scholarly journals Gallic Acid-Dextran Conjugate: Green Synthesis of a Novel Antioxidant Molecule

Antioxidants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 478
Author(s):  
Moacir Fernandes Queiroz ◽  
Diego Araujo Sabry ◽  
Guilherme Lanzi Sassaki ◽  
Hugo Alexandre Oliveira Rocha ◽  
Leandro Silva Costa
Keyword(s):  
Gallic Acid ◽  
High Performance ◽  
Superoxide Radical ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Size Exclusion ◽  
Exclusion Chromatography ◽  
Total Antioxidant ◽  
Potential Applications ◽  
A Minor

A novel derivative of dextran, dextran–gallic acid (Dex–Gal), obtained from simple conjugation with gallic acid, was synthesized by an efficient free radical-mediated method. To verify the synthesis of Dex–Gal, 1H-nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FTIR) spectrometry, and high-performance size-exclusion chromatography (HPSEC) were employed. The results revealed the conjugation of gallic acid with the 15.5 kDa dextran from Leuconostoc mesenteroides. Dex–Gal had a molecular weight of 11.2 kDa, indicating that the conjugation reaction was accompanied by a minor degradation of Dex–Gal. In addition, Dex–Gal contained 36.8 ± 1.4 mg gallic acid per gram dextran. These molecules were also evaluated as antioxidants using total antioxidant capacity (TAC), reducing power, ferric chelation, and superoxide radical-scavenging assays. Both polysaccharides had no ferric chelation activity. In addition, Dex–Gal was more efficient as an antioxidant agent in TAC (13 times) and was more efficient than dextran in superoxide radical-scavenging (60 times) and reducing power (90 times) assays. These data demonstrate that Dex–Gal is a natural-compound-based antioxidant with potential applications in the pharmaceutical, cosmetic, and food industries.

scholarly journals Synthesis, Characterization, and Antioxidant Activity of 8-Hydroxygenistein

2020 ◽  
Vol 15 (1) ◽  
pp. 1934578X2090139 ◽  
Author(s):  
Jin Shao ◽  
Tong Zhao ◽  
Hui-Ping Ma ◽  
Zheng-Ping Jia ◽  
Lin-Lin Jing
Keyword(s):  
Antioxidant Activity ◽  
High Performance ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Positive Control ◽  
Raw Material ◽  
Biochanin A ◽  
Total Antioxidant Activity ◽  
Nitric Oxide Radical ◽  
Total Antioxidant

It was reported that 8-hydroxygenistein (8-OHG) was synthesized by methylation, bromination, methoxylation, and demethylation using cheap and readily available biochanin A as raw material. All synthesized products were structurally confirmed by ultra-high-performance liquid chromatography (UHPLC), infrared spectroscopy, mass spectrometry, 1H-nuclear magnetic resonance (NMR), and 13C-NMR. In addition, we examined the antioxidant capacity of 8-OHG using 6 different methods such as 1,1-diphenyl-2-picrylhydrazyl radical scavenging, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS) scavenging, nitric oxide radical (NO) scavenging, superoxide radical (O2 −•) scavenging, reducing power assay, and total antioxidant activity using ascorbic acid (VC) as a positive control. Compared with VC, 8-OHG exhibited higher total antioxidant activity and stronger scavenging activity on ABTS, NO, and O2 −•. These results indicate that 8-OHG is an excellent antioxidant agent and may be effective in preventing damage induced by free radical.

scholarly journals DETERMINATION OF ANTIOXIDANT CAPACITY AND GALLIC ACID CONTENT IN ETHANOLIC EXTRACT OF PUNICA GRANATUM L. LEAF

2018 ◽  
Vol 11 (4) ◽  
pp. 319
Author(s):  
Sreedevi P ◽  
Vijayalakshmi K
Keyword(s):  
Gallic Acid ◽  
High Performance ◽  
Research Work ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Ethanolic Extract ◽  
Punica Granatum ◽  
Hplc Method ◽  
Ic50 Values

