Anthocyanins Inhibits Oxidative Injury in Human Retinal Pigment Epithelial ARPE-19 Cells via Activating Heme Oxygenase-1

Anthocyanins belong to phenolic pigments and are known to have various pharmacological activities. This study aimed to investigate whether anthocyanins could inhibit hydrogen peroxide (H2O2)-induced oxidative damage in human retinal pigment epithelial ARPE-19 cells. Our results indicated that anthocyanins suppressed H2O2-induced genotoxicity, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione. Anthocyanins also suppressed H2O2-induced apoptosis by reversing the Bcl-2/Bax ratio and inhibiting caspase-3 activation. Additionally, anthocyanins attenuated the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Moreover, anthocyanins increased the expression of heme oxygenase-1 (HO-1) as well as its activity, which was correlated with the phosphorylation and nuclear translocation of nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the cytoprotective and anti-apoptotic effects of anthocyanins were significantly attenuated by the HO-1 inhibitor, demonstrating that anthocyanins promoted Nrf2-induced HO-1 activity to prevent ARPE-19 cells from oxidative stress. Therefore, our findings suggest that anthocyanins, as Nrf2 activators, have potent ROS scavenging activity and may have the potential to protect ocular injury caused by oxidative stress.

β-Asarone Alleviates High-Glucose-Induced Oxidative Damage via Inhibition of ROS Generation and Inactivation of the NF-κB/NLRP3 Inflammasome Pathway in Human Retinal Pigment Epithelial Cells

Diabetic retinopathy (DR) is the leading cause of vision loss and a major complication of diabetes. Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is an important risk factor for DR. β-asarone, a major component of volatile oil extracted from Acori graminei Rhizoma, exerts antioxidant effects; however, its efficacy in DR remains unknown. In this study, we investigated whether β-asarone inhibits high-glucose (HG)-induced oxidative damage in human retinal pigment epithelial (RPE) ARPE-19 cells. We found that β-asarone significantly alleviated cytotoxicity, apoptosis, and DNA damage in HG-treated ARPE-19 cells via scavenging of ROS generation. β-Asarone also significantly attenuated the excessive accumulation of lactate dehydrogenase and mitochondrial ROS by increasing the manganese superoxide dismutase and glutathione activities. HG conditions markedly increased the release of interleukin (IL)-1β and IL-18 and upregulated their protein expression and activation of the nuclear factor-kappa B (NF-κB) signaling pathway, whereas β-asarone reversed these effects. Moreover, expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome multiprotein complex molecules, including thioredoxin-interacting protein, NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain, and cysteinyl aspartate-specific proteinase-1, were increased in ARPE-19 cells under HG conditions. However, their expression levels remained similar to those in the control group in the presence of β-asarone. Therefore, β-asarone protects RPE cells from HG-induced injury by blocking ROS generation and NF-κB/NLRP3 inflammasome activation, indicating its potential as a therapeutic agent for DR treatment.

A systematic review on anti-diabetic action of 7-O-galloyl-D-sedoheptulose, a polyphenol from Corni Fructus, in type 2 diabetic mice with hepatic and pancreatic damage

Traditional medicines are recently being focused on to treat diabetes and its complications because of their lack of toxic and/or side effects. This report describes the effects of 7-O-galloyl-D-sedoheptulose (GS), a polyphenolic compound isolated from Corni Fructus, on type 2 diabetic db/db mice with hepatic and pancreatic damage. We examined several biochemical factors and oxidative stress- and inflammation-related markers. In the serum, levels of glucose, leptin, insulin, C-peptide, resistin, tumor necrosis factor-α, and interleukin-6 were down-regulated, while adiponectin was augmented by GS treatment. In addition, GS suppressed the reactive oxygen species and lipid peroxidation in the serum, liver, and pancreas, but increased the pancreatic insulin and pancreatic C-peptide contents. These results were derived from attenuating the expression of nicotinamide adenine dinucleotide phosphate oxidase subunit proteins, Nox-4 and p22^phox. Augmented nuclear factor (NF)-E2-related factor 2 and heme oxygenase-1 were reduced with a decrease in oxidative stress during GS treatment. NF-κB-related pro-inflammatory factors were also alleviated in hepatic tissue. Moreover, GS modulated the protein expressions of pro-inflammatory NF-κB, cyclooxygenase-2, inducible nitric oxide synthase, c-Jun N-terminal kinase (JNK), phosphor-JNK, activator protein-1, transforming growth factor-β₁, and fibronectin. Based on these results, we demonstrated that the anti-diabetic action of GS may be due to its anti-oxidative stress property and anti-inflammatory action.

