1-1-diphenyl-2-picrylhydrazyl and Arteriosclerosis

Geiji-Bokryung-Hwan (GBH), a drug preparation consisting of five herbs of Cinnamomi Ramulus (Geiji), Poria Cocos (Bokryun), Mountan Cortex Radicis (Mokdanpi), Paeoniae Radix (Jakyak) and Persicae Semen (Doin), is a traditional Korean herbal medicine that is widely used in the treatment of atherosclerosis-related disorders. A water extract of GBH was found to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and inhibit low-density lipoprotein (LDL) oxidation more effectively than probucol, a well-known commercially available antioxidant. In order to evaluate the anti-atherogenic potential of this medication, New Zealand White (NZW) rabbits were fed a normal diet for 12 weeks, a high cholesterol diet, a high cholesterol diet containing 1% probucol or a high cholesterol diet containing 5% water-soluble extract of GBH. Both GBH and probucol reduced plasma cholesterol levels. LDLs from the GBH-treated group were more resistant to Cu(2+)-induced oxidation and contained more vitamin E than LDLs from the high cholesterol diet group. Endothelial damage, determined at week 6, was reduced by 55% in the GBH group (P<0.01). GBH treatment reduced an atherosclerotic area in the abdominal aorta by 58% (P<0.05) and cholesterol deposition in the thoracic aorta by 55% (P<0.05). The severity of atherosclerosis in the GBH group was significantly reduced after an adjustment using cholesterol exposure as an index of the cholesterol-lowering effect. On the other hand, diet-induced hyperlipidemic rabbits were given water extract of GBH in doses of 50 (Group B) and 200 mg/kg (Group C) and compared with controls (Group A). At 40 days after intervention in groups A, B and C, total and LDL cholesterol levels were significantly lowered (P<0.01). LDL/high density lipoprotein (HDL) ratio was also significantly decreased (P<0.01). This study concludes that the reduction in atherosclerosis by GBH relies not only on its cholesterol-lowering effect but also more heavily on its antioxidant potential, which prevents endothelial damage and inhibits LDL oxidative modification in hypercholesterolemic animals.

Topics: Animals; Anticholesteremic Agents; Arteriosclerosis; Biphenyl Compounds; Cholesterol, Dietary; Cholesterol, LDL; Endothelium, Vascular; Free Radical Scavengers; Hypercholesterolemia; Lipoproteins; Male; Oxidation-Reduction; Phytotherapy; Picrates; Plant Extracts; Rabbits; Vitamin E

Studies in vitro reveal that fluvastatin, an HMG-CoA reductase inhibitor, has a strong DPPH radical scavenging activity and achieves concentration-dependent inhibition of copper- and cell-induced oxidation of low-density lipoprotein (LDL). To further examine the anti-oxidative activity of fluvastatin in vivo, we elucidated the effects of chronic treatment with fluvastatin at a dose insufficient to reduce plasma cholesterol levels (2 mg/kg per day) on vasomotion and vascular oxidative stress in thoracic aortas of 0.5% cholesterol-fed rabbits. After 12 weeks of dietary treatment, aortic segments from rabbits fed cholesterol alone showed impaired endothelium-dependent relaxation responses to acetylcholine and A23187 compared to normal chow-fed rabbits in association with a significant increase in plasma total cholesterol levels. In contrast, although plasma total cholesterol levels were not different from those in control cholesterol-fed rabbits, aortic segments from fluvastatin-treated rabbits showed normal relaxation. Compared with rabbits fed cholesterol alone, fluvastatin treatment decreased susceptibility of LDL to ex vivo copper-induced oxidation, reduced vascular superoxide generation, and atheromatous plaque formation. In conclusion, the potent anti-oxidative properties of fluvastatin in addition to its cholesterol-lowering activity appear to contribute to its anti-atherosclerotic effect in vivo.

