title: Structural analysis of novel bioactive acylated steryl glucosides in pre-germinated brown rice bran.
abstract: Previous studies from our laboratory indicated that pre-germinated brown rice (PR) contained certain unknown bioactive lipids that activated two enzymes related to diabetes: Na+/K+ATPase and homocysteine-thiolactonase. In this paper, we report on the isolation and structural characterization of the activator lipids from PR bran as acylated steryl glucosides (ASGs). The activator lipid was isolated by silica gel column chromatography, and its chemical structure was determined by NMR, GC-MS, and tandem mass spectrometry. We demonstrated that the bioactive component consists of a mixture of acylated steryl beta-glucosides. Delta8-cholesterol and 2-hydroxyl stearic acid were identified as constituents of ASGs. The steryl glucosides (SGs) subsequent to alkaline hydrolysis lost this enzyme activator activity. Soybean-derived ASGs were not active. This activity may be quite peculiar to PR-derived ASGs. Our findings suggest that the molecular species of ASG may play an important contributing role in the anti-diabetic properties of a PR diet.
authors.affiliation: Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912, USA.
authors.forename: Seigo
authors.initials: S
authors.lastname: Usuki
authors.forename: Toshio
authors.initials: T
authors.lastname: Ariga
authors.forename: Somsankar
authors.initials: S
authors.lastname: Dasgupta
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.forename: Keiko
authors.initials: K
authors.lastname: Morikawa
authors.forename: Shota
authors.initials: S
authors.lastname: Nonaka
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Okuhara
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kise
authors.forename: Robert K
authors.initials: RK
authors.lastname: Yu
mesh_terms: D000215:Acylation; D000818:Animals; D043182:Carboxylesterase / Q000378:metabolism; D008076:Cholesterol, HDL / Q000378:metabolism; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D004043:Dietary Fiber / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D018525:Germination; D005960:Glucosides / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D012275:Oryza / Q000737:chemistry* / Q000502:physiology; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D008076:Cholesterol, HDL; D004043:Dietary Fiber; D005960:Glucosides; D008055:Lipids; D043182:Carboxylesterase; D000254:Sodium-Potassium-Exchanging ATPase