Pectic Polysaccharides Research Articles

Towards the synthesis of UDP-apiofuranose

AbstractApiose is a rare sugar present in cell-wall glycans of all higher plants. Apiosyltransferases use uridine diphosphate-α-d-apiofuranose (UDP-Api) to biosynthesize apiose-containing pectic polysaccharides, namely rhamnogalacturonan-II (RG-II) and apiogalacturonan. However, the study of apiosyltransferases is hampered by the limited availability of UDP-Api. Here, we report the challenging chemical synthesis of α-apiosyl 1-phosphate as the key intermediate towards UDP-Api synthesis. Various protecting group patterns and synthetic routes, including phosphoglycosylation, phosphorylation of the hemiacetal, and phosphorylation of the anomeric bromide were screened. The latter strategy enabled the synthesis of apiosyl 1-phosphate with good α-selectivity (α:β = 5:1). Additionally, we describe a pyrophosphate coupling reaction of the synthesized glycosyl 1-phosphate with commercially available uridine-monophosphate morpholidate to obtain UDP-Api. This test reaction was monitored by 31P-NMR spectroscopy, which showed formation of the desired product and its partial hydrolysis due to an unwanted intramolecular cyclisation typical of 1,2-cis UDP-sugars. Graphical abstract

Naturally Occurring Microbiota-Accessible Borates: A Focused Minireview

Recently, we discovered and proved the essentiality of organic boron species (OBS), such as borate–pectic polysaccharides and borate–phenolic esters, for healthy symbiosis (HS) between microbiota and human/animal (H/A) host. The essentiality of OBS will provide new options for B supplementation in H/A nutrition for a healthy and long life. New knowledge on the essentiality of naturally occurring microbiota-accessible borate species for HS between microbiota and H/A host will allow the use of natural B-based dietary supplements to target the H/A microbiome (the gut, skin, oral, scalp, and vaginal microbiome). In the literature, there is evidence that certain bacteria need B (autoinducer-2 borate) for communication and our preliminary data show that HS takes place when the colonic mucus gel layer contains B. Subsequently, OBS become novel prebiotic candidates and target the colon as novel colonic foods.

Effects of Centella asiatica-isolated pectic polysaccharide on dextran sulfate sodium-induced colitis

Dietary supplementation of polysaccharides demonstrates strong therapeutic actions on inflammatory bowel disease (IBD). Centella asiatica (CA) has traditionally been used in Ayurveda and Chinese medicine. However, the effects of CA-isolated pectic polysaccharides on IBD remain unknown. This study determined the effect of a CA-isolated pectic polysaccharide on IBD. The crude polysaccharide (CA-CP), isolated from a hot-water extract of CA, is a typical pectic polysaccharide composed mainly of galacturonic acid (40.6 %), galactose (27.6 %), arabinose (13.5 %), and rhamnose (8.5 %). CA-CP improved clinical symptoms in a DSS-induced colitis murine model, including weight change (9.9–12.0 %), disease activity index (31.6–51.9 %), colon length (13.2–21.5 %), and spleen weight (21.8–26.3 %). CA-CP effectively regulated the levels of inflammatory and junctional factors by mediating the MAPK and NF-κB pathways. CA-CP partially alleviated DSS-induced crypt destruction, submucosal edema, inflammatory infiltration, and mucin secretion. The content of total short-chain fatty acids increased substantially (cecum 29.8–53.7 %, feces 75.4–109.3 %) with oral CA-CP administration compared to the DSS group. Cecal microbial community analysis revealed that CA-CP administration regulated DSS-induced colitis by reducing the abundance of Escherichia (5.0–10.9 %) and Clostridium (0.3–0.4 %), while increasing the abundance of Bacteroidetes (6.8–8.5 %), Ligilactobacillus (2.7–6.0 %), and Bilophilia (0.3–0.6 %). The findings provide fundamental data for developing novel functional therapeutic agents for the prevention and treatment of colitis, using CA-isolated pectic polysaccharides. Furthermore, to the best of our knowledge, our study is the first to demonstrate the effects of pectic polysaccharides isolated from CA on IBD.

