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.
Spectral analysis allows using the DPPH* UV–Vis assay to estimate antioxidant activity of colored compounds
Celiz, Gustavo,Renfige, Melisa,Finetti, Mariela
, p. 3101 - 3109 (2020)
Abstract: An accurate measurement of antiradical activity to samples, such as herbal extract and natural or synthetic pure compounds, is essential to estimate its scope as antioxidant, for example, in functional foods. The 2,2-diphenyl-1-picrylhydrazyl (DPPH*) UV–Vis assay is the most widely used method for this aim. Nevertheless, it can drive to erroneous results if the spectroscopic properties of each substance, in the reaction medium, are not considered. To overcome this limitation, we present a new methodology based on spectral analysis which, instead of reading at fixed wavelength, uses the UV–Vis spectra of selected compounds, as well as simple algebraic operations and fitting by residual sum of squares. The proposed methodology was assayed successfully to determine the antiradical activity of three compounds: naringin, which does not present absorbance in the absorption band of DPPH*, naringin-Cu(II) complex, with moderate absorbance at this range, and naringin-Fe(III) complex, which shows intense absorption at the studied range. The proposed methodology is simple with a broad scope, since it allows to study the free radical scavenging activity on samples with high color that could not be analyzed, by UV–Vis spectrophotometry, up to the moment. Graphic abstract: [Figure not available: see fulltext.].
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.
Kaempferol Binding to Zinc(II), Efficient Radical Scavenging through Increased Phenol Acidity
Xu, Yi,Qian, Ling-Ling,Yang, Jing,Han, Rui-Min,Zhang, Jian-Ping,Skibsted, Leif H.
, p. 10108 - 10117 (2018)
Zinc(II) enhances radical scavenging of the flavonoid kaempferol (Kaem) most significantly for the 1:1 Zn(II)-Kaem complex in equilibrium with the 1:2 Zn(II)-Kaem complex both with high affinity at 3-hydroxyl and 4-carboxyl coordination. In methanol/chloroform (7/3, v/v), 1:1 Zn(II)-Kaem complex reduces β-carotene radical cation, β-Car?+, with a second-order rate constant, 1.88 × 108 L·mol-1·s-1, while both Kaem and 1:2 Zn(II)-Kaem complex are nonreactive, as determined by laser flash photolysis. In ethanol, 1:1 Zn(II)-Kaem complex reduces the 2,2-diphenyl-1-picrylhydrazyl radical, DPPH?, with a second-order rate constant, 2.48 × 104 L·mol-1·s-1, 16 times and 2 times as efficient as Kaem and 1:2 Zn(II)-Kaem complex, respectively, as determined by stopped-flow spectroscopy. Density functional theory calculation results indicate significantly increased acidity of Kaem as ligand in 1:1 Zn(II)-Kaem complex other than in 1:2 Zn(II)-Kaem complex. Kaem in 1:1 Zn(II)-Kaem complex loses two protons (one from 3-hydroxyl and one from phenolic hydroxyl) forming 1:1 Zn(II)-(Kaem-2H) during binding with Zn(II), while Kaem in 1:2 Zn(II)-Kaem complex loses one proton in each ligand forming Zn(II)-(Kaem-H)2, as confirmed by UV-vis absorption spectroscopy. Zn(II)-(Kaem-2H) is a far stronger reductant than Kaem and Zn(II)-(Kaem-H)2 as determined by cyclic voltammetry. Significant rate increases for the 1:1 complex in both β-Car?+ scavenging by electron transfer and DPPH? scavenging by hydrogen atom transfer were ascribed to decreases of ionization potential and of bond dissociation energy of 4′-OH for deprotonated Zn(II)-(Kaem-2H), respectively. Increased phenol acidity of plant polyphenols by 1:1 coordination with Zn(II) may explain the unique function of Zn(II) as a biological antioxidant and may help to design nontoxic metal-based drugs derived from natural bioactive molecules.
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.
Acidity of hydroxyl groups: An overlooked influence on antiradical properties of flavonoids
Musialik, Malgorzata,Kuzmicz, Rafal,Pawlowski, Tomasz S.,Litwinienko, Grzegorz
, p. 2699 - 2709 (2009)
The reactions of 10 flavonoids with 2,2-diphenyl-1-picrylhydrazyl radical (dpph.) carried out in alcohols always occur significantly faster than in acidified alcohols or in dioxane. These fast kinetics benefit from the contribution of the elect
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.
(+)-kunstlerone, a new antioxidant neolignan from the leaves of beilschmiedia kunstleri gamble
Mollataghi, Abbas,Hadi, A. Hamid M.,Awang, Khalijah,Mohamad, Jamaludin,Litaudon, Marc,Mukhtar, Mat Ropi
, p. 6582 - 6590 (2011)
A new neolignan, 3,4-dimethoxy-3',4'-methylenedioxy-2,9-epoxy-6,7-cyclo- 1,8-neolign-11-en-5(5H)-one, which has been named (+)-kunstlerone (1), together with six known alkaloids: (+)-norboldine (2), (+)-N-methylisococlaurine (3), (+)-cassythicine (4), (+)
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.
