Dong Young Rhyu

The inhibitory effects of 12 medicinal plants and their component compounds on lipid peroxidation

The antioxidative activities of 12 medicinal plants and the compounds isolated from them were investigated using the thiocyanate method to evaluate inhibitory effects on lipid peroxidation in the linoleic acid system. The peroxide levels gradually increased during incubation in the presence of linoleic acid over 3 days, and most of the plants inhibited lipid peroxidation. In particular, of the plants tested, Cudrania tricuspidata, Zanthoxylum piperitum, Houttuynia cordata and Ulmus parvifolia reduced lipid peroxidation more effectively as lipid peroxidation progressed, resulting in inhibition of about 80% relative to the control value by the 3rd day of incubation. In addition, the polyphenols isolated from the plants also showed marked and dose-dependent inhibitory effects on lipid peroxidation. The compounds with the strongest activities were 3,4-dihydroxylbenzoic acid, quercetin, the quercetin glycosides quercetin-3-O-beta-D-galactoside, quercetin-3-O-alpha-L-rhamnoside, quercetin-3-O-beta-D-glucoside and quercetin-3-O-rutinose, catechin, gallic acid, methyl gallate and rosamultin isolated from Zanthoxylum piperitum, Houttuynia cordata, Rosa rugosa and Cedrela sinensis. Moreover, quercetin glycosides showed stronger activity than quercetin, suggesting that glycosylation increases the antioxidative activity of quercetin. Our results indicate that the medicinal plants and their polyphenols show promise as therapeutic agents for various disorders involving free radical reactions.

Glycyrrhizae Radix attenuates peroxynitrite-induced renal oxidative damage through inhibition of protein nitration

We investigated the protective effects of Glycyrrhizae Radix extract against peroxynitrite (ONOO−)-induced oxidative stress under in vivo as well as in vitro conditions. The extract showed strong ONOO− and nitric oxide (NO) scavenging effects under in vitro system, in particular higher activity against ONOO−. Furthermore, elevations of plasma 3-nitrotyrosine levels, indicative of in vivo ONOO− generation and NO production, were shown using a rat in vivo ONOO−-generation model of lipopolysaccharide injection plus ischemia-reperfusion. The administration of Glycyrrhizae Radix extract at doses of 30 and 60 mg/kg body weight/day for 30 days significantly reduced the concentrations of 3-nitrotyrosine and NO and decreased inducible NO synthase activity. In addition, the nitrated tyrosine protein level and myeloperoxidase activity in the kidney were significantly lower in rats given Glycyrrhizae Radix extract than in control rats. However, the administration of Glycyrrhizae Radix extract did not result in either significant elevation of glutathione levels or reduction of lipid peroxidation in renal mitochondria. Moreover, the in vivo ONOO− generation system resulted in renal functional impairment, reflected by increased plasma levels of urea nitrogen and creatinine, whereas the administration of Glycyrrhizae Radix extract reduced these levels significantly, implying that the renal dysfunction induced by ONOO− was ameliorated. The present study suggests that Glycyrrhizae Radix extract could protect the kidneys against ONOO− through scavenging ONOO− and/or its precursor NO, inhibiting protein nitration and improving renal dysfunction caused by ONOO−.

Potential of Sanguiin H-6 against Oxidative Damage in Renal Mitochondria and Apoptosis Mediated by Peroxynitrite in vivo

