scholarly journals Scavenging ability of dendritic PAMAM bridged hindered phenolic antioxidants towards DPPH˙ and ROO˙ free radicals

RSC Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 1869-1876 ◽  
Author(s):  
Cuiqin Li ◽  
Peng Sun ◽  
Hongyang Yu ◽  
Na Zhang ◽  
Jun Wang
Keyword(s):  
Free Radicals ◽  
Oxygen Uptake ◽  
Tertiary Amine ◽  
Synergistic Effects ◽  
Phenolic Antioxidants ◽  
Dpph Method ◽  
Amine Groups ◽  
Hindered Phenol ◽  
Uptake Method

The intramolecular synergistic effects of two dendritic antioxidants between hindered phenol groups and tertiary amine groups were investigated using the DPPH˙ method and the oxygen uptake method.

A novel antioxidant action of ethanolamine plasmalogens in lowering the oxidizability of membranes

2004 ◽  
Vol 32 (1) ◽  
pp. 141-143 ◽  
Author(s):  
R. Maeba ◽  
N. Ueta
Keyword(s):  
Free Radicals ◽  
Oxygen Uptake ◽  
Water Soluble ◽  
Antioxidant Action ◽  
Unilamellar Vesicles ◽  
Radical Initiator ◽  
Large Unilamellar Vesicles ◽  
Ethanolamine Plasmalogens ◽  
Uptake Method

We have demonstrated a novel antioxidant action of ethanolamine plasmalogens both in protecting cholesterol from oxidation by free radicals and in lowering the oxidizability of membranes, along with the action of scavenging radicals, by the oxygen-uptake method using large unilamellar vesicles and the water-soluble azo-radical initiator, AAPH [2,2´-azobis-(2-amidino-propane) dihydrochloride].

Synthesis and oxidative stability of hyperbranched macromolecule-bridged hindered phenols

2017 ◽  
Vol 41 (14) ◽  
pp. 6395-6404 ◽  
Author(s):  
Cuiqin Li ◽  
Peng Sun ◽  
Hua Wang ◽  
Li Ma ◽  
Weiwei Kang ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Oxidative Stability ◽  
Dpph Method ◽  
Hindered Phenols ◽  
Uptake Method ◽  
Hyperbranched Macromolecule

The oxidative stability of hyperbranched macromolecule-bridged hindered phenols was investigated using the DPPH method and the oxygen uptake method.

scholarly journals Electrochemiluminescence Enhancement and Particle Structure Stabilization of Polymer Nanoparticle by Doping Anionic Polyelectrolyte and Cationic Polymer Containing Tertiary Amine Groups and Its Highly Sensitive Immunoanalysis

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1054
Author(s):  
Noor Ul Ain ◽  
Tian-Yu Wang ◽  
Xiao-Ning Wu ◽  
Tong-Hong Wei ◽  
Jing-Shuo Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Tertiary Amine ◽  
Hepatitis B Surface Antigen ◽  
Particle Diameter ◽  
Cationic Polymer ◽  
Suspension Stability ◽  
Good Precision ◽  
Polymer Nanoparticle ◽  
Anionic Polyelectrolyte ◽  
Amine Groups

A doped polymer nanoparticle (dPNP) of electrochemiluminescence (ECL) was prepared via doping the anionic polyelectrolyte polyacrylic acid (PAA) and the cationic polymer poly-ethyleneimine (PEI) into the polymer nanoparticle (PNP), which was self-assembled by Ru(bpy)32+ derivative-grafted PAA (PAA–Ru) with both cations and anions. The good electrical conductivity of the doped polyelectrolyte PAA enhanced the ECL intensity of PNP to 109.1%, and the involvement of a large number of tertiary amine groups of the doped PEI further enhanced that to 127.3%; meanwhile, doping low-molecular-weight PEI into PNP, while simultaneously doping high-molecular-weight PAA, avoided the precipitation of PAA and PEI, due to interaction of the two oppositely charged polymers; and these also made the self-assembly procedure more effective and the nanoparticle structure more stable than PNP and also led to the production of rich residual PAA chains on the surface of dPNP. The storage results showed that the average hydrated particle diameter kept almost constant (197.5–213.1 nm) during 15-day storage and that the nanoparticles have rich surface charge of −11.47 mV (zeta potential), well suspension stability and good dispersity without detectable aggregation in the solution during the storage. Therefore, the nanoparticle is quite suitable for the antibody labeling, immunoassay and the storage. As a result, a high-sensitive ECL immunoassay approach with good precision, accuracy and selectivity was established and an ultra-low detection limit of 0.049 pg mL−1 (S/N = 3) for magnetic bead-based detection of Hepatitis B surface antigen was observed.

