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Fourier transform-infrared spectroscopy (FT-IR) spectra of HG pectins from plants. (A) HG-PN-2 (Class I); (B) HG-PJ-1 (Class II); (C) HG-CC-1 (Class III); and (D) HG-KL-1 (Class IV).
Source publication
Homogalacturonan (HG)-type pectins are nutrient components in plants and are widely used in the food industry. The methyl-esterification pattern is a crucial structural parameter used to assess HG pectins in terms of their nutraceutical activity. To better understand the methyl-esterification pattern of natural HG pectins from different plants, we...
Citations
... Since the cell wall is a cell's first protective line, accumulates higher concentrations of HMs followed by other organelles and cytoplasm [14,29]. Cosmos bipinnatus accumulated most of the Cr in their root's cell walls, and changes in pectin content significantly affected the concentration of Cr accumulation in these cell walls [30]. Herein, the pectin concentration in rice tissues was independent of Cr(VI) doses supplied, while Pro application significantly increased the pectin concentration in Cr(VI)-treated rice seedlings (Fig. 2). ...
Background
Plants are equipped with several sophisticated mechanisms to deal with heavy metals (HMs) toxicity. Cell walls, which are rich in pectin, are important in the sequestration and compartmentalization of HMs. Pectin demethylation is carried out by pectin methylesterase (PME), which is a crucial activity in cell walls for the adsorption of HMs. This study focused on the factors that contribute to chromium (Cr) adsorption in rice plants exposed to Cr(VI) treatments without proline (Pro) “Cr(VI)” and with Pro “Pro + Cr(VI)” application.
Results
The results exhibited that when rice plants were treated with Cr(VI), their PME activity decreased, because Cr(VI) was bound to certain isoforms of PME and prevented the demethylation of pectin. The application of Pro increased PME activity by promoting the transcription of several PME-related genes. These genes were recognized on the basis of their similarity with PME genes in Arabidopsis. Gene expression variation factors (GEVFs) between the “Cr(VI)” and “Pro + Cr(VI)” treatments revealed that OsPME7 and OsPME9 have the highest positive GEVF values than other OsPME genes of rice. In addition, Pro application increased pectin content significantly in rice plants exposed to Cr(VI) stress. Proline application also leads to an increased concentration of Cr in rice roots compared with “Cr(VI)” treatments alone.
Conclusions
These findings suggest that Pro increased Cr(VI) adsorption in cell walls of rice plants by enhancing the PME activity and pectin content when exposed to “Cr(VI)” treatments, mainly regulated by OsPME7 and OsPME9.
Graphical Abstract
... HG is the most abundant form of pectin polysaccharide that comprises ~ 65% of pectin, with α-1,4-GalA repeat units. O-2 and O-3 are often acetylated, and methyl ester of varying degrees often occurs at C-6 carboxyl groups [9]. The ratio of the methylated GalA unit to the total GalA unit is called the degree of esterification (DE). ...
Galectin-3 has a variety of important pathophysiological significance in the human body. Much evidence shows that the abnormal expression of galectin-3 is related to the formation and development of many diseases. Pectin is mostly obtained from processed citrus fruits and apples and is a known natural inhibitor of galactin-3. A large number of peels produced each year are discarded, and it is necessary to recycle some of the economically valuable active compounds in these by-products to reduce resource waste and environmental pollution. By binding with galectin-3, pectin can directly reduce the expression level of galectin-3 on the one hand, and regulate the expression level of cytokines by regulating certain signaling pathways on the other hand, to achieve the effect of treating diseases. This paper begins by presenting an overview of the basic structure of pectin, subsequently followed by a description of the structure of galectin-3 and its detrimental impact on human health when expressed abnormally. The health effects of pectin as a galectin-3 inhibitor were then summarized from the perspectives of anticancer, anti-inflammatory, ameliorating fibrotic diseases, and anti-diabetes. Finally, the challenges and prospects of future research on pectin are presented, which provide important references for expanding the application of pectin in the pharmaceutical industry or developing functional dietary supplements.
Graphical Abstract
... The molecular main chain and branch chain structures of pectin are different. They are divided into four configurations, namely, homocysteine, rhamnogalacturonan I, rhamnogalacturonan II, and xylogalacturonan (3). The backbone of RG-I is different: it is composed of repeating units of galacturonic acid (GalA) residues and rhamnose (Rha). ...