Phloroglucinol Attenuates DNA Damage and Apoptosis Induced by Oxidative Stress in Human Retinal Pigment Epithelium ARPE-19 Cells by Blocking the Production of Mitochondrial ROS

Phloroglucinol, a phenolic compound, is known to possess a potent antioxidant ability. However, its role in retinal cells susceptible to oxidative stress has not been well elucidated yet. Thus, the objective of this study was to evaluate whether phloroglucinol could protect against oxidative damage in cultured human retinal pigment epithelium ARPE-19 cells. For this purpose, ARPE-19 cells were stimula ted with hydrogen peroxide (H₂O₂) to mimic oxidative stress. Cell viability, cytotoxicity, apoptosis, reactive oxygen species (ROS) generation, mitochondrial function, DNA damage, and autophagy were then assessed. Our results revealed that phloroglucinol ameliorated cell viability, cytotoxicity, and DNA damage in H₂O₂-exposued ARPE-19 cells and blocked production of ROS. Phloroglucinol also counteracted H₂O₂-induced apoptosis by reducing Bax/Bcl-2 ratio, blocking activation of caspase-3, and inhibiting degradation of poly (ADP-ribose) polymerase. H₂O₂ caused mitochondrial impairment and increased expression levels of mitophagy markers such as PINK1and PARKIN known to be associated with mitochondrial ROS (mtROS) generation and cytosolic release of cytochrome c. However, these changes were significantly attenuated by phloroglucinol. Mito-TEMPO, a selective mitochondrial antioxidant, further enhanced the protective effect of phloroglucinol against dysfunctional mitochondria. Furthermore, H₂O₂ induced autophagy, but not when ARPE-19 cells were pretreated with phloroglucinol, meaning that autophagy by H₂O₂ contributed to the pro-survival mechanism and that phloroglucinol protected ARPE-19 cells from apoptosis by blocking autophagy. Taken together, these results suggest that phloroglucinol can inhibit oxidative stress-induced ARPE-19 cell damage and dysfunction by protecting DNA damage, autophagy, and subsequent apoptosis through mitigation of mtROS generation. Thus, phloroglucinol might have therapeutic potential to prevent oxidative stress-mediated damage in RPE cells.

Fisetin Attenuated Oxidative Stress-Induced Cellular Damage in ARPE-19 Human Retinal Pigment Epithelial Cells Through Nrf2-Mediated Activation of Heme Oxygenase-1

Fisetin is a kind of bioactive flavonol, widely present in various fruits such as strawberries and apples, and is known to act as a potent free radical scavenger. However, the mechanism of action related to the antioxidant activity of this compound in human retinal pigment epithelial (RPE) cells is not precisely known. In this study, we aimed to investigate whether fisetin could attenuate oxidative stress-induced cytotoxicity on human RPE ARPE-19 cells. To mimic oxidative stress, ARPE-19 cells were treated with hydrogen peroxide (H₂O₂), and fisetin significantly inhibited H₂O₂-induced loss of cell viability and increase of intracellular reactive oxygen species (ROS) production. Fisetin also markedly attenuated DNA damage and apoptosis in H₂O₂-treated ARPE-19 cells. Moreover, mitochondrial dysfunction in H₂O₂-treated cells was alleviated in the presence of fisetin as indicated by preservation of mitochondrial membrane potential, increase of Bcl-2/Bax expression ratio, and suppression of cytochrome c release into the cytoplasm. In addition, fisetin enhanced phosphorylation and nuclear translocation of nuclear factor erythroid 2 related factor 2 (Nrf2), which was associated with increased expression and activity of heme oxygenase-1 (HO-1). However, the HO-1 inhibitor, zinc protoporphyrin, significantly reversed the protective effect of fisetin against H₂O₂-mediated ARPE-19 cell injury. Therefore, our results suggest that Nrf2-mediated activation of antioxidant enzyme HO-1 may play an important role in the ROS scavenging activity of fisetin in RPE cells, contributing to the amelioration of oxidative stress-induced ocular disorders.

