A comparison of a polysaccharide extracted from ginger (Zingiber officinale) stems and leaves using different methods: preparation, structure characteristics, and biological activities

This study investigates how extraction method impacts the yield, chemical composition, structure characteristics, hypoglycemic and antioxidant activity of polysaccharides from ginger (Zingiber officinale Roscoe) stems and leaves (GSLP). Four extraction methods were employed to obtain the GSLP, including hot water extraction (HWE), ultrasound-assisted extraction (UAE), alkaline solution extraction (ASE), and enzyme-assisted extraction (EAE). The data showed that ASE produced highest extraction yield compared to the other extraction methods. Scanning electron microscopy indicated that GSLP microstructures were greatly influenced by extraction method. Moreover, in vitro hypoglycemic activity and antioxidant activity experiments demonstrated that the biological capacities of ASE-GSLP were superior to GSLPs extracted by the other methods. Taken together, these results indicate that polysaccharides from ginger stems and leaves obtained by alkali, complex enzyme, and ultrasonic-assisted extractions are imbued with different characteristic mechanisms of degradation, despite the uniformity of their main structures. In addition, ASE-GSLP displayed better biological activities probably due to its abundant uronic acid content, higher sulfate radical, and smaller molecular weight. Thus, it can be concluded that ASE has great potential as an effective strategy for obtaining polysaccharides from stems and leaves because of its higher yield and the remarkable bioactivity of its products. (C) 2020 Elsevier B.V. All rights reserved.