A pectic polysaccharide from Typhonii Rhizoma: Characterization and antiproliferative activity in K562 cells through regulating mitochondrial function and energy metabolism

The pectic polysaccharide WTRP-A0.2b (43 kDa) has been isolated from Typhonii rhizoma and analyzed in terms of its structural features, anti-tumor activities and mechanism of action. NMR, FT-IR, monosaccharide composition, and enzymology demonstrate that WTRP-A0.2b is composed of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 3.7:1:1.7, respectively. The RG-I domains contain a highly branched structure that is substituted primarily with β-D-1,4-galactan, α-L-1,5-arabinan, and AG-II. The HG domains contain un-esterified and methyl-esterified and/or acetyl-esterified oligogalacturonides with a degree of polymerization of 1–8. In vitro experiments demonstrate that WTRP-A0.2b inhibits proliferation of K562 cells by inducing mitochondrial damage and suppressing glycolysis. This activity promotes mitochondrial permeability, increases production of reactive oxygen species (ROS), boosts extracellular oxygen consumption and adenosine triphosphate (ATP) content, while it decreases uncoupling protein-2 (UCP2) expression and lactic acid content. Our results provide valuable insight for screening natural polysaccharide-based anti-tumor effects of polysaccharides from Typhonii rhizoma.

Structural characteristics and antioxidant activity of a low-molecular-weight jujube polysaccharide by ultrasound assisted metal-free Fenton reaction

This study used an ultrasonically accelerated metal-free Fenton (H2O2-Vc system) reaction to promote water-extracted degrading polysaccharides from Ziziphus Jujuba cv. Muzao (DZMP). A novel jujube polysaccharide (DPZMP3) was obtained by degradation using DEAE-Sepharose Fast Flow and Sephacryl S-100 column chromatography. Methylation analysis, HPGPC, ion chromatography, FT-IR, and NMR spectroscopies were used to clarify the chemical structures of DPZMP3. Monosaccharide compositional analysis of DPZMP3 revealed the presence of Rha, Ara, Gal, and GalA at a molar ratio of 1.00:1.49:1.60:7.68, and the HPGPC data demonstrated the average Mw of 34.3 kDa. Based on the structural and linkage research using NMR spectroscopy and GC–MS, it was determined that DPZMP3 was a homogalacturonan pectic polysaccharide with a (1 → 4)-Galp branch at C-6 and a small amount of Araf and Rhap residues. The ultrasonic-aided Fenton treatment did not significantly alter the structure of DPZMP3. It may also be useful for DZMP and enhancing their antioxidant activity in vitro. The current study's findings could pave the way for the food sector to use jujube polysaccharides obtained by degradation as a functional food component.

Effects of cooking and market classes on nutritional and antioxidant properties of dry bean flours and soluble dietary fiber-rich fractions

Dry beans are a rich source of proteins, starch, dietary fiber, and phenolic compounds, thus exhibiting potential health benefits. Fractionating dry beans, especially soluble dietary fiber (SDF), could be considered a valuable functional food ingredient. This study investigated the effects of pinto and black dry bean market classes and atmospheric pressure cooking on the physicochemical attributes of dry bean flours and the extraction and characterization of SDF-rich fractions. Cooking significantly (p < 0.05) increased the dietary fiber content, altering the macronutrient profile. Raw flours exhibited higher levels of extractable phenols and antioxidant capacity, while cooked flours had more hydrolyzable phenols and associated antioxidant activities. Pinto beans were found to have higher levels of slowly digestible starch (23.76%) and resistant starch (5.24%) compared to black beans (20.63% and 3.22%, respectively). The SDF-rich fraction from cooked flours showed a reduced residual protein content and included pectic polysaccharides, hemicelluloses, and raffinose family oligosaccharides (RFOs), with cooking affecting their molecular weight distribution. These fractions demonstrated shear-thinning behavior and temperature-dependent viscosity. The study highlights the significant influence of market class and cooking process on the nutritional and antioxidant properties of dry beans, suggesting their potential contributions to dietary health.

