Main Monosaccharides Research Articles

A Comparative Study of the Fatty Acids and Monosaccharides of Wild and Cultivated Ulva sp.

There is a need to find new possible raw food sources with interesting nutritional values. One of the most unexploited sources are seaweeds. Thus, Ulva sp. is a green edible seaweed that shows a high growth rate in nature and can support drastic abiotic changes, such as temperature and salinity. This work aims to determine the main nutritional compounds, fatty acids (FAs) and monosaccharides profiles of Ulva sp. (collected from Mondego estuary, Portugal), to identify the potential of this seaweed as a food source. The present study also highlights the potential of controlled and semi-controlled cultivation systems in Ulva sp. profiles. The results showed that the controlled cultivation systems had higher essential FA and monosaccharide content than the semi-controlled cultivation systems. However, they are in some cases identical to wild individuals of Ulva sp., supporting that cultivation of Ulva sp. can be a key for food safety. It is crucial to control the associated risks of contamination that can occur in wild specimens.

Strategies for Efficient Expression of Heterologous Monosaccharide Transporters in Saccharomyces cerevisiae.

In previous work, we developed a Saccharomyces cerevisiae strain (DLG-K1) lacking the main monosaccharide transporters (hxt-null) and displaying high xylose reductase, xylitol dehydrogenase and xylulokinase activities. This strain proved to be a useful chassis strain to study new glucose/xylose transporters, as SsXUT1 from Scheffersomyces stipitis. Proteins with high amino acid sequence similarity (78–80%) to SsXUT1 were identified from Spathaspora passalidarum and Spathaspora arborariae genomes. The characterization of these putative transporter genes (SpXUT1 and SaXUT1, respectively) was performed in the same chassis strain. Surprisingly, the cloned genes could not restore the ability to grow in several monosaccharides tested (including glucose and xylose), but after being grown in maltose, the uptake of 14C-glucose and 14C-xylose was detected. While SsXUT1 lacks lysine residues with high ubiquitinylation potential in its N-terminal domain and displays only one in its C-terminal domain, both SpXUT1 and SaXUT1 transporters have several such residues in their C-terminal domains. A truncated version of SpXUT1 gene, deprived of the respective 3′-end, was cloned in DLG-K1 and allowed growth and fermentation in glucose or xylose. In another approach, two arrestins known to be involved in the ubiquitinylation and endocytosis of sugar transporters (ROD1 and ROG3) were knocked out, but only the rog3 mutant allowed a significant improvement of growth and fermentation in glucose when either of the XUT permeases were expressed. Therefore, for the efficient heterologous expression of monosaccharide (e.g., glucose/xylose) transporters in S. cerevisiae, we propose either the removal of lysines involved in ubiquitinylation and endocytosis or the use of chassis strains hampered in the specific mechanism of membrane protein turnover.

Rocket seed (Eruca sativa Mill) gum: physicochemical and comprehensive rheological characterization

This study aimed to determine the physicochemical and rheological characterization of Rocket seed gum (RSG) as a plant-based natural gum. Moisture, ash, protein, monosaccharide composition, and pH value were determined. Mannose and galactose were the main monosaccharides with a ratio of (mannose/galactose) 1.52. The absorptions at wavenumber 2855 cm-1 and 2922 cm-1 indicate the presence of galactose and arabinose. RSG showed shear-thinning flow behavior at all concentrations. The K value of the RSG ranged between 0.24 and 6.31 Pa.sn and significantly increased with increased gum concentration. Hysteresis area was found 11.53-183.23 and increased with increasing gum concentration. The percentage recovery for the G′ was significantly affected by gum concentrations and found as 42.54-81.20. RSG showed a solid-like structure, the storage modulus (G′) was higher than the loss modulus (G′′) in all frequency range. G′ and G′′ value increased with increased RSG concentration. The physicochemical and rheological characterization indicated that RSG could be evaluated as thickeners and gelling agents in the food industry.

