1707-75-1Relevant articles and documents
Use of 2,2-Diphenyl-1-picrylhydrazyl To Investigate the Chemical Behavior of Free Radicals Induced by Ultrasonic Cavitation
Sehgal, C.,Yu, T. J.,Sutherland, R. G.,Verall, R. E.
, p. 2982 - 2986 (1982)
The sonolysis of 2,2-diphenyl-1-picrylhydrazyl (DPPH) has been studied in methanol-water solutions in the presence of air, oxygen, and argon.It is found that, for a specific solvent composition, 83 percent of the reacted DPPH is reduced to 2,2-diphenyl-1-picrylhydrazine (DPPH2) with all the gases examined.The absolute amount of DPPH converted is greatest with oxygen and it is believed that the latter combines with the primary radicals produced in the cavitation process to give a greater concentration of stable free radicals which can readily diffuse out of the bubble to react with DPPH.The conversion of DPPH DPPH2 decreases with increasing methanol concentration and it is believed to be due to the volatile alcohol inhibiting the cavitation process.
Abnormal solvent effects on hydrogen atom abstraction. 2. Resolution of the curcumin antioxidant controversy. The role of sequential proton loss electron transfer
Litwinienko, Grzegorz,Ingold
, p. 5888 - 5896 (2004)
The rates of reaction of 1,1-diphenyl-2-picrylhydrazyl (dpph.) radicals with curcumin (CU, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3, 5-dione), dehydrozingerone (DHZ, "half-curcumin"), and isoeugenol (IE) have been measured in methanol and ethanol and in two non-hydroxylic solvents, dioxane and ethyl acetate, which have about the same hydrogen-bond-accepting abilities as the alcohols. The reactions of all three substrates are orders of magnitude faster in the alcohols, but these high rates can be suppressed to values essentially equal to those in the two non-hydroxylic solvents by the addition of acetic acid. The fast reactions in alcohols are attributed to the reaction of dpph. with the CU, DHZ, and IE anions (see J. Org. Chem. 2003, 68, 3433), a process which we herein name sequential proton loss electron transfer (SPLET). The most acidic group in CU is the central keto-enol moiety. Following CU's ionization to a monoanion, ET from the [-(O)CCHC(O)-]- moiety to dpph. yields the neutral [-(O)CCHC(O)-]. radical moiety which will be strongly electron withdrawing. Consequently, a phenolic proton is quickly lost into the alcohol solvent. The phenoxide anion so formed undergoes charge migration to produce a neutral phenoxyl radical and the keto-enol anion, i.e., the same product as would be formed by a hydrogen atom transfer (HAT) from the phenolic group of the CU monoanion. The SPLET process cannot occur in a nonionizing solvent. The controversy as to whether the central keto-enol moiety or the peripheral phenolic hydroxyl groups of CU are involved in its radical trapping (antioxidant) activity is therefore resolved. In ionizing solvents, electron-deficient radicals will react with CU by a rapid SPLET process but in nonionizing solvents, or in the presence of acid, they will react by a slower HAT process involving one of the phenolic hydroxyl groups.
Antioxidant activity of hydrazones with sterically hindered phenol fragments
Nikolaevskii,Kniga,Khizhan,Tikhonova,Vinogradov,Khizhan
, p. 1816 - 1820 (2012)
Kinetic parameters of the antiradical activity of derivatives of hydrazones of 4-hydroxy-3,5-di-tert-butyl-benzaldehyde are determined photocolorimetrically in their reactions with a stable diphenylpicrylhydrazyl radical, and by chemiluminescence from the capture of peroxide radicals upon the initiated oxidation of ethylbenzene. It is found that during inhibited oxidation, the reactive centers (N-H and O-H) in hetaryl-and acylhydrazone molecules operate in parallel. Regularities of the compounds' inhibiting effect are studied in heterogeneous systems upon the initiated oxidation of ethylbenzene in emulsion, and in a waterlipid model of the oxidation of phosphatidylcholine dispersion. It is established that hydrazone derivatives are antioxidants of combined action in heterophase processes of the oxidation of unsaturated substrates, displaying properties of hydroperoxide deactivators in addition to their antiradical activity. Pleiades Publishing, Ltd., 2012.
