was 9.17 ± 0.39%, which was well matched with value predicted by the model 9.26%. The results indicated that the purified LCLP exerted obvious scavenging effects on free radicals in vitro. Furthermore, motherwort polysaccharides could be used as a novel antimicrobial additive.