Extraction, preparation, and carboxymethyl of polysaccharide from Lotus root

In this study, we extracted lotus root polysaccharide (LRP) and synthesized carboxymethylated lotus root polysaccharide (CM-LRP) using response surface methodology (RSM). The monosaccharide component of LRP was analyzed by pre-column derivatization high performance liquid chromatography (PCD-HPLC). The polysaccharide was characterized by ultraviolet (UV) spectroscopy scan, Fourier transform infrared spectroscopy (FTIR), circular dichroism spectrometer (CD), and scanning electron microscopy (SEM). It was found that the main monosaccharide component of LRP was glucose, accounting for more than 98% of the total polysaccharide component. RSM analyses revealed that the optimal conditions for CM-LRP synthesis were a reaction duration of 2.22 h, the chloroacetic acid dosage is 2.02 g, and a temperature of 46.87 °C. Under these conditions, the predicted degree of substitution (DS) was determined to be 0.5101. The superoxide anion, ferrous ion and hydroxyl radical antioxidant system were constructed to study the antioxidant activity of LRP and CMLRP. The activity of CMLRP to remove ferrous ions and hydroxyl radicals were significantly stronger than that of LRP, and it also showed a certain concentration-dependent. LRP has a better scavenging ability than CMLRP in scavenging superoxide anion free radicals. Our data revealed that CM-LRP is a promising natural antioxidant with potential value as a food supplement.

Growth and Biochemical Composition Characteristics of Arthrospira platensis Induced by Simultaneous Nitrogen Deficiency and Seawater-Supplemented Medium in an Outdoor Raceway Pond in Winter.

Arthrospira platensis, a well-known cyanobacterium, is widely applied not only in human and animal nutrition but also in cosmetics for its high amounts of active products. The biochemical composition plays a key role in the application performance of the Arthrospira biomass. The present study aimed to evaluate the growth and biochemical composition characteristics of A. platensis, cultured with a nitrogen-free and seawater-supplemented medium in an outdoor raceway pond in winter. The results showed that the biomass yield could achieve 222.42 g m−2, and the carbohydrate content increased by 247% at the end of the culture period (26 d), compared with that of the starter culture. The daily and annual areal productivities were 3.96 g m−2 d−1 and 14.44 ton ha−1 yr−1 for biomass and 2.88 g m−2 d−1 and 10.53 ton ha−1 yr−1 for carbohydrates, respectively. On the contrary, a profound reduction was observed in protein, lipid, and pigment contents. Glucose, the main monosaccharide in the A. platensis biomass, increased from 77.81% to 93.75% of total monosaccharides. Based on these results, large-scale production of carbohydrate-rich A. platensis biomass was achieved via a low-cost culture, involving simultaneous nitrogen deficiency and supplementary seawater in winter.

Overexpression of the rice BAHD acyltransferase AT10 increases xylan-bound p-coumarate and reduces lignin in Sorghum bicolor

BackgroundThe development of bioenergy crops with reduced recalcitrance to enzymatic degradation represents an important challenge to enable the sustainable production of advanced biofuels and bioproducts. Biomass recalcitrance is partly attributed to the complex structure of plant cell walls inside which cellulose microfibrils are protected by a network of hemicellulosic xylan chains that crosslink with each other or with lignin via ferulate (FA) bridges. Overexpression of the rice acyltransferase OsAT10 is an effective bioengineering strategy to lower the amount of FA involved in the formation of cell wall crosslinks and thereby reduce cell wall recalcitrance. The annual crop sorghum represents an attractive feedstock for bioenergy purposes considering its high biomass yields and low input requirements. Although we previously validated the OsAT10 engineering approach in the perennial bioenergy crop switchgrass, the effect of OsAT10 expression on biomass composition and digestibility in sorghum remains to be explored.ResultsWe obtained eight independent sorghum (Sorghum bicolor (L.) Moench) transgenic lines with a single copy of a construct designed for OsAT10 expression. Consistent with the proposed role of OsAT10 in acylating arabinosyl residues on xylan with p-coumarate (pCA), a higher amount of p-coumaroyl-arabinose was released from the cell walls of these lines upon hydrolysis with trifluoroacetic acid. However, no major changes were observed regarding the total amount of pCA or FA esters released from cell walls upon mild alkaline hydrolysis. Certain diferulate (diFA) isomers identified in alkaline hydrolysates were increased in some transgenic lines. The amount of the main cell wall monosaccharides glucose, xylose, and arabinose was unaffected. The transgenic lines showed reduced lignin content and their biomass released higher yields of sugars after ionic liquid pretreatment followed by enzymatic saccharification.ConclusionsExpression of OsAT10 in sorghum leads to an increase of xylan-bound pCA without reducing the overall content of cell wall FA esters. Nevertheless, the amount of total cell wall pCA remains unchanged indicating that most pCA is ester-linked to lignin. Unlike other engineered plants overexpressing OsAT10 or a phylogenetically related acyltransferase with similar putative function, the improvements of biomass saccharification efficiency in sorghum OsAT10 lines are likely the result of lignin reductions rather than reductions of cell wall-bound FA. These results also suggest a relationship between xylan-bound pCA and lignification in cell walls.

