Effects of Extraction Methods on the Physicochemical Properties and Biological Activities of Polysaccharides from Polygonatum sibiricum

Abstract

Polygonatum sibiricum polysaccharides (PSPs) have important biological functions, such as antioxidation, immunomodulatory, and hypolipidemic functions. Different extraction methods have effects on their structures and activities. In this study, six extraction methods, including hot water extraction (HWE), alkali extraction (AAE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), microwave-assisted extraction (MAE), and freeze–thaw-assisted extraction (FAE) were used to extract PSPs, and their structure–activity relationships were analyzed. The results showed that all six PSPs had similar functional group compositions, thermal stability, and glycosidic bond compositions. PSP-As (PSPs extracted by AAE) exhibited better rheological properties due to their higher molecular weight (Mw). PSP-Es (PSPs extracted by EAE) and PSP-Fs (PSPs extracted by FAE) had better lipid-lowering activity due to their lower Mw. PSP-Es and PSP-Ms (PSPs extracted by MAE), which do not contain uronic acid and have a moderate Mw, had better 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical-scavenging activity. On the contrary, PSP-Hs (PSPs extracted by HWE) and PSP-Fs, with the Mw of uronic acid, had the best OH-radical-scavenging activity. The high-Mw PSP-As had the best Fe2+-chelating ability. In addition, mannose (Man) may play an important role in the immunomodulatory activity. These results indicate that different extraction methods affect the structure and biological activity of polysaccharides to varying degrees, and these results are helpful for understanding the structure–activity relationship of PSPs.

A New Method of Extracting Polygonatum sibiricum Polysaccharide with Antioxidant Function: Ultrasound-Assisted Extraction-Deep Eutectic Solvents Method

“…This finding suggested that PsP may enhance the catalase activity within a specific concentration range, and provided a novel pathway for future research on the effects of PsP on catalase activity. The above results of antioxidant activity experiments were consistent with others similar research [ 16 , 18 ].…”

“…[12][13][14][15]. Jing et al [16] once compared the extraction yields of these different extraction methods for PsP. This study perfects the basic research on the extraction process of PsP and provides valuable experience for the follow-up research.…”

“…This study adopted RSM involved to the extraction yield and antioxidant effects of polysaccharide to determine the optimal extraction conditions of the UAE-DESs method, which included a liquid–solid ratio of 26:1 (mL:g), ultrasonic power of 82 W, ultrasonic time of 51 min and extraction temperature of 80 °C. Under the above conditions, the extraction yield of PsP could reach 43.61%, which is obviously higher than 33.81% if only using DESs (the solid:liquid ratio is 1:40, extraction time is 48 min, extraction temperature 89 °C) and 5.83% of only using ultrasound-assisted extraction (the solid:liquid ratio is 1:30, extraction time is 40 min, extraction temperature 60 °C, ultrasonic power is 100 W) in extracting PsP [ 16 , 25 ].…”

“…Therefore, the ultrasound method could also realize the diffusion of polysaccharides, which owes a series of advantages, such as short extraction time and simplified operation [ 27 , 28 ]. Jing et al [ 16 ] once adopted the ultrasound method to extract PsP, of which the extraction yield was 5.83%. Although the extraction yield of only ultrasound is low, it is still possible to use ultrasound as an assistance condition to improve the extraction yield of other methods, because the material matrix is more easily broken, enabling the efficient and short-term release of polysaccharides under the conditions of ultrasound assistance [ 29 ].…”

Comparison of Polygonatum sibiricum Polysaccharides Found in Young and Mature Rhizomes

“…One reason is mentioned in the above discussion. The other reason might be, the polysaccharide, that can donate more hydrogen atoms or electrons, can neutralize more free radicals by providing more hydrogen atoms or electrons, and thus better inhibit the oxidation process and reduce oxidative stress [48]. Therefore, the reason that the DPPH free radicals scavenging ability of the PsP of young rhizome was higher than that of mature rhizome, might be that the young rhizome possesses more hydrogen atoms or electrons.…”