Protection against Oxidative Stress-Induced Apoptosis by Fermented Sea Tangle (Laminaria japonica Aresch) in Osteoblastic MC3T3-E1 Cells through Activation of Nrf2 Signaling Pathway

The purpose of the present study was to explore the efficacy of fermented extract of sea tangle (Laminaria japonica Aresch, FST) with Lactobacillus brevis on DNA damage and apoptosis in hydrogen peroxide (H₂O₂)-stimulated osteoblastic MC3T3-E1 cells and clarify related signaling pathways. Our results showed that exposure to FST significantly improved cell viability, inhibited apoptosis, and suppressed the generation of reactive oxygen species (ROS) in H₂O₂-stimulated cells. In addition, H₂O₂ triggered DNA damage in MC3T3-E1 cells was markedly attenuated by FST pretreatment. Moreover, H₂O₂-induced mitochondrial dysfunctions associated with apoptotic events, including loss of mitochondrial membrane potential (MMP), decreased Bcl-2/Bcl-2 associated x-protein (Bax) ratio, and cytosolic release of cytochrome c, were reduced in the presence of FST. FST also diminished H₂O₂-induced activation of caspase-3, which was associated with the ability of FST to protect the degradation of poly (ADP-ribose) polymerase. Furthermore, FST notably enhanced nuclear translocation and phosphorylation of nuclear factor erythroid 2-related factor 2 (Nrf2) in the presence of H₂O₂ with concomitant upregulation of heme oxygenase-1 (HO-1) expression. However, artificial blockade of this pathway by the HO-1 inhibitor, zinc protoporphyrin IX, greatly abolished the protective effect of FST against H₂O₂-induced MC3T3-E1 cell injury. Taken together, these results demonstrate that FST could protect MC3T3-E1 cells from H₂O₂-induced damage by maintaining mitochondrial function while eliminating ROS along with activation of the Nrf2/HO-1 antioxidant pathway.

Loganin Inhibits Lipopolysaccharide-Induced Inflammation and Oxidative Response through the Activation of the Nrf2/HO-1 Signaling Pathway in RAW264.7 Macrophages

Inflammation caused by the excessive secretion of inflammatory mediators in abnormally activated macrophages promotes many diseases along with oxidative stress. Loganin, a major iridoid glycoside isolated from Cornus officinalis, has recently been reported to exhibit anti-inflammatory and antioxidant effects, whereas the underlying mechanism has not yet been fully clarified. Therefore, the aim of the present study is to investigate the effect of loganin on inflammation and oxidative stress in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Our results indicated that loganin treatment markedly attenuated the LPS-mediated phagocytic activity and release of nitric oxide (NO) and prostaglandin E₂, which was associated with decreased the expression of inducible NO synthase and cyclooxygenase-2. In addition, loganin suppressed the expression and their extracellular secretion of LPS-induced pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-1β. Furthermore, loganin abolished reactive oxygen species (ROS) generation, and promoted the activation of nuclear factor-E2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1) in LPS-stimulated macrophages. However, zinc protoporphyrin, a selective HO-1 inhibitor, reversed the loganin-mediated suppression of pro-inflammatory cytokines in LPS-treated macrophages. In conclusion, our findings suggest that the upregulation of the Nrf2/HO-1 signaling pathway is concerned at least in the protective effect of loganin against LPS-mediated inflammatory and oxidative stress, and that loganin can be a potential functional agent to prevent inflammatory and oxidative damage.

Hemistepsin A protects human keratinocytes against hydrogen peroxide-induced oxidative stress through activation of the Nrf2/HO-1 signaling pathway

Hemistepsin A, a sesquiterpene lactone compound isolated from Hemistepta lyrata, has been identified a variety of pharmacological actions including anti-hepatotoxic, anti-inflammatory and anti-cancer activities. Nevertheless, the antioxidant effects of hemistepsin A and the underlying mechanisms have not been investigated properly. Therefore, in the present study, we investigated the protective effect of hemistepsin A against oxidative stress in HaCaT human keratinocytes. The results demonstrated that hemistepsin A suppressed 500 μM hydrogen peroxide (H₂O₂)-induced cytotoxicity and DNA damage by blocking ROS accumulation. 10 μM Hemistepsin A also prevented apoptosis by preventing the mitochondrial dysfunction and the cytosolic release of cytochrome c, reducing the rate of Bax/Bcl-2 expression, and decreasing the activation of caspase-9 and caspase-3, suggesting that hemistepsin A protected cells from H₂O₂-induced mitochondria-mediated apoptosis. In addition, hemistepsin A markedly promoted the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was associated with the enhanced expression and activity of heme oxygenase-1 (HO-1) in the presence of 500 μM H₂O₂. However, inhibiting the expression of HO-1 by artificially blocking the expression of Nrf2 or HO-1 using siRNA significantly eliminated the protective effect of hemistepsin A, indicating that hemistepsin A activates the Nrf2/HO-1 signaling pathway in HaCaT cells to protect against oxidative stress. Therefore, these results suggest that hemistepsin A may be useful as a potential therapeutic agent against various oxidative stress-related skin diseases.