scholarly journals UJI AKTIVITAS ANTIOKSIDAN SPONS Stylissa sp. DENGAN MENGGUNAKAN METODE DPPH (1,1-difenil-2-pikrilhidrazil)

PHARMACON ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 419
Author(s):  
Samuel I.M. Sibarani ◽  
Adithya Yudistira ◽  
Deby A. Mpila
Keyword(s):  
Antioxidant Activity ◽  
Cell Wall ◽  
Free Radicals ◽  
Ethanol Extract ◽  
Dna Bases ◽  
Oxidation Reactions ◽  
Terrestrial Plants ◽  
Dpph Method ◽  
High Antioxidant Activity ◽  
Ethanol Extracts

ABSTRACTHabitat of sponge Stylissa sp., were under the sea and these sponges contain active compounds, which are more active than the compounds produced by terrestrial plants. Antioxidants are inhibitors of oxidation reactions due to the free radicals, which can cause weak damage to unsaturated cells, cell wall membranes, blood vessels, DNA bases, and lipid tissue, that causing disease. The study was conducted to determine the antioxidant activity of ethanol extracts  of sponge Stylissa sp., which is located on the Bangka Island, Likupang District, North Minahasa Regency. Sponge Stylissa sp., was extracted by maceration with using ethanol. Testing of antioxidant activity was carried out by the DPPH method measured by a UV-Vis spectrophotometer. The results of the study showed that ethanol extracts of sponge Stylissa sp., has antioxidant activity in each concentration and the highest at a concentration of 100 mg / L. The conclusion is a ethanol extract of sponge Stylissa sp. have high antioxidant activity with a concentration of 25 mg/L (77,40%), concentration of 50 mg/L (85,63%), concentration of 75 mg/L (88,66%), and concentration 100 mg/L (88,96%). Key words: Stylissa sp. Sponge, Antioxidant, DPPH (1,1-diphenyl-2-picrylhydrazyl) ABSTRAKHabitat dari spons Stylissa sp. terdapat di bawah laut dan spons ini mengandung senyawa aktif yang persentase keaktifannya lebih besar dibandingkan dengan senyawa-senyawa yang dihasilkan oleh tumbuhan darat. Antioksidan adalah zat penghambat reaksi oksidasi akibat radikal bebas yang dapat menyebabkan kerusakan lemah tak jenuh, membran dinding sel, pembuluh darah, basa DNA, dan jaringan lipid sehingga menimbulkan penyakit. Penelitian dilakukan untuk mengetahui aktivitas antioksidan ekstrak etanol biota laut spons Stylissa sp. yang terdapat di pulau Bangka, Kecamatan Likupang, Kabupaten Minahasa Utara. Spons Stylissa sp. ini diekstrak dengan metode maserasi menggunakan etanol. Pengujian aktivitas antioksidan ini dilakukan dengan metode DPPH yang diukur dengan alat spektrofotometer UV-Vis. Hasil dari penelitian menunjukan bahwa ekstrak etanol spons Stylissa sp. memiliki aktivitas antioksidan disetiap konsentrasi dan yang tertinggi pada konsentrasi 100 mg/L. Kesimpulan yang didapat bahwa ekstrak etanol spons Stylissa sp. memiliki aktivitas antioksidan yang tinggi dengan konsentrasi 25 mg/L (77,40%), konsentrasi 50 mg/L (85,63%), konsentrasi 75 mg/L (88,66%), dan konsentrasi 100 mg/L (88,96%). Kata Kunci : Spons Stylissa sp., Antioksidan, DPPH (1,1-difenil-2-pikrilhidrazil)

scholarly journals Limpasu Pericarpium : an Alternative Source of Antioxidant From Borneo with Sequential Maceration Method