Crosslinked complex films based on chitosan and ulvan with antioxidant and whitening activities

The aim of this study was to prepare complex films based on chitosan and ulvan through crosslinking and analyze their bioactivities. The ulvan extracted from Ulva lactuca was composed of uronic acid and sulfated rhamnose as the main monosaccharides in which it had a sulfate content of 16.25 ± 1.19 wt%. During preparation, ionic crosslinking occurred between chitosan and ulvan and enhanced by adding tripolyphosphate and glycerol, in which the tensile strength was increased from 1.09 to 2.67 MPa. Compared to chitosan-based film, the complex films had higher swelling ratio and water vapor transmission rate. The complex films showed antioxidant and whitening activities mainly due to the ulvan. A sustained ulvan release (40–65% for 12-h releasing) from these films was observed. Especially, addition of chlorophyll to films increased the ulvan release to 64.8% and enhanced their bioactivities, showing a synergism effect. They were biocompatible to normal cells but toxic to melanoma cancer cell, presenting cell selectivity which was related to the reactive oxygen species generation. Briefly, the crosslinked complex films based on chitosan and ulvan with suitable physicochemical properties and improved antioxidant and whitening ability could have a great potential to be used as a new biomaterial in the future.

De novo Sequencing and Comparative Transcriptome Analyses Provide First Insights Into Polysaccharide Biosynthesis During Fruiting Body Development of Lentinula edodes.

Polysaccharides separated from Lentinula edodes are well known for their medicinal properties. However, the precise molecular mechanisms of polysaccharide biosynthesis in L. edodes remain unclear. In this study, the fruiting bodies of L. edodes in four developmental stages with significant differences in polysaccharide yield were collected, and the characteristics of polysaccharides were studied. De novo sequencing and comparative transcriptomic analysis were performed by using high-throughput Illumina RNA-sequencing. KS1P30, KS2P30, KS3P30, and KS4P30 were obtained from the four developmental stages, respectively, by hot water extraction and 30% ethanol precipitation. These four polysaccharides had good immune activity in vitro; all of them were β-glucopyranose with a high molecular weight. Glucose was the main monosaccharide component of these polysaccharides. High-quality clean reads (57.88, 53.17, 53.28, and 47.56 million for different growth stages) and mapping ratios ranging from 84.75 to 90.11% were obtained. In total, 11,493 (96.56%) unigenes and 18,924 (97.46%) transcripts were successfully annotated in five public databases. The biosynthetic pathway and related genes of LEFP30 were mined. The molecular mechanism of LEFP30 yield change in the different developmental stages was predicted. The results provide some insights into the possible mechanisms involved in the biosynthetic pathway of this kind of polysaccharide in L. edodes fruiting bodies. They also indicate that candidate genes can be used as important resources for biotechnology and molecular breeding to regulate L. edodes fruiting body polysaccharide biosynthesis.

Fermentable sugars production from wheat bran and rye bran: response surface model optimization of dilute sulfuric acid hydrolysis

ABSTRACT Optimization of hydrolysis conditions of lignocellulosic biomass is crucial to able to produce value-added products by fermentation. This study not only determines optimal dilute sulfuric acid (H2SO4) hydrolysis conditions of wheat bran (WB) and rye bran (RB) by using one-factor-at-a-time method and subsequently Box–Behnken design but also elucidates chemical composition of hydrolysates yielded under optimal hydrolysis conditions. Based on the results, optimal hydrolysis conditions of WB and RB were 121 and 130°C of temperature, 1/8 and 1/8 w/v of solid to liquid ratio, 2.66 and 1.58% v/v of dilute H2SO4 ratio, and 30 and 16 min of implementation time, respectively. Hydrolysates obtained from WB and RB at these conditions contained 72.7 (0.58 g sugar/g biomass) and 89.4 g/L (0.72 g sugar/g biomass) of reducing sugar concentration, respectively. Hydrolysis rates of WB and RB were 87.79 and 91.33%, respectively. Main reducing sugar in RB hydrolysate was glucose with 31.17 g/L (0.25 g glucose/g biomass) while glucose and xylose were the main monosaccharides with 20.90 (0.17 g glucose/g biomass) and 18.69 g/L (0.15 g xylose/g biomass) in WB hydrolysate, respectively. With acidic hydrolysis of WB and RB, inhibitors such as phenolics, 5-Hydroxymethylfurfural, 2-Furaldehyde (not for RB), acetic acid, and formic acid (not for WB) formed. Catalytic efficiency values of H2SO4 for WB and RB were 15.2 and 24.4 g /g, respectively, indicating that inhibitor concentration in WB hydrolysate was higher than that of RB. These results indicated that WB and RB have a high potential in production of value-added products by fermentation.