Regulatory Effects of Skate Skin-Derived Collagen Peptides with Different Molecular Weights on Lipid Metabolism in the Liver and Adipose Tissue

This study investigated the effects of skate skin collagen peptide (SSCP) with different molecular weights (MWs) on the lipid metabolism in the liver and adipose tissue. Male db/db mice were orally administered with water (control group) or low SSCP (LCP group) or high SSCP (HCP group) MW for 8 weeks whereas male m/m mice were used for comparison (normal group) (n = 10 each group). Compared to the control group, the LCP and HCP groups had lower adipose tissue mass, plasma and hepatic lipid concentrations, and plasma leptin levels (p < 0.05). Protein expression levels of lipogenesis-related protein were reduced in both liver and adipose tissues of SSCP-fed groups whereas those for lipolysis were elevated (p < 0.05). In particular, the LCP had the higher effects relative to the HCP. The above results were supported by histological analysis, revealing that SSCP administration decreased the size of adipose droplets and suppressed hepatic lipid accumulation. Our results showed that SSCP has potential antiobesity properties through the improvement of lipid metabolism in the liver and adipose tissue; in particular, the lower MW of collagen peptide had the greater effects.

Effect of fermented oyster extract on growth promotion in Sprague-Dawley rats

Background

Oysters (Crassostrea gigas) are a popular marine product worldwide and have the advantage of nutritional benefits. This study aimed to investigate the effect of fermented oyster extract (FO) on growth promotion, including analysis of body size, bone microarchitecture, hematology and biochemistry in vivo.

Methods

The amount of nutrients and gamma aminobutyric acid (GABA) were determined. Sprague–Dawley rats were randomly divided into four groups: the control group, FO 50 group (FO 50 mg/kg), and FO 100 group (FO 100 mg/kg) were administered orally once daily and the recombinant human growth hormone (rhGH) group (200 μg/kg) was intraperitoneally injected once daily for 14 days.

Results

Oral administration of FO 100 significantly increased body length and had no effect on organ damage or hematological profiles. However, administration of rhGH significantly induced hypertrophy of the liver, kidney and spleen along with a marked increase in body length. Tibia length and the growth plate were increased, and bone morphometric parameters were slightly improved by FO and rhGH administration. Serum analysis showed that the levels of GH and insulin like growth factor-1 (IGF-1) were slightly upregulated by FO administration. Nevertheless, the protein expression of hepatic IGF-1 was markedly increased by FO 100 and rhGH administration.

Conclusions

FO have high content of GABA, and induced positive effects on body length, tibial length, growth-plate length and hepatic IGF-1 synthesis in SD rats with no toxicity or alterations of hematological profile. Therefore, these results suggest that GABA-enriched FO could be considered a potential alternative treatment for growth stimulation.

Skate cartilage extracts containing chondroitin sulfate ameliorates hyperlipidemia-induced inflammation and oxidative stress in high cholesterol diet-fed LDL receptor knockout mice in comparison with shark chondroitin sulfate

BACKGROUND/OBJECTIVES

In this study, we investigated the beneficial effects of skate cartilage extracts containing chondroitin sulfate (SCS) on hyperlipidemia-induced inflammation and oxidative stress in high cholesterol diet (HCD)-fed mice in comparison with the effects of shark cartilage-derived chondroitin sulfate (CS).

MATERIALS/METHODS

Low-density lipoprotein receptor knockout (LDLR-KO) mice were fed HCD with an oral administration of CS (50 and 100 mg/kg BW/day), SCS (100 and 200 mg/kg BW/day), or water, respectively, for ten weeks.

RESULTS

The administration of CS or SCS reduced the levels of serum triglyceride (TG), total cholesterol (TC), and LDL cholesterol and elevated the levels of high-density lipoprotein cholesterol, compared with those of the control group (P < 0.05). Furthermore, CS or SCS significantly attenuated inflammation by reducing the serum levels of interleukin (IL)-1β and hepatic protein expression levels of nuclear factor kappa B, inducible nitric oxide synthase, cyclooxygenase-2, and IL-1beta (P < 0.05). In particular, the serum level of tumor necrosis factor-alpha was reduced only in the 100 mg/kg BW/day of SCS-fed group, whereas the IL-6 level was reduced in the 100 and 200 mg/kg BW/day of SCS-fed groups (P < 0.05). In addition, lipid peroxidation and nitric oxide production were attenuated in the livers of the CS and SCS groups mediated by the upregulation of hepatic proteins of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase (P < 0.05).

