Structure characterization and gelling properties of RG-I-enriched pectins extracted from citrus peels using four different methods.

To facilitate the application of rhamnogalacturonan-I (RG-I)-enriched pectins (RGPs) as novel, healthy, and gelling food additives, this study compared the structural characteristics and gelling properties of RGPs extracted from citrus peel via four methods (alkali: AK, high-temperature/pressure: TP, citric acid: CA, and enzyme-assisted: EA extractions). AK and CA yielded pectins with the highest RG-I proportions (54.8 % and 51.9 %, respectively) by disrupting the homogalacturonan region; TP and EA increased the RG-I proportions by ~10 %. Among the four methods, AK induced the lowest degree of esterification (DE) (6.7 %) and longer side chains that form strong entanglement, contributing to its highest gel hardness. The relatively low DE (18.5 %) of CA RGP facilitated stable gel formation. Notably, its highly branched RG-I region afforded more intramolecular hydrophobic interactions, making a more highly cross-linked gel network of better gel resilience. In contrast, TP induced the highest DE (57 %) and curved molecular chains; it inhibited Ca2+ binding, entanglement, and intramolecular hydrophobic interactions, and thus no gel formed. EA RGP was associated with the lowest molecular size, rendering it more difficult for Ca2+ to form links, which resulted no gel. These findings offer insights into the relationship among the extraction methods, molecular structures, and gelling properties of RGPs.

Characterization of a novel sulfated-rhamnoglucuronan isolated from Korean seaweed Ulva pertusa and its efficacy for treatment of inflammatory bowel disease in mice.

This study aimed to isolate Ulva pertusa polysaccharide (UPP), which elicits anti-inflammatory bowel disease (IBD) effects, from the Korea seaweed U. pertusa and identify its structure. Firstly, UPP was isolated from U. pertusa using hydrothermal extraction and ethanol precipitation. UPP is a novel polysaccharide that exhibits unique structural features such as 3-sulfated rhamnose, glucuronic acid, iduronic acid, and 3-sulfated xylose, which are repeated in 1,4-glycosidic bonds. Prophylactic oral administration of UPP in mice with dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) suppressed the levels of inflammatory cytokines and MAPK- and NF-κB-related factors in the serum and colon tissue. Tight junction (TJ)-related factors such as occludin, claudin-1, and mucin were effectively augmented by UPP in the colon tissue. In addition, UPP administration prevented the DSS treatment-led cecal short chain fatty acid imbalance, and this effect was most evident for propionic acid. In conclusion, UPP isolated from the Korean U. pertusa demonstrates potent anti-IBD activity. Characterization of this ulvan revealed its unique structure. Moreover, its efficacy may be associated with its anti-inflammatory effects and regulation of gut microbiota and TJ proteins. Thus, this study provides new insights into the biological effects of UPP in IBD.

Arabinoxylo-oligosaccharides production from unexploited agro-industrial sesame (Sesamum indicum L.) hulls waste.

This work demonstrates that sesame (Sesamum indicum L.) hull, an unexploited food industrial waste, can be used as an efficient source for the extraction of hemicellulose and/or pectin polysaccharides to further obtain functional oligosaccharides. Different polysaccharides extraction methods were surveyed including alkaline and several enzymatic treatments. Based on the enzymatic release of xylose, arabinose, glucose, and galacturonic acid from sesame hull by using different enzymes, Celluclast®1.5 L, Pectinex®Ultra SP-L, and a combination of them were selected for the enzymatic extraction of polysaccharides at 50 °C, pH 5 up to 24 h. Once the polysaccharides were extracted, Ultraflo®L was selected to produce arabinoxylo-oligosaccharides (AXOS) at 40 °C up to 24 h. Apart from oligosaccharides production from extracted polysaccharides, alternative approaches for obtaining oligosaccharides were also explored. These were based on the analysis of the supernatants resulting from the polysaccharide extraction, alongside a sequential hydrolysis performed with Celluclast®1.5 L and Ultraflo®L of the starting raw sesame hull. The different fractions obtained were comprehensively characterized by determining low molecular weight carbohydrates and monomeric compositions, average Mw and dispersity, and oligosaccharide structure by MALDI-TOF-MS. The results indicated that sesame hull can be a useful source for polysaccharides extraction (pectin and hemicellulose) and derived oligosaccharides, especially AXOS.

Effect of Organic Acid-Aided Extraction on Characteristics and Functional Properties of Pectin from Cannabis sativa L.

