Pectin Research Articles

Pectin methyltransferase QUASIMODO2 functions in the formation of seed coat mucilage in Arabidopsis

Pectin, cellulose, and hemicelluloses are major components of primary cell walls in plants. In addition to cell adhesion and expansion, pectin plays a central role in seed mucilage. Seed mucilage contains abundant pectic rhamnogalacturonan-I (RG-I) and lower amounts of homogalacturonan (HG), cellulose, and hemicelluloses. Previously, accumulated evidence has addressed the role of pectin RG-I in mucilage production and adherence. However, less is known about the function of pectin HG in seed coat mucilage formation. In this study, we analyzed a novel mutant, designated things fall apart2 (tfa2), which contains a mutation in HG methyltransferase QUASIMODO2 (QUA2). Etiolated tfa2 seedlings display short hypocotyls and adhesion defects similar to qua2 and tumorous shoot development2 (tsd2) alleles, and show seed mucilage defects. The diminished uronic acid content and methylesterification degree of HG in mutant seed mucilage indicate the role of HG in the formation of seed mucilage. Cellulosic rays in mutant mucilage are collapsed. The epidermal cells of seed coat in tfa2 and tsd2 display deformed columellae and reduced radial wall thickness. Under polyethylene glycol treatment, seeds from these three mutant alleles exhibit reduced germination rates. Together, these data emphasize the requirement of pectic HG biosynthesis for the synthesis of seed mucilage, and the functions of different pectin domains together with cellulose in regulating its formation, expansion, and release.

Pectin-associated mannans and xylans play distinct roles in cell-cell adhesion in pine and poplar wood

Wood particles of pine required longer treatments of acidic chlorite and dilute alkali to achieve similar proportions of cell separation as of poplar. Chemical extraction and enzymatic digestion studies indicated that rhamnogalacturonan-I (RG-I), mannan and xylan contribute to cell-cell adhesion in pine wood. Mannan associated with lignin in an acidic chlorite fraction and with xylan in a dilute alkali fraction. RG-I and xylan were extracted in both chlorite and dilute alkali in poplar. Scanning electron microscopy and a probe diffusion study using Fluorescence Recovery After Photobleaching showed that lignin, RG-I and mannan initiated cell separation at cell corners and dilute alkali extraction of xylan was required for complete cell separation in pine. Cell-cell separation increased enzymatic saccharification within 24 h by 2-fold in poplar and 3.4-fold in pine. Our results inform a strategy to reduce particle size in woody biomass and provide insights into different molecular bases of cell-cell adhesion.

Pectin mediated green synthesis of CuO nanoparticles: evaluation of its cytotoxicity, antioxidant and anti-human cervical cancer properties

Regarding applicative, facile, green chemical research, a bio-inspired approach is being reported for the synthesis of CuO nanoparticles by pectin (PEC) as a natural reducing and stabilizing agentin alkaline medium without using any toxic reducing agent. The biosynthesized CuO NPs@Pectin were characterized by advanced physicochemical techniques like ultraviolet–visible (UV–Vis), Fourier Transformed Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) study. It has been established that pectin-stabilized copper nanoparticles have a spherical shape with a mean diameter from approximately 10 nm. To survey the cytotoxicity and anti-human cervical cancer effects of CuO NPs@Pectin, MTT assay was used on C-33 A [c-33a], SiHa, Ca Ski, DoTc2 4510, HT-3 and LM-MEL-41 cell lines. The resulting IC50 values of the CuO NPs@Pectin against C-33 A [c-33a], SiHa, Ca Ski, DoTc2 4510, HT-3 and LM-MEL-41 cell lines were 231, 214, 243, 376, 315 and 169 µg/mL, respectively. Antioxidant properties of CuO NPs@Pectin were surveyed through the DPPH test in presence of butylated hydroxytoluene as the positive control. The CuO NPs@Pectin inhibited half of the DPPH molecules in the concentration of 98 µg/mL. The cell viability of the treated cell lines was found to reduce dose-dependently over the CuO NPs@Pectin nanocomposite. After approving the above results in the clinical trial studies, the CuO NPs@Pectin can be used as a chemotherapeutic drug for the treatment of several types of cervical cancers.