Potential of sanguiin H-6, a component of Sanguisorbae Radix, to protect against oxidative damage in renal mitochondria and apoptosis mediated by peroxynitrite (ONOO–) was examined using a model in which rats were injected with lipopolysaccharide (LPS) and then subjected to renal ischemia followed reperfusion (LPS plus ischemia-reperfusion). Ischemia-reperfusion was achieved by occluding bilateral renal artery for 60 min and then releasing for 350 min. At 50 min after ischemia started, LPS was injected intravenously. LPS plus ischemia-reperfusion induced a large amount of 3-nitrotyrosine, an oxidative product of protein that is produced via ONOO– nitration, which was not detectable in normal group. Oxidative damage of mitochondria was indicated by an accumulated thiobarbituric acid (TBA)-reactive substance, glutathione (GSH) depletion and glutathione peroxidase (GSH-Px) inactivation in the mitochondria. Treatment of rats with sanguiin H-6 (10 mg/kg body weight/day) for 30 days prior to LPS plus ischemia-reperfusion attenuated the oxidative damage in the mitochondria. The amount of TBA-reactive substance was decreased and the GSH levels significantly increased as compared with that in control group. However, its effect on GSH-Px activity was much weaker. Apoptosis induced by LPS plus ischemia-reperfusion was detected by fluorescence staining, TdT-mediated dUTP-biotin nick end labeling and electrophoretic analysis. Sanguiin H-6 appeared to inhibit apoptosis, and this was associated with the suppression of caspase-3 activity. These beneficial effects of sanguiin H-6 against oxidative damage in mitochondria and apoptosis contributed to the improvement in renal function by reversing the elevated levels of blood urea nitrogen and creatinine caused by ONOO–.

(-)-Epicatechin 3-O-gallate ameliorates the damages related to peroxynitrite production by mechanisms distinct from those of other free radical inhibitors.

This study was carried out to elucidate whether the protective activity of (–)‐epicatechin 3‐O‐gallate (ECg) against excessive peroxynitrite (ONOO−) production, is distinct from the activity of several well‐known free radical inhibitors, the ONOO− inhibitors ebselen and uric acid, the superoxide anion (O2−) scavenger copper zinc superoxide dismutase (CuZnSOD) and the selective inducible nitric oxide synthase inhibitor l‐N6‐(1‐iminoethyl)lysine hydrochloride (l‐NIL). To generate ONOO−, male Wistar rats (n = 6/group) were subjected to ischaemia–reperfusion process together with lipopolysaccharide (LPS) injection. Although ECg did not scavenge the ONOO− precursors nitric oxide (NO) and O2−, it reduced the 3‐nitrotyrosine level, a property similar to that of uric acid, but distinct from l‐NIL. In addition, the elevation in myeloperoxidase activity was reversed by the administration of ECg, uric acid and SOD, but not by that of l‐NIL. Furthermore, ECg was the more potent scavenger of the ONOO− decomposition product, the hydroxyl radical (·OH), than any other free radical inhibitor tested. The LPS plus ischaemia–reperfusion process resulted in renal dysfunction, estimated by measuring the parameters of renal function – serum urea nitrogen and creatinine levels. However, administration of ECg ameliorated renal dysfunction more than that of the other free radical inhibitors. Moreover, ECg reduced the excessive uric acid level, while the others did not, suggesting a property of ECg distinct from the others. Furthermore, proteinuria, which was demonstrated by the low‐ and high‐molecular weight (LMW and HMW) protein bands of the sodium dodecyl sulfate‐polyacrylamide gel electrophoresis pattern, caused by LPS plus ischaemia–reperfusion, was attenuated by administration of ECg and l‐NIL, after which the HMW band intensities decreased and LMW protein bands were absent. This study indicates that, in an in‐vivo model of ONOO− generation, ECg, l‐NIL and uric acid exert stronger protective activity against ONOO−‐induced oxidative damage than SOD and ebselen, and that the mechanism whereby ECg protects against ONOO− is distinct from that of l‐NIL or uric acid.

Prevention of peroxynitrite-induced renal injury through modulation of peroxynitrite production by the Chinese prescription Wen-Pi-Tang

