Effects of extraction methods on the digestibility, cytotoxicity, prebiotic potential and immunomodulatory activity of taro (Colocasia esculenta) water-soluble non-starch polysaccharide

Topological structure, rheological characteristics and biological activities of exopolysaccharides produced by Saccharomyces cerevisiae ADT

Saccharomyces cerevisiae ADT is an edible fungus, with limited research on its exopolysaccharides (EPS). Three types of exopolysaccharides (EPS60, EPS80, and EPS100) were obtained through multiple purification steps using varying concentrations of ethanol in this study. The topological structure, rheological properties, and biological characteristics of EPS were investigated. High performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) analyses indicated that the three EPS are primarily made up of mannose with a small amount of glucose. Acetyl groups were also found, along with the presence of α-type pyranose and β-type pyranose. The Congo Red test and X-ray diffraction results reflected the absence of a triple helix structure and crystal properties. Atomic force microscopy (AFM) revealed the self-assembly of three exopolysaccharides into various topological structures under different concentration gradients, and a clear network structure of entangled chains was observed. EPS60, EPS80 and EPS100 displayed pseudoplasticity, weak gel behavior and thermal stability. Significantly, EPS exhibited antioxidant activity in a dose-dependent manner and showed no acute cytotoxicity to RAW264.7 and HEK293T cells. Therefore, EPS in this study is anticipated to be utilized in natural antioxidants, medications, and functional materials.

Separation, purification, structure characterization, and immune activity of a polysaccharide from Alocasia cucullata obtained by freeze-thaw treatment

In this study, ACP-1, a water-soluble polysaccharide was isolated from the roots of Alocasia cucullata (AC) using freeze-thaw treatment (FTT). Structural characterization revealed ACP-1 (2.10×105 Da) to be a homogeneous heteropolysaccharide primarily consisting of glucose, galactose, and arabinose, and a trace of fucose, rhamnose, and glucuronic acid. Methylation analysis and nuclear magnetic resonance spectroscopy revealed that the backbone of ACP-1 consisted of →[3)-β-D-Galp-(1]4→3,6)-β-D-Glcp-(1→3,6)-β-D-Glcp-(1→, with a branch at C-3. In vitro experiments demonstrated that ACP-1 significantly enhanced the proliferation and phagocytosis of RAW264.7 cells, upregulated the expression of co-stimulatory molecules (CD80 and CD86), and activated RAW264.7 cells via the nuclear factor kappa-B signal transduction pathway, resulting in nitric monoxide release and the secretion of the cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. Overall, ACP-1 shows potential as a novel immunostimulant.

Structural Characteristics and Immunological Function of a New Non-Starch Polysaccharide from Red Sprout Taro

Taro is a tuber crop that is used for nutritional and medicinal purposes due to its abundance of non-starch polysaccharides (NSPs). Red Sprout taro is a local variety in Southern China, but the characteristics and bioactivities of its NSPs are currently unknown. In this study, NSPs were isolated from the corms of Red Sprout taro using hot-water extraction, ion-exchange chromatography, and ethanol precipitation; their molecular weight, monosaccharide composition, structural formulae, and immunomodulatory effects were examined. A novel NSP named Colocasia esculenta polysaccharide 1 (CEP1) was purified and characterized and was shown to mainly consist of glucose (60.49%) and galactose (25.92%) and have a molecular weight of 4556.272 kDa. The backbone of CEP1 consisted primarily of →4)-α-D-Glcp-(1→, →4,6)-β-D-Galp-(1→, and →3)-β-D-Galp-(1→ residues, with a branch consisting of the β-D-Glcp-(1→ residue. In addition, 25-400 µg/mL CEP1 was shown to have immunomodulatory effects on RAW264.7 macrophages. CEP1 not only increased cell viability, phagocytic capacity, inducible nitric oxide synthase secretion, and nitric oxide generation in RAW264.7 cells, but it also activated M1 and M2 macrophages to generate tumor necrosis factor α, interleukin 6, transforming growth factor β, and interleukin 10. These findings could lead to the use of CEP1 from Red Sprout taro as a possible immunomodulatory polysaccharide in functional foods.