A combined approach using slightly acidic electrolyzed water spraying and chitosan and pectin coating on the quality of the egg cuticle, prevention of bacterial invasion, and extension of shelf life of eggs during storage

Slightly acidic electrolyzed water (SAEW) is often used on eggs to remove microorganisms, but the cuticle will be damaged, causing bacterial invasion and deterioration of egg quality during preservation. Therefore, a combination of SAEW disinfection with chitosan (CS) and pectin (PT) composite coating (CS + PT) was tried in preventing bacterial invasion and prolonging the shelf life of eggs. The results showed the order of decontamination effectiveness on contaminated eggs was SAEW > Electrolyzed reduced water (ERW) + SAEW > ERW > deionized water. The CS + PT coating used on SAEW-disinfected eggs inhibits the S. enteritidis invasion (reduced by 63.3%) and was successfully used to maintain the quality of eggs (Haugh unit 48.63, Weight loss 7.34%, Yolk index 0.29, pH 8.93) after 8 weeks storage at 25 ℃. The results revealed that the combination of SAEW and CS + PT was a very promising method for egg preservation.

Curcumin loading and colon release of pectin gel beads: Effect of different de-esterification method

Low methoxyl citrus pectin (LMP) de-esterified from high hydrostatic pressure assisted enzymatic (HHP-pectin) and two other traditional methods was characterized, and curcumin-pectin calcium gel beads were prepared to study curcumin-loading and colon-targeted delivery abilities. It was found there was no significant difference among different LMP on amorphous structure, while significantly higher Rha/GalA ratio of HHP-pectin indicated higher rhamnogalacturonan Ⅰ (RG-I) proportion and branching extent. Curcumin was well embedded in LMP beads with improved stability. HHP-pectin beads showed significantly higher hardness, chewiness and encapsulation efficiency, while lower swelling ratio. Moreover, in vitro simulated digestion showed gel beads can deliver curcumin to colon and inhibit premature release. HHP-pectin beads could release curcumin more quickly in colon, probably because of differences on texture properties, which may be depended on molecular structure. Thus, LMP especially HHP-pectin calcium gel as colon-targeted delivery system for curcumin may have potential application in function food and drug delivery.

Fabrication and digestive characteristics of high internal phase Pickering emulsions stabilized by ovalbumin-pectin complexes for improving the stability and bioaccessibility of curcumin

In this study, ovalbumin (OVA) interacted with pectin (PE) to form soluble electrostatic complexes to improve the functional properties of high internal phase Pickering emulsions (HIPEs) under extreme conditions. The results showed that the stability of the OVA-PE soluble complexes-stabilized HIPEs was significantly better than that of the free OVA-stabilized HIPEs and was modulated by the biopolymer ratio. In particular, the complexes at an OVA:PE ratio of 1:1 (C-1:1) may form particulates with a core-shell structure by a flocculation mechanism. The C-1:1-stabilized HIPEs had the smallest oil droplet size (11.34 ± 1.14 μm) and the best resistance to extreme environmental stresses due to their strong, rigid structure and dense interfacial architecture. The in vitro digestion results showed that the bioaccessibility (from 18.3% ± 0.5% to 38.8% ± 4.8%) of curcumin improved with increasing PE content. Our work is helpful in understanding OVA-PE complexes as stabilizers for HIPEs and their potential applications in food delivery systems.

EXTRACTION AND CHARACTERIZATION OF PECTIN FROM PASSION FRUIT (PASSIFLORA EDULIS L.) USING CHLORIDE ACID SOLUTION

Pectin is a natural substance found in most food crops. In general, pectin extraction uses mineral and organic acids, such as sodium hexametaphosphate acid, sulfuric acid, hydrochloric acid, acetic acid, nit citric, and citric acid. The study aimed to obtain the concentration of HCl, which gave the best value for the physical and chemical properties of passion fruit pectin. This study was a completely randomized design. The tested factor was 400 ml HCl solution with five treatment levels of HCl concentration: 1 N; 1.5 N; 2 N; 2.5 N; and 3 N. Each treatment was repeated three times, and therefore 15 experimental units were tested. The variables observed were pectin yield, methoxyl content, galacturonic content, esterification degree, clarity, water content, and ash content. The results showed that the 2.5 N HCl concentration resulted a yield value of 27.47%, methoxyl content 5.20%, galacturonic content 121.62%, esterification degree 24.26%, clarity 14.65%, water content 4.37 %, and 0.54% ash content, so the 2.5 N HCl concentration was the HCl concentration that gave the best effect on the physical and chemical properties of passion fruit pectin extraction.

