Xyloglucan Research Paper

Xyloglucans (XGs) are complex polysaccharides found in the primary cell walls of higher plants. However, few studies report the characterization of xyloglucans from the pulp of fruits. In this work a xyloglucan rich fraction, PF-SPK-100R, was obtained from alkali prune extract. Characterization was conducted through monosaccharide composition, methylation and 13C-NMR analysis. PF-SPK-100R was composed of a fucogalactoxyloglucan (∼68%) and an arabinoxylan. Finally, this paper brings important features of xyloglucans found in prunes, and provides new insights into the diversity of fruit hemicellulosic polymers.

Keywords: Prunes/ Prunus domestica/ Polysaccharides/ Xyloglucan/ Structural characterization.

1. Introduction

Xyloglucans

According to their structures, XGs hold many potential applications in the food industry as well as to biotechnology processes (Maeda, Yamashita, & Morita, 2007; Lima-Nishimura et al., 2003). Furthermore, as a constituent of dietary fiber, xyloglucans may possess nutritional attributes of biological significance and value (Itoh et al., 2008), such as anti-viral (Mastromarino et al., 1997), hypolipidemic (Yamatoya, Shirakawa, Kuwano, Suzuki, & Baba, 1996), anti-tumoral (Kato, Uchida, Ito, & Mitsuishi, 2001; Hensel & Meier, 1999), immunomodulatory (Rosário et al., 2008; Pauly et al., 1999; Puhlmann, Zenk, & Wagner, 1991; Wagner, Stuppner, Schafer, & Zenk, 1988)and hypoglycemic (Maiti, Jana, Das, & Ghosh, 2004; Sone, Makino, & Misaki, 1992; Martinello et al., 2006), activities.

Additional evidence concerning structural features of xyloglucans from diverse sources is necessary to understand the central relationship between biological functions of xyloglucans and their structures. In this work, we describe structural features of a xyloglucan rich fraction extracted from Prunes, the dried fruits from Prunus domestica

The per-O-methylated polysaccharide was further submitted to methanolysis in 3% HCl–MeOH (80 °C, 2 h) followed by hydrolysis with H2SO4 (0.5M, 12 h) and neutralization with BaCO3. The material was then reduced an acetylated as described above for monossacarides composition, except that NaBD4 was used for reduction. The resultants partially O-methylated alditol acetates were analyzed with a GC-MS. For separation, a 30 m x 0.25 mm i.d. capillary column of DB-225 was held at 50 ºC during injection for 1 min, then programmed at 40 ºC/min to 210 ºC and held at this temperature for 31 min. Typical electron impact breakdown profiles and retention times of partially O-methylated alditol acetates were used for identification (Sassaki, Gorin, Souza, Czelusniak, & Iacomini, 2005).

2.6 Nuclear magnetic resonance (NMR) spectroscopy

Spectra of 13C NMR were acquired using a Bruker spectrometer (DRX 400 MHz AVANCE III NMR - Bruker Daltonics, Germany). Samples were dissolved in D2O and placed in a 5 mm inverse gradient probe, at 70 C for analysis. Chemical shifts were expressed as  ppm and acetone CH3 groups resonance was used as internal standard ( 30.2). The spectra were handled using the Topspin® (Bruker) computer program.

3. Results and