Simultaneous amperometric detection of ascorbic acid and antioxidant capacity in orange, blueberry and kiwi juice, by a telemetric system coupled with a fullerene- or nanotubes-modified ascorbate subtractive biosensor

2015 ◽  
Vol 67 ◽  
pp. 214-223 ◽  
Author(s):  
Antonio Barberis ◽  
Ylenia Spissu ◽  
Angela Fadda ◽  
Emanuela Azara ◽  
Gianfranco Bazzu ◽  
...  
2019 ◽  
Vol 11 (3) ◽  
pp. 771-784
Author(s):  
Elisa Tatiana S. Damasceno ◽  
Regiamara R. Almeida ◽  
Bruna C. Pires ◽  
Flavia Viana A. Dutra ◽  
Keyller B. Borges ◽  
...  

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Taslima Nigar ◽  
Annekathryn Goodman ◽  
Shahana Pervin

Abstract Purpose Over the past several decades, research has suggested reactive oxygen species act as cofactors for cervical cancer development. The aim of this study is to evaluate the antioxidant and lipid peroxidation status in cervical cancer patients in Bangladesh. Methods From December 2017 to 2018, a cross-sectional observational study was conducted on 50 cervical cancer patients and 50 controls. Plasma levels of lipid peroxidation and total antioxidant capacity were measured. The Student’s t test was used for statistical analysis. P values less than 0.05 were taken as a level of significance. Results There was a significant reduction in total antioxidant levels in patients with cervical cancer, 972.77 ± 244.22 SD µmol equivalent to ascorbic acid/L, compared to normal controls, 1720.13 ± 150.81 SD µmol equivalent to ascorbic acid/L (P < 0.001). Levels of lipid peroxidation were found to be significantly higher in cervical cancer, 7.49 ± 2.13 SD µmol/L, than in women without cervical cancer, 3.28 ± 0.58 SD µmol/L (P < 0.001). The cervical cancer patients had significantly higher levels of oxidative stress index (0.83 ± 0.31) in comparison to controls (0.19 ± 0.04) (P < 0.001). Conclusion There was an increased oxidative stress index due to imbalance between lipid peroxidation generation and total antioxidant capacity in cervical cancer patients. Further studies are needed to explore the role of oxidative stress as a cofactor for cervical carcinogenesis.


2020 ◽  
Vol 18 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Ping Tang ◽  
Xiaosheng Tang ◽  
Shiyong Mei ◽  
Yixi Xie ◽  
Liangliang Liu ◽  
...  

AbstractIn this study, an electrochemical biosensor based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE) was developed and employed for antioxidant screening and antioxidant capacity evaluation. The oxidation peak current of guanine was improved and nearly tripled after modifications of chitosan and MoS2 nanosheet. The immobilized guanine could be damaged by hydroxyl radicals generated in Fenton solution. However, in the presence of antioxidants, the guanine was protected and the oxidation peak current of guanine increased. This process mimics the mechanism of antioxidant protection in human body. The factors affecting preparation of sensor and detection of antioxidant capacity were optimized. At the optimum conditions, the guanine/CS/MoS2/GCE showed wide linear range, low detection limit, satisfactory reproducibility and stability for detection. Ascorbic acid was used as a model antioxidant to evaluate the antioxidant capacity. A good linearity was observed with a correlation coefficient of 0.9959 in the concentrations between 0.5 and 4.0 mg L-1. The antioxidant capacities of three flavonoids were also tested and the rank of antioxidant capacities was ascorbic acid (51.84%), quercetin (45.82%), fisetin (34.39%) and catechin (16.99%). Due to the rapid measurement and low cost, this sensor could provide an available sensing platform for antioxidant screening and evaluation.


2012 ◽  
Vol 40 (1) ◽  
pp. 222 ◽  
Author(s):  
Otakar ROP ◽  
Martin POSOLDA ◽  
Jiri MLCEK ◽  
Vojtech REZNICEK ◽  
Jiri SOCHOR ◽  
...  