CONCLUSIONS

These results suggest that the biological effects of SCS, similar to those of CS, are attributed to improved lipid profiles as well as suppressed inflammation and oxidative stress induced by the intake of HCD.

Effects of collagen peptides from skate (Raja kenojei) skin on improvements of the insulin signaling pathway via attenuation of oxidative stress and inflammation

It has been well established that hepatic insulin signaling is significantly affected by the antioxidative status of the liver.

Magma Seawater Inhibits Hepatic Lipid Accumulation through Suppression of Lipogenic Enzymes Regulated by SREBPs in Thioacetamide-Injected Rats

Thioacetamide (TAA) is known to induce lipid accumulation in the liver. In the present study, we investigated the effects of magma seawater (MS) rich in minerals on hepatic lipid metabolism by evaluating lipogenic enzymes regulated by sterol regulatory element-binding proteins (SREBPs). Rats (n = 10 per group) were intraperitoneally injected with TAA (200 mg/kg bw) thrice a week for seven weeks in combination with a respective experimental diet. Rats in the TAA-treated group received either a chow diet (Control group) or a chow diet containing MS (TMS group, 2.05%) or silymarin (TSM group, 0.05%). Rats in the normal group were injected with PBS as a vehicle and received a chow diet. Rats in the TMS group showed significantly lower hepatic lipid concentrations than rats in the control group (p < 0.05). Hepatic protein expression levels of fatty acid synthase, SREBP-1, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, and SREBP-2 were significantly downregulated in the TMS group, whereas carnitine palmitoyltransferase 1 levels were upregulated (p < 0.05). Hepatic thiobarbituric acid reactive substances levels were lower in the TMS group, whereas protein levels of glutathione peroxidase and catalase were elevated (p < 0.05). The effects of MS were comparable to those of silymarin. Our results evidently showed that MS inhibits hepatic lipid accumulation by suppressing lipid synthesis, accompanied by lipid oxidation and elevation of antioxidative status.

Anti-Obesity Effects of Collagen Peptide Derived from Skate (Raja kenojei) Skin Through Regulation of Lipid Metabolism

This study investigated the anti-obesity effects of collagen peptide derived from skate skin on lipid metabolism in high-fat diet (HFD)-fed mice. All C57BL6/J male mice were fed a HFD with 60% kcal fat except for mice in the normal group which were fed a chow diet. The collagen-fed groups received collagen peptide (1050 Da) orally (100, 200, or 300 mg/kg body weight per day) by gavage, whereas the normal and control groups were given water (n = 9 per group). The body weight gain and visceral adipose tissue weight were lower in the collagen-fed groups than in the control group (p < 0.05). Plasma and hepatic lipid levels were significantly reduced by downregulating the hepatic protein expression levels for fatty acid synthesis (sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC)) and cholesterol synthesis (SREBP-2 and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR)) and upregulating those for β-oxidation (peroxisome proliferator-activated receptor alpha (PPAR-α) and carnitine palmitoyltransferase 1 (CPT1)) and synthesis of bile acid (cytochrome P450 family 7 subfamily A member 1 (CYP7A1)) (p < 0.05). In the collagen-fed groups, the hepatic protein expression level of phosphorylated 5' adenosine monophosphate-activated protein kinase (p-AMPK) and plasma adiponectin levels were higher, and the leptin level was lower (p < 0.05). Histological analysis revealed that collagen treatment suppressed hepatic lipid accumulation and reduced the lipid droplet size in the adipose tissue. These effects were increased in a dose-dependent manner. The findings indicated that skate collagen peptide has anti-obesity effects through suppression of fat accumulation and regulation of lipid metabolism.