The extraction of cannabinoids from the inflorescence and leaves of Cannabis sativa L. is gaining interest from researchers, in addition to addressing the under-utilization of the by-products in the stems and roots of the trees. The present study investigated the recovery of pectin from the left-over parts of hemp tress using an eco-friendly method with the aid of organic acids. Different cannabis cultivars-Chalotte's Angels (CHA) and Hang-Krarog (HKR)-were used as plant materials. The stems of both cannabis cultivars contained more pectin than the roots, and tartaric acid-aided extraction provided higher yields than from citric acid. Extracting the acid solution affected some characteristics, thereby differentiating the functional properties of the derived pectin. Extraction using tartaric acid provided pectin with a higher galacturonic acid content, whereas pectin with a higher methylation degree could be prepared using citric acid. The pectin samples extracted from the stems of CHA (P-CHA) and HKR (P-HKR) had low methoxyl pectin. P-CHA had better free radical scavenging capability, whereas P-HKR showed more potent reducibility. Considering the functional properties, P-CHA showed greater emulsion formability and foaming activity, whereas P-HKR possessed a better thickening effect. The present work suggests the feasible utilization of P-CHA and P-HKR as food additives with bioactivity.

Extraction and characterization of pectin from coffee (Coffea arabica L.) pulp obtained from four different coffee producing regions.

The pectin was extracted using H2SO4, HNO3, and HCl from the pulp of four coffee varieties (Harar, Sidama, Jimma, and Guji) collected from different regions of Ethiopia. The effect of extraction temperature, time, solid-to-liquid ratio, types of acid and coffee varieties on the physiochemical properties and yield of pectin were studied. A maximum pectin yield, which was 12.7 %, was obtained from Harar coffee pulp treated with H2SO4. The equivalent weight of the extracted pectin varied from 1111 to 1667 g/mol. The methoxyl contents of the extracted pectin ranged from 4.23 to 7.13 %. The degrees of esterification and anhydrouronic acid of the pectin ranged from 53 to 68.5 % and 35.5 to 68.8 %, respectively. The results show the yield and physiochemical properties of the coffee pulp pectin depend on extraction parameters, acid types, and coffee varieties. Moreover, the pectin extracted from coffee pulp showed strong gelling properties.

Extraction of Heracleum dissectum soluble dietary fiber by different methods: Structure and antioxidant properties.

Heracleum dissectum is rich in nutrients, but there is little research on its soluble dietary fiber (SDF). In this study, SDF from H. dissectum was extracted by enzyme extraction (E-SDF), enzyme chemical extraction (EC-SDF), and fermentation extraction (F-SDF). The composition, molecular weight (Mw), structural characterization, and antioxidant activity of SDF extracted by the three methods were compared. This study showed that different extraction methods lead to differences in their structure. The Mw results showed that F-SDF had the largest Mw, the structure of SDF could be destroyed by enzymatic hydrolysis, and large molecules could be converted into small molecules. The monosaccharide composition analysis showed that the main sugars of E-SDF, EC-SDF, and F-SDF were galacturonic acid and galactose, and the main components of the three SDF samples were hemicellulose hydrolyzed pectin and soluble polysaccharide. Notably, E-SDF had the greatest antioxidant effect at the same concentration. In summary, different extraction methods can affect the structure and antioxidant capacity of H. dissectum SDF, among which E-SDF has potential as a functional food ingredient.

Extraction of cellulose from halophytic plants for the synthesis of a novel biocomposite.

Cellulose nanofibers, a sustainable and promising material with widespread applications, exhibit appreciable strength and excellent mechanical and physicochemical properties. The preparation of cellulosic nanofibers from food or agricultural residue is not sustainable. Therefore, this study was designed to use three halophytic plants (Cressa cretica, Phragmites karka, and Suaeda fruticosa) to extract cellulose for the subsequent conversion to cellulosic nanofibers composites. The other extracted biomass components including lignin, hemicellulose, and pectin were also utilized to obtain industrially valuable enzymes. The maximum pectinase (31.56 IU mL-1), xylanase (35.21 IU mL-1), and laccase (15.89 IU mL-1) were produced after the fermentation of extracted pectin, hemicellulose, and lignin from S. fruticosa, P. karka, and C. cretica, respectively. Cellulose was methylated (with a degree of substitution of 2.4) and subsequently converted into a composite using polyvinyl alcohol. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed the successful synthesis of the composites. The composites made up of cellulose from C. cretica and S. fruticosa had a high tensile strength (21.5 and 15.2 MPa) and low biodegradability (47.58% and 44.56%, respectively) after dumping for 3 months in soil, as compared with the composite from P. karka (98.79% biodegradability and 4.9 MPa tensile strength). Moreover, all the composites exhibited antibacterial activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and gram-positive bacteria (Staphylococcus aureus). Hence, this study emphasizes the possibility for various industrial applications of biomass from halophytic plants.