... Studies have shown that the configuration is an important parameter of pectin, which is closely related to the physical and chemical properties and biological activity of pectin (1). Studies have shown that substituting rhamnose-galacturonic acid (RGs) for pectin can prevent cancer (4) by inducing cancer cell apoptosis (3). There are many methods for extracting pectin, including acid extraction (1), alkali extraction (1), ion exchange (5), microwave extraction (6), ultrasonic extraction (7), enzyme extraction (8), continuous countercurrent extraction (9), and supercritical fluid extraction (10). ...
... Its galacturonic acid residues are often esterified by some groups such as methoxyl and amide. The degree of esterification is also called methoxylation, which refers to the sum of the proportions of methylesterification, acetylation, and amidation in pectin (3). Although the esterification degree of UAP (66.6%) is lower than the SAP (75%), indicating that the cavity effect of ultrasound may have broken the ester bond, resulting in the esterification degree of pectin decreasing the UAP and the SAP all belong to the high ester pectin (≥50%) (7). ...
Pectin was extracted from Actinidia arguta Sieb. et Zucc (A.arguta) using the ultrasound-assisted acid method and the single acid method. The physicochemical properties, structure, and antioxidant properties of two different pectins were investigated. The results showed that the extraction yield of the ultrasound-assisted acid method is higher than that of the single acid method. The molecular structure of A. arguta pectin extracted by the ultrasound-assisted acid method belongs to a mixed structure of RG-I and HG-type domains. Through structural feature analysis, the ultrasound-assisted extraction pectin (UAP) has a more branched structure than the single acid-extracted pectin (SAP). The SAP has a higher degree of esterification than the UAP. The physical property results show that the viscosity, solubility, and water-holding capacity of the UAP are better than those of the SAP. The antioxidant test results show that the hydroxyl radical scavenging and reducing powers of the UAP are superior to those of the SAP. This study shows the composition, physicochemical properties, and antioxidant activity of A. arguta pectin extracted by the ultrasonic-assisted extraction method to provide a theoretical basis for its application as an antioxidant and other food additives in the food industry.
... The two medium peaks shown in regions 1425.72 cm −1 and 1415.2 cm −1 proved the existence connected to the stretching of the methyl ester group in the pectin-CH3. These perhaps indicate the esterification of some of the uronic acid carboxyl [27]. ...
This study explores the isolation and characterization of two acidic polysaccharides from baobab (Adansonia digitata) fruits, named ADPs40-F3 and ADPs60-F3; the two types of acidic polysaccharides exhibited high sugar content and chemical structural features characterized by O–H, C–H, carbonyl C=O, and COOH carboxyl functional groups. The two fractions showed molecular weights of 1.66 × 105 and 9.59 × 104 Da. ADPs40-F3 residues consist of arabinose (2.80%), galactose (0.91%), glucose (3.60%), xylose (34.70%), and galacturonic acid (58.10%). On the other hand, ADPs60-F3 is composed of rhamnose (1.50%), arabinose (5.50%), galactose (2.50%), glucose (3.10%), xylose (26.00%), and galacturonic acid (61.40%). Furthermore, NMR analysis showed that the main acidic structures of ADPs40-F3 and ADPs60-F3 are formed by 4,6)-α-d-GalpA-(1→, →4)-β-d-Xylf-(1→, →4,6)-β-d-Glcp-(1→, →5)-α-L-Araf-(1→, →4,6)-α-d-Galp-(1→ residues and 4)-α-d-GalpA-(1→, →4)-β-d-Xylf-(1→, →6)-β-d-Glcp-(1→, →5)-α-l-Araf-(1→ 4,6)-α-d-Galp-(4,6→, →2)-α-Rhap- residues, respectively, based on the observed signals. Antioxidant assays against DPPH, ABTS+, and FRAP revealed significant antioxidant activities for ADPs40-F3 and ADPs60-F3, comparable to ascorbic acid (VC). Additionally, both polysaccharides exhibited a dose-dependent inhibition of α-glucosidase and α-amylase activities, suggesting potential anti-diabetic properties. In vivo evaluation demonstrated that ADPs60-F3 significantly reduced blood glucose levels, indicating promising therapeutic effects. These findings underscore the potential utility of baobab fruit polysaccharides as natural antioxidants and anti-diabetic agents.
... The most abundant component of pectin is homogalacturonan (HG), which is composed of galacturonic acid (GalA) residues; GalA residues exist in methyl esterified and/or acetylated states. 13 Another component of pectin, rhamnogalacturonan-I (RG-I), is a heteropolymer consisting of a backbone of alternating rhamnose and GalA residues with arabinose-and/or galactose-containing sidechains, and possible O-methyl-and acetyl esterified GalA residues 14,15 (Fig. 1). ...