Low-Molecular-Weight Oligonol, a Polyphenol Derived from Lychee Fruit, Attenuates Experimental Reflux Esophagitis and HCl/Ethanol-Induced Gastric Ulcer

Oligonol, a polyphenol derived from lychee fruit, is produced by an oligomerization process that converts high-molecular-weight polyphenol polymers into low-molecular-weight oligomers. Evidence suggests that oligonol exerts its beneficial effects based on antioxidant and anti-inflammatory properties. This study was the first to investigate the antioxidative and anti-inflammatory effects of oligonol on gastroesophageal inflammatory models: surgically induced acute reflux esophagitis (RE) and gastric ulcer (GU) induced by HCl/ethanol. In the in vitro study, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS) radical scavenging assays were performed to determine the antioxidant activity of oligonol. The experimental groups were each composed of normal, vehicle, and oligonol groups. RE rats and GU mice were treated orally with oligonol (100 mg/kg bw) or distilled water as a vehicle (n = 8 for each group). Oligonol exhibited potent free radical-scavenging capacities for DPPH and ABTS radicals, activities that were similar to those of ascorbic acid. The in vivo study revealed that oligonol consumption significantly prevented RE and GU formation and decreased the gross mucosal injury from oxidative stress. Oligonol decreased the reactive oxygen species levels and elevated levels of both inflammatory mediators and cytokines (p-IκB, NF-κBp65, COX-2, iNOS, TNF-α, and IL-1β) in the RE and GU models. Oligonol had a protective effect against oxidative stress by regulating antioxidant enzyme (superoxide dismutase, catalase, and GPx-1/2) activities in GU mice. Oligonol has potential as a preventive and therapeutic agent for gastroesophageal inflammatory diseases, including RE and GU.

Bioactive Compounds of Kimchi Inhibit Apoptosis by Attenuating Endoplasmic Reticulum Stress in the Brain of Amyloid β-Injected Mice

This study investigated the inhibitory effects of kimchi bioactive compounds against endoplasmic reticulum (ER) stress-induced apoptosis in amyloid beta (Aβ)-injected mice. Mice received a single intracerebroventricular injection of Aβ_25-35, except for the normal group. Mice were subjected to oral administration of 10 mg of capsaicin, 50 mg of 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA), 50 mg of quercetin, 50 mg of ascorbic acid, or 200 mg of kimchi methanol extract (KME) per kilogram of body weight for 2 weeks ( n = 7 per group). In the in vitro blood-brain barrier (BBB) permeability test, all bioactive compounds penetrated the BBB except ascorbic acid. The protein expression level of APP, BACE, and p-Tau elevated by Aβ injection was decreased by kimchi bioactive compounds ( P < 0.05). Quercetin, HDMPPA, and KME decreased oxidative stress, as indicated by ROS and TBARS levels ( P < 0.05). The protein expression level of ER stress markers GRP78, p-PERK, p-eIF2α, XBP1, and CHOP and the proapoptotic molecules Bax, p-JNK, and cleaved caspases-3 and -9 decreased ( P < 0.05). In contrast, the protein expression level of antiapoptotic molecules Bcl2 and cIAP increased ( P < 0.05). These results were supported by histological analysis.

Antioxidative and Cholesterol-Lowering Effects of Lemon Essential Oil in Hypercholesterolemia-Induced Rabbits

The cholesterol-lowering and anti-atherogenic effects of lemon essential oil (LEO) were investigated and compared with the effects of limonene. Owing to their volatility, both LEO and limonene were microencapsulated before preparation of the diet (20%, w/w). Hypercholesterolemia-induced rabbits were divided into 3 groups based on plasma total cholesterol (TC) levels and fed coating matrix (control group), LEO (LEO group), or limonene (Limonene group) for 8 weeks. LEO dose-dependently inhibited low-density lipoprotein oxidation in vitro. Plasma TC levels were the lowest in the LEO group (P<0.05). Erythrocytes in the LEO group had a normal disc shape, whereas the erythrocytes in the limonene and control groups were aggregated and star-shaped, respectively. The aortic intima thickness was thinnest in the LEO group followed by the control and limonene groups. Plasma TC lowering and anti-atherogenic effects of LEO were greater than limonene, suggesting that other bioactive compounds besides limonene in LEO might contribute to these effects. The bioactive compounds in LEO were limonene (67.57%), β-pinene (10.00%), and γ-terpinene (9.95%). In addition, sabinene, α-pinene, myrcene, and geranial were also present but the amount was in the range of 1~2%. Several bioactive compounds were also detected. In conclusion, LEO had beneficial effects on hypercholesterolemia due to its antioxidative and cholesterol lowering effects.