Newly crosslinked chitosan- and chitosan-pectin-based hydrogels with high antioxidant and potential anticancer activity

Monoaldehydes, due to natural origin and therapeutic activity, have attracted great attention for their ability to crosslink chitosan hydrogels for biomedical applications. However, most studies have focused on single-component hydrogels. In this work, chitosan-based hydrogels, crosslinked for the first time with 2,3,4-trihydroxybenzaldehyde (THBA), were modified with pectin (PC), bioactive glass (BG), and rosmarinic acid (RA). All of these were not only involved in the crosslinking, but also modulated properties or imparted completely new ones. THBA functioned as a crosslinker, resulting in improved mechanical properties, high swelling capacity and delayed degradation and also imparted high antioxidant activity and antiproliferative effect on cancer cells without cytotoxicity for normal cells. Hydrogels containing PC showed enhanced mechanical strength, while the combination with BG gave improved stability in PBS. All hydrogels modified with BG exhibited the ability to mineralise in SBF. The addition of RA enhanced antioxidant and anticancer activities and promoting the mineralisation process.

Structural Characterization of a Low Molecular Weight HG-Type Pectin From Gougunao Green Tea.

Tea is a popular beverage with a long history of safe and healthy use. Tea polysaccharide is a bioactive component extracted from tea, which has attracted more and more attention in recent decades. In this article, an acidic polysaccharide Gougunao tea polysaccharide (GPS) was isolated from Gougunao green tea by hot water extraction and ethanol precipitation. After purification by a diethylaminoethyl (DEAE) Sepharose Fast Flow column and a Sephacryl S-400 column, several homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) fractions were obtained. Fraction GPS2b with the highest yield was selected for structural characterization by methylation and nuclear magnetic resonance (NMR) analysis. GPS2b was found to be an HG-type pectic polysaccharide (degree of methyl esterification [DE], 51.6%) with low molecular weight (Mw, 36.8 kDa). It was mainly composed of →4)-α-GalpA- (1→ and →4)-α-GalpA-6-OMe-(1→. In addition, a minor highly branched RG-I domain was identified in this fraction. The investigation of structural features of tea polysaccharides can provide insights to understand their structure-bioactivity relationship.

A Comparative Evaluation of Sustained Release of Chlorphenamine Based on a Nanocomposite of Chitosan, Pectin and Montmorillonite

AbstractThe scenario of the current investigation is to prepare an inclusion complex (IC) of chlorphenamine (CPM) and montmorillonite (MONT) by microwave method for sustained drug delivery system and to analyze the comparison of inclusion complex with direct loading of free drug. A nanocomposite was synthesized from chitosan (CH), pectin (PC) by incorporating montmorillonite (MONT). The confirmation of inclusion complex formation and nanocomposite was characterized by FTIR, XRD, and FESEM‐EDS. Drug release study from chitosan, pectin nanocomposite containing free CPM and inclusion complex of CPM: MONT were investigated under different pH 2, 7 and 7.4 at 37 °C. The concentration of drug release from inclusion complex loaded nanocomposite was found to be 97.4 % in 22 hours. Four different kinetic models were studied to check the real mechanism involved in drug release. In all cases, the best fitted kinetic model for CPM release from the inclusion complex loaded nanocomposite was Peppas‐Sahlin and Korsmeyer Peppas, implying that diffusion and relaxation phenomena were responsible for the drug release. Diffusion phenomena have more contribution than relaxation is confirmed by the Peppas‐Sahlin equation. Montmorillonite is responsible for the sustained drug release because of host‐guest interactions. Montmorillonite has a layered structure that allows it to intercalate the drug molecule into its cavity, resulting in sustained chlorphenamine release.