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Irfan Zamzani ◽  
Nita Triadisti
Keyword(s):  
Antioxidant Activity ◽  
Free Radicals ◽  
Ethyl Acetate ◽  
Methanol Extract ◽  
Oxidation Process ◽  
Antioxidant Activities ◽  
Alternative Source ◽  
Dpph Method ◽  
Indigenous Plant ◽  
Ic50 Values

Antioxidants are substances that can slow down the oxidation process of free radicals. Limpasu plant (Baccaurea lanceolata (Miq) Muell. Arg), an indigenous plant of Borneo, is a natural antioxidant source. The purpose of this study was to determine the antioxidant activity of the limpasu pericarpium extract. The extraction of the limpasu pericarpium was done by maceration method using solvents with increasing polarity ranging from n-hexane, ethyl acetate, and methanol. Antioxidant activities of the three extracts were measured by the DPPH and FRAP methods. The IC50 values of n-hexane, ethyl acetate, and methanol extracts, as well as quercetin using the DPPH method were 517,45 µg/mL, 530,64 µg/mL, 10,63 µg/mL and 6,83 µg/mL, respectively. Meanwhile, the IC50 values obtained from FRAP method were 198,96 µg/mL, 190,07 µg/mL, 661,36 µg/mL, and 7,09 µg/mL, respectively. The results revealed that the methanol extract is more potent than other extracts tested for antioxidant activity.

Molecular Rearrangements. Part IV. Aryl (Alkyl) Amines (1), Thermal Rearrangement of N-Benzyl-N-Methylaniline

1974 ◽  
Vol 52 (2) ◽  
pp. 293-298 ◽  
Author(s):  
M. Zarif A. Badr ◽  
M. M. Aly
Keyword(s):  
Free Radicals ◽  
Reaction Mechanism ◽  
Tertiary Amine ◽  
Thermal Rearrangement ◽  
Molecular Rearrangements ◽  
Intermediate Products ◽  
Alkyl Amines ◽  
Rearrangement Process ◽  
Homolytic Fission

Heating N-benzyl-N-methylaniline under reflux or heating at ∼315° in sealed tubes, in the absence of any promotor for 100 h, resulted in its rearrangement, producing methylamine, diphenylmethane, and dibenzyl together with o-toluidine and 4-methylacridine. Heating N-methylaniline in a sealed tube under the same conditions, in absence of any promotor, resulted in its rearrangement, producing methylamine and o-toluidine together with unidentified neutral products.When pyrolysis of the tertiary amine was carried out with quinoline as a solvent, the normal products of rearrangement were obtained together with 2-and 4-benzylquinolines and 2,2′-biquinolyl.The reaction mechanism is discussed on the basis of the products separated, from which it is concluded that the tertiary amine undergoes homolytic fission to benzyl and N-methylphenylamino free radicals, followed by a series of homolytic fissions of initially separated intermediate products, during the rearrangement process. Throughout the whole mechanism, the C—N bonds are the only ones to suffer homolytic fission.

One-shot synthesis and solution properties of ROS/pH responsive methoxy poly(ethylene glycol)-b-polycarbonate

2019 ◽  
Vol 10 (17) ◽  
pp. 2143-2151 ◽  
Author(s):  
Yan Zhang ◽  
Yue Xu ◽  
Chao Wei ◽  
Chuanhao Sun ◽  
Bingkun Yan ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Tertiary Amine ◽  
Solution Properties ◽  
Ph Responsive ◽  
Poly Ethylene Glycol ◽  
Amine Groups ◽  
Poly Ethylene

A one-shot method was employed to synthesize ROS/pH responsive methoxy poly(ethylene glycol)-b-polycarbonate (mPEG-b-poly(MN-co-MSe)) with the selenide and tertiary amine groups situated on the backbone.

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