Investigation of the chemical structure and analgesic and anti-inflammatory properties of polysaccharides that constitute the dietary fibers of soursop (Annona muricata) fruit.

Soursop fruits are widely used in the folk medicine to treat a variety of health conditions. Once the chemical structure of dietary fibers from fruits is closely related to its biological functions in the human body, we aimed to explore structural features and biological activity of dietary fibers from soursop. Polysaccharides that constitute the soluble and insoluble fibers were extracted and further analyzed using monosaccharide composition, methylation, molecular weight determination and 13C NMR data. Soursop soluble fibers (SWa fraction) were characterized as having type II arabinogalactan and a highly methyl esterified homogalacturonan, while non-cellulosic insoluble fibers (SSKa fraction) were mainly composed by a pectic arabinan, a xylan-xyloglucan complex and a glucuronoxylan. The oral pre-treatment with SWa and SSKa promoted antinociception in mice writhing test, reducing the number of pain-like behaviors (in 84.2 % and 46.9 %, respectively, at 10 mg/kg) and peritoneal leucocyte migration (55.4 % and 59.1 %, at 10 mg/kg), effects possibly associated with the pectins present in fruit pulp extractions. SWa also significantly inhibited the plasmatic extravasation of Evans blue dye in 39.6 % at 10 mg/kg. This paper describes for the first time the structural features of soursop dietary fibers that may be of biological significance in future.

Characterization and technological properties of peach palm (Bactris gasipaes var. gasipaes) fruit starch.

Peach palm fruit mesocarp (Bactris gasipaes var. gasipaes) is already consumed in the Northern region of Brazil, after its cooking and is known as a source of starch and carotenoids and like all fruits it has low storage stability. This work characterized the starch extracted from the mesocarp of peach palm fruit using with water in terms of its physical and chemical properties. The SEM micrographs show that starch presented bimodal distribution (size 3.9-10.4 µm), while the smaller granules had a smooth surface and an oval or conical shape, the larger granules were spherical with holes and cracks on the surface. The starch presented low amylose content (<20%) and amylopectin branch chain length distribution with the absence of a shoulder, which is suggestive of perfect crystalline structure, and a higher proportion of medium chains (DP 13-24), despite the large number of short chains (DP 6-12), and on average DP 21. X-ray diffraction showed a mixture of polymorphs A and B, which can be considered C-type crystalline pattern, which is indicative of being a slow digestible starch. Through paste viscosity results, by RVA, we can observe low values for thermal and pasting properties, suggesting greater homogeneity of crystals. Also, due to interaction with lipids originally present (2.69%), the starch showed lower retrogradation rate (22.64%), which resulted in a weak gel after 24 h of storage. As a product with greater storage stability, peach palm fruit starch, extracted for the purpose of promoting its regional use, has shown that it can be used in products where slow and smooth retrogradation is desired, such as in breads, soups, chowder and porridges, without the use of emulsifiers or fat.