Immune-instructive copolymer scaffolds using plant-derived nanoparticles to promote bone regeneration

BackgroundAge-driven immune signals cause a state of chronic low-grade inflammation and in consequence affect bone healing and cause challenges for clinicians when repairing critical-sized bone defects in elderly patients.MethodsPoly(l-lactide-co-ɛ-caprolactone) (PLCA) scaffolds are functionalized with plant-derived nanoparticles from potato, rhamnogalacturonan-I (RG-I), to investigate their ability to modulate inflammation in vitro in neutrophils and macrophages at gene and protein levels. The scaffolds’ early and late host response at gene, protein and histological levels is tested in vivo in a subcutaneous rat model and their potential to promote bone regeneration in an aged rodent was tested in a critical-sized calvaria bone defect. Significant differences were tested using one-way ANOVA, followed by a multiple-comparison Tukey’s test with a p value ≤ 0.05 considered significant.ResultsGene expressions revealed PLCA scaffold functionalized with plant-derived RG-I with a relatively higher amount of galactose than arabinose (potato dearabinated (PA)) to reduce the inflammatory state stimulated by bacterial LPS in neutrophils and macrophages in vitro. LPS-stimulated neutrophils show a significantly decreased intracellular accumulation of galectin-3 in the presence of PA functionalization compared to Control (unmodified PLCA scaffolds). The in vivo gene and protein expressions revealed comparable results to in vitro. The host response is modulated towards anti-inflammatory/ healing at early and late time points at gene and protein levels. A reduced foreign body reaction and fibrous capsule formation is observed when PLCA scaffolds functionalized with PA were implanted in vivo subcutaneously. PLCA scaffolds functionalized with PA modulated the cytokine and chemokine expressions in vivo during early and late inflammatory phases. PLCA scaffolds functionalized with PA implanted in calvaria defects of aged rats downregulating pro-inflammatory gene markers while promoting osteogenic markers after 2 weeks in vivo.ConclusionWe have shown that PLCA scaffolds functionalized with plant-derived RG-I with a relatively higher amount of galactose play a role in the modulation of inflammatory responses both in vitro and in vivo subcutaneously and promote the initiation of bone formation in a critical-sized bone defect of an aged rodent. Our study addresses the increasing demand in bone tissue engineering for immunomodulatory 3D scaffolds that promote osteogenesis and modulate immune responses.

Impact of thermally induced wall breakage on the structural properties of water-soluble polysaccharides in chickpeas

The present work aimed to elucidate the influence of wall breakage induced by thermal processing on the molecular, structural, and antioxidant activities of water-soluble polysaccharides in chickpeas. Different extents of cell wall disruption were observed by fluorescence microscopy in chickpea cotyledons. Moreover, a decreasing fluorescence intensity of cell wall fragments was observed in the flour residues upon heat fluidization, autoclaving, and microwave heating, and the polysaccharide extraction rates were increased by 31.47%, 25.52%, and 9.79%, respectively. Furthermore, WPUCP, WPHCP, WPMCP, and WPACP (water-soluble polysaccharides from unprocessed, heat fluidized, microwaved, and autoclaved chickpeas, respectively) were RG-I (rhamnogalacturonan-I)-enriched pectic polysaccharides composed of galactose, arabinose, galacturonic acid, and rhamnose. After chickpea thermal processing, the degrees of branching decreased to 2.87, 3.79, and 2.53 in WPHCP, WPMCP, and WPACP, respectively, and the molecular weights were reduced by 46.46%, 24.83%, and 59.91%, respectively. Structural analysis showed that the semicrystalline regions of WPHCP, WPMCP, and WPACP were slightly damaged without changing the functional groups, but their thermal stability decreased. Interestingly, WPACP formed an ordered conformation (microporous network structure) through the formation of hydrogen bonds. Moreover, the antioxidant activities of WPHCP, WPMCP, and WPACP were enhanced, and the strongest radical scavenging activity was observed for WPHCP.

Effect of in vitro gastric digestion conditions on physicochemical properties of raw apple fruit cell wall polysaccharides

