Synthesis and Antioxidant Activity of Modified (+)-Catechin Derivatives. Structure-Activity Relationship

2007 ◽  
Vol 2 (7) ◽  
pp. 618-629 ◽  
Author(s):  
Nour-Eddine Es-Safi ◽  
Josiane Beauhaire ◽  
Christine Le Guerneve ◽  
Paul-Henri Ducrot
Keyword(s):  
Antioxidant Activity ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Structure Activity

scholarly journals Antioxidant Activity of 1’-Hydroxyethylnaphthazarins and their Derivatives

2017 ◽  
Vol 12 (12) ◽  
pp. 1934578X1701201
Author(s):  
Natalia K. Utkina ◽  
Natalia D. Pokhilo
Keyword(s):  
Antioxidant Activity ◽  
Radical Cation ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Hydroxyl Group ◽  
Side Chains ◽  
Scavenging Activity ◽  
Structure Activity

The ABTS•+ radical cation scavenging activity of known (2-5, 9, 10) and new (6-8) 1’-hydroxyethylnaphthazarins and their products of esterification and etherification was evaluated and a structure-activity relationship was studied. It was shown, that the structure of side chains does not affect the radical scavenging activity of 1’-hydroxyethylnaphthazarins and their derivatives. The presence of methoxyl groups on the naphthazarin core slightly enhanced the antioxidant activity of compounds compared with compounds without methoxyl groups. The presence of the additional hydroxyl group on the naphthazarin moiety of isonorlomazarin (5) and its derivative (6) is essential for the activity.

scholarly journals CYTOTOXIC AND ANTIOXIDANT ACTIVITIES OF SECONDARY METABOLITES FROM PULICARIA UNDULATA

2016 ◽  
Vol 8 (9) ◽  
pp. 150 ◽  
Author(s):  
Taha A. Hussien ◽  
Sayed A. El-toumy ◽  
Hossam M. Hassan ◽  
Mona H. Hetta
Keyword(s):  
Antioxidant Activity ◽  
Secondary Metabolites ◽  
Antioxidant Activities ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Hep G2 ◽  
Structure Activity ◽  
Dpph Method ◽  
Mcf 7

<p><strong>Objective:</strong><strong> </strong>To evaluate the <em>in vitro</em> cytotoxicity, antioxidant activities and structure-activity relationship of secondary metabolites isolated from <em>Pulicaria undulata</em>.</p><p><strong>Methods: </strong>The methylene chloride-methanol (1:1) extract of the air-dried aerial parts of <em>Pulicaria undulata</em> was fractionated and separated to obtain the isolated compounds by different chromatographic techniques. Structures of the isolated compounds were determined on the basis of the extensive spectroscopic analysis, including 1D and 2D NMR and compared with the literature data. The crude extract and the isolated compounds were evaluated for <em>in vitro</em> antioxidant activity using the 2,2 diphenyl dipicryl hydrazine (DPPH) method and cytotoxic assay using human breast cancer (MCF-7) and hepatoma (Hep G2) cell line.</p><p><strong>Results: </strong>Nine secondary metabolites were isolated from <em>Pulicaria undulata</em> in this study. Of which two terpenoidal compounds; 8-epi-ivalbin and 11β, 13-dihydro-4H-xanthalongin 4-<em>O</em>-β-D-glucopyranoside firstly isolated from the genus <em>pulicaria</em> and three flavonoids; eupatolitin, 6-methoxykaempferol, and patulitrin firstly isolated from <em>P. undulata</em>. 6-methoxykaempferol (IC<sub>50</sub> 2.3 µg/ml) showed the most potent antioxidant activity. The highest cytotoxic effect against MCF-7 and Hep G2 cells was obtained with eupatolitin (IC<sub>50</sub> 27.6 and 23.5 µg/ml) respectively. The structure-activity relationship was also examined and the findings presented here showed that 3, 5, 7, 4' and 3, 5, 4', 5'-hydroxy flavonoids were potent antioxidant and has cytotoxic activity.</p><p><strong>Conclusion: </strong><em>Pulicaria undulata</em> is a promising medicinal plant, and our study tends to support the therapeutic value of this plant as antioxidant drug and in the treatment of cancer.</p>

scholarly journals Antioxidant and Chemosensitizing Effects of Flavonoids with Hydroxy and/or Methoxy Groups and Structure-Activity Relationship

2007 ◽  
Vol 10 (4) ◽  
pp. 537 ◽  
Author(s):  
Ju-Mi Jeong ◽  
Cheol-Hee Choi ◽  
Su-Kyeong Kang ◽  
In-Hwa Lee ◽  
Ji-Yoon Lee ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Oh Groups ◽  
Structure Activity ◽  
P Glycoprotein ◽  
Ic50 Values

