Optimum extraction of polysaccharides from Opuntia dillenii and evaluation of its antioxidant activities

Response surface methodology (RSM) was applied to optimize the extraction of crude polysaccharides from Opuntia dillenii (Ker–Gaw) Haw. A three-level, four-variable Box–Behnken design was employed to obtain the best possible combination of extraction temperature (80–90 °C), extraction time (50–70 min), number of extraction cycle (1–3 times), and ratio of water to raw material (8:1–12:1, v/w) for maximum yield of crude polysaccharide. Besides, the antioxidant capacity of crude polysaccharide was evaluated by DPPH assay. The results showed that optimized extraction conditions were extraction temperature 85 °C, extraction time 63.7 min, extraction 2 times and ratio of water to raw material 11.14:1. Under these conditions, the experimental yield was 27.36 ± 0.21%, which is well in close agreement with the value (27.44%) predicted by RSM model. Pharmacological test showed that O. dillenii crude polysaccharides had a good antioxidant activity.