Study on Extraction Process of Root of Henry Wood Betony Polysaccharides and Their Antitumor Activity against S180.

We optimized the hot water extraction of polysaccharides from the root of Henry wood betony (RHWPs) using a uniform test and explored their anti-tumor activities in vitro and in vivo. The optimal extraction conditions were as follows: 40 min extraction time, liquid/solid ratio 30 mL/g, 100 min soaking time, two extraction cycles, 100% ethanol concentration, and extraction temperature of 80 °C. The molecular weight distribution of RHWPs with MWs was 228,600 g/mol and 5001 g/mol. The IR spectrum further indicated that RHWPs are acidic polysaccharides containing pyranose and furan rings. The main monosaccharides found in RHWPs were mannose, ribose, l-rhamnose monohydrate, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose, and fucose. RHWPs inhibited the proliferation of S180 tumor cells and induced apoptosis in vitro. Oral administration of RHWPs to tumor-bearing mice significantly inhibited the growth of the S180 xenografts, accelerated apoptosis in tumor cells, and expanded the necrotic regions. Furthermore, RHWPs also markedly increased the levels of TNF-α, IFN-γ, and IL-2 in the sera of tumor-bearing mice, and activated immune cells such as lymphocytes, NK cells, and macrophages, thereby inducing tumor cell apoptosis. Taken together, RHWPs are a promising anti-tumor agent that ought to be explored further.

Transcriptome Analysis Reveals Possible Immunomodulatory Activity Mechanism of Chlorella sp. Exopolysaccharides on RAW264.7 Macrophages.

In this study, the exopolysaccharides of Chlorella sp. (CEP) were isolated to obtain the purified fraction CEP4. Characterization results showed that CEP4 was a sulfated heteropolysaccharide. The main monosaccharide components of CEP4 are glucosamine hydrochloride (40.8%) and glucuronic acid (21.0%). The impact of CEP4 on the immune activity of RAW264.7 macrophage cytokines was detected, and the results showed that CEP4 induced the production of nitric oxide (NO), TNF-α, and IL-6 in a dose-dependent pattern within a range of 6 μg/mL. A total of 4824 differentially expressed genes (DEGs) were obtained from the results of RNA-seq. Gene enrichment analysis showed that immune-related genes such as NFKB1, IL-6, and IL-1β were significantly upregulated, while the genes RIPK1 and TLR4 were significantly downregulated. KEGG pathway enrichment analysis showed that DEGs were significantly enriched in immune-related biological processes, including toll-like receptor (TLR) signaling pathway, cytosolic DNA-sensing pathway, and C-type lectin receptor signaling pathway. Protein–protein interaction (PPI) network analysis showed that HSP90AB1, Rbx1, ISG15, Psmb6, Psmb3, Psmb8, PSMA7, Polr2f, Rpsa, and NEDD8 were the hub genes with an essential role in the immune activity of CEP4. The preliminary results of the present study revealed the potential mechanism of CEP4 in the immune regulation of RAW264.7 macrophages, suggesting that CEP4 is a promising immunoregulatory agent.

Analytical Characterization of an Inulin-Type Fructooligosaccharide from Root-Tubers of Asphodelusramosus L.