RG-I pectin-like polysaccharide from Rosa chinensis inhibits inflammation and fibrosis associated to HMGB1/TLR4/NF-κB signaling pathway to improve non-alcoholic steatohepatitis.

A novel RG-I pectin-like polysaccharide, YJ3A1, was purified from the flowers of Rosa chinensis and its structure and hepatoprotective effect in vivo and in vitro were investigated. The backbone of this polysaccharide is mainly composed of 1, 4-galactan, 1, 4-linked α-GalpA and 1, 2-linked α-Rhap disaccharide repeating unit attached by 1, 6-linked ß-Galp or 1, 5-linked α-Araf on C-4 of the Rhap. Interestingly, oral administration of YJ3A1 significantly ameliorates NASH-associated inflammation, oxidative stress and fibrosis and does not affect the liver morphology of normal mice at a dose of 50 mg/kg. The mechanism study suggests that the biological activity may associate to inactivating of high-mobility group box 1 protein (HMGB1)/TLR4/NF-κB and Akt signaling pathways by restraining the expression and release of HMGB1, thereby impeding the effect of NASH. The current findings outline a novel leading polysaccharide for new drug candidate development against NASH.

The effect of ultrasonic power on the physicochemical properties and antioxidant activities of frosted figs pectin.

Ultrasound has been widely used in industry due to its high energy and efficiency. This study optimized the ultrasonic-assisted extraction (UAE) process of frosted figs pectin (FFP) using response surface methodology (RSM), and further investigated the effect of ultrasonic power on the structural characteristics and antioxidant activities of FFPs. The UAE method of FFP through RSM was optimized, and the optimal extraction process conditions, particle size of 100 mesh, pH value of 1.95, liquid-solid ratio of 47:1 (mL/g), extraction temperature of 50 °C and extraction time of 65 min, were obtained. The extraction rate of FFP under this condition was 37.97 ± 2.56 %. Then, the four FFPs modified by ultrasound were obtained by changing the ultrasonic power. Research had found that ultrasonic power had little effect on the monosaccharide composition, Zeta potential, as well as the thermal stability and appearance structure of the four FFPs. However, ultrasonic power had a significant impact on other properties of FFP: as the ultrasonic power increased, the DM% and particle size decreased continuously, while the total carbohydrate content increased. Meanwhile, ultrasonic power also had a significant impact on antioxidant activities of FFPs. From the research results, it could be seen that different ultrasonic power had certain changes in its spatial structure and properties, and the structural changes also affected the biological activity of FFP. The study of the effects of ultrasonic power on the physicochemical properties and biological activity of FFP lays the foundation for the development and application of FFP in food additives and natural drug carriers.

Physicochemical and antioxidant properties of pectin fractions extracted from lemon (Citrus Eureka) peels.

Pectin, a natural polysaccharide, holds versatile applications in food and pharmaceuticals. However, there is a need for further exploration into extracting novel functional fractions and characterizing them thoroughly. In this study, a sequential extraction approach was used to obtain three distinct lemon pectin (LP) fractions from lemon peels (Citrus Eureka): LP extracted with sodium acetate (LP-SA), LP extracted with ethylenediaminetetraacetic acid (LP-EDTA), and LP extracted with sodium carbonate and sodium borohydride (LP-SS). Comprehensive analysis revealed low methyl-esterification in all fractions. LP-SA and LP-SS displayed characteristics of rhamnogalacturonan-I type pectin, while LP-EDTA mainly consisted of homogalacturonan pectin. Notably, LP-SA formed self-aggregated particles with rough surfaces, LP-EDTA showed interlocking linear structures with smooth planes, and LP-SS exhibited branch chain structures with smooth surfaces. Bioactivity analysis indicated that LP-SA had significant apparent viscosity and ABTS radical scavenging activity, while both LP-EDTA and LP-SS showed excellent thermal stability according to thermogravimetric analysis (TGA). Furthermore, LP-SS exhibited remarkable gel-forming ability and significant hydroxyl free radicals scavenging activity. In conclusion, this study presents a novel method for extracting various lemon pectin fractions with unique structural and bioactive properties, contributing insights for advanced applications in the food and pharmaceutical sectors.

