title: Structural analyses and immunomodulatory properties of fructo-oligosaccharides from onion (Allium cepa).
abstract: Onion (Allium cepa) is an immune-boosting food rich in fructans. The major aim of this study is to characterize and investigate the immunomodulatory properties of onion fructo-oligosaccharides (FOS). FOS was isolated from onion bulbs by hot 80% ethanol extraction (yield: ∼4.5 g/100 g fw) followed by gel permeation chromatography. NMR of onion FOS revealed unusual β-D-Glc terminal residue at the non-reducing end. TLC and ESI-MS analyses showed that onion FOS ranged from trisaccharides to hexasaccharides. Onion FOS (50 μg/mL) significantly increased (∼3-fold) the proliferation of mouse splenocytes/thymocytes vs. control. Further, onion FOS enhanced (∼2.5-fold) the production of nitric oxide by peritoneal exudates cells (PECs) from Wistar rats; intracellular free radicals production and phagocytic activity of isolated murine PECs were also augmented. Our structural and in vitro results indicate that onion FOS comprising of tri- to hexasaccharide units belongs to inulin-type fructans, and possess immunostimulatory activities towards murine lymphocytes and macrophages.
authors.affiliation: Department of Biochemistry and Nutrition, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, India.
authors.forename: V Prasanna
authors.initials: VP
authors.lastname: Kumar
authors.affiliation: Department of Meat and Marine Sciences, CSIR-Central Food Technological Research Institute, Mysore, Karnataka, India.
authors.forename: K V Harish
authors.initials: KVH
authors.lastname: Prashanth
authors.affiliation: Department of Biochemistry and Nutrition, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, India. Electronic address: venkatyp@yahoo.com.
authors.forename: Y P
authors.initials: YP
authors.lastname: Venkatesh
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D000431:Ethanol / Q000737:chemistry; D005609:Free Radicals / Q000378:metabolism; D005630:Fructans / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D007155:Immunologic Factors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry*; D019697:Onions / Q000737:chemistry*; D010587:Phagocytosis / Q000187:drug effects; D051381:Rats; D013154:Spleen / Q000166:cytology
chemical_list: D005609:Free Radicals; D005630:Fructans; D007155:Immunologic Factors; D009844:Oligosaccharides; D009569:Nitric Oxide; D000431:Ethanol
keywords: Fructo-oligosaccharides; Immunomodulation; Inulin; Mitogenicity; Onion; Phagocytosis