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

Abstract

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.

Polysaccharides of Salsola passerina: Extraction, Structural Characterization and Antioxidant Activity

“…Thus, the correlation analysis showed that the DPPH scavenging activity of the sample from S. passerine is associated with the content of PCs. This is consistent with the results of Ref [ 54 ], whose authors evaluated the activity of apple pectins, and our previous study on fireweed pectins [ 56 ]. It is known that PCs may bind covalently to the side chains of RG I through the Ara and Gal residues and may be involved in the cross-linking of macromolecules [ 60 ].…”

“…It should be noted that some other polysaccharides demonstrated the same level of DPPH scavenging activity at lower concentrations. These include pectins from Chaenomeles sinensis fruits [ 55 ], Epilobium angustifolium L. [ 56 ], Thymus quinquecostatus Celak. leaves [ 57 ], Gardenia jasminoides J. Ellis flowers [ 58 ] and Ziziphus jujuba cv.…”

“…Several authors suggest that the antioxidant activity of pectins may be due to the hydroxyl and carboxyl groups of GalA residues [ 52 , 61 ]. Previously, we showed that the antioxidant activity of fireweed pectins is partly related to the xylogalacturonan chains [ 56 ]. However, in the present study, we failed to find the polysaccharide chains responsible for the DPPH radical scavenging activity of Salsola pectins.…”

Enrichment of Agar Gel with Antioxidant Pectin from Fireweed: Mechanical and Rheological Properties, Simulated Digestibility, and Oral Processing

“…The results demonstrated that FP was efficiently incorporated into A gel by the method used. The efficiency of loading of pectin-associated PCs into agar gel was calculated to be equal to 78–97% as the total phenolic content in FP was earlier determined to be as much as 27 mg GAE/g [ 20 ].…”

“…LMP possessing antioxidant activity higher than commercial apple pectin has previously isolated from leaves of fireweed (Epilobium angustifolium L.) [ 20 ]. Fireweed pectin (FP) fractions scavenge 1,1-diphenyl-2-picrylhydrazyl- and superoxide radicals in vitro depending on the content of associated PCs [ 20 ]. In the present study, we assumed that incorporating FP into the agar gel would make it possible to obtain a mixed food gel with antioxidant activity.…”