The safety of a rhamnogalacturonan-I-enriched pectin extract (G3P-01) from pumpkin (Cucurbita moschata var. Dickinson) was evaluated for use as an ingredient in food and dietary supplements. G3P-01 was tested in a battery of genetic toxicity studies including reverse mutagenicity and in vitro micronucleus assay. In addition, Sprague-Dawley rats were randomized and orally dosed with G3P-01 incorporated in animal diet at concentrations of 0, 9000, 18,000, and 36,000 ppm daily for 13-weeks (n=10/sex/group) in line with OECD guidelines (TG 408). The results of the in vitro bacterial reverse mutation assay and micronucleus assay in TK6 cells demonstrated a lack of genotoxicity. The 13-week oral toxicity study in Sprague-Dawley rats demonstrated that the test article, G3P-01 was well tolerated; there were no mortalities and no adverse effects on clinical, gross pathology, hematology, blood chemistry, and histological evaluation of the essential organs of the animals. The present study demonstrates that G3P-01 is non-genotoxic and is safe when ingested in diet at concentrations up to 36, 000 ppm. The subchronic no-observed-adverse-effect level (NOAEL) for G3P-01 was concluded to be 36,000 ppm, equivalent to 1,899 and 2,361 mg/kg/day for male and female rats respectively.
... The resonances in the regions of 60-80 ppm and 97-105 ppm were characteristic of C2-C5 of monosaccharides and C1 (anomeric) of monosaccharides, respectively. Additionally, the resonances at 53.1 and 170.8 ppm were attributed to the CH 3 of methyl ester and C-6 of galacturonic acid, respectively [8,18,21,22]. Notably, these resonances decreased when the MW processing temperature exceeded 140 • C, which is indicative of thermal degradation and the decarboxylation of homogalacturonan (HG). ...
... The resonances in the regions of 60-80 ppm and 97-105 ppm were characteristic of C2-C5 of monosaccharides and C1 (anomeric) of monosaccharides, respectively. Additionally, the resonances at 53.1 and 170.8 ppm were attributed to the CH3 of methyl ester and C-6 of galacturonic acid, respectively [8,18,21,22]. Notably, these resonances decreased when the MW processing temperature exceeded 140 °C, which is indicative of thermal degradation and the decarboxylation of homogalacturonan (HG). ...
The exploitation of unavoidable food supply chain wastes resulting from primary and secondary processing for chemicals, materials, and bioenergy is an important concept in the drive towards circular-based, resource-efficient biorefineries rather than petroleum refineries. The potential production of hydrogels (materials) from unavoidable food supply chain wastes, which are naturally rich in biopolymers such as cellulose, hemicellulose, pectin, and lignin, represents an interesting opportunity. However, these intertwined and interconnected biopolymers require separation and deconstruction prior to any useful application. Thus, this study aims to explore the formation of hydrogels from defibrillated celluloses (MW-DFCs) produced via acid-free stepwise microwave hydrothermal processing of blackcurrant pomace residues. Initially, pectin was removed from blackcurrant pomace residues (MW, 100-160 • C), and the resultant depectinated residues were reprocessed at 160 • C. The pectin yield increased from 2.36 wt.% (MW, 100 • C) to 3.07 wt.% (MW, 140 • C) and then decreased to 2.05 wt.% (MW, 160 • C). The isolated pectins were characterized by attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA), and 13 C NMR (D 2 O). The cellulosic-rich residues were reprocessed (MW, 160 • C) and further characterized by ATR-IR, TGA, and Klason lignin analysis. All the MW-DFCs contained significant lignin content, which prevented hydrogel formation. However, subsequent bleaching (H 2 O 2 /OH −) afforded off-white samples with improved gelling ability at the concentration of 5% w/v. Confocal laser microscopy (CLSM) revealed the removal of lignin and a more pronounced cellulosic-rich material. In conclusion, the microwave-assisted defibrillation of blackcurrant pomace, an exploitable unavoidable food supply chain waste, affords cellulosic-rich materials with the propensity to form hydrogels which may serve useful applications when put back into food products, pharmaceuticals, cosmetics, and home and personal care products.
