Infrared Spectroscopy as a Tool to Study the Antioxidant Activity of Polyphenolic Compounds in Isolated Rat Enterocytes

The protective effect of different polyphenols, catechin (Cat), quercetin (Qc) (flavonoids), gallic acid (GA), caffeic acid (CfA), chlorogenic acid (ChA) (phenolic acids), and capsaicin (Cap), against H2O2-induced oxidative stress was evaluated in rat enterocytes using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and Fourier Transform Infrared Microspectroscopy (FTIRM), and results were compared to standard lipid peroxidation techniques: conjugated dienes (CD) and Thiobarbituric Acid Reactive Substances (TBARS). Analysis of ATR-FTIR and FTIRM spectral data allowed the simultaneous evaluation of the effects of H2O2and polyphenols on lipid and protein oxidation. All polyphenols showed a protective effect against H2O2-induced oxidative stress in enterocytes, when administered before or after H2O2. Cat and capsaicin showed the highest protective effect, while phenolic acids had weaker effects and Qc presented a mild prooxidative effect (IR spectral profile of biomolecules between control and H2O2-treated cells) according to FTIR analyses. These results demonstrated the viability to use infrared spectroscopy to evaluate the oxidant and antioxidant effect of molecules in cell systems assays.

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Effect of oxidative stress on stability and structure of neurofilament proteins

Biochemistry and Cell Biology ◽

10.1139/o00-070 ◽

2000 ◽

Vol 78 (6) ◽

pp. 667-674 ◽

Cited By ~ 30

Author(s):

Sylvie Gélinas ◽

Camille Chapados ◽

Marc Beauregard ◽

Isabelle Gosselin ◽

Maria-Grazia Martinoli

Keyword(s):

Oxidative Stress ◽

Fourier Transform ◽

Infrared Spectroscopy ◽

Circular Dichroism ◽

Free Radical ◽

Fourier Transform Infrared Spectroscopy ◽

Fourier Transform Infrared ◽

Random Coil ◽

Neurofilament Proteins ◽

Circular Dichroïsm

Neurofilament proteins are highly phosphorylated molecules in the axonal compartment of the adult nervous system. We report the structural analysis of neurofilament proteins after oxidative damage. SDS-PAGE, immunoblotting, circular dichroism, and Fourier transform infrared spectroscopy were used to investigate the relative sensitivity of neurofilaments to oxidative stress and to identify changes in their molecular organization. An ascorbate-Fe+3-O2 buffer system as well as catechols were used to generate free radicals on a substrate of phosphorylated and dephosphorylated neurofilaments. By Fourier Transform Infrared spectroscopy and circular dichroism, we established that the neurofilament secondary structure is mainly composed of α-helices and that after free radical damage of the peptide backbone of neurofilaments, those helices are partly modified into β-sheet and random coil structures. These characteristic reorganizations of the neurofilament structure after oxidative exposure suggest that free radical activity might play an important role in the biogenesis of the cytoplasmic inclusions found in several neurodegenerative diseases.Key words: neurofilaments, oxidative stress, neurodegeneration, phosphorylation, infrared spectroscopy, circular dichroism.

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