Synthesis of luteolin loaded zein nanoparticles for targeted cancer therapy improving bioavailability and efficacy
Shinde, Priyanka,Agraval, Hina,Singh, Ajeet,Yadav, Umesh C.S.,Kumar, Umesh
, p. 369 - 378 (2019)
A naturally occurring flavonoid, Luteolin possess wide range of pharmaceutical activities from anti-inflammatory to anticancer effect. Luteolin inhibits cell proliferation by arresting cell cycle pathways and triggers apoptotic cell death. Poor aqueous solubility of luteolin limits its oral bioavailability. Therefore, to improve the oral bioavailability of luteolin by use of biodegradable protein zein and sodium caseinate as nanocarrier. The nanoparticles were prepared by simple precipitation process. The resulting nanoparticles had mean size of 200–300 nm with negative zeta potential with 92% encapsulation efficiency and luteolin release at intestinal pH. Anti-oxidant activity of loaded molecule with respect to parent molecule significantly indicate the free radical scavenging potential of luteolin increases after encapsulation in zein nanoparticles. Luteolin loaded zein nanoparticles showed enhanced cytotoxicity against SW480 colon cancer cells and induces apoptosis. In this paper, we have shown the potential of luteolin loaded zein nanoparticles for treating colon cancer which could serve as promising strategy to develop oral formulation of this water insoluble drug enhancing its bioavailability.
Electron-transfer mechanism in radical-scavenging reactions by a vitamin E model in a protic medium
Nakanishi, Ikuo,Kawashima, Tomonori,Ohkubo, Kei,Kanazawa, Hideko,Inami, Keiko,Mochizuki, Masataka,Fukuhara, Kiyoshi,Okuda, Haruhiro,Ozawa, Toshihiko,Itoh, Shinobu,Fukuzumi, Shunichi,Ikota, Nobuo
, p. 626 - 629 (2005)
The scavenging reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) or galvinoxyl radical (GO*) by a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), was significantly accelerated by the presence of Mg(ClO4)2 in de-aerated methanol (MeOH). Such an acceleration indicates that the radical-scavenging reaction of 1H in MeOH proceeds via an electron transfer from 1H to the radical, followed by a proton transfer, rather than the one-step hydrogen atom transfer which has been observed in acetonitrile (MeCN). A significant negative shift of the one-electron oxidation potential of 1H in MeOH (0.63 V vs. SCE), due to strong solvation as compared to that in MeCN (0.97 V vs. SCE), may result in change of the radical-scavenging mechanisms between protic and aprotic media.
Linking an α-tocopherol derivative to cobalt(0) nanomagnets: Magnetically responsive antioxidants with superior radical trapping activity and reduced cytotoxicity
Viglianisi, Caterina,Di Pilla, Veronica,Menichetti, Stefano,Rotello, Vincent M.,Candiani, Gabriele,Malloggi, Chiara,Amorati, Riccardo
, p. 6857 - 6860 (2014)
Covalent attachment of a phenolic antioxidant analogue of α-tocopherol to graphite-coated magnetic cobalt nanoparticles (CoNPs) provided a novel magnetically responsive antioxidant capable of preventing the autoxidation of organic materials and showing a reduced toxicity toward human cells.
Kinetics of the reaction between the antioxidant Trolox and the free radical DPPH? in semi-aqueous solution
Friaa, Ouided,Brault, Daniel
, p. 2417 - 2423 (2006)
Reaction of the free-radical diphenylpicrylhydrazyl (DPPH) with Trolox (TrOH) was investigated in buffered hydroalcoholic media by using a stopped-flow system. DPPH was reduced to the hydrazine analogue DPPH-H with a measured stoichiometry of about 2. DPPH-H was characterized by an acid-base equilibrium (pKa = 8.6). Time-resolved absorption spectra recorded with an excess of either TrOH or DPPH indicated that no significant amount of the TrO radical was accumulated. The TrO radical formed in a first step further reacted quickly with DPPH. For 1: 1 ethanol-buffer mixtures at pH 7.4, the bimolecular rate constants of the first and second steps were 1.1 × 104 M-1 s-1 and 2 × 106 M -1 s-1, respectively. A significant increase of the measured rate constant was observed for ethanol-buffer solutions as compared to ethanol. The rate was also increased at higher pH. A deuterium isotopic effect of 2.9 was measured. These data are discussed with regards to mechanisms involving either electron or proton exchange as rate determining steps in the reaction of DPPH with Trolox. The importance of solvent acidity control in investigation of antioxidant properties is outlined. The Royal Society of Chemistry 2006.
Synthesis and evaluation of the antioxidant and antiinflammatory activities of some benzo[l]khellactone derivatives and analogues
Nicolaides, Demetrios N.,Gautam, Daman R.,Litinas, Konstantinos E.,Hadjipavlou-Litina, Dimitra J.,Fylaktakidou, Konstantina C.
, p. 323 - 332 (2004)
Treatment of 3-hydroxy-β-lapachone 4 with ylide 5 gave the coumarin derivative 7a, which was transformed to compounds 10-14. Compound 14 was then transformed to benzo[f]seselin 15 as well as to benzo[l]khellactones 16, 18 from which the title compounds 17, 19I, 19II, 20, 21 I and 21II were prepared. All the tested compounds were found to interact with DPPH in a concentration and time dependent manner. All the tested compounds highly inhibited the soybean lipoxygenase, whereas compounds 12, 17 and 19II highly compete with DMSO for ?OH. Compounds 7a, 7b, 12 and 17 induced at 48.7-58.9% protection against carrageenin induced rat paw edema.
