scholarly journals Formation of free radical products by the reaction of dehydro-ascorbic acid or ninhydrin with aromatic amines.

1978 ◽  
Vol 42 (4) ◽  
pp. 809-817 ◽  
Author(s):  
Midori YANO ◽  
Tateki HAYASHI ◽  
Mitsuo NAMIKI
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Aromatic Amines ◽  
Dehydro Ascorbic Acid

scholarly journals Antioxidant, Antibacterial and Cytotoxic Activity of the Methanol Extract of Urtica Crenulata

2009 ◽  
Vol 2 (1) ◽  
pp. 169-177
Author(s):  
M. A. Rahman ◽  
M. S. Rana ◽  
M. M. Zaman ◽  
S. A. Uddin ◽  
R. Akter
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Cytotoxic Activity ◽  
Brine Shrimp ◽  
Methanol Extract ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Brine Shrimp Lethality ◽  
Brine Shrimp Lethality Assay ◽  
Stem Extract

The antioxidant, antibacterial and cytotoxic properties of methanol extract of Urtica crenulata (syn: Laportea crenulata Gaud) stem has been investigated in the present study. The antioxidant and cytotoxic activity of the Urtica crenulata methanol extract were assessed by DPPH free radical scavenging method and brine shrimp lethality bioassay method, respectively. The antibacterial activity of the plant extract (500 μg/disc) was also carried out by disc diffusion technique. Stem extract showed DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging effect compared with ascorbic acid. IC50 value of ascorbic acid and stem extract was found 14.72 μg/ml and 1468.9 μg/ml, respectively. In antibacterial experiment, Urtica crenulata stem extract showed 8, 14 and 10 mm of diameter of zone inhibition against Salmonella typhi, Shigella flexneri and Shigella sonnei, respectively and 9 and 8 mm of diameter of zone inhibition against Bacillus subtilis and Bacillus cereus but no activity was observed against Staphylococcus aureus. In brine shrimp lethality assay, the LC50 value of the extract was found 104.0 μg/ml, which indicates that the extract has high cytoxic effect. The present study demonstrates that methanol extract of Urtica crenulata stem has significant cytotoxic effect. The extract also showed some moderate antibacterial and minimum significant antioxidant effects.  Keywords: Urtica crenulata;  Antioxidant; Antibacterial; Cytotoxic; BHT. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.2872             J. Sci. Res. 2 (1), 169-177 (2010) 

Free Radical Scavenging and Antioxidant Activity of Ascorbigen Versus Ascorbic Acid: Studies in Vitro and in Cultured Human Keratinocytes

2008 ◽  
Vol 56 (24) ◽  
pp. 11694-11699 ◽  
Author(s):  
Anika E. Wagner ◽  
Patricia Huebbe ◽  
Tetsuya Konishi ◽  
M. Mamunur Rahman ◽  
Meiko Nakahara ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Free Radical ◽  
Radical Scavenging ◽  
Human Keratinocytes ◽  
Free Radical Scavenging

scholarly journals Ascorbic acid improves brachial artery vasodilation during progressive handgrip exercise in the elderly through a nitric oxide-mediated mechanism

2016 ◽  
Vol 310 (6) ◽  
pp. H765-H774 ◽  
Author(s):  
Joel D. Trinity ◽  
D. Walter Wray ◽  
Melissa A. H. Witman ◽  
Gwenael Layec ◽  
Zachary Barrett-O'Keefe ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Ascorbic Acid ◽  
Free Radical ◽  
Brachial Artery ◽  
Vascular Function ◽  
The Elderly ◽  
Voluntary Contraction ◽  
Dependent Manner ◽  
Handgrip Exercise ◽  
Age Related

The proposed mechanistic link between the age-related attenuation in vascular function and free radicals is an attractive hypothesis; however, direct evidence of free radical attenuation and a concomitant improvement in vascular function in the elderly is lacking. Therefore, this study sought to test the hypothesis that ascorbic acid (AA), administered intra-arterially during progressive handgrip exercise, improves brachial artery (BA) vasodilation in a nitric oxide (NO)-dependent manner, by mitigating free radical production. BA vasodilation (Doppler ultrasound) and free radical outflow [electron paramagnetic resonance (EPR) spectroscopy] were measured in seven healthy older adults (69 ± 2 yr) during handgrip exercise at 3, 6, 9, and 12 kg (∼13–52% of maximal voluntary contraction) during the control condition and nitric oxide synthase (NOS) inhibition via NG-monomethyl-l-arginine (l-NMMA), AA, and coinfusion of l-NMMA + AA. Baseline BA diameter was not altered by any of the treatments, while l-NMMA and l-NMMA + AA diminished baseline BA blood flow and shear rate. AA improved BA dilation compared with control at 9 kg (control: 6.5 ± 2.2%, AA: 10.9 ± 2.5%, P = 0.01) and 12 kg (control: 9.5 ± 2.7%, AA: 15.9 ± 3.7%, P < 0.01). NOS inhibition blunted BA vasodilation compared with control and when combined with AA eliminated the AA-induced improvement in BA vasodilation. Free radical outflow increased with exercise intensity but, interestingly, was not attenuated by AA. Collectively, these results indicate that AA improves BA vasodilation in the elderly during handgrip exercise through an NO-dependent mechanism; however, this improvement appears not to be the direct consequence of attenuated free radical outflow from the forearm.

Free-radical-mediated oxidation of ascorbic acid by peroxomonosulphate

2003 ◽  
Vol 29 (4) ◽  
pp. 393-405 ◽  
Author(s):  
P. Raja ◽  
A. S. Faritha ◽  
N. Kumaraguru ◽  
R. Renganathan
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Mediated Oxidation
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