Plant-based systems continue to play a pivotal role in healthcare, and their use has been extensively documented. Asphodelus L. is a genus comprising various herbaceous species, known by the trivial name Asphodelus. These plants have been known since antiquity for both food and therapeutic uses, especially for treating several diseases associated with inflammatory and infectious skin disorders. Phytochemical studies revealed the presence of different constituents, mainly anthraquinones, triterpenoids, phenolic acids, and flavonoids. Although extensive literature has been published on these constituents, a paucity of information has been reported regarding the carbohydrate composition, such as fructans and fructan-like derivatives. The extraction of water-soluble neutral polysaccharides is commonly performed using water extraction, at times assisted by microwaves and ultrasounds. Herein, we reported the investigation of the alkaline extraction of root-tubers of Asphodelus ramosus L., analyzing the water-soluble polysaccharides obtained by precipitation from the alkaline extract and its subsequent purification by chromatography. A polysaccharide was isolated by alkaline extraction; the HPTLC study to determine its composition showed fructose as the main monosaccharide. FT-IR analysis showed the presence of an inulin-type structure, and NMR analyses allowed us to conclude that A. ramosus roots contain polysaccharide with an inulin-type fructooligosaccharide with a degree of polymerization of 7–8.

Revisiting a 'simple' fungal metabolic pathway reveals redundancy, complexity and diversity.

SummaryNext to d‐glucose, the pentoses l‐arabinose and d‐xylose are the main monosaccharide components of plant cell wall polysaccharides and are therefore of major importance in biotechnological applications that use plant biomass as a substrate. Pentose catabolism is one of the best‐studied pathways of primary metabolism of Aspergillus niger, and an initial outline of this pathway with individual enzymes covering each step of the pathway has been previously established. However, although growth on l‐arabinose and/or d‐xylose of most pentose catabolic pathway (PCP) single deletion mutants of A. niger has been shown to be negatively affected, it was not abolished, suggesting the involvement of additional enzymes. Detailed analysis of the single deletion mutants of the known A. niger PCP genes led to the identification of additional genes involved in the pathway. These results reveal a high level of complexity and redundancy in this pathway, emphasizing the need for a comprehensive understanding of metabolic pathways before entering metabolic engineering of such pathways for the generation of more efficient fungal cell factories.

Ornithogalum cuspidatum mucilage as a new source of plant-based polysaccharide: Physicochemical and rheological characterization

The aim of this research was to introduce and characterize a novel plant-based polysaccharide. Ornithogalum cuspidatum (OC) was used for mucilage extraction and chemical, physical, thermal and rheological properties of raw extracted mucilage (OMA), purified (OMB) and acid hydrolyzed mucilage (OMC) were compared. The purified mucilage (OMB) had the highest molecular weight (1.7 × 106 kDa). Nuclear magnetic resonance spectroscopy showed that the extracted mucilage is a member of arabinogalactan family. high performance liquid chromatography analysis showed that the mucilage is a hetropolysaccharide composed of galactose, glucose, arabinose and galacturonic acid, that galactose was the main monosaccharide in all samples. The functional groups and morphology of samples were characterized by Fourier transform infrared and Field emission scanning electron microscope analyses, respectively. Zeta potential was negative for three samples indicating the anionic nature of mucilage. The thermal analysis showed that the highest thermal stability was related to sample OMC. Water holding capacity of sample OMB was significantly higher than other two samples (p < 0.05). According to rheological studies, pseudoplastic behavior of three samples was confirmed. Sample OMB had the highest viscosity, and three samples followed the Herschel Balkley model. In the frequency sweep test, the loss modulus of all samples was greater than the storage modulus that indicates a weak gel structure of mucilage. In general, this research revealed that the OC mucilage as a liquid viscoelastic material can be introduced as a new thickener or stabilizer in food industry and purification and partial hydrolysis can affect its physicochemical and functional properties.

Assessment of seasonal and spatial variations in the nutritional content of six edible marine bivalve species by the response of a set of integrated biomarkers