Preparation and structural characteristics of polysaccharides from loquat peel waste, and their preliminary bioactivities.

Loquat peel, often as food waste, is a valuable source of bioactive polysaccharides. However, study of such polysaccharides is insufficient, leaving a significant gap in understanding their preparation, structure and bioactivities. In this study, three types of loquat peel polysaccharides (LPWP, LPHP and LPNP) were sequentially extracted using hot water, HCl and NaOH solutions, respectively. Among them, LPWP was the purest, with a yield of 3.4% and molecular weight of 470.6 kDa, and it differed from LPHP and LPNP in structure, as evidenced by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy, which demonstrated that LPWP consisted of more arabinose (Ara) but less galacturonic acid, rhamnose and galactose, with molar percentages of 71.3%, 23.3%, 3.5% and 1.9%, respectively. Besides, LPWP also exhibited superior antioxidant and antihyperglycemic activities in vitro, particularly in inhibiting α-amylase and α-glucosidase. Methylation and nuclear magnetic resonance analysis confirmed that LPWP was a methyl-esterified pectic polysaccharide rich in branched arabinan, as evidenced by the notable proportion of α-Ara residues, including T-α-Araf, 1,5-α-Araf and 1,2,3,5-α-Araf, with molar percentages of 27.1%, 23.1% and 10.2%, respectively. AFM imaging further revealed its branched-chain morphology and aggregation behavior. This study highlights the potential of loquat peel polysaccharides as a bioactive ingredient with significant antioxidant and antihyperglycemic properties, particularly LPWP, which was found as a methyl-esterified pectic polysaccharide with abundant-branched arabinan. Our work provides valuable insights into the application of loquat peel polysaccharides in functional foods. © 2024 Society of Chemical Industry.

Valorisation of Blackcurrant Pomace by Extraction of Pectin-Rich Fractions: Structural Characterization and Evaluation as Multifunctional Cosmetic Ingredient

Blackcurrant pomace is a widely available waste stream derived from the industrial production of juice rich in pectin and unextracted polyphenols. Since pectin, an emerging class of gastrointestinal prebiotics, is also a common cosmetic ingredient, the aim of this work was to evaluate blackcurrant pomace as a source of pectin-rich fractions suitable for application in prebiotic cosmetics. Hereby, this raw material was valorised by sequential extraction of acid-soluble (by citric acid, CAP) and Ca-bound (by ammonium oxalate, AOPP) pectic polysaccharides. Both fractions had favourable physicochemical features and a similar degree of methyl-esterification between low- and high-methoxyl pectin (approx. 50%), but CAP had significantly higher galacturonic acid content (72.3%), branching, and purity. Regardless of that, both had very high oil (18.96 mL/g for CAP and 19.32 mL/g for AOPP) and water (9.97 mL/g for CAP and 7.32 mL/g for AOPP)-holding capacities and excellent emulsifying properties, making them promising cosmetic ingredients. The polyphenol content was 10 times higher in CAP, while corresponding antioxidant activity was 3-fold higher. Finally, the influence of varying CAP and AOPP concentrations on common skin pathogen, Staphylococcus aureus, and beneficial skin bacteria, Staphylococcus epidermidis, was examined. The results show significant prebiotic potential of two pectic fractions since they were capable of selectively stimulating S. epidermidis, while S. aureus growth was inhibited, whereas CAP demonstrated a particularly high capacity of up to 2.2, even with methicillin-resistant S. aureus.

