scholarly journals Reaction of tyrosine oxidation products with proteins of the lens

1968 ◽  
Vol 109 (2) ◽  
pp. 301-305 ◽  
Author(s):  
Antoinette Pirie
Keyword(s):  
Ascorbic Acid ◽  
Fluorescence Spectra ◽  
Ferrous Sulphate ◽  
Oxidation Products ◽  
Thiol Groups ◽  
Lens Proteins ◽  
Bovine Lens ◽  
Tyrosine Oxidation ◽  
Cataractous Lens

Oxidation of tyrosine in the presence of bovine lens proteins leads to the formation of brown or black melanoproteins. Both tyrosinase and the oxidizing system of ferrous sulphate–ascorbic acid–EDTA are effective. The fluorescence of the lens proteins is both altered and enhanced by the tyrosine-oxidizing systems. Their fluorescence spectra resemble those of urea-insoluble proteins of human cataractous lens and of 1,2-naphthaquinone–proteins of naphthalene cataract. The lens proteins lose their thiol groups and, in acid hydrolysates of treated β-and γ-crystallins, a substance has been detected chromatographically that behaves similarly to a compound formed when 3,4-dihydroxyphenylalanine (dopa) is oxidized by tyrosinase in the presence of cysteine. Analysis and behaviour of this substance from hydrolysates of lens proteins suggest that it is a compound of cysteine and dopa.

scholarly journals Glycation by ascorbic acid oxidation products leads to the aggregation of lens proteins

2008 ◽  
Vol 1782 (1) ◽  
pp. 22-34 ◽  
Author(s):  
Mikhail Linetsky ◽  
Ekaterina Shipova ◽  
Rongzhu Cheng ◽  
Beryl J. Ortwerth
Keyword(s):  
Ascorbic Acid ◽  
Oxidation Products ◽  
Acid Oxidation ◽  
Lens Proteins

THE APPLICATION OF NATURAL AND SYNTHETIC ANTIOXIDANTS TO INCREASE THE OXIDATION RESISTANCE OF LINSeED OIL

2020 ◽  
Vol 13 (4(50)) ◽  
pp. 41-51
Author(s):  
I. P. Edimecheva ◽  
A. A. Sosnovskaya ◽  
O. I. Shadyro
Keyword(s):  
Ascorbic Acid ◽  
Kinetic Data ◽  
Room Temperature ◽  
Linseed Oil ◽  
Ascorbyl Palmitate ◽  
Natural Antioxidants ◽  
Oxidation Products ◽  
Free Access ◽  
Synthetic Antioxidants ◽  
Acid Esters

The effectiveness of several synthetic and natural antioxidants (AO) in inhibiting the oxidation of linseed oil has been studied. Under the conditions of accelerated oxidation at 100 °С, the values of the induction period of oxidation and stabilization factors of linseed oil in the presence of additives of known phenolic AOs, tocopherols, fat-soluble ascorbic acid esters and compositions based on them were determined. The data obtained indicate that ascorbic acid esters effectively inhibit the oxidation of linseed oil. The stabilizing effect of ascorbyl palmitate (AP) increases with an elevation in the content of α-linolenic acid in the oil and a decrease in the oxidative stability of the oil. One AP provided better stabilization efficiency than some known compositions based on it. Kinetic data on the accumulation of oxidation products in linseed oil with AP additives during the storage at room temperature and with free access of the air were obtained, demonstrating high inhibiting activity of AP under these conditions, which provides a possibility to increase the shelf life of the stabilized oil up to 18 months or more.

scholarly journals Iron absorption from rice meals cooked with fortified salt containing ferrous sulphate and ascorbic acid

1974 ◽  
Vol 31 (3) ◽  
pp. 367-375 ◽  
Author(s):  
M. H. Sayers ◽  
S. R. Lynch ◽  
R. W. Charlton ◽  
T. H. Bothwell ◽  
R. B. Walker ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Iron Absorption ◽  
Ferrous Sulphate ◽  
Striking Difference ◽  
Red Cell ◽  
Indian Women ◽  
Threefold Increase ◽  
Cooking Process ◽  
Wide Range ◽  
The Mean

1. Iron absorption from rice-containing meals was measured by red cell utilization of radioactive Fe in sixty-six volunteer multiparous Indian women.2. In all the studies salt added during the cooking process was used as the carrier for supplemental inorganic Fe and ascorbic acid.3. Intrinsic Fe in the rice and supplementary inorganic Fe were absorbed to the same extent, with a wide range of absorption values.4. There was a striking difference between the mean absorption of a 3 mg dose of ferrous Fe given to fasting subjects in a solution containing 30 mg ascorbic acid and that of Fe in a rice meal (48.7 and 3.5% respectively).5. When ascorbic acid was added during cooking there was a threefold increase in the absorption of both intrinsic Fe and supplementary Fe when a sufficient quantity (60 mg) was present.6. It is concluded that the Fe nutrition of rice-eating communities could be improved significantly by the addition of ascorbic acid to the diet.