Bivalves are widely distributed through diverse habitats, including estuaries and coastal lagoons which are extremely productive ecosystems, and play important roles in trophic webs and in ecosystems’ biological processes. Bivalves, as well as other marine resources, have been a part of the humans’ diet since mankind started fishing. These resources have high nutritional values, being constituted by high protein and low fat contents, and its consumption is associated with several health benefits. Marine resources, like bivalves, that are highly appreciated by humans, represent an important economic value, being under pressure due to an increasing demand. Thus, it is important a sustainable and balanced exploitation of these resources, based on the knowledge of the biochemical composition of the aquatic species to comprehend its’ potential and nutritional value.The present study was conducted in Portugal, a country that has one of the highest consumptions of seafood in the world. Six commercially valuable species of marine bivalves were harvested in two distinct areas, Mondego estuary and Ria Formosa lagoon, and in two seasons, winter 2016 and summer 2017. The aims of the study were to: 1) determine the biochemical composition of each species in terms of total protein content, fatty acid and carbohydrate profiles; 2) identify potential spatial and seasonal variations between bivalve species sampled in each study area and season; 3) assess feeding behaviour of the bivalve species in both seasons and study areas.The results indicated diverse biochemical composition among bivalve species, with total protein as the major component, followed by fatty acid content, particularly by the essential fatty acids DHA and EPA, and glycogen and glucose as the main polysaccharide and monosaccharide, respectively, found in all specimens. In general, all species demonstrated a tendency for omnivory, with only S. marginatus presenting a clear herbivorous behaviour in summer. Despite M. galloprovincialis and R. decussatus showed the highest nutritional value in the Mondego estuary, in both seasons, it was more noticeable in winter. In Ria Formosa, C. edule and R. decussatus showed the highest nutritious value in both seasons, while C. gigas showed higher nutritive value in summer.

Physicochemical and functional properties of dietary fiber from pummelo (Citrus grandis L. Osbeck) and grapefruit (Citrus paradisi Mcfad) cultivars

The contents and chemical structure of dietary fiber (DF), along with the physicochemical (water retention, water swelling and oil adsorption capacity) and functional properties (glucose adsorption, cholesterol adsorption and nitrite ion adsorption capacity) of insoluble and soluble dietary fiber (IDF, SDF) from the pulp of 5 pummelo (Citrus grandis L. Osbeck) and one grapefruit (Citrus paradisi Mcfad) cultivars were measured. The IDF, SDF and total DF (TDF) contents were 6.1–16.2, 1.8–5.66 and 7.9–22 g/100 g dw, respectively. Shatianyu (C. grandis) had the highest TDF content that was 1.37 and 2.78 times those from Guanximiyu (C. grandis) with white pulp and grapefruit, which had the second highest and the lowest TDF contents, respectively. The main monosaccharides of IDF were arabinose and glucose (68–71.3%) except grapefruit IDF. Meanwhile, arabinose, glucose and galactose were the main monosaccharides of SDF (89.5–97%). The molecular weights of SDF were in the range of 59–111 kDa. SDF and IDF from Guanximiyu with white and red pulp showed higher physicochemical properties, while those from Shatianyu and grapefruit showed slightly higher functional properties. Considering its highest DF content and middle-to high-level of physicochemical and functional properties, Shatianyu might show stronger health benefits because of its DF than other cultivars. Besides with a higher content, DF from Shatianyu also showed better physicochemical and functional properties compared with those from many other commonly consumed fruits. Therefore, pummelo, especially Shatianyu, is a good source of DF.

Microwave-assisted extraction of arabinan-rich pectic polysaccharides from melon peels: Optimization, purification, bioactivity, and techno-functionality

The effects of water to solids ratio (WSR, 10–30 mL/g), power (180–540 W), and irradiation time (IT, 5–15 min) in microwave-assisted extraction (MAE) were optimized to extract polysaccharides from melon peels (PMP). The maximum extraction yield (32.81 %) was obtained under 20.94 mL/g WSR, 414.4 W power, and 12.75 min IT. The main monosaccharide composition of purified PMP with an average molecular weight of 5.71 × 104 kDa were d-galacturonic acid, arabinose, glucose, and galactose. An ascending dose-dependent antiradical and antioxidant behavior for PMP (0–5.0 mg/mL) was found. The initial foaming capacity (38.6–110.3 %) and foaming stability (5.2–65.2 %) were significantly increased as a function of PMP concentration (1.0–5.0 %), while they reduced by increasing the mixing time (p < 0.05). The highest emulsifying activity index (44.1 m2/g) and emulsifying stability (69.3 %) at 5.0 % PMPs were determined. PMP gels with FTIR-identified functional groups can be formulated in new gluten-free functional products.

