Pectic polysaccharide from immature onion stick (Allium cepa): Structural and immunological investigation

• Published in: Carbohydrate polymers Vol. 92; no. 1; pp. 345 - 352
• Main Authors: Patra, Pradip, Sen, Ipsita K., Bhanja, Sunil K., Nandi, Ashis K., Samanta, Surajit, Das, Debsankar, Devi, K. Sanjana P., Maiti, Tapas K., Islam, Syed S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 30-01-2013; Elsevier
• Subjects: acid hydrolysis; Allium cepa; Animals; Applied sciences; Biological and medical sciences; carbon; Exact sciences and technology; galactose; Galactose - analogs & derivatives; Galactose - chemistry; Galactose - isolation & purification; Galactose - pharmacology; Immature onion stick (Allium cepa); Immunological study; Immunomodulators; Macrophage Activation - drug effects; Macrophage Activation - immunology; macrophages; Magnetic Resonance Spectroscopy; Medical sciences; methylation; Mice; Molecular Structure; Natural polymers; NMR Spectroscopy; nuclear magnetic resonance spectroscopy; onions; Onions - chemistry; oxidation; Pectic polysaccharide; Pectins - chemistry; Pharmacology. Drug treatments; Physicochemistry of polymers; polysaccharides; Polysaccharides - chemistry; Polysaccharides - immunology; Polysaccharides - isolation & purification; Polysaccharides - pharmacology; stable isotopes; Starch and polysaccharides; Structure; thymocytes; Thymocytes - drug effects; Thymocytes - immunology; Water; NMR Spectroscopy; Structure; Pectic polysaccharide; Immunological study; Immature onion stick (Allium cepa); Cell proliferation; Monocotyledones; Molecular structure; Onion; Thymocyte; Chemical isolation; Splenocyte; Experimental study; In vitro; Biological activity; Pectic substance; Immunomodulator; Water soluble compound; Liliaceae; Angiospermae; Plant origin; Oside polymer; Spermatophyta; Allium ascalonicum
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2012.09.013

► Pectic polysaccharide was isolated from immature onion stick. ► Its structure was established by chemical and 2D NMR studies. ► This molecule showed immunological activity.
The structure of a water-soluble pectic polysaccharide (PS) isolated from immature onion stick (Allium cepa) was investigated using acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies (1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC). The results of the above experiments indicated that the PS contained d-galactose, 6-O-Me-D-galactose, 3-O-acetyl-d-methyl galacturonate and d-methyl galacturonate in a molar ratio of nearly 1:1:1:1 and possesses a backbone of [→4)-α-d-GalpA6Me-(1→4)-α-d-GalpA6Me-(1→] in which one methyl galacturonate was substituted at O-3 position by an acetyl group and the neighboring methyl galacturonate being substituted at O-2 with a side chain, α-D-Galp-(1→4)-6-O-Me-β-D-Galp-(1→. The probable structure of repeating unit of the pectic polysaccharide was established as: [Display omitted]
The pectic polysaccharide showed in vitro splenocyte, thymocyte as well as macrophage activations.