Effect of Ascorbic and Isoascorbic acids on Survival of Campylobacter jejuni in Poultry Meat1

1988 ◽  
Vol 51 (6) ◽  
pp. 436-437 ◽  
Author(s):  
B. J. JUVEN ◽  
J. KANNER ◽  
H. WEISSLOWICZ ◽  
S. HAREL
Keyword(s):  
Ascorbic Acid ◽  
Toxic Effect ◽  
Campylobacter Jejuni ◽  
Death Rate ◽  
Test Organism ◽  
Oxidation Products ◽  
Turkey Meat

Samples of radiation-sterilized mechanically deboned turkey meat were inoculated with a strain of Campylobacter jejuni, stored at 5°C, and viable counts of the test organism determined during a 7-week period. As compared to results obtained with unsupplemented samples, addition of ascorbic acid or sodium isoascorbate (erythorbate) to the meat, at a concentration of 5 mmol/kg, caused an increase in the death rate of C. jejuni. Autooxidation of these compounds, during storage of the meat, supports the view that their toxic effect is mainly due to their oxidation products.

Tyrosine oxidation products: analysis and biological relevance

Amino Acids ◽  
2003 ◽  
Vol 25 (3-4) ◽  
pp. 227-232 ◽  
Author(s):  
C. Giulivi ◽  
N. J. Traaseth ◽  
K. J. A. Davies
Keyword(s):  
Oxidation Products ◽  
Biological Relevance ◽  
Tyrosine Oxidation ◽  
Products Analysis

scholarly journals Effects of menopause and tibolone on antioxidants in postmenopausal women

2005 ◽  
Vol 42 (3) ◽  
pp. 220-223 ◽  
Author(s):  
Perin Vural ◽  
Cemil Akgül ◽  
Mukaddes Canbaz
Keyword(s):  
Oxidative Stress ◽  
Ascorbic Acid ◽  
Postmenopausal Women ◽  
Plasma Concentrations ◽  
Lipid Peroxide ◽  
Lipid Peroxides ◽  
Thiol Groups ◽  
Plasma Ascorbic Acid ◽  
Total Thiol ◽  
Significant Difference

Background: Oxidative stress has been implicated in the pathogenesis of ageing and menopause, and can arise through the increased production of lipid peroxides and/or a deficiency of antioxidant defence. Aim: To investigate the effects of the menopause and tibolone treatment (2.5 mg/day for six months) on plasma antioxidants and lipid peroxidation. Methods: Plasma concentrations of ascorbic acid, α-tocopherol, total thiol groups, caeruloplasmin, erythrocyte glutathione (GSH) and malondialdehyde (MDA) were measured in 24 postmenopausal and 24 premenopausal healthy women. Results: Data analysis indicates a significant decrease in plasma ascorbic acid, α-tocopherol, total thiol groups, caeruloplasmin, erythrocyte GSH and a significant increase in lipid peroxides (expressed as MDA concentrations) in postmenopausal women. There was no significant difference between control and study groups in the mean plasma caeruloplasmin concentrations. It was found that there is a significant increase in α-tocopherol and significant decrease in lipid peroxide concentrations in postmenopausal after tibolone treatment. Conclusions: The menopause is associated with an increase in oxidative stress and a decrease of some antioxidants, such as ascorbic acid, α-tocopherol, total thiols and erythrocyte GSH. Tibolone treatment leads to a decrease in concentrations of plasma lipid peroxide, probably by stimulating direct and indirect mechanisms of tocopherol regeneration and increasing plasma concentrations of vitamin E. However, due to the relatively small numbers involved this study can be regarded as a pilot. Further studies performed on a larger scale are necessary to establish the exact mechanisms of tibolone in inhibiting oxidative stress in postmenopausal women.

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