 Objective: The present research work was carried out to evaluate the antioxidant potential of ethanolic extract of Punica granatum leaf (EPGL) that belongs to the family of Punicaceae and determine its gallic acid (GA) content using chromatography method.Methods: Six complementary test systems, namely, 1,1-diphenyl 2-picryl hydrazine (DPPH), hydrogen peroxide (H2O2), superoxide (SO), nitric oxide (NO), hydroxyl (OH) radical scavenging, and reducing power activities were analyzed for determining antioxidant activity of EPGL. The simple and novel chromatography techniques such as thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) were used for the detection and quantification of GA in EPGL.Results: IC50 values of EPGL were found to be 136 μg/ml for DPPH, 88.5 μg/ml for H2O2, 16.8 μg/ml for SO, 96.5 μg/ml for NO, and 143 μg/ml for OH. The ascorbic acid (AA) and GA were used as standard compounds. The absorbance of EPGL in reducing power assay was found to be 0.18 at 100 μg/ ml, while AA and GA absorbance was found to be 0.24 and 0.4 at the same concentration. The amount of GA in EPGL was found to be 1.189 mg/g.Conclusion: These findings suggested that EPGL could be a potential source of natural antioxidant, and HPLC method used for the determination of GA is simple, precise, accurate, and suitable for routine analysis of GA in EPGL.

Effect of different catalysts on the oxyalkylation of eucalyptus Lignoboost® kraft lignin

Holzforschung ◽  
2020 ◽  
Vol 74 (6) ◽  
pp. 567-576 ◽  
Author(s):  
Fernanda R. Vieira ◽  
Ana Barros-Timmons ◽  
Dmitry V. Evtuguin ◽  
Paula C. R. Pinto
Keyword(s):  
High Performance ◽  
Black Liquor ◽  
Kraft Lignin ◽  
Degree Of Polymerization ◽  
Kraft Pulping ◽  
Size Exclusion ◽  
Safe Procedure ◽  
Oh Groups ◽  
Exclusion Chromatography ◽  
A Minor

AbstractLignin obtained by Lignoboost® procedure from black liquor after kraft pulping of Eucalyptus globulus wood was characterized and converted into liquid polyols via an innovative and safe procedure using base catalyzed oxyalkylation with propylene carbonate (PC). The effect of four catalysts, Potassium carbonate (K2CO3), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU), dicyanodiamide (DICY), and 1,4-diazabicyclo [2.2.2] octane (DABCO) was evaluated in terms of lignin polyol yield and weight gain. The ensuing polyols were also characterized by fourier transform infrared (FTIR), 1H NMR, 13C NMR, and size exclusion chromatography (SEC) to determine the degree of the substitution (DS), degree of polymerization (DP), and the molecular weight, respectively. Only a minor proportion of PC (ca. 3–15%) was converted to propylene glycol/homooligomers as revealed by high performance liquid chromatography (HPLC). All catalysts promoted preferential derivatization of lignin phenolic OH groups by oxypropyl moieties. The maximum average DP of propylene oxide chains in oxyalkylated Lignoboost® kraft lignin (oKL) was 1.85 per one phenylpropane unit (PPU) using DBU. Conversely, the DP of oKL using DICY was very low (0.27/PPU). DICY’s catalytic activity seems to be jeopardized due to the formation of unreactive adducts with lignin. The oKL obtained using DBU, DABCO, and K2CO3 have potential to be used as polyols in the production of polyurethanes as the corresponding hydroxyl number (IOH) is in the range of 198–410 mg KOH g−1.

scholarly journals Periplasmic synthesis and purification of the human prolactin antagonist Δ1-11-G129R-hPRL

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Miriam F. Suzuki ◽  
Larissa A. Almeida ◽  
Stephanie A. Pomin ◽  
Felipe D. Silva ◽  
Renan P. Freire ◽  
...  
Keyword(s):  
Size Exclusion Chromatography ◽  
High Performance ◽  
Signal Sequence ◽  
Osmotic Shock ◽  
Size Exclusion ◽  
Specific Expression ◽  
E Coli ◽  
Human Prolactin ◽  
Exclusion Chromatography

AbstractThe human prolactin antagonist Δ1-11-G129R-hPRL is a 21.9 kDa recombinant protein with 188 amino acids that downregulates the proliferation of a variety of cells expressing prolactin receptors. Periplasmic expression of recombinant proteins in E. coli has been considered an option for obtaining a soluble and correctly folded protein, as an alternative to cytoplasmic production. The aim of this work was, therefore, to synthesize for the first time, the Δ1-11-G129R-hPRL antagonist, testing different activation temperatures and purifying it by classical chromatographic techniques. E. coli BL21(DE3) strain was transformed with a plasmid based on the pET25b( +) vector, DsbA signal sequence and the antagonist cDNA sequence. Different doses of IPTG were added, activating under different temperatures, and extracting the periplasmic fluid via osmotic shock. The best conditions were achieved by activating at 35 °C for 5 h using 0.4 mM IPTG, which gave a specific expression of 0.157 ± 0.015 μg/mL/A600 at a final optical density of 3.43 ± 0.13 A600. Purification was carried out by nickel-affinity chromatography followed by size-exclusion chromatography, quantification being performed via high-performance size-exclusion chromatography (HPSEC). The prolactin antagonist was characterized by SDS-PAGE, Western blotting, reversed-phase high-performance liquid chromatography (RP-HPLC) and MALDI-TOF–MS. The final product presented > 95% purity and its antagonistic effects were evaluated in vitro in view of potential clinical applications, including inhibition of the proliferation of cancer cells overexpressing the prolactin receptor and specific antidiabetic properties, taking also advantage of the fact that this antagonist was obtained in a soluble and correctly folded form and without an initial methionine.