Synthesis and characterization of a novel non-symmetrical bidentate Schiff base ligand and its Ni(II) complex: electrochemical and antioxidant studies
Bougossa, Imène,Aggoun, Djouhra,Ourari, Ali,Berenguer, Raúl,Bouacida, Sofiane,Morallon, Emilia
, p. 3825 - 3837 (2020)
Abstract: This paper describes the synthesis and properties of a new nitro-substituted bidentate Schiff base ligand (HL) and its nickel complex (Ni(II)-2L). Its ligand was derived from the condensation of 2′-methoxyphenyl-2-ethylamine with 5-nitro-2-hydroxybenzaldehyde. This ligand and its nickel complex were characterized through elemental analysis, UV–Vis, IR, 1H NMR and 13C NMR. The molecular structure of the nickel complex was confirmed using single-crystal X-ray diffraction. This complex crystallizes in dichloromethane in triclinic system, space group of P-1 with a = 6.6803 (2), b = 9.6702 (2), c = 12.1836 (3) and 1 formula unit in the cell. The obtained data revealed that the Ni(II) center is tetra-coordinated by two oxygen and two nitrogen atoms involving two ligands. Cyclic voltammograms of the nickel complex, recorded in DMF solutions, showed one quasi-reversible redox couple related to the Ni(II)/Ni(I) couple, demonstrating its electro-activity. This indicates a slow redox transition and/or electron exchange process, which implies that this electrochemical process is mainly diffusion-controlled. The antioxidant activity of the synthesized compounds was evaluated from the reactivity with the free radical DPPH, showing IC50 values between 0.4 and 4.5?mg/mL. Graphic abstract: [Figure not available: see fulltext.].
Total antioxidant capacity of some commercial fruit juices: Electrochemical and spectrophotometrical approaches
Pisoschi, Aurelia Magdalena,Cheregi, Mihaela Carmen,Danet, Andrei Florin
, p. 480 - 493 (2009)
The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH· (2,2-diphenyl-1- picrylhydrazyl)/DPPH (2,2-diphenyl-1
Radical-scavenging activities of citrus essential oils and their components: Detection using 1,1-diphenyl-2-picrylhydrazyl
Choi, Hyang-Sook,Sun Song, Hee,Ukeda, Hiroyuki,Sawamura, Masayoshi
, p. 4156 - 4161 (2000)
Thirty-four kinds of citrus essential oils and their components were investigated for radical-scavenging activities by the HPLC method using 1,1-diphenyl-2-picrylhydrazyl (DPPH). To examine the oils' relative radical-scavenging activities compared with that of a standard antioxidant, Trolox was employed. All of the essential oils were found to have scavenging effects on DPPH in the range of 17.7-64.0%. The radical-scavenging activities of 31 kinds of citrus essential oils were comparable with or stronger than that of Trolox (p 0.05). The oils of Ichang lemon (64.0%, 172.2 mg of Trolox equiv/mL), Tahiti lime (63.2%, 170.2 mg of Trolox equiv/mL), and Eureka lemon (61.8%, 166.2 mg of Trolox equiv/mL) were stronger radical scavengers than other citrus oils. Citrus volatile components such as geraniol (87.7%, 235.9 mg of Trolox equiv/mL), terpinolene (87.4%, 235.2 mg of Trolox equiv/mL), and γ-terpinene (84.7%, 227.9 mg of Trolox equiv/mL) showed marked scavenging activities on DPPH (p 0.05).
Effects of a Constant Magnetic Field on the Electrochemical Reactions of Quercetin
Zieliński, Marek,Burnat, Barbara,Mi?ko?, Ewa
, p. 1229 - 1235 (2020/07/13)
The paper presents a study of the effect of a constant magnetic field (CMF) on the basic processes of quercetin electrochemical reactions. According to the observation made in previous studies, the presence of a double bond in the C-ring of quercetin enhances the antioxidant properties of that compound, whereas the presence of ?OH groups also affects the antioxidant properties. Using cyclic voltammetry it was found that the constant magnetic field improves the efficiency of quercetin electrooxidation, especially of the third stage of the process, i. e. the stage in which the oxidation of the OH groups in the A-ring is the most difficult. The use of HPLC confirmed the electrochemical measurements and the results of cyclic voltammetry studies. The beneficial effect of the magnetic field on the efficiency of quercetin oxidation was confirmed by the results of impedance spectroscopy measurements.