Structural identification and anti-neuroinflammatory effects of a pectin-arabinoglucuronogalactan complex, AOPB-1-1, isolated from Asparagus officinalis.

Asparagus officinalis L. is a horticultural crop that contains a variety of bioactive compounds with anti-inflammatory effects. Aqueous extracts of A. officinalis can noticeably improve the learning and memory function of model mice. Herein, a pectin-arabinoglucuronogalactan complex (AOPB-1-1) with a relative molecular weight of 90.8 kDa was isolated from A. officinalis. The repeating structural unit of AOPB-1-1 was identified through monosaccharide composition, methylation analysis, uronic acid reduction, partial acid hydrolysis, and nuclear magnetic resonance spectroscopy. AOPB-1-1 contains the rhamnogalacturonan-I (RG-I) domain of pectin polysaccharides (PPs) and arabinoglucuronogalactan (AGG) regions. The backbone of the AGG region is composed of →3,6)-ß-D-Galp-(1→ and →4)-ß-D-Glcp-(1→ residues substituted at the 4-position to the →4)-α-D-GalAp-(1→ residues of the RG-I main chain. The anti-neuroinflammatory activity of AOPB-1-1 suggests that it can significantly reduce the content of inflammatory cytokines, including nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) and inhibit the expression of inflammatory genes including cyclooxygenase-2 (COX2), nitric oxide synthase (iNOS), TNF-α, IL-6, and interleukin-1ß (IL-1ß) in LPS-stimulated BV2 cells. Furthermore, its inhibitory effects on TNF-α and IL-6 levels were even better than those of minocycline. The significant anti-neuroinflammatory activity of AOPB-1-1 suggests its applicability as a therapeutic option for the treatment of Alzheimer's disease.

Differences in physicochemical properties of pectin extracted from pomelo peel with different extraction techniques.

In order to obtain high yield pomelo peel pectin with better physicochemical properties, four pectin extraction methods, including hot acid extraction (HAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction, and enzymatic assisted extraction (EAE) were compared. MAE led to the highest pectin yield (20.43%), and the lowest pectin recovery was found for EAE (11.94%). The physicochemical properties of pomelo peel pectin obtained by different methods were also significantly different. Pectin samples obtained by MAE had the highest methoxyl content (8.35%), galacturonic acid content (71.36%), and showed a higher apparent viscosity, thermal and emulsion stability. The pectin extracted by EAE showed the highest total phenolic content (12.86%) and lowest particle size (843.69 nm), showing higher DPPH and ABTS scavenging activities than other extract methods. The pectin extracted by HAE had the highest particle size (966.12 nm) and degree of esterification (55.67%). However, Fourier-transform infrared spectroscopy showed that no significant difference occurred among the different methods in the chemical structure of the extracted pectin. This study provides a theoretical basis for the industrial production of pomelo peel pectin.

Optimization of ultrasound-assisted pectin recovery from cocoa by-products using response surface methodology.

BACKGROUND: This study aimed to address the significant challenges associated with agricultural and cocoa waste disposal within the context of global food waste concerns. The magnitude of global food waste is staggering, estimated at 1.6 Gt of primary product equivalents, with 1.3 Gt attributed specifically to the edible parts of food. Focusing on cocoa waste, which constitutes around 80% of total cocoa production, management poses a considerable environmental challenge, with over 60% of this waste either burnt or left to rot in plantations. METHOD: Ultrasound-assisted extraction of pectin from cocoa pulp mucilage (CPM), cocoa pod husk (CPH), and cocoa bean shell (CBS) was achieved with a central composite design (CCD) using response surface methodology (RSM). RESULTS: Ultrasound-assisted extraction takes into consideration independent factors such as temperature, sonication time, pH, solid-liquid ratio, and ultrasonic power intensity. This study achieved the highest yield, anhydrouronic acid content, and degree of esterification under optimum conditions - sonication time of 20 min, pH of 2.5, solid-solvent ratio of 1:40 g mL-1, and ultrasonic power intensity of 64 W cm-2. The composition and characterization of pectin showed that its anhydrouronic acid content was 68.59 ± 0.2% when extracted from CPH, 50.7 ± 0.5% when extracted from CBS, and 43.97 ± 0.17% when extracted from CPM with citric acid. CONCLUSION: This study underscored the potential to reduce the environmental impact of cocoa waste, offering improved pectin extraction and sustainable methods for handling agricultural by-products. It is relevant for individuals interested in waste reduction and resource efficiency within the broader agricultural industry, showcasing the potential for practical and sustainable solutions in cocoa waste management. © 2024 Society of Chemical Industry.