Topics: Animals; Antioxidants; Aorta; Arteriosclerosis; Bepridil; Biphenyl Compounds; Cells, Cultured; Cholesterol, Dietary; Copper; Endothelium, Vascular; Fatty Acids, Monounsaturated; Fluvastatin; Free Radical Scavengers; Free Radicals; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; In Vitro Techniques; Indoles; Ions; Lipids; Lipoproteins, LDL; Male; Muscle, Smooth, Vascular; Picrates; Rabbits; Superoxides

Flavonoids, a group of polyphenolic compounds, exist naturally and serve as antioxidants in vegetables, fruits, and so on. The inhibition of low density lipoprotein (LDL) oxidation may be an effective way to prevent or delay the progression of atherosclerosis. In the present study, we analyzed the radical scavenging capacity of 10 flavonoids (catechin, epicatechin [EC], epigallocatechin [EGC], epicatechin gallate [ECg], epigallocatechin gallate [EGCg], myricetin, quercetin, apigenin, kaempferol, and luteolin) toward 1,1-diphenyl-2-picryl-hydrazyl [DPPH]. After 20 min of incubation, EGCg was the most effective DPPH radical scavenger, luteolin being the least active of this flavonoid group. The mutual antioxidant effect of flavonoids with alpha-tocopherol (alpha-toc) on LDL oxidizability was investigated by using the lipophilic azo radical initiator 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) [AMVN-CH3O]. An inhibitory effect of flavonoids on LDL oxidation was observed in the order of luteolin>ECg>EC>quercetin>catechin>EGCg>EGC>myricetin>kaempferol> apigenin. The shortened lag time induced by higher doses of alpha-toc (6 mg/100 mL) was restored by flavonoids. These results suggest that 1) radical trapping effects of flavonoids differ according to their structure, and 2) flavonoids act as hydrogen donors to alpha-toc radical; furthermore, by interaction with alpha-toc, they have a greater potential to delay the oxidation of LDL.

Topics: Antioxidants; Arteriosclerosis; Biphenyl Compounds; Catechin; Dose-Response Relationship, Drug; Flavonoids; Free Radical Scavengers; Humans; In Vitro Techniques; Indicators and Reagents; Lipoproteins, LDL; Oxidation-Reduction; Phenols; Picrates; Polymers

Antioxidants that prevent LDL from oxidation may reduce atherosclerosis. Salvia miltiorrhiza Bunge is a Chinese herb widely used for the treatment of atherosclerosis-related disorders. Salvianolic acid B (Sal B), a water-soluble polyphenolic antioxidant isolated from the roots of this plant, was found to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals and inhibit LDL oxidation more effectively than probucol. In order to evaluate the antiatherogenic potential, New Zealand White rabbits were fed for 12 weeks a normal diet, a high cholesterol diet, a high cholesterol diet containing 1% probucol, or a high cholesterol diet containing a 5% water-soluble extract of S miltiorrhiza (SM). Both SM and probucol feeding reduced plasma cholesterol. LDLs from the SM-treated group were more resistant to Cu2+-induced oxidation and contained more vitamin E (21.7+/-2.1 mmol/micromol LDL cholesterol) than did LDLs from the high cholesterol diet group (9.6+/-1.8 nmnol/micromol LDL cholesterol) (P<.005). Endothelial damage, determined at week 6, was reduced by 53% in the SM group (P<.01). SM treatment reduced the atherosclerotic area in the abdominal aorta by 56% (P<.005) and cholesterol deposition in the thoracic aorta by 50% (P<.005). The severity of atherosclerosis in the SM group was significantly reduced after adjustment by using cholesterol exposure as an index of the cholesterol-lowering effect. This study concludes that the reduction of atherosclerosis by SM relies not only on its cholesterol-lowering effect but more heavily on its antioxidant potential to prevent endothelial damage and inhibit LDL oxidative modification in hypercholesterolemic animals.