Comparison of determination of sugar-PMP derivatives by two different stationary phases and two HPLC detectors: C18 vs. amide columns and DAD vs. ELSD

Reducing sugars, especially aldoses with their ring structures, have strong reducibility to react with 1-phenyl-3-methyl-5-pyrazolone (PMP) to form sugar-PMP derivatives detected by ultraviolet (UV) detector at 248 nm. In this study, several carbohydrates and some of their alcohols, including 1). seven main monosaccharides, 2). three common disaccharides, 3). two oligosaccharides, and 4). some sweeteners like sugar alcohols were investigated for their reactivities with PMP. Analytes were separated chromatographically by two common high performance liquid chromatography (HPLC) columns and subsequently detected by two tandem detectors. Results pointed out that C18 column had a stronger capacity to separate the reducing sugar-PMP derivatives rather than the sugar themselves. While amide column could only effectively separate the original sugars. These phenomena demonstrated that polarity of reducing sugars decreased after their PMP derivatization. Moreover, both diode array detector (DAD) and evaporative light scattering detector (ELSD) were able to detect the reducing sugar-PMP derivatives, including the PMP-derivative of the oligosaccharide hydrolysate of chitosan, though the DAD exhibits a higher sensitivity than ELSD. In conclusion, carbohydrates themselves are more likely to be efficiently separated by an amide column and detected by ELSD, while DAD combined with a C18 column has more power to determine carbohydrates derivatives.

Functional soluble dietary fiber from ginseng residue: Polysaccharide characterization, structure, antioxidant, and enzyme inhibitory activity.

Ginseng (Panax ginseng C.A. Meyer) is the most famous edible Chinese herbal medicine. In the present study, soluble dietary fiber of ginseng (ginseng-SDF, 8.98% content) was extracted from ginseng residue, and its physicochemical characterization, structure, and biological activities were studied. Ginseng-SDF was an acidic heteropolysaccharide (uronic acid, 4.42% content) rich in protein, amino acids, and mineral elements. Glucose was its main monosaccharide composition (58.03%). Ginseng-SDF had a porous microstructure, a typical cellulose I structure and a large number of hydroxyl functional groups. These chemical composition and structural characteristics gave ginseng-SDF a good water solubility (98.56%), oil-holding capacity (OHC) (3.01g/g), and biological activities, as the antioxidant activity (13.35μM TE/g, 105.17μM TE/g, 54.20μM TE/g for DPPH, ABTs, and FRAP assays, respectively), glucose diffusion retardation index (GDRI, 33.33%-7.43%), and α-amylase/α-glucosidase inhibitory activities (IC50 , 6.70mg/ml, and 4.89mg/ml, respectively). The results suggested that ginseng residue is a valuable source of functional dietary fiber, and the ginseng-SDF has a potential use in antioxidant and hypoglycemic foods. PRACTICAL APPLICATIONS: Ginseng has long been popular as a health food in Asia, North America, and Europe. Ginseng residue is rich in polysaccharides, dietary fiber, proteins, and other components, which is also of great research value. However, there are few studies focus on the soluble dietary fiber of ginseng at present. The research shows that ginseng residue is a valuable source of functional dietary fiber. The chemical components and structural characteristics give ginseng-SDF a noteworthy antioxidant activity and enzyme inhibitory activity in vitro. These properties and biological activities indicate that ginseng-SDF has application value in antioxidant and hypoglycemic foods.

Dietary fiber extracted from pomelo fruitlets promotes intestinal functions, both in vitro and in vivo

Pomelo fruitlets contain various active substances that are easily collected and processed. Here, the biological effects of pomelo fruitlet dietary fiber were investigated in vivo and in vitro. Total dietary fiber (TDF), soluble dietary fiber (SDF), and insoluble dietary fiber (IDF) values of pomelo fruitlets were 75.64 ± 3.65 %, 10.10 ± 1.39 %, and 62.48 ± 3.68 %, respectively. The main monosaccharides identified were rhamnose, arabinose, galactose, and glucose. All fibers scavenged free 2,2′-diphenyl-1-picrylhydrazyl radicals and reduced ferric cations. The water-holding, oil-holding, and swelling capacities of the fibers retarded glucose diffusion, inhibited α-amylase, and influenced cholesterol micelle formation. In a mouse model of alloxan-induced diabetes, SDF improved glucose tolerance, controlled blood glucose, and reduced serum insulin better than TDF or IDF. All fiber types decreased the total cholesterol content and the prevalence of Bacteroidetes, Proteobacteria, and Ruminococcaceae, but increased the abundance of Firmicutes, Lactobacillus, and Prevotellaceae in hyperglycemic mice.