title: Grewia gum as a potential aqueous film coating agent. I: Some physicochemical characteristics of fractions of grewia gum.
abstract: BACKGROUND
  Grewia gum has received attention as a polymeric pharmaceutical excipient in the recent times, being employed as a suspending, film coating, mucoadhesive, and binding agent. The low aqueous solubility, however, has limited its characterization and application.
  
  
  OBJECTIVE
  The purpose of this study was to fractionate and evaluate some physicochemical properties of the gum.
  
  
  METHODS
  Aqueous dispersion of the gum was treated at 80°C for 30 min in the presence of sodium chloride and was subsequently fractionated by successively centrifuging it at 3445 rpm for 30 min. Skeletal density, solubility, particle size, and rheological as well as thermal characteristics of the fractions were evaluated. The (1)H nuclear magnetic resonance (NMR) and near infrared (NIR) profiles of the fractions were also investigated. The solubility of the gum increased up to fourfold while the viscosity decreased from 244 to as low as70 cP at 40 rpm with some fractions.
  
  
  RESULTS
  Grewia gum and the fractions showed good thermal stability exhibiting no thermal events, but charred irreversibly at 297°C irrespective of the fraction. The molecular weight averages by weight and by number of the fractions were between 233,100 and 235,000. The (1)H nuclear magnetic resonance (NMR) spectra showed broad peaks. The NMR and NIR spectra suggested the presence of -OH and -OCH3 functional groups in this gum.
  
  
  CONCLUSIONS
  The fractionation improved solubility and facilitated further investigations on its characteristics that may have implication on its processing, application, and optimization as a potential pharmaceutical excipient.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, University of Jos, PMB 2084, JOS, Nigeria ; Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20N Pine Street, Baltimore MD 21201, USA.
authors.forename: Ikoni J
authors.initials: IJ
authors.lastname: Ogaji
authors.forename: Ignatius S
authors.initials: IS
authors.lastname: Okafor
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Hoag
keywords: Characterization; fractions; grewia gum; pharmaceutical excipient; potential
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