Abstract:

In this study, we investigated the optimization of polysaccharides extraction from the dried barks of Magnolia
officinalis Rehd. et Wils. by response surface methodology (RSM) based on Box-Behnken design and measured the
antioxidant activities of the extracted polysaccharides by superoxide anion radical scavenging, 1,1-diphenyl-2-picrylhydrazyl
(DPPH·) scavenging, 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS+·) radical scavenging, Fe2+ chelating
activity, as well as Ferric reducing antioxidant power (FRAP) assays. The results indicated that the optimal extraction
conditions for polysaccharides from Magnolia officinalis Rehd. et Wils. were obtained as follows: pH, 7.3; liquid-to-solid
ratio, 32:1 (mL/g); temperature, 78 ℃; and extraction time, 139 min. Under these conditions, the yield of polysaccharides
was 3.35%-3.52%. The extracted polysaccharides exhibited powerful antioxidant activities. The radical scavenging activities
against superoxide anion, DPPH and ABTS+· radicals, Fe2+ chelating activity and FRAP value were (18.72 ± 2.12) μmol
ascorbic acid equivalent (AAE)/mg, (0.59 ± 0.05) μmol Trolox equivalent (TE)/mg, (0.57 ± 0.04) μmol TE/mg, (0.38 ±
0.02) μmol EDTA-2Na equivalent (EE)/mg, and (2.19 ± 0.31) μmol TE/mg, respectively.

Key words: Magnolia officinalis Rehd. et Wils., polysaccharides, extraction, response surface methodology, antioxidant activity