Effects of simulated saliva-gastrointestinal digestion on the physicochemical properties and bioactivities of okra polysaccharides.

This study was to investigate the effects of in vitro simulated saliva-gastrointestinal digestion on the physicochemical properties and bioactivities of okra polysaccharides (OPS). Results showed that the digestibilities of OPS were about 5.1%, 37.5%, and 41.3% after saliva digestion (SD), saliva-gastric digestion (SGD), and saliva-gastrointestinal digestion (SGID), respectively. The SGID significantly changed the physicochemical properties of OPS, such as total uronic acids, total flavonoids, monosaccharide composition, rheological properties, and molecular weights (Mw). Especially, Mw changes resulted in the breakdown of glycosidic bonds during SGD, and the degradation of OPS during SGID was mainly caused by disrupting aggregates. Furthermore, the bioactivities of OPS were also affected by SGID. After SGID, OPS still possessed strong antioxidant activities, binding capacities, and prebiotic activities, but the α-glucosidase inhibitory effect was obviously decreased. Overall, results can provide valuable and scientific support on the oral administration of OPS as functional foods and medicines in the future.

Influences of different drying methods on the structural characteristics and multiple bioactivities of polysaccharides from okra (Abelmoschus esculentus).

In this study, in order to evaluate the influences of drying methods on the chemical structures and bioactivities of polysaccharides from okra (OPPs), four drying methods, including microwave drying at 400 W, 600 W, and 800 W, freezing drying, hot air drying, and vacuum drying, were applied to dry okra fruits. Six different OPPs were extracted from okra dried by different drying methods. Results showed that physicochemical characteristics and bioactivities of OPPs varied by different drying methods. Noticeable variations in extraction yields, molecular weights, rheological properties, molar ratios of constituent monosaccharides, contents of uronic acids, degrees of esterification, and contents of total phenolics were observed in OPPs obtained by different drying methods. In addition, results showed that OPPs, especially OPP-H and OPP-V obtained by hot air drying and vacuum drying, respectively, exhibited remarkable antioxidant activities (ABTS, DPPH, and nitric oxide radical scavenging activities, and ferric reducing antioxidant powers), strong in vitro binding capacities (fat, cholesterol, and bile acids binding capacities), and obvious inhibitory activities on α-amylase and α-glucosidase. Results suggested that the hot air and vacuum drying techniques could be appropriate drying methods before extraction of OPPs with high bioactivities for applications in the functional food and medicine industries.

Structural characterization, antioxidant activity, and antiglycation activity of polysaccharides from different chrysanthemum teas.

Polysaccharides are one of the major bioactive components in chrysanthemum teas. In order to understand well the chemical structures and bioactivities of polysaccharides from different chrysanthemum teas (JHPs) collected in China, the physicochemical characteristics, antioxidant activity, and antiglycation activity of polysaccharides extracted from different chrysanthemum teas, including Coreopsis tinctoria, Chrysanthemum indicum, C. morifolium 'Huangju', C. morifolium 'Gongju', and C. morifolium 'Hangbaiju', were investigated. The results showed that the contents of total uronic acids and total phenolics in JHPs ranged from (28.4 ± 0.3)% to (36.2 ± 0.2)%, and from 9.4 ± 0.7 to 70.2 ± 1.7 mg GAE per g, respectively. The molecular weights of fraction 1 and fraction 2 in JHPs ranged from 4.29 × 105 to 5.88 × 105 Da, and from 4.11 × 104 to 5.24 × 104 Da, respectively. The dominant constituent monosaccharides of JHPs were galacturonic acid, arabinose, and galactose. Furthermore, JHPs, especially polysaccharides extracted from C. tinctoria, exerted remarkable ABTS, DPPH, nitric oxide, and hydroxyl radical scavenging activities, as well as strong antiglycation activities. The results are helpful for better understanding of the chemical structures and bioactivities of JHPs, and JHPs may have good potential applications in the functional-food industry.