Extraction, Characterization and Immunological Activity of Polysaccharides from Rhizoma gastrodiae

Abstract

A response surface and Box-Behnken design approach was applied to augment polysaccharide extraction from the residue of Rhizoma gastrodiae. Statistical analysis revealed that the linear and quadratic terms for three variables during extraction exhibited obvious effects on extraction yield. The optimum conditions were determined to be a liquid-to-solid ratio of 54 mL/g, an extraction temperature of 74 °C, an extraction time of 66 min, and three extractions. These conditions resulted in a maximum Rhizoma gastrodiae polysaccharide (RGP) extraction yield of 6.11% ± 0.13%. Two homogeneous polysaccharides (RGP-1a and RGP-1b) were obtained using DEAE cellulose-52 and Sephadex G-100 columns. The preliminary characterization of RGP-1a and RGP-1b was performed using HPLC-RID, HPGPC, and FTIR. Tests of the immunological activity in vitro showed that the two polysaccharides could significantly stimulate macrophages to release NO and enhance phagocytosis in a dose-dependent manner. In particular, RGP-1b (200 μg/mL) and LPS (2 μg/mL) had almost the same influence on the NO production and phagocytic activity of RAW 264.7 macrophages (p > 0.05). All the data obtained indicate that RGP-1a and RGP-1b have the potential to be developed as a health food.

Gastrodia elata Blume Polysaccharides: A Review of Their Acquisition, Analysis, Modification, and Pharmacological Activities

“…Therefore, before the extraction of polysaccharides degreasing using organic solvents, including chloroform–ethanol [16,17], ether [17], petroleum ether [18,19], methanol [20], and different concentrations of ethanol [20,21] is required to remove some interfering components [22]. G. elata can be degreased with different concentrations of ethanol, such as 75% ethanol [23], 80% ethanol [24], 85% ethanol [25,26], and 95% ethanol [10,27]. Chen et al obtained crude G. elata polysaccharide (RGP) in a yield of 6.11% after degreasing with 75% ethanol [23].…”

“…G. elata can be degreased with different concentrations of ethanol, such as 75% ethanol [23], 80% ethanol [24], 85% ethanol [25,26], and 95% ethanol [10,27]. Chen et al obtained crude G. elata polysaccharide (RGP) in a yield of 6.11% after degreasing with 75% ethanol [23]. Lee et al obtained 2.47 g of crude G. elata polysaccharide degreased with 80% ethanol [24].…”

“…Water is widely used as the solvent to extract G. elata polysaccharides under different conditions. Most of the G. elata polysaccharides, e.g., glucan PGEB-3 H [25,26], WGEW [10], WTMA [27], RGP-1a and RGP-1b [23], the acidic polysaccharides [24] and PGE [28], were extracted by traditional heating methods with different extraction times, extraction frequencies (for assisted methods), and extraction temperatures. Specific information can be found in Table 1.…”

“…The merits of these methods are their compatibility with polysaccharides. Due to the fact the Sevag method is much milder than the others, G. elata aqueous extract is typically deproteinized using the Sevag method [23,41,54]. The enzyme method is another effective and alternative to the common methods to eliminate proteins.…”

“…For example, Zhu et al separated the crude polysaccharides on a Sephadex G-200 column at a flow rate of 0.30 mL/min, and then collected and further purified them by ultra-filtration tubes to obtain G. elata polysaccharides (PGE) [28]. Moreover, it has been reported that polysaccharides, such as PGEB-3H [25,26], RGP-1a and RGP-1b, can be purified by ion-exchange chromatography combined with size exclusion chromatography [23]. The macroporous resin D101 purifies G. elata polysaccharides well and can increase the purity of G. elata polysaccharides to 65.7% under optimal purification conditions [57].…”