Neuroprotective Effects of the Methanol Extract of Kimchi, a Korean Fermented Vegetable Food, Mediated Via Suppression of Endoplasmic Reticulum Stress and Caspase Cascade Pathways in High-Cholesterol Diet-Fed Mice

Endoplasmic reticulum (ER) stress-related unfolded peptide accumulation is closely associated with the development of neurodegenerative diseases known as protein misfolding disorders. The antioxidative properties of kimchi, a traditional Korean fermented vegetable dish, have been well established. In this study, the neuroprotective effects of the kimchi methanol extract (KME) were examined in high-cholesterol diet (HCD)-fed mice. The animals were fed a HCD, with oral administration of either KME (KME group, 200 mg·kg bw^-1·day^-1, n = 10) or distilled water (Control group, n = 10) for 8 weeks. Compared with the levels in the control group, the reactive oxygen species, peroxynitrite, and lipid peroxidation levels in the brain were significantly decreased in the KME group (P < .05), whereas the glutathione level was increased (P < .05). In addition, the ER stress biomarkers, phospho-eukaryotic initiation factor 2 subunit α, glucose-regulated protein 78, X-box binding protein 1, inositol-requiring enzyme 1, and C/EBP homologous protein and the nuclear factor-kappaB-mediated inflammation were significantly reduced in the KME group (P < .05). In contrast, the expression levels of antioxidative enzymes regulated by nuclear factor erythroid 2-related factor-2 were elevated (P < .05). The amyloid-beta expression levels of the KME group were lower than that of the control group (P < .05). Moreover, the expression levels of Bcl-2-associated X, and caspases-3 and -9 were downregulated, with a concomitant upregulation of B cell lymphoma 2 (P < .05). Accordingly, KME provide neuronal cell protection via suppressing ER stress and caspase cascade signaling.

Beneficial Effects of Kimchi, a Korean Fermented Vegetable Food, on Pathophysiological Factors Related to Atherosclerosis

Atherosclerosis is a progressive disease that is characterized by accumulation of lipids and fibrous elements in large arteries. Its etiology is involved with pathophysiological factors such as lipoprotein oxidation, inflammation, and dyslipidemia. Kimchi is a Korean fermented vegetable side dish made with vegetables and kimchi condiments. To date, numerous in vitro, in vivo, and human studies have cited the health benefits of kimchi. 3-(4'-Hydroxyl-3',5'-dimethoxyphenyl)propionic acid is one of the active compounds of kimchi, and its antioxidant and anti-atherosclerosclerotic effects have been reported. This review presents the laboratory and clinical evidence of the anti-atherosclerotic effects of kimchi based on its lipid-lowering, antioxidant, and anti-inflammatory activities.

Preventative activity of kimchi on high cholesterol diet-induced hepatic damage through regulation of lipid metabolism in LDL receptor knockout mice

This study investigated the effect of kimchi on hepatic lipid metabolism and inflammatory response. Low-density lipoprotein receptor knockout mice fed high cholesterol diet (HCD) with an oral administration of kimchi methanol extracts (KME, 200 mg kg bw^-1 day^-1) or distilled water for 8 weeks (n = 10 per group). Compared with the control group, plasma and hepatic lipid concentrations were lower in the kimchi group (p < 0.05), which was confirmed with hepatic histological examination by Oil Red O staining. Hepatic expressions for fatty acid synthesis were downregulated whereas those for beta-oxidation were upregulated in the kimchi group (p < 0.05). Hepatic expressions for cholesterol synthesis were decreased but those for cholesterol export was increased in the kimchi group (p < 0.05). Moreover, kimchi intake reduced expression for inflammatory cytokines (p < 0.05). Kimchi exerted beneficial effects on HCD-induced hepatic damage by suppressing lipid synthesis and inflammation, and facilitating fatty acid oxidation and cholesterol excretion.

Kimchi attenuates fatty streak formation in the aorta of low-density lipoprotein receptor knockout mice via inhibition of endoplasmic reticulum stress and apoptosis

BACKGROUND/OBJECTIVES

Endoplasmic reticulum (ER) stress is positively associated with atherosclerosis via elevating macrophage cell death and plaque formation, in which oxidative stress plays a pivotal role. Antioxidative, lipid-lowering, and anti-atherogenic effects of kimchi, a Korean fermented vegetable, have been established, wherein capsaicin, ascorbic acid, quercetin, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, and lactic acids were identified. In this study, mechanisms of action of kimchi methanol extracts (KME) on fatty streak formation via suppression of ER stress and apoptosis in aorta were examined in low-density lipoprotein receptor knockout mice.

MATERIALS AND METHODS

Mice fed a high cholesterol diet with an oral administration of KME (KME group, 200 mg·kg-bw⁻¹·day⁻¹) or distilled water (control group) for 8 weeks (n = 20 for group). Plasma lipid and oxidative stress levels were evaluated. Protein expression was measured by western blot assay. Fatty streak lesion size and the degree of apoptosis were examined in the aorta.