The effects of in vitro gastric digestion conditions on the properties of the soluble (SC) and insoluble (IC) components of apple cell walls were investigated. Apple fruits were homogenized and successively treated in natural saliva (3 min, 37 °C) and in simulated gastric fluid (SGF, 2 h, 37 °C). The incubation pH (5.0, 3.0, 1.8) and the ratio of apple mixture to SGF (1:0.05, 1:0.5, 1:1, v/v) were varied. Pectin (GalA 74 wt%, Mw 1800 × 103 g/mol, yield 1.9–2.4%) was a major high-molecular-weight component of SC obtained at pH 1.8, whereas at pH 3.0 and 5.0, proteins (41–55 wt%) and phenolic compounds (2.7–3.1 wt%) were dissolved together with pectins (15–24 wt% GalA, Mw 28-33 × 103 g/mol, yield 0.6–0.8%). Rhamnogalacturonan-I (RG-I) and homogalacturonan (HG) were identified in all pectins. HG was the major component of pectins extracted at pH 1.8; RG-I was the major component of pectins extracted at pH 3.0 and 5.0. The dissolution of cell wall pectins of apple fruits in SGF increased the viscosity of the SC of the apple mixture, decreased the hardness of the apple mixture, increased the water retention and water swelling capacity of the IC, and improved the capacity of high-molecular-weight soluble and insoluble components to retard glucose diffusion. The difference in surface morphology of insoluble components obtained at different values of pH incubation was observed under a SEM.

Comparative study of water-soluble polysaccharides isolated from leaves and roots of Isatis indigotica Fort.

Water-soluble polysaccharides were isolated from the leaves and roots of Isatis indigotica Fort., and their structural features were studied and compared. One neutral polysaccharide fraction (WFIP-N) and three pectin fractions (WFIP-A-A, WFIP-A-B and WFIP-A-C) were obtained from the leaves, and one neutral polysaccharide fraction (WRIP-N) and two pectin fractions (WRIP-A-A and WRIP-A-B) were obtained from the roots. WFIP-A-B (Mw = 34.6 kDa) and WRIP-A-B (Mw = 29.9 kDa) were the major pectic polysaccharides. Monosaccharide composition, FT-IR, enzymatic hydrolysis, NMR and methylation analysis indicated that both WFIP-A-B and WRIP-A-B are composed of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 1.5:1.0:0.4 and 0.3:1.0:1.7, respectively. WFIP-A-B and WRIP-A-B were found to be rich in RG-I and HG domains, respectively, and mainly contained type II arabinogalactan (AG-II) and α-L-1,5-arabinan side chains, but those in WRIP-A-B were more numerous and longer. Our results provide structural features and differences between these polysaccharides which will help to elucidate their functional differences.

Polysaccharide-Zein Composite Nanoparticles for Enhancing Cellular Uptake and Oral Bioavailability of Curcumin: Characterization, Anti-colorectal Cancer Effect, and Pharmacokinetics.

Curcumin (CUR) has demonstrated promising potential as a therapeutic agent against colorectal cancer (CRC). However, its intrinsic shortcomings, including oxidative instability, sensitivity to gastrointestinal (GI) hydrolytic/enzymatic action, and susceptibility to biotransformation and systemic elimination, have greatly undermined its value for application in clinical settings. The development of carriers, in particular oral formulations, for its efficient delivery has remained an important direction in nutraceutical research. In the present work, CUR-encapsulated nanoparticles were fabricated with zein alone (Zein-CUR) and with zein and a polysaccharide (PS) [gum Arabic (GA), hyaluronic acid (HA) and pectin (PC), respectively] (PS-Zein-CUR). Their physicochemical and biological properties were evaluated in a series of in vitro and in vivo assays. Dynamic light scattering analysis showed an increase in the particle size of the nanoparticles from 129.0 nm (Zein-CUR) to 188.8–346.4 nm (PS-Zein-CUR). The three PS-Zein-CUR formulations had significantly higher (17–22%) CUR encapsulation efficiency (EE) than Zein-CUR. Among them, HA-Zein-CUR exhibited the highest EE and loading capacity. Zeta potential and FTIR spectra indicated the involvement of electrostatic and hydrophobic interactions and hydrogen bonds in the formation of the PS-Zein-CUR. In human CRC cell lines (HCT8, HCT29, and HCT116), the three PS-Zein-CUR and CUR all effectively inhibited cell viability and colony formation (HA-Zein-CUR > PC-Zein-CUR > GA-Zein-CUR/CUR). HA-Zein-CUR and PC-Zein-CUR also resulted in significantly higher cellular uptake of CUR than GA-Zein-CUR and CUR. Simulated GI-digestion assay demonstrated significantly improved controlled-release properties of these two formulations. Further pharmacokinetics and tissue distribution assays in a CRC subcutaneous xenograft model in nude mice corroborated the enhanced pharmacokinetic properties of intragastric administration of HA-Zein-CUR compared with that of free CUR (3 times higher Cmax and 9.18 times higher plasma AUC). HA-Zein-CUR also led to enhanced delivery and accumulation of CUR in major organs/tissues, in particular CRC tumors and colon. These results together support that HA-Zein-CUR has promising potential as an oral agent for the control of CRC.