scholarly journals (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation

Antioxidants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 133
Author(s):  
Urška Jug ◽  
Katerina Naumoska ◽  
Irena Vovk
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
High Performance ◽  
Radical Scavenging ◽  
Size Exclusion ◽  
Solvent Mixtures ◽  
Japanese Knotweed ◽  
Compound Identification ◽  
Rp Hplc ◽  
Ic50 Value

The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol(aq), acetone, 70% acetone(aq), ethanol, 70% ethanol(aq), and 90% ethyl acetate(aq)), were determined using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. Low half maximal inhibitory concentration (IC50) values (2.632–3.720 µg mL−1) for all the extracts were in the range of the IC50 value of the known antioxidant ascorbic acid at t0 (3.115 µg mL−1). Due to the highest extraction yield (~44%), 70% ethanol(aq) was selected for the preparation of the extract for further investigations. The IC50 value calculated for its antioxidant activity remained stable for at least 14 days, while the IC50 of ascorbic acid increased over time. The stability study showed that the container material was of great importance for the light-protected storage of the ascorbic acid(aq) solution in a refrigerator. Size exclusion–high-performance liquid chromatography (SEC-HPLC)–UV and reversed phase (RP)-HPLC-UV coupled with multistage mass spectrometry (MSn) were developed for fractionation of the 70% ethanol(aq) extract and for further compound identification, respectively. In the most potent antioxidant SEC fraction, determined using an on-line post-column SEC-HPLC-DPPH assay, epicatechin, resveratrol malonyl hexoside, and its in-source fragments (resveratrol and resveratrol acetyl hexoside) were tentatively identified by RP-HPLC-MSn. Moreover, epicatechin was additionally confirmed by two orthogonal methods, SEC-HPLC-UV and high-performance thin-layer chromatography (HPTLC) coupled with densitometry. Finally, the latter technique enabled the identification of (−)-epicatechin. (−)-Epicatechin demonstrated potent and stable time-dependent antioxidant activity (IC50 value ~1.5 µg mL−1) for at least 14 days.

scholarly journals Optimization of sunflower head pectin extraction by ammonium oxalate and the effect of drying conditions on properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xuemei Ma ◽  
Jiayi Yu ◽  
Jing Jing ◽  
Qian Zhao ◽  
Liyong Ren ◽  
...  
Keyword(s):  
High Performance ◽  
Freeze Drying ◽  
Antioxidant Activities ◽  
Structural Characteristics ◽  
Radical Scavenging ◽  
Ammonium Oxalate ◽  
Extraction Process ◽  
Size Exclusion ◽  
Pharmaceutical Industries

AbstractPectin is a kind of natural and complex carbohydrates which is extensively used in food, chemical, cosmetic, and pharmaceutical industries. Fresh sunflower (Helianthus annuus L.) heads were utilized as a novel source of pectin extracted by ammonium oxalate. The conditions of the extraction process were optimized implementing the response surface methodology. Under optimal extraction parameters (extraction time 1.34 h, liquid–solid ratio 15:1 mL/g, ammonium oxalate concentration 0.76% (w/v)), the maximum experimental yield was 7.36%. The effect of spray-drying and freeze-drying on the physiochemical properties, structural characteristics, and antioxidant activities was investigated by FT-IR spectroscopy, high performance size exclusion chromatography, and X-ray diffraction. The results showed freeze-drying lead to decrease in galacturonic acid (GalA) content (76.2%), molecular weight (Mw 316 kDa), and crystallinity. The antioxidant activities of pectin were investigated utilizing the in-vitro DPPH and ABTS radical-scavenging systems. This study provided a novel and efficient extraction method of sunflower pectin, and confirmed that different drying processes had an effect on the structure and properties of pectin.

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