Effect of in vitro simulated gastrointestinal digestion on structural characteristics and anti-proliferative activities of the polysaccharides from the shells of Juglans regia L.

The present research was designed to investigate the effects of simulated gastrointestinal digestion in vitro on the structural characteristics and anti-proliferative activities of polysaccharides from the shells of Juglans regia L. (JRP). Results suggested that JRP was composed of glucose, ribose, galactose, mannose, arabinose and rhamnose in a molar ratio of 10.7:4.9:16.4:2.3:10.8:2.3, with the molecular weight distributed from 3.21 × 10⁵ to 4.55 × 10⁵ Da. JRP belonged to non-crystalline substance, with irregular, smooth and compact morphological characteristics. Nevertheless, during gastrointestinal digestion in vitro, the physicochemical properties of JRP including molecular weight, monosaccharide composition, crystalline properties and morphology were significantly changed, accompanying with the increase of reducing sugar in digestive juice. Through measurements of anti-proliferation activities, the results showed that the digested JRP could remarkably inhibit the viabilities of HeLa cells by induction of apoptosis as a result of the excessive ROS accumulation and cell cycle arrest at G2/M phase, all of which were pronouncedly stronger than the ones induced by undigested JRP. These findings suggested that JRP processed by gastrointestinal digestion possessed more potential anti-proliferative applications that need to be exploited.