Composition and yield of non-cellulosic and cellulosic sugars in soluble and particulate fractions during consolidated bioprocessing of poplar biomass by Clostridium thermocellum

BackgroundTerrestrial plant biomass is the primary renewable carbon feedstock for enabling transition to a sustainable bioeconomy. Consolidated bioprocessing (CBP) by the cellulolytic thermophile Clostridium thermocellum offers a single step microbial platform for production of biofuels and biochemicals via simultaneous solubilization of carbohydrates from lignocellulosic biomass and conversion to products. Here, solubilization of cell wall cellulosic, hemicellulosic, and pectic polysaccharides in the liquor and solid residues generated during CBP of poplar biomass by C. thermocellum was analyzed.ResultsThe total amount of biomass solubilized in the C. thermocellum DSM1313 fermentation platform was 5.8, 10.3, and 13.7% of milled non-pretreated poplar after 24, 48, and 120 h, respectively. These results demonstrate solubilization of 24% cellulose and 17% non-cellulosic sugars after 120 h, consistent with prior reports. The net solubilization of non-cellulosic sugars by C. thermocellum (after correcting for the uninoculated control fermentations) was 13 to 36% of arabinose (Ara), xylose (Xyl), galactose (Gal), mannose (Man), and glucose (Glc); and 15% and 3% of fucose and glucuronic acid, respectively. No rhamnose was solubilized and 71% of the galacturonic acid (GalA) was solubilized. These results indicate that C. thermocellum may be selective for the types and/or rate of solubilization of the non-cellulosic wall polymers. Xyl, Man, and Glc were found to accumulate in the fermentation liquor at levels greater than in uninoculated control fermentations, whereas Ara and Gal did not accumulate, suggesting that C. thermocellum solubilizes both hemicelluloses and pectins but utilizes them differently. After five days of fermentation, the relative amount of Rha in the solid residues increased 21% indicating that the Rha-containing polymer rhamnogalacturonan I (RG-I) was not effectively solubilized by C. thermocellum CBP, a result confirmed by immunoassays. Comparison of the sugars in the liquor versus solid residue showed that C. thermocellum solubilized hemicellulosic xylan and mannan, but did not fully utilize them, solubilized and appeared to utilize pectic homogalacturonan, and did not solubilize RG-I.ConclusionsThe significant relative increase in RG-I in poplar solid residues following CBP indicates that C. thermocellum did not solubilize RG-I. These results support the hypothesis that this pectic glycan may be one barrier for efficient solubilization of poplar by C. thermocellum.

The Class II KNOX family members KNAT3 and KNAT7 redundantly participate in Arabidopsis seed coat mucilage biosynthesis.

The production of Arabidopsis seed mucilage involves complex polysaccharide biosynthetic pathways and developmental processes in seed epidermal cells. Although the polysaccharide components of Arabidopsis seed mucilage have been identified, their regulatory mechanism requires further investigation. Here, we show that Class II KNOX gene family members KNAT3 and KNAT7 play an essential role in regulating mucilage production in the early developmental stages of Arabidopsis seeds. Double mutant knat3knat7 resulted in defective seed mucilage production and columellae formation, whereas knat3 showed a normal phenotype compared with wild type, and the mucilage thickness in knat7 was slightly disturbed. Rhamnogalacturonan I (RG-I) and its biosynthetic substrates galacturonic acid and rhamnose were reduced in both the adherent and soluble mucilage of knat3knat7. Comparative transcriptome analysis on whole seeds suggested that polysaccharide, glucosinolate and anthocyanin biosynthetic pathways were specifically repressed in knat3knat7. Transient co-expression of KNAT3 and KNAT7 with promoter regions of candidate genes in Arabidopsis protoplasts revealed that both KNAT3 and KNAT7 act as positive regulators of the RG-I biosynthetic gene MUCILAGE-MODIFIED 4 (MUM4, AT1G53500). Collectively, our results demonstrate that KNAT3 and KNAT7 are multifunctional transcription factors in secondary cell wall development and redundantly modulate mucilage biosynthesis in Arabidopsis seeds.