... In WHNP-A2b and WHNP-A3b, the characteristic signals for RG-II domain were not found, suggesting NMR results were consistent with TBA assay results in these fractions. Also, the complex, overlapping signals at 60 ppm-85 ppm are attributed to C-2 to C-5 groups of different linkages in α-L-Araf and α-L-Rhap, and C-2 to C-6 groups of β-D-Galp and α-D-GalpA [38,39]. These assignments are summarized in Table 3. ...
... A2c-E3 was oligogalacturonic acids obtained from the degradation of non-or low-methyl-esterified HG domains of WHNP-A2c. The structural features of A2c-E3 were analyzed in more detail using ESI-MS [39,[42][43][44]. As shown in Fig. 7B, the oligosaccharide fragments in A2c-E3 included non-esterified monomer 1 00 -type ion (m/z 193), dimer 2 00 -type ion (m/z 369) and trimer 3 00 -type ion (m/z 545). ...
Background
Hedera nepalensis is a traditional medicinal plants, and the dried leaves of it are generally used for the cure and treatment of many diseases, also widely known as Chang-Chun-Teng in Chinese. Until now, structural characterization of water-soluble polysaccharides isolated from leaves of Hedera nepalensis have been scarcely studied, even though the chemical compounds derived from it and their biological activities have been widely studied.
Methods
Water-soluble polysaccharides (WHNP) were isolated from the dried leaves of Hedera nepalensis, and their structural features were investigated. One neutral polysaccharide fraction (WHNP-N) and three major pectin fractions (WHNP-A2b, WHNP-A2c and WHNP-A3b) were obtained from WHNP, respectively. There was no analysis of the neutral fraction (WHNP-N), while the structural characterization of three major pectin fractions (WHNP-A2b, WHNP-A2c and WHNP-A3b) were further studied by monosaccharide composition, HPGPC, NMR and methylation analyses.
Results
The results indicated that two fractions WHNP-A2b (Mw = 45.8 kDa) and WHNP-A3b (Mw = 58.6 kDa) were mainly composed of rhamnogalacturonan I (RG-I). In WHNP-A2b, RG-I domains primarily substituted with α-L-1,5/1,3,5-arabinan, type II arabinogalactan (AG-II), β-D-1,4-galactan and/or type I arabinogalactan (AG-I) as side chains, while RG-I-type pectin of WHNP-A3b mainly branched with α-L-1,5/1,3,5-arabinan, β-D-1,4-galactan and AG-II side chains. WHNP-A2c (Mw = 12.4 kDa) was primarily comprised of galacturonic acid (GalA, 60.8%), and enzymatic analysis indicated that this fraction mainly consisted of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 1.8:1.0:0.6. On the other hand, WHNP-A2c was found to be rich in RG-I domains, which contained α-L-1,5/1,3,5-arabinan, AG-II, β-D-1,4-galactan and/or AG-I as side chains. The HG domains of WHNP-A2c was released in the form of un-esterified and partly methyl-esterified and/or acetyl-esterified oligogalacturonides with a 1 to 7 degree of polymerization after endo-polygalacturonase degradation.
Conclusion
Our results reveal the structural characteristics of these polysaccharide fractions, which will contribute to elucidating their structure–activity relationships.
Graphical Abstract
In this study, we isolated the pectic polysaccharide WSMP-A2b (37 kDa) from the stems and leaves of Swertia mileensis, and we investigated its compositional/structural features and antioxidant activity. FT-IR, NMR, monosaccharide composition, enzymatic hydrolysis and methylation analyses indicated that WSMP-A2b is composed of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 2.1:1.0:2.2. The RG-I domain is primarily substituted with α-L-1,5-arabinan and type II arabinogalactan (AG-II) side chains, as well as minor contributions of β-D-1,4-galactan and/or type I arabinogalactan (AG-I) side chains. The HG domain was released in the form of un-esterified and partly methyl-esterified and/or acetyl-esterified oligogalacturonides with a 1 to 7 degree of polymerization after endo-polygalacturonase degradation. WSMP-A2b showed stronger antioxidant activity in vitro, in part this might due to the presence of galacturonic acid (GalA). In addition, WSMP-A2b exerted a protective effect on tert-butyl hydroperoxide (tBHP)-induced oxidative stress in INS-1 cells by reducing reactive oxygen species (ROS) production and increasing the glutathione/oxidized glutathione (GSH/GSSG) ratio. Our results provide crucial structural information on this pectic polysaccharide from Swertia mileensis, thus prompting further investigation into its structure-activity relationship.
