Abstract: Objective: To find optimal conditions for the extraction of polysaccharides from whole plants of Gonostegia hirta (BL.) Miq. Methods: Solvent reflux extraction was used for polysaccharide extraction. Five parameters that influence extraction efficiency were investigated using one-factor-at-a-time and orthogonal array design methods, and three main ones were optimized based on a quadratic rotation-orthogonal composite experimental design. Results: In decreasing order of their effect on extraction efficiency, five influential parameters were ranked as extraction temperature＞solvent-to-solid ratio＞extraction time ＞extraction number＞soaking time. Their optimal levels were 96.26 ℃, 27.28:1 (mL/g), 109.20 min each time, 2 and 90 min, respectively, resulting in an extraction yield of 25.121%. Conclusion: Quadratic rotation-orthogonal composite experimental design permits reasonable optimization of polysaccharide extraction from Gonostegia hirta (BL.) Miq.

Key words: Gonostegia hirta (BL.) Miq., polysaccharides, quadratic rotation-orthogonal composite experimental design, extraction rate