Structure of Ascorbic Acid and Its Biological Function:

It could be shown by the reduction of the spin label (1,14) located within DPPC vesicles, that Na-ascorbate and K-isoascorbate can permeate membranes. At physiologic pH value, these two compounds exist as electroneutral radicals with a cyclic side chain structure. Ascorbic acid and isoascorbic acid, on the contrary, can hardly permeate such an artificial membrane. Since the radical will cause lipid peroxidation, it must be modified prior to permeation. This can be done by GSH which changes the radical state but maintains the electroneutral bicyclic configuration

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Structure of ascorbic acid and its biological function. Determination of the conformation of ascorbic acid and isoascorbic acid by infrared and ultraviolet investigations

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1984.tb07941.x ◽

1984 ◽

Vol 138 (3) ◽

pp. 479-480 ◽

Cited By ~ 31

Author(s):

Wolfgang LOHMANN ◽

Detlef PAGEL ◽

Volker PENKA

Keyword(s):

Ascorbic Acid ◽

Biological Function ◽

Isoascorbic Acid

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Notizen: Influence of Temperature on the Transport of Ascorbate across Artificial Membranes as Studied by the Spin Label Technique

Zeitschrift für Naturforschung C ◽

10.1515/znc-1986-0317 ◽

1986 ◽

Vol 41 (3) ◽

pp. 348-350 ◽

Cited By ~ 5

Author(s):

W. Lohmann ◽

P. z. Tian ◽

D. Holz

Keyword(s):

Phase Transition ◽

Vitamin C ◽

Spin Label ◽

Chain Structure ◽

Permeation Rate ◽

Effect Of Temperature ◽

Side Chain ◽

Influence Of Temperature ◽

Label Technique ◽

Influence Of Temperature On

The effect of temperature on the permeation of vitamin C across membranes of DPPC vesicles labelled with the spin label 1,14 has been investigated. It could be shown that at temperatures above 40 °C the permeation rate is diminished considerably despite the fact that, at these temperatures, the spin label can rotate freely (above phase transition temperature) indicating that the membrane is more fluid. The results obtained agree well with previous findings (W. Lohmann and D. Holz. Biophys. Struct. Mech. 10, 197 (1984)) according to which the furanoid ring formed by the side chain of this vitamin opens at these temperatures. The existence of a bicyclic side-chain structure seems to be a prerequisite for the permeation of vitamin C.

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Molecularly Imprinted Sensor for Ascorbic Acid Based on Gold Nanoparticles and Multiwalled Carbon Nanotubes

Current Analytical Chemistry ◽

10.2174/1573411015666191029152332 ◽

2020 ◽

Vol 16 (7) ◽

pp. 905-913

Author(s):

Youyuan Peng ◽

Qingshan Miao

Keyword(s):

Carbon Nanotubes ◽

Gold Nanoparticles ◽

Ascorbic Acid ◽

Multiwalled Carbon Nanotubes ◽

Ph Value ◽

Biological Fluids ◽

Water Soluble ◽

Multiwalled Carbon ◽

Experimental Conditions ◽

Molecularly Imprinted

Background: L-Ascorbic acid (AA) is a kind of water soluble vitamin, which is mainly present in fruits, vegetables and biological fluids. As a low cost antioxidant and effective scavenger of free radicals, AA may help to prevent diseases such as cancer and Parkinson’s disease. Owing to its role in the biological metabolism, AA has also been utilized for the therapy of mental illness, common cold and for improving the immunity. Therefore, it is very necessary and urgent to develop a simple, rapid and selective strategy for the detection of AA in various samples. Methods: The molecularly imprinted poly(o-phenylenediamine) (PoPD) film was prepared for the analysis of L-ascorbic acid (AA) on gold nanoparticles (AuNPs) - multiwalled carbon nanotubes (MWCNTs) modified glass carbon electrode (GCE) by electropolymerization of o-phenylenediamine (oPD) and AA. Experimental parameters including pH value of running buffer and scan rates were optimized. Scanning electron microscope (SEM), fourier-transform infrared (FTIR) spectra, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for the characterization of the imprinted polymer film. Results: Under the selected experimental conditions, the DPV peak currents of AA exhibit two distinct linear responses ranging from 0.01 to 2 μmol L-1 and 2 to 100 μmol L-1 towards the concentrations of AA, and the detection limit was 2 nmol L-1 (S/N=3). Conclusion: The proposed electrochemical sensor possesses excellent selectivity for AA, along with good reproducibility and stability. The results obtained from the analysis of AA in real samples demonstrated the applicability of the proposed sensor to practical analysis.

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Relationship of 25-hydroxyvitamin D3 side chain structure to biological activity.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)42004-8 ◽

1975 ◽

Vol 250 (1) ◽

pp. 226-230

Author(s):

M F Holick ◽

M Garabedian ◽

H K Schnoes ◽

H F DeLuca

Keyword(s):

Biological Activity ◽

Chain Structure ◽

Side Chain ◽

Relationship Of

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Total Antioxidant Capacity and Lipid Peroxidation Status in Cervical Cancer Patients Compared with Women Without Cervical Cancer in Bangladesh

Indian Journal of Gynecologic Oncology ◽

10.1007/s40944-021-00560-6 ◽

2021 ◽

Vol 19 (4) ◽

Author(s):

Taslima Nigar ◽

Annekathryn Goodman ◽

Shahana Pervin

Keyword(s):

Oxidative Stress ◽

Cervical Cancer ◽

Lipid Peroxidation ◽

Ascorbic Acid ◽

Antioxidant Capacity ◽

Cancer Patients ◽

Total Antioxidant Capacity ◽

Stress Index ◽

Oxidative Stress Index ◽

Total Antioxidant

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.

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