Degradation of pectic polysaccharides by ascorbic acid/H2O2–pectinase system and its application in cotton scouring

Degradation of pectic polysaccharides by ascorbic acid/H2O2–pectinase system and its application in cotton scouring

Uncovering cocoa shell as a safe bioactive food ingredient: Nutritional and toxicological breakthroughs

This work aimed to analyze the chemical composition of the cocoa shell flour (CSF) and aqueous extract (CSE) and conduct acute and sub-chronic toxicity assays to ensure safety. CSF was composed of 59.1 % dietary fiber, primarily insoluble fiber (48.1 %). CSE consisted entirely of soluble fiber (72.8 %), mainly pectic polysaccharides. The amino acid profile revealed CSF's potential as a high-quality plant protein source, whereas CSE was rich in free amino acids, especially leucine, valine, and alanine (59.6–62.5 mg 100 g−1). Higher levels of macroelements, especially potassium, were found in CSE. Silicon was the most abundant microelement, and heavy metal levels were within acceptable limits for both cocoa shell matrices. This study confirmed the bioactive potential of CSF and CSE, enriched in phenolic compounds and methylxanthines, including theobromine, caffeine, gallic acid, (+)-catechin, as well as N-phenylpropenoyl-l-amino acids. The high theobromine content in both matrices, especially in CSE (2605.3 mg 100 g−1), did not harm the mice's health; acute and sub-chronic toxicity studies demonstrated the safety of oral administration of CSF and CSE in mice, showing no lethality or remarkable histopathological changes. This research supports the safe use of CSF and CSE, establishing these ingredients as suitable for incorporation into food products.

Unveiling the Nutritional Profile and Safety of Coffee Pulp as a First Step in Its Valorization Strategy.

The coffee pulp, a significant by-product of coffee processing, is often discarded but has potential for recycling and high-value uses. This study aimed to investigate the chemical composition of two coffee pulp ingredients, a flour (CPF) and an aqueous extract (CPE), and conducted acute and sub-chronic toxicity assays to determine their safety. The proximate composition revealed the high fiber content of both ingredients; the CPF mainly contained insoluble fiber, while CPE consisted exclusively of soluble pectic polysaccharides. The CPF had higher concentrations of amino acids and a better balance of essential/non-essential amino acids, whereas the CPE exhibited higher concentrations of free amino acids, ensuring higher bioavailability. Both ingredients showed elevated mineral content, while heavy-metal concentrations remained within acceptable limits. This study established the bioactive potential of the CPF and the CPE, demonstrating the high content of caffeine and gallic, protocatechuic, and 4-caffeoylquinic acids. The toxicity studies revealed that the CPF and the CPE exhibited safety when orally administered to mice. Administered doses were non-toxic, as they did not induce lethality or adverse effects in the mice or produce significant histopathological or biochemical adverse changes. This study represents a first step in valorizing the CPF and the CPE as safe novel food ingredients with health benefits for functional and nutritional foods.

Pengaruh Bulai pada Perubahan Indeks Kadar Klorofil, Serapan Fosforus dan Boron pada Jagung Manis

Maize production and quality are affected by infection with plant pathogens. One of the maize's essential and main diseases is downy mildew caused by Peronosclerospora spp. Downy mildew is a limiting factor in increasing production and can reduce production by 80-100%. It is because the affected plant cannot produce cobs. Pathogens obtain nutrients from the host cell, which can kill the cell and damage the surrounding tissues, resulting in visible downy mildew symptoms. Boron (B) plays a role in forming phloem, increasing the fruit's number, weight, bunch weight, and diameter. The primary function of B at the molecular level is the cross-linking of pectin in the plant cell wall. Ramnogalacturonan II (RG II) is a pectic polysaccharide that contributes to the mechanical strength and properties of the primary wall cross-linked by borate diesters. Phosphorus (P) controls the downsides in the greenhouse and field conditions. This study aims to measure changes in chlorophyll index, P and B uptakes in downy mildew affected plants. The field experiment used a group randomized design with six natural phosphate (FA) application treatments and four groups of borax doses as replicates. The results showed that the downy mildew decreased the chlorophyll index of the leaves at different levels of attack. The results of P concentration according to the position of healthy plant leaves were significantly different due to P treatment. In contrast to concentration B, there is no real difference. P and B uptake results in downy mildew-infested plants showed a significant difference only in P uptake in leaves with 1 FA treatment. Keywords: boron, downy mildew, maize, phosphate