Evaluation of citrus pectin extraction methods: Synergistic enhancement of pectin's antioxidant capacity and gel properties through combined use of organic acids, ultrasonication, and microwaves.

The biological potency of pectin is intricately intertwined with its intricate molecular architecture. The fine structure of pectin is influenced by the extraction method, while the specific impact of these methods on the fine structure and the affected attributes thereof remains enigmatic. This study delves into the profound analysis of eight distinct extraction methods influence on the structure and biological activity of citrus peel pectin. The findings demonstrate that citric acid ultrasound-assisted microwave extraction yields pectin (PectinCA-US/MV) with higher viscosity and a dense, rigid chain. Pectin extracted with acetic acid ultrasound (PectinAA-US) and citric acid ultrasound (PectinCA-US) exhibits elevated galacturonic acid (GalA) levels and reduced D-galactose (Gal) content, enhancing antioxidant activity. Eight pectin-chitosan (CS) hydrogels, especially PectinCA-US/MV-CS, demonstrate commendable thermal stability, rheological properties, self-healing capability, and swelling behavior. This study characterizes citrus peel pectin properties from different extraction methods, laying a foundation for its application in food, pharmaceuticals, and industry.

Deep eutectic solvent (DES)-assisted extraction of pectin from Ficus carica Linn. peel: optimization, partial structure characterization, functional and antioxidant activities.

BACKGROUND: The pectin from Ficus carica Linn. (fig) peels is a valuable and recyclable constituent that may bring huge economic benefits. To maximize the utilization of this resource, deep eutectic solvent (DES)-assisted extraction was applied to extract pectin from fig peels, and the extraction process was optimized with response surface methodology. RESULTS: When DES (choline chloride/oxalic acid = 1:1) content was 168.1 g kg-1, extraction temperature was 79.8 °C, liquid-solid ratio was 23.3 mL g-1, and extraction time was 120 min, the maximum yield of 239.6 g kg-1 was obtained, which was almost twice the extraction of hot water. DES-extracted fig peel pectin (D-FP) exhibited better nature than hot water-extracted fig peel pectin (W-FP) in terms of uronic acid content, particle size distribution, and solubility, but lower molecular weight and esterification degree. D-FP and W-FP had similar infrared spectra and thermodynamic peaks but differed in monosaccharide compositions. D-FP also showed good antioxidant capacities and exhibited better functional activities than W-FP. CONCLUSION: These results indicated that D-FP was of promising quality being utilized in food or medical industries and the optimal DES-assisted extraction method might be applied as a sustainable process for the effective extraction of bioactive pectin from fig peels with the excellence of low equipment requirements and simple operation. © 2024 Society of Chemical Industry.

Properties of cell wall polysaccharides of raw nectarine fruits after treatment under conditions that modulate gastric digestion.

The results of the study of the physicochemical properties of the high-molecular-weight soluble and insoluble components of nectarine cell walls obtained by fruit treatment under conditions that modulate of gastric digestion are presented. Homogenized nectarine fruits were sequentially treated by natural saliva and simulated gastric fluid (SGF) at pH 1.8 and 3.0. The isolated polysaccharides were compared with polysaccharides obtained by sequential extraction of nectarine fruit with cold, hot, and acidified water, solutions of ammonium oxalate and sodium carbonate. As a result, high-molecular-weight water-soluble pectic polysaccharides, weakly bound in the cell wall, were dissolved in the simulated gastric fluid, regardless of pH. Homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) were identified in all pectins. It was shown that their quantity and ability to form highly viscous solutions determine high values of the rheological characteristics of the nectarine mixture formed under simulated gastric conditions. The modifications occurring with the insoluble components under the influence of acidity of SGF were importance. They determined difference in the physicochemical properties of both the insoluble fibres and the nectarine mixtures.

Effect of Ultrasound-Assisted, Microwave-Assisted and Ultrasound-Microwave-Assisted Extraction on Pectin Extraction from Industrial Tomato Waste.

