CHARACTERIZATION AND LAXATIVE EFFECT OF INSOLUBLE DIETARY FIBERS EXTRACTED FROM MANGABA FRUIT (Hancornia speciosa)

Hancornia speciosa (HS), popularly known as mangaba, is a Brazilian native fruit consumed among Midwest, North and Northeast regions. Our research group already elucidated Mangaba’s pulp laxative effect as a food matrix, and since the fruit is rich in dietary fiber, the aim of the current work was to isolate, characterize and evaluate the laxative potential of the insoluble dietary fibers (IDF) from H. speciosa fruit pulp. The polysaccharides that compose the dietary fiber fractions were extracted using the enzymatic-gravimetric method, giving soluble (3.7%) and insoluble (21.1%, IDF fraction) dietary fibers. The IDF showed a complex monosaccharide composition, being composed of arabinose (49.0%), galactose (19.0%), xylose (17.0%), glucose (10.0%), mannose (4.0%) and trace amounts of rhamnose and fucose, identified by gas chromatography and mass spectrometry. The predominant monosaccharide arabinose is commonly found in biopolymers such as arabinans, arabinogalactans or arabinoxylans. The effects of IDF on small intestine transit was evaluated in a loperamide-induced constipation experimental model. Treatments were administered by gavage, over an 8-day period, at the dose of 500 mg/kg body weight for IDF and psyllium, as a positive control group, and 10 mL/kg body weight for loperamide. Animals received loperamide solution 1-hour before IDF treatment. Small intestine transit was accessed using 10 mL/kg body weight of charcoal meal solution. The intestinal portion was removed from the pylorus to the beginning of the cecum and the distance traveled by the charcoal was registered by metric system. The administration of HS IDF fraction resulted in a statistical significative increase (p < 0.05) in the distance traveled by the charcoal meal in the small intestine compared to the psyllium treatment. The laxative effect presented by the experimental treatment is due to the capacity of IDF of acting as bulking agents, since they resist fermentation and remain intact and present throughout the length of the large bowel, increasing fecal mass and decreasing intestinal transit time. Thus, the results obtained suggest that IDF present a potential composition to be explored by different types of industries, mainly food and pharmaceutical ones. Furthermore, the HS IDF demonstrate its laxative effect through the improvement of the intestinal transit, enhancing the quality of life of patients who suffer from functional constipation, which are now around 10% of worldwide population.