Purpose. Flavonoids have been used as antioxidant, chemopreventive and chemosensitizing agents. In this study, eleven flavonoids containing a variety of hydroxy (OH) and/or methoxy (OMe) groups were evaluated for their antioxidant, cytotoxic and chemosensitizing effects to create a structure-activity relationship (SAR). Methods. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical solution-based chemical assay and and 2',7'-dichlorofluorescin diacetate (DCFH-DA) cellular-based assay were used to compare the free radical scavenging activity on the same molar concentration basis using the AML-2/DX100 cells which are characterized by the down-regulated expression of catalase and resulting supersensitiviy to hydrogen peroxide. The chemosensitization and cytotoxicity were determined by the MTT assay in the presence or absence of an anticancer drug using the P-glycoprotein-overexpressing AML-2 subline AML-2/D100 cells. Results. The antioxidant activity of the flavonoid (3,5,7,3’,4’-OH) was higher than that of the flavonoid (5,7,3’,4’-OH). Flavonoids substituted with the various number of OMe decreased antioxidant activity. Flavonoids with 7-OH or 5,7-OH groups have the highest cytotoxicity, and flavonoids with 5,7-OMe group intermediate cytotoxicity. The IC50 values of flavonoid (5,7-OMe, 3’,4’,5’-OMe) and flavonoid (5,7-OMe, 4’-OMe), 0.4 M and 1.4 M. The IC50 values of flavonoid (5,6,7-OMe, 3’,4’-OMe) and flavonoid (5,6,7-OMe, 3’,4’,5’-OMe), 3.2 uM and 0.9 M, respectively, and those of flavonoid (5,6,7-OMe, 3’,4’,5’-OMe) and flavonoid (5,7-OMe,3’,4’,5’-OMe) were 0.9 M and 0.4 M, respectively. Conclusions. These results suggest that flavonoids with 3-OH group play a positive role in antioxidant activities, flavonoids with 5-OH and/or 7-OH groups show the higher cytotoxicity, and flavonoids with 3’-OMe and/or 5’-OMe groups plays positive but 6-OMe groups negative roles in the P-glycoprotein (Pgp) inhibition. It is believed that these SAR results can be taken into account for the development of flavonoids with high therapeutic index.

scholarly journals Probing the Structure-Activity Relationship of an Antioxidant Tuna-Backbone Derived Peptide

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 398-398
Author(s):  
Varun Gopinatth ◽  
Elaine Ballinger ◽  
Jung Kwon
Keyword(s):  
Antioxidant Activity ◽  
Reactive Oxygen ◽  
Structure Activity Relationship ◽  
Peptide Sequence ◽  
Cellular Damage ◽  
Activity Relationship ◽  
Antioxidant Peptides ◽  
Antioxidant Peptide ◽  
Structure Activity ◽  
Relationship Of

Abstract Objectives DNA is easily degraded by reactive oxygen and nitrogen species, and once damaged can cause significant biological problems. Endogenous mechanisms exist to neutralize reactive oxygen species, but nutritional antioxidants provide extra protection against cellular damage. There is interest in identifying antioxidant peptide nutraceuticals that can provide health benefits when included in diets. Current research identifies antioxidant peptides from natural sources but often stops short of examining mechanisms for activity. An antioxidant peptide (APTBP) was previously characterized from tuna backbone protein. This study investigates the structure-activity relationship of APTBP to identify how the specific peptide sequence contributes to the antioxidant activity. Better understanding of the mechanism of antioxidant peptides can provide insight into future screens and combine with predictive software to identify potential antioxidative sequences from protein sources of interest. Methods Peptide array was synthesized by Thermo Fisher. Modifications were chosen in broad categories with possible mechanistic impact including altering the peptide PI, disrupting the secondary structure, increasing or decreasing hydrophobicity, and increasing aromaticity. The array was tested for activity based on the ability to scavenge ABTS free radical. Results APTBP analogs without hydrophilic, and aromatic residues showed significant loss of activity, up to 76.8%. Notably, substitution of a single tryptophan on either terminal end of the peptide resulted in up to 63.1% increased activity, while substitution of tryptophan on both ends decreased activity by 10.3%. Conclusions The antioxidant activity of APTBP is likely the result of a delicate interplay between amino acids in the peptide, but tryptophan residues had an important impact on activity. Tryptophan has an indole side chain, and is a non-polar, aromatic amino acid. The antioxidant activity of ABTBP is significantly linked to the presence of tryptophan, indicating that aromaticity and electron sharing contributes majorly to the ability of ABTBP to scavenge free radicals. The results from this study can help in future research that aims to identify other potential antioxidant peptides as well as ways to increase antioxidant activity of existing peptides. Funding Sources OSU Honors College.

Cytotoxic and antioxidant effects of methoxylated stilbene analogues on HepG2 hepatoma and Chang liver cells: Implications for structure activity relationship

2010 ◽  
Vol 30 (2) ◽  
pp. 138-144 ◽  
Author(s):  
AH Hasiah ◽  
AR Ghazali ◽  
JFF Weber ◽  
S. Velu ◽  
NF Thomas ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Activities ◽  
Structure Activity Relationship ◽  
Liver Cells ◽  
Activity Relationship ◽  
Hydroxyl Groups ◽  
Structure Activity ◽  
Total Antioxidant ◽  
Stilbene Analogues ◽  
Chang Liver

Stilbenes possess a variety of biological activities including chemopreventive activity. This study was conducted to evaluate the structural activity relationships of six methoxylated stilbene analogues with respect to their cytotoxic effects and antioxidant activities on HepG2 hepatoma and Chang liver cells. The cytotoxic and total antioxidant activities of six stilbene analogues were determined by MTT and Ferric Reducing Antioxidant Power (FRAP) assays, respectively. We found that the cis-methoxylated stilbene: (Z)-3,4,4'-trimethoxystilbene was the most potent and selective antiproliferative agent (IC50 89 µM) in HepG2 cells. For the total antioxidant activity, compounds possessing hydroxyl groups at the 4' position namely (E)-3-methoxy-4'-hydroxystilbene, (E)-3,5-dimethoxy-4'-hydroxystilbene (pterostilbene), (E)-4-methoxy-4'-hydroxystilbene showed the highest antioxidant activity. Structure activity relationship studies of these compounds demonstrated that the cytotoxic effect and antioxidant activities of the tested compounds in this study were structurally dependent.

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