Characterization of squash polysaccharide and the anti-diabetic effect on type 2 diabetic rat revealed by urine metabolomics analysis

The present study reports the structural characteristics of 3 polysaccharide fractions (SPS-F1, SPS-F2 and SPS-F3) isolated and purified from squash. SPS-F1 (molecular weight (Mw) = 12.30 kDa) and SPS-F2 (Mw = 19.40 kDa) were likely to contain HG and RG-I domain of pectic polysaccharide, respectively. SPS-F2 (Mw = 270.4 kDa) was mainly composed of rhamnose, galactose and arabinose. The treatment with SPS decreased body weight gain, glucose and TG levels in type 2 diabetes rats. Besides, 25 differential metabolites were identified based on urinary metabolomics analysis, which are crucial to the anti-diabetic effect of SPS. The regulation of nicotinamide N-oxide, histamine, cis-aconitate, citrate, L-malic acid, 3-(3-hydroxyphenyl) propanoic acid and N-acetyl-L-aspartic acid were mainly associated with energy metabolism, gut microbiota and inflammation. Study of surface plasmon resonance revealed the binding kinetics with galectin-3 (Gal-3) and fibroblast growth factor 2 (FGF2). The KD values of SPS-F2 and SPS-F3 to Gal-3 were 4.97 × 10-3 and 1.48 × 10-3 mol/L, indicating a weak binding affinity. All 3 fractions showed moderate binding to FGF2 and the affinity was SPS-F3 > SPS-F2 > SPS-F1. Thus, the metabolomics and SPR approach were proved to be a promising tool in exploring the anti-diabetes effects of SPS and provided a deep understanding of the mechanisms.

Investigation of the Structural Properties and Antioxidant Potency of Pectic Polysaccharides Derived from Rohdea japonica (Thunb.) Roth.

This study investigated the structural composition and antioxidant properties of pectic polysaccharides extracted from Rohdea japonica (Thunb.) Roth. Pectins, which belong to a complex category of acidic polysaccharides, possess a wide range of biological effects stemming from their distinctive structural domains. The polysaccharides were extracted using water, and were subsequently purified through ion exchange and gel permeation chromatography. In order to elucidate their structural features, Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance techniques were applied. Two specific polysaccharides, WRJP-A2a and WRJP-A3b, with molecular weights of 42.7 kDa and 64.1 kDa, respectively, were identified to contain varying proportions of homogalacturonan, rhamnogalacturonan I, and rhamnogalacturonan II domains. Regarding antioxidant capacity, WRJP-A3b exhibited superior scavenging capabilities against DPPH, ABTS, and hydroxyl radicals, potentially attributed to its higher galacturonic acid content and abundance of homogalacturonan domains. These results enhance our comprehension of the structure-activity interplay of pectic polysaccharides sourced from Rohdea japonica (Thunb.) Roth and their potential utility in the healthcare and functional food sectors.

Utilization of electron beam irradiation pretreatment for the extraction of pectic polysaccharides from Diaphragma juglandis fructus: Structural, physicochemical, and functional properties

The effects of electron beam irradiation (EBI) pretreatment on the alkaline extraction of pectic polysaccharides from Diaphragma juglandis fructus (DJF) are highly dependent on the irradiation dosage. Comprehensive characterizations encompassing physicochemical, structural, and functional properties were conducted on crude pectic polysaccharide extract from DJF subjected to various EBI doses. EBI pretreatment significantly increased the yields of crude pectic polysaccharides extract (increasing by 41.89 %), also facilitating the extraction of uronic acid, RG-I structure, and protein content, despite causing a decrease in total sugar content. EBI pretreatment induced the degradation of pectin, resulting in decreased molecular weight, particle size, crystallinity, viscosity, thermal stability, and water holding capacity, while enhancing solubility and oil holding capacity. Variations in physicochemical and structural properties induced by different EBI doses influenced the functional activities of DJF pectic polysaccharides. Low-dose EBI (at 5 kGy) pretreatment markedly improved the emulsifying activity/stability (increasing by 20.82/74.10 %) and ABTS/DPPH radical scavenging activity (increasing by 27.91/12.40 %), whereas high-dose EBI pretreatment (50 kGy) greatly enhanced foaming capacity/stability (increasing by 259.99/175.56 %). These findings provide a novel regulatory strategy for the functional activity of pectic polysaccharides.