Characterization of Taro (Colocasia esculenta) stolon polysaccharide and evaluation of its potential as a tablet binder in the formulation of matrix tablet

This investigation focuses on the extraction, characterization, and evaluation of taro (Colocasia esculenta) stolon polysaccharide (TSP) as a tablet binding agent, which is obtained from edible taro stolon. TSP was subjected to phytochemical screening and characterized by FTIR, DSC, TGA, DTA, XRD, particle size, polydispersity index, zeta potential, rheological behavior, and SEM. The tablets prepared with varying concentrations of TSP (2.5 %, 5 %, 7.5 %, and 10 % w/w) and diclofenac sodium (DS) were evaluated and compared with the same concentrations of gum acacia and PVP K-30. The presence of carbohydrates was confirmed by Molisch's test. The FTIR spectra established the compatibility of the drug with excipients. The SEM images revealed asymmetric and elongated particles of TSP powder. The hydration kinetics study showed matrix hydration and water penetration velocity within the range of 0.602-0.753 g/g and 0.112-0.189 cm/g.h, respectively. The tablets showed drug release of >75 % at 45 min. The release-exponent value above 0.89 indicated a super case II drug transport combining matrix erosion and diffusion. Optimum tablet hardness and very low friability, even at 2.5 % binder concentration, suggested the potential application of the novel TSP as a tablet binder in the formulation of the tablets.

Functional fractions of Astragalus polysaccharides as a potential prebiotic to alleviate ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the intestine that is significantly influenced by an imbalance in the gut microbiota. Astragalus membranaceus, particularly its polysaccharide components, has shown therapeutic potential for the treatment of UC, although the specific active constituents and their mechanistic pathways remain to be fully elucidated. In this study, we investigated two molecular weight fractions of Astragalus polysaccharides (APS), APS1 (Mw < 10 kDa) and APS2 (10 kDa < Mw < 50 kDa), isolated by ultrafiltration, focusing on their prebiotic effects, effects on UC, and the underlying mechanism. Our results showed that both APS1 and APS2 exhibit prebiotic properties, with APS1 significantly outperforming APS2 in ameliorating UC symptoms. APS1 significantly attenuated weight loss and UC manifestations, reduced colonic pathology, and improved intestinal mucosal barrier integrity. In addition, APS1 significantly reduced the levels of inflammatory cytokines in the serum and colonic tissue, and downregulated colonic chemokines. Furthermore, APS1 ameliorated dextran sulfate sodium salt (DSS)-induced intestinal dysbiosis by promoting the growth of beneficial microbes and inhibiting the proliferation of potential pathogens, leading to a significant increase in short-chain fatty acids. In conclusion, this study highlights the potential of APS1 as a novel prebiotic for the prevention and treatment of UC.

Changes in physicochemical and gut microbiota fermentation property induced by acetylation of polysaccharides from Cyperus esculentus

In this study, the impact of acetylation on physicochemical, digestive behavior and fermentation characteristics of Cyperus esculentus polysaccharides (CEP) was investigated. Results indicated that the acetylation led the molecules to be more likely aggregated, followed by a higher crystallinity, a lower apparent viscosity and a higher ratio of G" to G' (tan δ). Importantly, the acetylated polysaccharides (ACEP) had a lower digestibility, but its molecular weight was lower than that of original polysaccharides (CEP) following a simulated saliva-gastrointestinal digestion. Gut microbiota fermentation indicated that both polysaccharides generated outstanding short-chain fatty acids (SCFAs), in which the acetylated polysaccharides had a faster fermentation kinetics than the original one, followed by a quicker reduction of pH and a more accumulation of SCFAs, particularly butyrate. Fermentation of both polysaccharides promoted Akkermansia, followed by a reduced richness of Klebsiella. Importantly, the current study revealed that the fermentation of acetylated polysaccharides enriched Parabacteroides, while fermentation of original ones promoted Bifidobacterium, for indicating their individual fermentation characteristics and gut environmental benefits.