During the last century due to the changes in landscape management, in country people’s lives and with intensive fruit-growing the native cultivars of apple fruit trees have been gradually disappearing. The aim of the study was to compare the juices made of native apple cider cultivars. The cultivars-‘Boikovo’, ‘Jadernicka moravska’, ‘Kardinal zihany’, ‘Panenske ceske’, ‘Parmena zlata zimni’, ‘Strymka’ growing in the locality of the Litencicke Hills in the eastern part of the Czech Republic were selected. For comparison, the fruits of commercial ‘Idared’ cultivar were also included. The chemical composition, antioxidant capacity, phenols, flavonoids and ascorbic acid content and the influence of juices on scavenging activity of nitric oxide and hydroxyl radical were measured. The mutual ratio of examined properties which were found, provide information about qualities and possibilities of use of native cultivars. High antioxidant properties characterize the juice of native apple cultivars. In particular, the ‘Strymka’ cultivar contained 2,637.34 mg of AAE (ascorbic acid equivalent) per litre in case of antioxidant capacity. In the juice of this cultivar the value of 144.05 mg of ascorbic acid per litre was recorded. As regards the ‘Panenske ceske’ cultivar, antioxidant capacity was 2,548.38 mg of AAE l-1 and in relation to ascorbic acid, the value was 145.35 mg l-1. Similarly, high values were observed in both cultivars concerning the scavenging effect of apple juices on hydroxyl radical and nitric oxide (the ‘Strymka’ cultivar 16.38% and 19.26%, the ‘Panenske ceske’ cultivar 16.31% and 18.60%).


Author(s):  
Лукьянова ◽  
Yuliya Lukyanova

The aim of the study was to detect significant biochemical changes in antioxidant status during acute period of ischemic stroke in its various pathogenic subtypes in patients aged 45–74years. The most important results were blood levels of ascorbic acid, malondialdehyde and free/ oxidized glutathione ratio. Cardioembolic stroke was associated with: the reduced ascorbic acid level of 62–74% comparable to control group; 5-times increased malondialdehyde level at the end of the first week of the disease; and also 50% decreasing of cell antioxidant capacity comparable to control group and other stroke subtypes. In lacunary stroke minimal changes in antioxidant status were measured, possibly because of small size of brain damage. Positive clinical dynamics was followed by decreasing of free glutathione levels. It could be related with its previous significant expenditure in process of cell recovery in penumbra area. In case of favorable outcome all of the markers return to the levels which were comparable to control group. The differences in the dynam-ics of the cells antioxidant capacity and consumption of native antioxidants, the time from the onset of the disease, the severity of the clinical picture, depending on the stroke subtype, were revealed. Further research of this problem may help to create new methods of diagnostics and selective pharmacological correction of this pathology.


2013 ◽  
Vol 2 (2) ◽  
pp. 33-37 ◽  
Author(s):  
Fatema Nasrin

Modern civilization is facing more than hundreds of disorders associated with free radicals and natural antioxidants from non-edible plants are gaining importance to fight these disorders. The intention of this report is to evaluate a well known medicinal weed Ageratum conyzoides stems for its antioxidant and cytotoxic Effects. Antioxidant potentiality of the crude methanolic extract of the Ageratum conyzoides (AC) stems was investigated on DPPH scavenging activity, reducing ability, total antioxidant capacity as well as total phenolic contents. Cytotoxic study was done by brine shrimp lethality bioassay and vincristin sulphate was used as standard. The total phenols and total antioxidant capacity of AC was found to be 38.125 ± 2.01mg/g equivalent of gallic acid and 333.37 ± 4.22mg/gm equivalent of ascorbic acid, respectively. The percentage (%) scavenging of DPPH free radical of the extract was found to be concentration dependent with IC50 value 46.01 ± 2.23µg/ml while IC50 value of standard ascorbic acid was found to be 29.56 ± 0.11?g/ml. The reducing power of AC was found to be concentration dependent. The cytotoxicity exhibited by AC was found promising with LC50 value 1.32?g/ml, comparing with the LC50 (0.689?g/ml) values of vincristin sulphate. The present investigation suggests that Ageratum conyzoides possesses remarkable antioxidant and cytotoxic property.DOI: http://dx.doi.org/10.3329/icpj.v2i2.13195 International Current Pharmaceutical Journal 2013, 2(2): 33-37


2018 ◽  
Vol 6 (48) ◽  
pp. 13293-13304 ◽  
Author(s):  
Sandra Hernandez-Aldave ◽  
Robert B. Kaspar ◽  
Michael P. Letterio ◽  
Afshin Tarat ◽  
Yushan Yan ◽  
...  

Ionomer (TPQPCl)/graphite nanoplatelet-coated electrodes are developed as a new sensing platform for amperometric detection of ascorbic acid.


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