RG-I pectic polysaccharides and hesperidin synergistically modulate gut microbiota: An in vitro study targeting the proportional relationship

In this study, we investigated how different proportions blends of Rhamnogalacturonan-I pectic polysaccharides and hesperidin impact the gut microbiota and metabolites using an in vitro simulated digestion and fermentation model. The results indicated that both of them could modulate the gut microbiota and produce beneficial metabolites. However, their blends in particular proportions (such as 1:1) exhibited remarkable synergistic effects on modulating the intestinal microenvironment, surpassing the effects observed with individual components. Specifically, these blends could benefit the host by increasing short-chain fatty acids production (such as acetate), improving hesperidin bioavailability, producing more metabolites (such as hesperetin, phenolic acids), and promoting the growth of beneficial bacteria. This synergistic and additive effect was inseparable from the role of gut microbiota. Certain beneficial bacteria, such as Blautia, Faecalibacterium, and Prevotella, exhibited strong preferences for those blends, thereby contributing to host health through participating in carbohydrate and flavonoid metabolism.

Extraction of water-soluble polysaccharides from lupin beans and their function of protein dispersion and stabilization under acidic conditions

In the current environment whereby new sources of proteins are extracted from plant material, it is also important to study the potential use of the resulting side streams. Although a number of studies have been conducted on various polysaccharides extracted from plant raw material, a polysaccharide fraction extracted from lupin bean is yet to be explored, in spite of the emerging interest in this crop as a source of food ingredients. In this work lupin soluble polysaccharide (LuPS) was obtained with a recovery as high as 46 % by extraction at pH 8, 120 °C, for 90 min. This fraction, named LuPS-8, was composed of a mostly linear pectic polysaccharide with a weight average molecular mass of 6608 kg/mol, and containing 71.0 % galactose, with minor amounts of arabinose (16.0 %), glucuronic acid 4.6 %, and galacturonic acid 4.1 %. When added to an acid milk dispersion, LuPS-8 improved its dispersibility, providing storage stability against sedimentation over a wider pH range than a HM-pectin reference, between 3.6–4.4. This research demonstrated the potential for upcycling of a side stream of lupin protein production, by the creation of value-added novel functional polysaccharide.

Pectic polysaccharides from Tartary buckwheat sprouts: Effects of ultrasound-assisted Fenton treatment and mild alkali treatment on their physicochemical characteristics and biological functions

Buckwheat sprouts are rich in pectic polysaccharides, which possess numerous health-improving benefits. However, the precise structure–activity relationship of pectic polysaccharides from Tartary buckwheat sprouts (TP) is still scant, which ultimately restricts their applications in the food industry. Hence, both ultrasound-assisted Fenton treatment (UAFT) and mild alkali treatment (MATT) were utilized for the modification of TP, and then the effects of physicochemical characteristics of original and modified TPs on their bioactivities were assessed. Our findings reveled that the UAFT treatment could precisely reduce TP’s molecular weight, with the levels decreased from 8.191 × 104 Da to 0.957 × 104 Da. Meanwhile, the MATT treatment could precisely reduce TP’s esterification degree, with the values decreased from 28.04 % to 4.72 %. Nevertheless, both UAFT and MATT treatments had limited effects on the backbone and branched chain of TP. Moreover, our findings unveiled that the UAFT treatment could notably promote TP’s antioxidant, antiglycation, and immunostimulatory effects, while remarkedly reduce TP’s anti-hyperlipidemic effect, which were probably owing to that the UAFT treatment obviously reduced TP’s molecular weight. Additionally, the MATT treatment could also promote TP’s immunostimulatory effect, which was probably attributed to that the MATT treatment significantly decreased TP’s esterification degree. Interestingly, the MATT treatment could regulate TP’s antioxidant and antiglycation effects, which was probably attributed to that the MATT treatment simultaneously reduced its esterification degree and bound phenolics. Our findings are conducive to understanding TP’s structure–activity relationship, and can afford a scientific theoretical basis for the development of functional or healthy products based on TPs. Besides, the UAFT treatment can be a promising approach for the modification of TP to improve its biological functions.