The effect of Wen-Pi-Tang extract on renal injury induced by peroxynitrite (ONOO m ) production was investigated using rats subjected to intravenous lipopolysaccharide (LPS) injection and then renal ischemia followed by reperfusion. The plasma level of 3-nitrotyrosine, a marker of cytotoxic ONOO m formation in vivo, was enhanced markedly in control rats subjected to LPS plus ischemia-reperfusion, but was significantly reduced by the oral administration of Wen-Pi-Tang extract, at doses of 62.5 and 125 mg/kg body weight/day, for 30 days prior to LPS plus ischemia-reperfusion. The activities of inducible nitric oxide synthase (iNOS) and xanthine oxidase (XOD) in renal tissue of control and Wen-Pi-Tang extract-treated rats did not change significantly, while those of the antioxidant enzymes, superoxide dismutase, catalase and gluta-thione peroxidase, were significantly increased by the administration of Wen-Pi-Tang extract, indicating that Wen-Pi-Tang improved the defense system by scavenging free radicals, not by directly inhibiting nitric oxide and superoxide production by iNOS and XOD. In addition, the levels of the hydroxylated products, m - and p -tyrosine, declined, whereas that of phenylalanine increased, after oral administration of Wen-Pi-Tang extract. Furthermore, the elevated plasma urea nitrogen and creatinine levels resulting from LPS plus ischemia-reperfusion process were significantly reduced by Wen-Pi-Tang extract, implying amelioration of renal impairment. The present study indicates that Wen-Pi-Tang extract contributes to the regulation of ONOO m formation and plays a beneficial role against ONOO m -induced oxidative injury and renal dysfunction in vivo .

Protection by the Chinese prescription Wen-Pi-Tang against renal tubular LLC-PK1 cell damage induced by 3-morpholinosydnonimine.

We investigated the effects of Wen‐Pi‐Tang extract on the protective mechanisms of renal tubular LLC‐PK1 cells, as renal tubular cells are the most vulnerable renal tissue to oxidative stress. Exposure to 800 μM 3‐morpholinosydnonimine (SIN‐1) resulted in a marked increase in cellular peroxynitrite (ONOO−), which converted nonfluorescent dihydrorhodamine 123 to fluorescent rhodamine 123, a detectable probe for the long‐lived ONOO−. In addition, it resulted in apoptotic cell death, assessed by a DNA fragmentation assay. However, treatment with Wen‐Pi‐Tang extract, at concentrations of 50 and 100 μg mL−1 together with SIN‐1 protected renal tubular cells against ONOO− through scavenging ONOO− and inhibiting apoptotic cell death in a dose‐dependent manner. Moreover, treatment with Wen‐Pi‐Tang extract both before and after exposure to SIN‐1 was also protective: it reduced cellular ONOO− levels, increased cell viability and decreased the DNA fragmentation rate. These results suggest that Wen‐Pi‐Tang would have protective activity against ONOO−‐induced renal tubular injury through the inhibition of ONOO− production and apoptotic cell death by both preventing and treating renal injury. Furthermore, morphological characteristics of apoptosis were observed in SIN‐1 treated tubular cells, while the addition of Wen‐Pi‐Tang extract with SIN‐1 attenuated these morphological changes. ONOO− generated by SIN‐1 also disturbed the cell cycle by decreasing the cellular G2/M phase ratio, while Wen‐Pi‐Tang extract regulated the cell cycle by G2/M phase arrest.

Protective Activity of (−)-Epicatechin 3- O -gallate against Peroxynitrite-mediated Renal Damage

The protective effect of ( m )-epicatechin 3- O -gallate (ECg) against peroxynitrite (ONOO m )-mediated damage was examined using an animal model and a cell culture system. In rats subjected to lipopolysaccharide (LPS) administration plus ischemia-reperfusion, the plasma 3-nitrotyrosine level, an indicator of ONOO m production in vivo, was elevated, whereas it declined significantly and dose-dependently after the oral administration of ECg at doses of 10 and 20 w moles/kg body weight/day for 20 days prior to the process. Moreover, oral administration of ECg significantly enhanced the activities of the antioxidant enzymes, superoxide dismutase, catalase and glutathione peroxidase, and the antioxidant glutathione, showing enhancement of the biological defense system against the damage induced by ONOO m . In addition, the significant increase in the renal mitochondrial thiobarbituric acid-reactive substance level of LPS and ischemic-reperfused control rats was attenuated in rats given ECg. Furthermore, the elevations in the plasma urea nitrogen and creatinine (Cr) levels and the urinary methylguanidine/Cr ratio induced by the procedure were attenuated markedly after oral administration of ECg, implying amelioration of renal impairment. The addition of ECg (25 or 125 w M) prior to 3-morpholinosydnonimine (SIN-1, 800 w M) exposure reduced ONOO m formation and increased the viability of cultured renal epithelial (LLC-PK 1 ) cells in a dose-dependent manner. In particular, ECg inhibited ONOO m -mediated apoptotic cell death, which was confirmed by decreases in the DNA fragmentation rate and the presence of apoptotic morphological changes, i.e. small nuclei and nuclear fragmentation. Furthermore, adding ECg before SIN-1 treatment regulated the cell cycle by enhancing G 2 /M phase arrest. This study provides evidence that ECg has protective activity against the renal damage induced by excessive ONOO m in cellular and in vivo systems.

