3 results on '"K. Singh, Brajendra"'
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2. Antioxidant properties of 4-methylcoumarins in in vitro cell-free systems
- Author
-
Giuseppa Morabito, K. Prasad Ashok, Omidreza Firuzi, Domenico Trombetta, Antonina Saija, Mariateresa Cristani, S. Parmar Virinder, Ferdinando Mancari, Clara Naccari, Luciano Saso, and K. Singh Brajendra
- Subjects
hypochlorous ,Antioxidant ,antioxidant ,DPPH ,medicine.medical_treatment ,Phospholipid ,4-Methylcoumarins ,AAPH ,Liposome ,Hypochlorous ,Nitric Oxide ,Biochemistry ,Redox ,chemistry.chemical_compound ,Coumarins ,Superoxides ,cell-free systems ,medicine ,Structure–activity relationship ,Animals ,aaph ,ABTS ,Cell-Free System ,Superoxide ,4-methylcoumarins ,General Medicine ,antioxidants ,liposome ,Hypochlorous Acid ,chemistry ,Liposomes ,Lipid Peroxidation ,Artemia ,Fluorescence Recovery After Photobleaching - Abstract
4-Methylcoumarins that possess two hydroxyl groups ortho to each other in the benzenoid ring have shown to have excellent antioxidant and radical-scavenging properties in different experimental models. Furthermore, they cannot be metabolized by the liver P450 monoxygenases and thus cannot form 3,4-coumarin epoxides, which are believed to be mutagenic. Herein, we present a study on the structure activity relationship of eight synthetic 4-methylcoumarins, carried out by employing a series of different chemical cell-free tests. These compounds were tested by means of three assays involving one redox reaction with the oxidant (DPPH assay, ABTS + assay and FRAP). Other assays were employed to evaluate the antioxidant properties of the coumarins under investigation against NO, O2 − and HClO, which are some of the major reactive oxygen and nitrogen species causing damage in the human body. Finally, we have measured the protective capacity of these coumarins against the oxidative damage in a simple biomimetic model of phospholipid membranes. Our results confirm the good antioxidant activity of the 7,8-hydroxy-4-methylcoumarins. In general, their activity is not significantly affected by the introduction of an ethoxycarbonylmethyl or an ethoxycarbonylethyl moiety at the C3 position. A discrete antioxidant activity is retained also by the 7,8-diacetoxy-4-methylcoumarins, although they are less efficient than the corresponding 7,8-dihydroxy compounds. Furthermore, as demonstrated in the brine shrimp toxicity test, none of the tested coumarins significantly affect the larvae viability. Two of the 4-methylcoumarins (7,8-dihydroxy-4-methylcoumarin and 7,8-dihydroxy-3-ethoxycarbonylethyl-4-methylcoumarin), very interestingly, showed strong scavenging activities against the superoxide anion and were also very effective in protecting the lipid bilayer against peroxidation. On the basis of these findings, these 4-methylcoumarins may be considered as potential therapeutic candidates for pathological conditions characterized by free radical overproduction.
- Published
- 2010
3. Antioxidant properties of 4-methylcoumarins in in vitro cell-free systems.
- Author
-
Morabito G, Trombetta D, Singh Brajendra K, Prasad Ashok K, Parmar Virinder S, Naccari C, Mancari F, Saija A, Cristani M, Firuzi O, and Saso L
- Subjects
- Animals, Artemia drug effects, Coumarins pharmacology, Fluorescence Recovery After Photobleaching, Hypochlorous Acid chemistry, Lipid Peroxidation drug effects, Liposomes chemistry, Nitric Oxide chemistry, Superoxides chemistry, Antioxidants chemistry, Antioxidants pharmacology, Cell-Free System, Coumarins chemistry
- Abstract
4-methylcoumarins that possess two hydroxyl groups ortho to each other in the benzenoid ring have shown to have excellent antioxidant and radical-scavenging properties in different experimental models. Furthermore, they cannot be metabolized by the liver P450 monoxygenases and thus cannot form 3,4-coumarin epoxides, which are believed to be mutagenic. Herein, we present a study on the structure activity relationship of eight synthetic 4-methylcoumarins, carried out by employing a series of different chemical cell-free tests. These compounds were tested by means of three assays involving one redox reaction with the oxidant (DPPH assay, ABTS.+ assay and FRAP). Other assays were employed to evaluate the antioxidant properties of the coumarins under investigation against NO, O2.- and HClO, which are some of the major reactive oxygen and nitrogen species causing damage in the human body. Finally, we have measured the protective capacity of these coumarins against the oxidative damage in a simple biomimetic model of phospholipid membranes. Our results confirm the good antioxidant activity of the 7,8-hydroxy-4-methylcoumarins. In general, their activity is not significantly affected by the introduction of an ethoxycarbonylmethyl or an ethoxycarbonylethyl moiety at the C3 position. A discrete antioxidant activity is retained also by the 7,8-diacetoxy-4-methylcoumarins, although they are less efficient than the corresponding 7,8-dihydroxy compounds. Furthermore, as demonstrated in the brine shrimp toxicity test, none of the tested coumarins significantly affect the larvae viability. Two of the 4-methylcoumarins (7,8-dihydroxy-4-methylcoumarin and 7,8-dihydroxy-3-ethoxycarbonylethyl-4-methylcoumarin), very interestingly, showed strong scavenging activities against the superoxide anion and were also very effective in protecting the lipid bilayer against peroxidation. On the basis of these findings, these 4-methylcoumarins may be considered as potential therapeutic candidates for pathological conditions characterized by free radical overproduction., (Copyright (c) 2010 Elsevier Masson SAS. All rights reserved.)
- Published
- 2010
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