RG-I-containing sugar domains from Centella Asiatica bind strongly to galectin-3 to inhibit cell–cell interactions

BackgroundCentella Asiatica has been shown to have beneficial value for the treatment of tumors. However, its active ingredients and molecular mechanisms of action have not been fully elucidated. Pectic polysaccharides are the primary active components from medicinal plants. Moreover, these polysaccharides are regarded as potential inhibitors of galectins, such as galectin-1, -3, -7, that generally promote tumor growth. Nevertheless, detailed structural analysis of pectic polysaccharides from Centella Asiatica is sorely lacking, as is knowledge of their interactions with galectins.MethodsWater-soluble pectic polysaccharides (WCAP) isolated from Centella Asiatica were purified into two homogeneous fractions (WCAP-A2b and WCAP-A5b) by a combination of anion-exchange and gel-permeation chromatography. Monosaccharide composition, FT-IR, NMR and enzymatic analyses were used to characterize their structural features. Furthermore, the interactions between galectin-1, -3, -7 and a series of these polysaccharides, including two pectin fractions and their structural domains produced by enzymatic hydrolysis, were evaluated by using hemagglutination and biolayer interferometry.ResultsWCAP-A2b and WCAP-A5b have weight averaged molecular weights of 30.0 kDa and 34.0 kDa, respectively, and both polysaccharides consist of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains, with mass ratios of 1.3: 1.0: 1.4 and 1.1: 1.0: 2.4, respectively. Their RG-I domains contain arabinan, galactan, and/or arabinogalactan, along with neutral sugar side chains that are more prevalent in WCAP-A2b than in WCAP-A5b. Hemagglutination and biolayer interferometry binding assays indicate that galectin-3 vis-à-vis galectin-1 and -7, binds strongly to the RG-I domain (likely via its neutral side chains) in WCAP-A5b, thereby inhibiting galectin-3-mediated cell–cell interactions.ConclusionsOur study provides structural information on pectin polysaccharides from Centella Asiatica. Results suggest that RG-I domains from WCAP-A5b and WCAP-A2b may be developed as potential inhibitors of galectin-3-mediated cell–cell adhesion and tumor growth.Graphical

Structural characteristics of cell wall pectic polysaccharides from wampee and their decreased binding with pectinase by wampee polyphenol

To investigate the structural characteristics of cell wall pectic polysaccharides from wampee, water soluble pectin (WSP), chelator-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) were purified. And the inhibitory effects of wampee polyphenol (WPP) on pectinase when these cell wall pectic polysaccharides were used as substrates were also explored. Purified WSP (namely PWSP) had the lowest molecular weight (8.47 × 105 Da) and the highest GalA content (33.43%). While purified CSP (called PCSP) and SSP contained more abundant rhamnogalacturonan I side chains. All of them were low-methoxy pectin (DE < 50%). Enzyme activity and kinetics analysis showed that the inhibition of pectinase by wampee polyphenol was reversible and mixed type. When SSP was used as the substrate, WPP had the strongest inhibition (IC50 = 1.96 ± 0.06 mg/mL) on pectinase. Fluorescence quenching results indicated that WPP inhibited enzyme activity by interacting with substrates and enzymes. Therefore, WPP has the application potential in controlling softening of fruits and vegetables.