Optimization of Ultrasound-Assisted Extraction and Structural Characterization of the Polysaccharide from Pumpkin (Cucurbita moschata) Seeds

Abstract

In the present study, ultrasound-assisted extraction (UAE) of crude polysaccharides (PSP) from pumpkin seeds was optimized by response surface method (RSM). The polysaccharide yield (2.29 ± 0.14%), which agreed closely with the theoretical predicted value 2.40%, was obtained under the optimal extraction conditions: extraction time 24 min, extraction temperature 50 °C, ultrasonic power 347 W, and liquid to solid ratio 23 mL/g. After further purification by two-step column chromatography, a novel polysaccharide (PSP-1) was isolated from pumpkin seeds. PSP-1 was composed of mannose, glucose, and galactose in a molar ratio of 1.00:4.26:5.78 with molecular weight of 3728 g/mol. 1D and 2D NMR spectroscopy analysis revealed that the backbone of PSP-1 was mainly formed by β→6)-β-d-Galp-(1→, →6)-α-d-Glcp-(1→, and →3,6)-β-d-Manp-(1→ with branching at O-3 and O-6 of →3,6)-β-d-Manp-(1→. Branch linkages were composed of α-d-Glcp-(1→ and →4)-α-d-Galp-(1→.

Enzyme Assisted Extraction, Purification and Structure Analysis of the Polysaccharides from Naked Pumpkin Seeds

“…Obviously, EAE showed higher efficiency with a shorter extraction time. At the same time, the yield of PSP (3.22%) using EAE was also higher than that of UAE (2.29%) with extraction time of 24 min and extraction temperature of 50 • C [14]. These data showed that EAE was an excellent method for polysaccharides extraction from pumpkin seeds.…”

“…Sci. 2018, 8, x FOR PEER REVIEW 9 of 14 that of UAE (2.29%) with extraction time of 24 min and extraction temperature of 50 °C [14]. These data showed that EAE was an excellent method for polysaccharides extraction from pumpkin seeds.…”

“…The main backbone structure of PSP-1 comprised →6)-β-D-Galp-(1→, →6)-α-D-Glcp-(1→, and →3,6)-β-D-Manp-(1→. Branch linkage was composed of α-D-Glcp-(1→ and →4)-α-D-Galp-(1→ [14]. The present result confirmed that PSPE consisted of →4)-α-D-Glcp-(1→, →3,6)-β-D-Glap-(1→, →4)-β-D-Manp-(1→, and β-D-galactose.…”

“…In our earlier work, hot-water extraction (HWE) and ultrasound-assisted extraction (UAE) have been employed for the polysaccharides from pumpkin seeds [13,14]. After separation by two-step column chromatography, two purified polysaccharides (PSP-I and PSP-1) were obtained from pumpkin seeds, respectively [14,15]. PSP-1 extracted with UAE had a lower molecular weight of 3728 g/mol than PSP-I of 21,100 g/mol from HWE.…”

Ionic Liquid–Ultrasound-Based Extraction of Biflavonoids from Selaginella helvetica and Investigation of Their Antioxidant Activity

“…Recently IL-ultrasound-assisted extraction (IL-UAE) has been found for natural product extraction and has many advantages, including less organic solvent usage, shortening of extraction time, high extraction efficiency, and is also environmentally friendly [22]. For instance, Xu et al [23] extracted curcuminoid constituents from rhizomes of Curcuma longa with IL-UAE.…”