scholarly journals Structural dependence of flavonoid interactions with Cu2+ ions: implications for their antioxidant properties

1998 ◽  
Vol 330 (3) ◽  
pp. 1173-1178 ◽  
Author(s):  
E. Jonathan BROWN ◽  
Hicham KHODR ◽  
C. Robert HIDER ◽  
Catherine A. RICE-EVANS
Keyword(s):  
Antioxidant Activity ◽  
Complex Formation ◽  
Hydroxy Group ◽  
Low Density Lipoprotein ◽  
Antioxidant Properties ◽  
Density Lipoprotein ◽  
Low Density ◽  
Structural Dependence ◽  
Chelate Formation

The flavonoids constitute a large group of polyphenolic phytochemicals with antioxidant properties in vitro. The interactions of four structurally related flavonoids (quercetin, kaempferol, rutin and luteolin) with Cu2+ ions were investigated in terms of the extent to which they undergo complex formation through chelation or modification through oxidation, as well as in their structural dependence. The ortho 3ʹ,4ʹ-dihydroxy substitution in the B ring is shown to be important for Cu2+-chelate formation, thereby influencing the antioxidant activity. The presence of a 3-hydroxy group in the flavonoid structure enhances the oxidation of quercetin and kaempferol, whereas luteolin and rutin, each lacking the 3-hydroxy group, do not oxidize as readily in the presence of Cu2+ ions. The results also demonstrate that the reactivities of the flavonoids in protecting low-density lipoprotein (LDL) against Cu2+ ion-induced oxidation are dependent on their structural properties in terms of the response of the particular flavonoid to Cu2+ ions, whether chelation or oxidation, their partitioning abilities between the aqueous compartment and the lipophilic environment within the LDL particle, and their hydrogen-donating antioxidant properties.

scholarly journals Influence of Honey on the Suppression of Human Low Density Lipoprotein (LDL) Peroxidation (In Vitro)

2009 ◽  
Vol 6 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Ahmed G. Hegazi ◽  
Faten K. Abd El-Hady
Keyword(s):  
Antioxidant Activity ◽  
Hplc Analysis ◽  
Low Density Lipoprotein ◽  
Radical Scavenging ◽  
Density Lipoprotein ◽  
Free Radical Scavenging ◽  
Low Density ◽  
Dpph Assay ◽  
Free Radical Scavenging Assay

The antioxidant activity of four honey samples from different floral sources (Acacia, Coriander, Sider and Palm) were evaluated with three different assays; DPPH free radical scavenging assay, superoxide anion generated in xanthine–xanthine oxidase (XOD) system and low density lipoprotein (LDL) peroxidation assay. The dark Palm and Sider honeys had the highest antioxidant activity in the DPPH assay. But all the honey samples exhibited more or less the same highly significant antioxidant activity within the concentration of 1mg honey/1 ml in XOD system and LDL peroxidation assays. The chemical composition of these samples was investigated by GC/MS and HPLC analysis, 11 compounds being new to honey. The GC/MS revealed the presence of 90 compounds, mainly aliphatic acids (37 compounds), which represent 54.73, 8.72, 22.87 and 64.10% and phenolic acids (15 compound) 2.3, 1.02, 2.07 and 11.68% for Acacia, Coriander, Sider and Palm honeys. In HPLC analysis, 19 flavonoids were identified. Coriander and Sider honeys were characterized by the presence of large amounts of flavonoids.

Antioxidant properties of aged garlic extract: an in vitro study incorporating human low density lipoprotein

Life Sciences ◽  
2003 ◽  
Vol 72 (14) ◽  
pp. 1583-1594 ◽  
Author(s):  
Stephanie A Dillon ◽  
Rajpal S Burmi ◽  
Gordon M Lowe ◽  
David Billington ◽  
Khalid Rahman
Keyword(s):  
Low Density Lipoprotein ◽  
Antioxidant Properties ◽  
Density Lipoprotein ◽  
In Vitro Study ◽  
Garlic Extract ◽  
Vitro Study ◽  
Low Density ◽  
Aged Garlic Extract ◽  
Aged Garlic

scholarly journals Reductions of copper ion-mediated low-density lipoprotein (LDL) oxidations of trypsin inhibitors, the sweet potato root major proteins, and LDL binding capacities

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Yeh-Lin Lu ◽  
Chia-Jung Lee ◽  
Shyr-Yi Lin ◽  
Wen-Chi Hou
Keyword(s):  
Sweet Potato ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Trypsin Inhibitors ◽  
Water Soluble ◽  
Affinity Column ◽  
Low Density ◽  
Native Page

Abstract Background The root major proteins of sweet potato trypsin inhibitors (SPTIs) or named sporamin, estimated for 60 to 80% water-soluble proteins, exhibited many biological activities. The human low-density lipoprotein (LDL) showed to form in vivo complex with endogenous oxidized alpha-1-antitrypsin. Little is known concerning the interactions between SPTIs and LDL in vitro. Results The thiobarbituric-acid-reactive-substance (TBARS) assays were used to monitor 0.1 mM Cu2+-mediated low-density lipoprotein (LDL) oxidations during 24-h reactions with or without SPTIs additions. The protein stains in native PAGE gels were used to identify the bindings between native or reduced forms of SPTIs or soybean TIs and LDL, or oxidized LDL (oxLDL). It was found that the SPTIs additions showed to reduce LDL oxidations in the first 6-h and then gradually decreased the capacities of anti-LDL oxidations. The protein stains in native PAGE gels showed more intense LDL bands in the presence of SPTIs, and 0.5-h and 1-h reached the highest one. The SPTIs also bound to the oxLDL, and low pH condition (pH 2.0) might break the interactions revealed by HPLC. The LDL or oxLDL adsorbed onto self-prepared SPTIs-affinity column and some components were eluted by 0.2 M KCl (pH 2.0). The native or reduced SPTIs or soybean TIs showed different binding capacities toward LDL and oxLDL in vitro. Conclusion The SPTIs might be useful in developing functional foods as antioxidant and nutrient supplements, and the physiological roles of SPTIs-LDL and SPTIs-oxLDL complex in vivo will investigate further using animal models.

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