In-depth understanding of the effects of different molecular weight pullulan interacting with protein and starch on dough structure and application properties

This work clarified the positive effects of pullulan on dough structure and application properties varied with its molecular weight. Pullulan with different molecular weights were introduced into dough system to explore their intervention effects on structural and technological properties of dough as well as physical and digestion properties of biscuits. Results showed that HPL (pullulan with molecule weight of 100- 300 kDa) could increase the intermolecular collisions, prompt the protein aggregation and limit the water migration in dough system, resulting in an integrate, continuous and dense network structure of the gel with strengthened elasticity and weakened extensibility, which caused an increase in biscuit thickness, hardness and crispness. On the contrary, LPL (pullulan with molecule weight of 3- 100 kDa) could go against the formation of stable and elastic dough through breaking down cross-linkage between protein and starch so as to provide biscuits with decreased hardness and crispness during baking. Both HPL and LPL delayed starch pasting and retrogradation process while HPL had the stronger retarding effect on starch digestibility of biscuits than LPL. These findings dedicated to a better understanding of pullulan function in dough system and provide suggestions for fractionation applications of pullulan in food field.

Functional profile and encapsulating properties of Colocasia esculenta (Taro)

Especially in tropical and subtropical countries, tuber and root crops have developed into important food crops. Due to its use in food preparation, aesthetics, and medicine, taro (Colocasia esculenta) is ranked as the fifth most important root crop. In comparison, it stores a considerable quantity of starch - even more than potatoes, sweet potatoes, cassava, and other similar crops. Colocasia leaves are lower in calories and high in dietary fiber minerals and proteins. The corms of Colocasia antiquorum contain anthocyanins such as pelargonidin-3-glucoside, cyanidin-3-glucoside, and cyanidin-3-chemnoside, which are reported to possess antifungal and antioxidative characteristics. The underground corms of taro (Colocasia esculenta), which contain 70%-80% starch, are the primary reason for its cultivation. Taro is a highly digestible root vegetable with a high content of mucilaginous gums and trivial starchy granules. It is used to make a variety of dishes. This review article highlights the functional properties, phytochemical profile, encapsulating properties, and various industrial applications. Its health advantages and dietary uses were also addressed.

Preparation, structural characteristics, and application of taro polysaccharides in food

Taro, a staple food for residents in Africa and parts of Asia, is an important source of carbohydrate. China has abundant taro resources. Taro contains polysaccharide, vitamins, minerals and other substances. Taro polysaccharides, as a significant active ingredient in taro, are mainly composed of monosaccharide units such as glucose, galactose, arabinose, mannose, and so on. Taro polysaccharides have antioxidant, lipid-lowering, and immunomodulatory effects. In today's world, people are interested in food containing natural ingredients, which stimulates the potential of taro polysaccharides in the food, pharmaceutical, medical, and other fields. Herein, the extraction and purification, structural characterization, functional activity, and application of taro polysaccharides are reviewed to strengthen the cognition of taro polysaccharides. It provides references for further research and development of taro polysaccharides. © 2022 Society of Chemical Industry.

Effects of different enzyme extraction methods on the properties and prebiotic activity of soybean hull polysaccharides

In this study, five different processes, including hot water (HW-ASP), single enzyme (cellulase, pectinase and papain; C-ASP, PE-ASP, and P-ASP), and compound-enzyme (cellulose: pectinase: papain = 3:3:1; CE-ASP) for the extraction of soybean hull polysaccharides (ASPs) were employed, and the characterization and prebiotics activity of five polysaccharides were analyzed. These polysaccharides possessed different primary structural characteristics, including molecular weight distribution, monosaccharide composition, chemical composition, surface morphology, potential particle size, etc., while similar functional groups. In vitro digestibility assay indicated that C-ASP had strong resistance to gastric juice hydrolysis and α-amylase as compared with HW-ASP. Furthermore, C-ASP elevated the acidifying activity and promoted the growth of probiotics (Lactobacillus paracasei, Lactobacillus rhamnosus, and Lactobacillus acidophilus) during the fermentation (p < 0.05). C-ASP improved the levels of total short-chain fatty acids (SCFAs) and had better prebiotic activity than HW-ASP (p < 0.05). These findings denote that enzyme-assisted polysaccharides extracted from soybean hulls have the potential to be served as novel probiotics.

