Structural Characterization and Hypoglycemic Effects of Arabinogalactan-Protein from the Tuberous Cortex of the White-Skinned Sweet Potato (Ipomoea batatas L.)

Abstract

An arabinogalactan-protein (WSSP-AGP) was isolated from the tuberous cortex of the white-skinned sweet potato (WSSP; Ipomoea batatas L.). It consists of 95% (w/w) carbohydrate and 5% (w/w) protein with high contents of hydroxyproline, alanine, and serine. Its sugar composition is α-L-Rha:α-L-Ara:β-D-Gal:β-D-GlcA in a molar ratio of 1.0:4.1:7.6:1.3. Its weight-average molecular weight was estimated to be 126,800 g/mol by high-performance size exclusion chromatography coupled with multiangle laser light scattering. Structural analysis indicated that WSSP-AGP is a (1→3)-β-D-galactan highly branched at O-6 with (1→6)-β-D-galactan, in which the branched chains are substituted at the O-3 position with α-L-Araf-(1→ and α-L-Araf-(1→5)-α-L-Araf-(1→ and at the O-6 position typically with α-L-Rhap-(1→4)-β-D-GlcAp-(1→ as terminating groups. Continuous administration of WSSP-AGP to KKAy mice significantly lowered fasting plasma glucose levels. This indicates that WSSP-AGP plays an important role in the hypoglycemic effects of WSSP.

Antitussive Activity of the Water-Extracted Carbohydrate Polymer fromTerminalia chebulaon Citric Acid-Induced Cough

“…The anomeric signals in the 1 H NMR spectrum (Figure 2) of CP were assigned according to sugar composition, glycosidic linkage makeup, and data in the literature [33, 34]. The signal at δ 5.05 was assigned to anomeric protons (H1) of the nonreducing terminal α -Ara f and the signals in between δ 5.23 and δ 5.32 originated from the anomeric protons (H1) of 1,5- and 1,3-linked Ara f , respectively.…”

Immune activity of sweet potato (Ipomoea batatas L.) glycoprotein after enzymatic and chemical modifications

“…Ozaki et al 8 and Oki et al 9 found that an arabinogalactan protein (WSSP-AGP) from the white-skinned sweet potato has hypoglycemic effects. In our previous study, 2 we found that SPG exhibits a dose-dependent hypolipidemic effect.…”

Chemical Optimization of Protein Extraction from Sweet Potato (Ipomoea batatas) Peel

“…Caiapo Potato powder, a protein extract from a white‐skinned sweet potato cultivar, lowered fasting blood glucose levels and increased insulin sensitivity in type II diabetics (Ludvik and others 2003, 2004, 2008; Kusano and others 2005). A 22 kDa acidic glycoprotein (Kusano and others 2001) and a 126.8 kDa arabinogalactan‐protein (Ozaki and others 2010) have been proposed as the active components of Caiapo Potato powder. Sweet potato trypsin inhibitor proteins (TIP) possess antioxidant properties against several reactive oxidizing species (Hou and others 2001; Huang and others 2007b).…”

“…Shivaraj and others (1979) used distilled water to extract alpha‐amylase inhibitory proteins from sweet potatoes, and Purcell and others (1978) and Walter and Catignani (1981) also started their protein extractions by blending with water. Kusano and others (2001) and Ozaki and others (2010) also began their process to isolate the protein responsible for the antidiabetic properties of sweet potatoes by mixing with distilled water. Few researchers have compared solvents.…”