Anti-Obesity Effects of the Mixture of Eriobotrya japonica and Nelumbo nucifera in Adipocytes and High-Fat Diet-Induced Obese Mice.

The present study is to evaluate the anti-obesity effects of Eriobotrya japonica (EJ), Nelumbo nucifera (NN), and their mixture (MIX, 1:1 ratio) in 3T3-L1 adipocytes and high-fat diet-induced obese mice. The treatment of EJ, NN, and MIX in 3T3-L1 adipocytes effectively inhibited lipid accumulation, significantly decreased expression of peroxisome proliferator-activated receptor gamma (PPARγ), sterol regulatory element binding protein (SREBP1c), and adipocyte lipid-binding protein (aP2), and significantly increased phosphorylation of AMP-activated protein kinase (AMPK). Moreover, oral treatment of MIX showed stronger effects than individual treatment. C57BL/6J mice (6 week old) were divided into two groups; low fat diet (LFD) containing 10% calories from fat and high fat diet (HFD) containing 60% calories from fat. The HFD groups were further divided into five subgroups; treated with distilled water (HFD), treated with 400 mg/kg EJ (EJ400), treated with 400 mg/kg NN (NN400), treated with 200 mg/kg MIX (MIX200), and treated with 400 mg/kg MIX (MIX400) during 13 weeks. In our results, the administration of EJ, NN, and MIX significantly decreased body weight (BW), fat weight, liver weight, hepatic triglyceride (TG) and total cholesterol (TC), lipid droplets in the liver, food efficacy ratio, and the plasma TG, TC, glucose, insulin, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in a dose-dependent manner, and MIX treatment showed stronger effect than their individual treatments. Similarly, MIX treatment decreased the expression of PPARγ, SREBP-1c, FAS, and ACC more strongly in the adipose tissue than single treatments. In conclusion, the MIX of EJ and NN extract may strongly regulate BW gain than EJ or NN alone, and its anti-obesity effect is associated with the control of lipid metabolism, including adipogenesis and lipogenesis.

Lespedeza davurica (Lax.) Schindl. Extract Protects against Cytokine-Induced β-Cell Damage and Streptozotocin-Induced Diabetes

Lespedeza has been used for the management of diabetes in folklore medicine. The purpose of this study is to investigate the protective effects of the methanol extract of Lespedeza davurica (LD) on cytokine-induced β-cell damage and streptozotocin- (STZ-) induced diabetes. RINm5F cells were treated with interleukin- (IL-) 1β and interferon- (IFN-) γ to induce pancreatic β-cell damage. The exposure of LD extract significantly decreased cell death, nitric oxide (NO) production, nitric oxide synthase (iNOS) expression, and nucleus factor-kappa B (NF-κB) p65 activation. Antidiabetic effects of LD extract were observed by oral glucose tolerance test (OGTT) in normal rats and by checking the biochemical, physiological, and histopathological parameters in STZ-induced diabetic rats. In OGTT, glucose clearance levels improved by oral treatment of LD extract. The water intake, urine volume, blood glucose, and serum TG, TC, TBARS, and DPP-IV levels were significantly decreased, and liver glycogen content was significantly increased by treatment of LD extract (250 mg/kg BW) in STZ-induced diabetic rats. Also, insulin immunoreactivity of the pancreases was increased in LD extract administrated rats compared with diabetic control rats. These results indicate that LD extract may protect pancreatic β-cell damage and regulate the blood glucose in STZ-induced diabetic rats.