Fabrication of rhamnogalacturonan-I enriched pectin-based emulsion gels for protection and sustained release of curcumin

Rhamnogalacturonan-I (RG-I) was considered to be incompatible with gel formation. Due to its important health benefits, our previous study reported synergistic gelation of RG-I enriched pectin from citrus membranes with sequential acidic and alkaline treatment. In the present study, we further fabricated RG-I enriched pectin-based emulsion gels with the synergistic gelation for hydrophobic bioactive encapsulation. The effect of oil fraction and interfacial compositions including pectin itself and Tween 20 on the physical properties and delivery characteristics of emulsion gels was investigated. As to interfacial compositions, pectin reduced syneresis and swelling ratio and increased water holding capacity. Oil fraction had no marked influence on syneresis and swelling ratio, but significantly increased water holding capacity. Particularly, all the emulsion gels showed an elastic behavior and a full structure recovery after shearing. Increase in pectin instead of Tween 20 onto the surface of oil droplets and oil fraction markedly improved their gel strength. Curcumin was encapsulated within the oil phase of emulsion gels. Improvement in gel strength provided enhanced protection of curcumin against heat-induced degradation. In vitro digestion revealed that interfacial compositions decelerated curcumin release by increasing the proportion of pectin onto the surface, but didn't change its bioaccessibility eventually. Increase in oil fraction accelerated curcumin release, but reduced its bioaccessibility. Overall, fabrication of RG-I enriched pectin-based emulsion gel with pectin itself as interfacial composition and low oil fraction would contribute to improving curcumin bioavailability for its sustained release, which should be further validated in vivo.

Hydrogen bonds to balance mechanical and adhesive properties of pectin/polyacrylic acid blends as efficient binders for cathode in lithium-sulfur battery

Although lithium-sulfur (Li-S) batteries have attracted great interest due to the high energy density and low cost of sulfur, practical applications are still in demand due to various adverse processes leading to rapid capacity decay and poor cycle stability. In this study, polyacrylic acid (PAA) was hydrogen bonded (H bonded) to different proportions of pectin (PEC), to result in PAA/PEC(x) (x: wt% of PEC; = 14.4, 28.8 and 57.6) blend binders for sulfur-coated polypyrrole (PPy) (as S@PPy), rendering S@PPy/PAA/PEC(x) cathodes with their performance dependent on the PEC content in the binders. For PAA/PEC(x) binders, extent of H bond interactions can be adjusted by varying the blend composition, through which mechanical robustness and adhesive force can be balanced to obtain a superior binder with desired properties. The balanced mechanical and adhesive properties of PAA/PEC (28.8) make it the best binder, superior to PAA/PEC (14.4) and PAA/PEC (57.6), which can be integrated into a sulfur cathode exhibiting a high capacity of 831 mAh g−1 at 0.2 C after 100 cycles. Therefore, the inter-relationships between binder’s composition, H bond interaction, mechanical and adhesive properties of the binders and the electrochemical performance of the cathode are the focuses of this research.

Chemical elucidation and rheological properties of a pectic polysaccharide extracted from Citrus medica L. fruit residues by gradient ethanol precipitation.

Citron (Citrus. medica L.) fruits are commonly utilized in the production of essential oil, therefore, the fruits residues turn out to be industrial byproducts. In the present study, a crude polysaccharide was extracted from citron fruit residues by hot water extraction and precipitation of ethanol (95%), after deproteinization, a major polysaccharide component (CMLP-2) was obtained by gradient ethanol precipitation (20%-80%). The physicochemical properties of CMLP-2 such as surface morphology, functional groups, and thermostability were examined by FT-IR spectroscopy, SEM, and thermogravimetric analysis. Moreover, the chemical structure of CMLP-2 was elucidated that CMLP-2 is an acidic pectic polysaccharide consisting of arabinose (Ara), galacturonic acid (GalA), and rhamnose (Rha) in a molar ratio of 4:2:1 with a molecular weight of 202.18kDa. CMLP-2 is a novel pectic polysaccharide rich in rhamnogalacturonan I (RG-I). Moreover, rheological tests revealed that CMLP-2 solution is pseudoplastic and temperature resistant. The result could be a good basis for the utilization of Citrus medica L. fruits residues as plant-derived food additive.