Search results for "Oxidation."
showing 10 items of 1877 documents
Phenolic profile of oils obtained from “horchata” by-products assisted by supercritical-CO2 and its relationship with antioxidant and lipid oxidation…
2019
Abstract In this study, the effect of different supercritical CO 2 (SC-CO 2 ) pressures (10–40 MPa) on phenolic compounds extraction in oils obtained from “ horchata ” by-products was evaluated, and the results were compared to those obtained after conventional oil extraction (CE). Moreover, the relationship between the individual phenolic compounds and the total antioxidant capacity as well as oil oxidative quality parameters was compared. The phenolic profile and contents were largely influenced by extracting conditions. The main phenolic compound obtained by SC-CO 2 was the isohydroxymatairesinol, particularly at 30 and 40 MPa, while 3-vinylphenol was the predominant compound in oils ext…
Tiliroside and gnaphaliin inhibit human low density lipoprotein oxidation.
2004
Two flavonoids, gnaphaliin and tiliroside, isolated from Helichrysum italicum, were studied in vitro for their capacity to inhibit Cu(2+)-induced human low density lipoprotein (LDL) and diluted plasma oxidation. LDL oxidation was monitored by conjugated diene, thiobarbituric acid-reactive substances (TBARS) formation and electrophoretic mobility on agarose gel. Gnaphaliin and tiliroside increased the lag-phase for diene conjugate production in a dose-dependent manner. The reduction of TBARS production confirmed the antioxidant activity of gnaphaliin and tiliroside with 50% inhibitory concentration (IC(50)) values of 8.0+/-3.9 microM and 7.0+/-2.6 microM respectively. Furthermore, the flavon…
Preparation of C-23 esterified silybin derivatives and evaluation of their lipid peroxidation inhibitory and DNA protective properties.
2009
A diverse series of C-23 esterified silybin derivatives (1a-n) were designed and synthesized. The antioxidative properties of these compounds were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical scavenging, ferrous ion chelation, and inhibition of rat liver homogenate lipid peroxidation. Their protective effects on the prevention of hydrogen peroxide induced DNA damage were also investigated. Most of the synthesized compounds exhibited more effective antioxidant activities than silybin. The esterified silybin analogues displayed satisfactory performance especially on iron chelation and antiperoxidative activity. Compound 1n in particular exhibited remarkable a…
Phytochemical profile and antioxidative properties of Plinia trunciflora fruits: A new source of nutraceuticals.
2020
Abstract This study evaluated the polyphenol profile and the antioxidative properties of Plinia trunciflora (O. Berg) Kausel fruits. Folin-Ciocalteau and pH-jumping methods indicated that these berries are a major source of antioxidant polyphenols (1201.05 mg GAE/100 g FW), particularly anthocyanins. HPLC-DAD-ESI-MS/MS analysis identified cyanidine glycosides as the main components. Flavon-3-ols and hydrolysable-tannins were also found. CAA assay showed that extracts of P. trunciflora fruits prevent lipid peroxidation in HepG2 cells with higher efficacy than other colourful fruits (CAA50 935.25 mg FW/mL cell medium). Moreover, our results suggested that the observed antioxidant protection i…
The Antioxidant Potential of White Wines Relies on the Chemistry of Sulfur-Containing Compounds: An Optimized DPPH Assay
2019
The DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay is an easy and efficient method commonly used to determine the antioxidant capacity of many food matrices and beverages. In contrast with red wines, white wines are poorer in antioxidant polyphenolics, and the more hydrophilic sulfur-containing compounds in them may contribute significantly to their antioxidant capacity. The modification of the classical DPPH method, with a methanol-buffer and the measure of EC20 (quantity of sample needed to decrease the initial DPPH concentration by 20%) has shown that sulfur-containing compounds such as cysteine (0.037 ±
Antioxidant and neuroprotective effects of synthesized sintenin derivatives
2009
Three series of sintenin derivatives (compounds 1-14) were designed and prepared and their antioxidative and neuroprotective effects were evaluated. The in vitro models of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, chelating ferrous ions, inhibiting the rat brain homogenates lipid peroxidation, and protecting neurons damaged by hydrogen peroxide were employed for bioassays. It was found that sintenin derivatives 4 and 13 showed remarkable antioxidative and neuroprotective activities.
A new dual inhibitor of arachidonate metabolism isolated from Helichrysum italicum.
2003
Six acetophenones (1-6) and one gamma-pyrone (7), previously isolated from Helichrysum italicum, were tested for their ability to inhibit enzymatic and non-enzymatic lipid peroxidation, the stable 1,1-diphenyl-2-pycryl-hydrazyl free radical, superoxide scavenging and arachidonic acid metabolism. In addition, they were studied in different experimental models such as the chronic inflammation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA), the phospholipase A(2)-induced mouse paw oedema test, the carrageenan-induced mouse paw oedema test, and the writhing induced by acetic acid in the mouse. Of the assayed compounds, only 1 inhibited enzymatic lipid peroxidation but had no effect on no…
Is the chromanol head group of vitamin E nature's final truth on chain-breaking antioxidants?
2012
AbstractTocopherol is believed to be the most potent naturally occurring chain-breaking antioxidant. Hence, its refined phenolic head group chromanol may represent an optimum evolutionary solution to the problem of free-radical chain reactions in the lipid bilayer. To test the universal validity of this assumption beyond phenolic head groups, we have synthesized aromatic amine analogues of vitamin E and trolox with otherwise closely matching physicochemical properties: NH-toc and NH-trox. We have found that NH-toc and NH-trox were significantly more potent free radical scavengers, lipid peroxidation inhibitors and cytoprotective agents than their phenolic templates, tocopherol and trolox. I…
Antioxidant Activity of All-trans-retinol in Homogeneous Solution and in Phosphatidylcholine Liposomes
1993
A kinetic quantification of the lipoperoxyl radical-scavenging activity of all-trans-retinol has been carried out in homogeneous solution, when radicals were produced from the oxidation of methyl linoleate in methanol, initiated by the lipid-soluble 2,2′-azobis (2,4-dimethyl-valeronitrile) (AMVN) as well as in a soybean phosphatidylcholine membrane model, in which peroxidation was induced either by AMVN or the hydrophylic 2,2′-azobis(2-amidinopropane)hydrochloride (AAPH). The physical microenvironment contributes to the determination of antioxidant efficiency of all-trans-retinol. In homogeneous solution the kinetic constant kinh is 3.5 × 105 M-1 s-1 and appears of the same order of magnitu…
Glucose and free radicals impair the antioxidant properties of serum albumin
1999
Epidemiological data consistently show that reduced levels of serum albumin, which is the most abundant protein in plasma, are associated with an increased mortality risk. Various biological properties evidenced by direct effects of the albumin molecule may explain its beneficial effects. The present work aimed to investigate in vitro whether glycation or free radicals or both factors would affect the antioxidant properties of bovine serum albumin (BSA). Glycation was performed by long-term incubations (60 days) of BSA with increasing concentrations of glucose (up to 500 mmol/l) at 37 degreesC. Minimally oxidized BSA was obtained after controlled incubations of dialyzed BSA samples with a w…