Effects of Taro (Colocasia esculenta) Water-Soluble Non-Starch Polysaccharide, Lactobacillus acidophilus, Bifidobacterium breve, Bifidobacterium infantis, and Their Synbiotic Mixtures on Pro-Inflammatory Cytokine Interleukin-8 Production

In the past decades, the regulation of pro-inflammatory cytokine production, including interleukin-8 (IL-8), has been the goal of many targeted therapeutic interventions for Necrotising enterocolitis (NEC), a gastrointestinal disease commonly associated with a very low birth weight in preterm infants. In this study, the ability to regulate the production of IL-8 of the water-soluble non-starch polysaccharide (WS-NSP) from taro corm (Tc-WS-NSP) extracted using a conventional (CE) or improved conventional (ICE) extraction method, of the probiotics Lactobacillus acidophilus, Bifidobacterium breve, and Bifidobacterium infantis, and their synbiotic mixtures were evaluated. The TNF-α stimulated HT-29 cells were incubated with undigested or digested Tc-WS-NSPs (CE or ICE), probiotics, and their synbiotic mixtures with Klebsiella oxytoca, an NEC-positive-associated pathogen. Overall, the synbiotic mixtures of digested Tc-WS-NSP-ICE and high bacterial concentrations of L. acidophilus (5.57 × 10⁹), B. breve (2.7 × 10⁸ CFU/mL), and B. infantis (1.53 × 10⁸) demonstrated higher (42.0%, 45.0%, 43.1%, respectively) ability to downregulate IL-8 compared to the sole use of Tc-WS-NSPs (24.5%), or the probiotics L. acidophilus (32.3%), B. breve (37.8%), or B. infantis (33.1%). The ability demonstrated by the Tc-WS-NSPs, the probiotics, and their synbiotics mixtures to downregulate IL-8 production in the presence of an NEC-positive-associated pathogen may be useful in the development of novel prophylactic agents against NEC.

Sources, Processing-Related Transformation, and Gut Axis Regulation of Conventional and Potential Prebiotics

One strategy to achieve a balanced intestinal microbiota is to introduce prebiotics. Some substances present in the diet, such as soybean extracts, koji glycosylceramides, grape extracts, tea polyphenols, and seaweed extracts, can be considered as potential prebiotics, because they can selectively stimulate the proliferation of beneficial bacteria in the intestine. However, the discovery of novel prebiotics also involves advances in screening methods and the use of thermal and non-thermal processing techniques to modify and enhance the properties of beneficial organisms. The health benefits of prebiotics are also reflected by their participation in regulating the microbiota in different gut axes. In the present review, we introduced the field of prebiotics, focusing on potential prebiotic substances, the process of screening potential prebiotics, the transformation of prebiotics by food-processing technologies, and the roles of prebiotics on gut axis regulation, which, it is hoped, will promote the discovery and utilization of novel prebiotics.

Structural Elucidation and Immunostimulatory Activities of Quinoa Non-starch Polysaccharide Before and After Deproteinization

Non-starch polysaccharides derived from natural resources play a significant role in the field of food science and human health due to their extensive distribution in nature and less toxicity. In this order, the immunostimulatory activity of a non-starch polysaccharide (CQNP) from Chenopodium quinoa was examined before and after deproteination in murine macrophage RAW 264.7 cells. The chemical composition of CQNP and deproteinated-CQNP (D-CQNP) were spectrometrically analysed that revealed the presence of carbohydrate (22.7 ± 0.8% and 39.5 ± 0.8%), protein (41.4 ± 0.5% and 20.8 ± 0.5%) and uronic acid (8.7 ± 0.3% and 6.7 ± 0.2%). The monosaccharide composition results exposed that CQNP possesses a high amount of arabinose (34.5 ± 0.3) followed by galactose (26.5 ± 0.2), glucose (21.9 ± 0.3), rhamnose (7.0 ± 0.1), mannose (6.0 ± 0.1) and xylose (4.2 ± 0.2). However, after deproteination, a difference was found in the order of the monosaccharide components, with galactose (41.1 ± 0.5) as a major unit followed by arabinose (34.7 ± 0.5), rhamnose (10.9 ± 0.2), glucose (6.6 ± 0.2), mannose (3.4 ± 0.2) and xylose (3.2 ± 0.2). Further, D-CQNP potentially stimulate the RAW 264.7 cells through the production of nitric oxide (NO), upregulating inducible nitric oxide synthase (iNOS) and various pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α). Moreover, stimulation of RAW 264.7 cells by D-CQNP takes place along the NF-κB and the MAPKs signaling pathways through the expression of cluster of differentiation 40 (CD40). This results demonstrate that RAW 264.7 cells are effectively stimulated after removal of the protein content in C. quinoa non-starch polysaccharides, which could be useful for develop a new immunostimulant agent.