Topics: Animals; Anticholesteremic Agents; Antioxidants; Aorta; Arteriosclerosis; Bepridil; Biphenyl Compounds; Cholesterol; Cholesterol, Dietary; Drugs, Chinese Herbal; Endothelium, Vascular; Free Radical Scavengers; Lipoproteins, LDL; Male; Oxidation-Reduction; Picrates; Probucol; Rabbits; Solubility; Vitamin E; Water

The effect of beta-blockers (alprenolol, oxprenolol, atenolol, acebutolol) and the non-steroidal anti-inflammatory drug, diclofenac, on modification of low-density lipoproteins (LDL) by sodium hypochlorite (NaOCl) was investigated in vitro. Beta-blockers and diclofenac inhibit the formation of thiobarbituric acid reactive substances in LDL modified by NaOCl. Beta-blockers, but not diclofenac, inhibit the hypochlorite-induced aggregation of LDL which was determined by photon correlation spectroscopy. The intracellular accumulation of cholesterol esters in J774 macrophages is inhibited by addition of beta-blockers, but not diclofenac, to LDL prior to the addition of NaOCl. The modification inhibiting effect of beta-blockers is inversely correlated to the binding capabilities of these substances to LDL which were assessed by laser electrophoresis. Inhibition of LDL modification in vivo by beta-blockers may reduce the risk of atherosclerosis and, therefore, compensate for the cholesterol-raising effect of these drugs in human plasma.

Topics: Acebutolol; Adrenergic beta-Antagonists; Alprenolol; Anti-Inflammatory Agents, Non-Steroidal; Arteriosclerosis; Atenolol; Bepridil; Biphenyl Compounds; Chemical Phenomena; Chemistry; Cholesterol Esters; Diclofenac; Free Radicals; Humans; Lipoproteins, LDL; Macrophages; Molecular Structure; Oxprenolol; Particle Size; Picrates; Sodium Hypochlorite; Spectrum Analysis; Thiobarbituric Acid Reactive Substances

Homocysteine is an independent risk factor for cardiovascular diseases. The mechanisms by which elevated plasma concentrations of homocysteine are related to the pathogenesis of atherosclerosis are not fully understood. To examine whether homocysteine is implicated in atherogenesis through the modification of low density lipoprotein (LDL), the effect of homocysteine on the oxidation of LDL was studied by three different oxidation systems. Thus, LDL was subjected to Cu(2+)-catalyzed, azo compound-initiated, and peripheral blood mononuclear cell-mediated oxidative modification. The extent of modification was assessed by measuring the formation of conjugated dienes, lipid peroxides, thiobarbituric acid-reactive substances, and the relative electrophoretic mobility. Homocysteine at a normal plasma concentration (6 microM) showed no effect, whereas a concentration corresponding to moderate hyperhomocysteinemia (25 microM) or to concentrations seen in homocystinuria patients (100, 250, and 500 microM) protected LDL from modification of the lipid as well as of the protein moiety. One exception was observed: when the oxidation was initiated by copper ions, homocysteine at concentrations 6 and 25 microM stimulated the lipid peroxidation of LDL to a small, but statistically significant extent. High concentrations of homocysteine showed antioxidative properties as long as the thiol groups were intact, thereby delaying the onset of the oxidation. The 1,1-diphenyl-2-picrylhydracyl radical test demonstrated that homocysteine at concentrations > or = 50 microM possessed marked free radical scavenging capacity. Finally, LDL isolated from two patients with homozygous homocystinuria showed similar extent of Cu(2+)-catalyzed oxidation as LDL from a group of healthy control subjects. Taken together, our data suggest that low concentrations of homocysteine in the presence of copper ions may enhance the lipid peroxidation of LDL, whereas high concentrations of homocysteine may protect LDL against oxidative modification in the lipid as well as in the protein moiety. Thus, homocysteine-induced atherosclerosis may be explained by mechanisms other than oxidative modification of low density lipoprotein.

Topics: Adolescent; Adult; Amidines; Arteriosclerosis; Azo Compounds; Bepridil; Biphenyl Compounds; Child; Copper; Female; Free Radical Scavengers; Homocysteine; Homocystinuria; Humans; Leukocytes, Mononuclear; Lipid Peroxidation; Lipoproteins, LDL; Male; Middle Aged; Picrates