This work aimed to study the effect of ultrasound-assisted (UAE), microwave-assisted (MAE), and ultrasound-microwave-assisted (UMAE) methods for pectin extraction from industrial tomato waste. The overall performance index from the fuzzy analytical method with three criteria, pectin yield, galacturonic acid, and lycopene content, was applied to evaluate the best extraction conditions by using the weight of 75, 20, and 5, respectively. The UAE conditions was performed at a temperature of 80 °C for 20 min with the variations in the extraction pH and the solid liquid (SL) ratio. The best UAE conditions with high pectin yield, and high total carboxyl group, as well as a lycopene content, was the pH of 1.5 and the SL ratio of 1:30. The MAE conditions was performed with variations in the microwave powers and times. The results showed that the best MAE conditions were 300 W for 10 min, which gave high pectin yield with high galacturonic acid and lycopene content. Various conditions of UMAE at the best conditions of MAE and UAE were performed and exhibited that the UAE had more positively affected the pectin yield. However, the FTIR spectra of obtained pectins from different extraction techniques showed a similar pectin structure.

Physicochemical, structural and rheological properties of pectin isolated from citrus canning processing water.

In order to better utilize the citrus pectin (CP) resource, the crude citrus pectin (CCP), obtained from the citrus fruit canning processing waste water, was purified by cellulose DEAE-52 column, providing neutral polysaccharide CP0 and two acidic polysaccharides (CP1 and CP3). CP1 had the highest yield among the three fractions, being 44.29%. The chemical composition, structure and morphology of these pectin components were analyzed. Monosaccharide composition analysis revealed that arabinose was the most abundant composition in these pectin samples. CCP, CP1 and CP3 were mainly composed of rhamnogalacturonan-I (RG-I) regions. Compared with CP3, CCP and CP1 had longer side chains, which are mainly consisted of arabinose. FT-IR and NMR analysis indicated that α-type glycosidic bonds are the main linkage in the four pectin components. These CP samples were found to possess different conformation, but no triple-helical conformation was observed in all these CP fractions. Scanning electron microscopy revealed that CCP, CP1 and CP3 all had irregular sheet-like structures and partly porous structures. The four pectin components showed the characteristics of non-Newtonian fluids and possessed good viscoelasticity. Due to these properties, the pectin might have potential application in food industry as food thickening agent.

Extraction, characterization and spontaneous gelation mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds.

Nicandra physaloides (Linn.) Gaertn seeds (NPGS) could be manually scrubbed to obtain water-soluble pectin, which forms gel at room temperature without additives. The extraction, characterization and spontaneous gelation (SG) mechanism of the pectin were studied. The results showed that the pectin was located on the surface of NPGS and easily to be dissolved. Chemically, the pectin was low methoxy pectin with esterification degree of 46.93%, Gal-A content of 65.80%, and average molar weight of 631.15 kDa. The SG occurred at the pectin concentration of 1.5%, it can be destroyed by urea and SDS, however, EDTA cannot. In addition, KCl and NaCl induced the gelation of 1.0% pectin solution and the ions of K, Mg, Ca and Na were detected in the pectin. Hydrogen bonding, electrostatic and hydrophobic interaction contributed to the SG. This study could promote the commercial applications of the pectin in the field of edible colloids and cosmetics.

Isolation, Chemical Characterization and Antioxidant Activity of Pectic Polysaccharides of Fireweed (Epilobium angustifolium L.).

The aim of this study was to isolate pectins with antioxidant activity from the leaves of Epilobium angustifolium L. Two pectins, EA-4.0 and EA-0.8, with galacturonic acid contents of 88 and 91% were isolated from the leaves of E. angustifolium L. by the treatment of plant raw materials with aqueous hydrochloric acid at pH 4.0 and 0.8, respectively. EA-4.0 and EA-0.8 were found to scavenge the DPPH radical in a concentration-dependent manner at 17-133 µg/mL, whereas commercial apple pectin scavenged at 0.5-2 mg/mL. The antioxidant activity of EA-4.0 was the highest and exceeded the activity of EA-0.8 and a commercial apple pectin by 2 and 39 times (IC50-0.050, 0.109 and 1.961 mg/mL), respectively. Pectins EA-4.0 and EA-0.8 were found to possess superoxide radical scavenging activity, with IC50s equal to 0.27 and 0.97 mg/mL, respectively. Correlation analysis of the composition and activity of 32 polysaccharide fractions obtained by enzyme hydrolysis and anionic exchange chromatography revealed that the antioxidant capacity of fireweed pectins is mainly due to phenolics and is partially associated with xylogalacturonan chains. The data obtained demonstrate that pectic polysaccharides appeared to be bioactive components of fireweed leaves with high antioxidant activity, which depend on pH at their extraction.