RESULTS

Compared to the control group, in the KME group, plasma lipids levels were decreased and oxidative stress was alleviated (P < 0.05). Protein expression levels of nuclear factor (erythroid-derived 2)-like 2-mediated antioxidants in aorta were increased whereas those for ER stress markers, glucose regulated protein 78, phospho-protein kinase RNA-like ER kinase, phospho-eukaryotic initiation factor 2 subunit α, X-box binding protein 1, and C/EBP homologous protein were decreased in the KME group (P < 0.05). Moreover, apoptosis was suppressed via downregulation of phospho-c-Jun N-terminal kinase, bcl-2-associated X protein, caspases-9, and -3 with a concomitant upregulation of anti-apoptotic protein, B-cell lymphoma 2 (P < 0.05). Fatty streak lesion size was reduced and the degree of apoptosis was less severe in the KME group (P < 0.05).

CONCLUSIONS

In conclusion, antioxidant activity of KME might prevent fatty streak formation through, in part, inhibition of ER stress and apoptosis in aortic sinus where macrophages are harbored.

Hot water extracts of pressure-roasted dried radish attenuates hepatic oxidative stress via Nrf2 up-regulation in mice fed high-fat diet

This study investigated the effect of pressure-roasted dried radish (PRDR) against oxidative stress. To prepare PRDR extract, dried radish (DR) was pressure-roasted, boiled, and then freeze-dried. Mice fed a chow diet with oral administration of distilled water (DW) (normal group) or a high-fat diet with DW (control, CON group), DR (DR group, 237 mg/kg bw/day), or PRDR (PRDR group, 237 mg/kg bw/day) (n = 8 each group) for 12 weeks. Hepatic lipid peroxidation level in the DR and PRDR groups was lower than that in the CON group, whereas hepatic glutathione level in these groups was higher (p < 0.05). Hepatic expression of nuclear factor (erythroid-derived 2)-like 2 and its related antioxidant enzymes such as catalase, glutathione S-transferase, and peroxidases was the highest in the PRDR group (p < 0.05). It is apparent that radish attenuate oxidative stress and the process of pressure roasting might contribute positively to this effect.

Persicarin isolated from Oenanthe javanica protects against diabetes-induced oxidative stress and inflammation in the liver of streptozotocin-induced type 1 diabetic mice

Persicarin is one of the major components of the Oenanthe javanica (water dropwort). The present study was aimed to evaluate the role of persicarin in the hepatic tissue of streptozotocin-induced type 1 diabetic mice. Diabetes was induced by single intra-peritoneal injection of streptozotocin (120 mg/kg body weight) and then oral administration of persicarin at a dose 2.5 and 5 mg/kg body weight for 10 days. Serum and hepatic glucose levels were increased in diabetic control mice, while persicarin treatment groups were markedly reduced. Also, the increased levels of ALT and AST in serum were improved by persicarin. In our results revealed that persicarin suppressed increased oxidative stress parameter (reactive oxygen species, peroxinitrite, and thiobarbituric acid-reactive substance), nicotinamide adenine dinucleotide phosphate oxidase subunit (Nox-4 and P47^phox) and inflammatory related makers (NF-κB, AP-1, TGF-β, COX-2, and iNOS). These results suggest that persicarin protects against liver damage by attenuating oxidative stress and inflammatory response under hyperglycemic conditions. Thus, persicarin could perform as a potential therapeutic agent for the treatment of diabetic mellitus.

The amelioration of plasma lipids by Korean traditional confectionery in middle-aged women: A cross-over study with western cookie

BACKGROUND/OBJECTIVES

The purpose of this study was to examine whether plasma lipid profiles are affected differently by snack kinds with equal calorific values.

SUBJECTS/METHODS

We compared a Korean traditional confectionery (dasik) with Western confectionery (cookie) in this regard. Controlled cross-over study consisted of two 3-week snack intake phases and for separating, a 2-week washout period (3–2–3) was carried out with 30 healthy women aged between 40-59 years old. Brown rice based Korean traditional confectionery and wheat flour based Western confectionery were used. The participants consumed either dasik or cookie every day for 3 weeks, providing 93 kcal a day.

RESULTS

The total cholesterol (TC) in the dasik group had decreased significantly after 3 weeks (P < 0.05). Furthermore, in the dasik group, reduction in TC and low-density lipoprotein-cholesterol were greater than those in the cookie group (P < 0.05).

CONCLUSIONS

Prioritizing functional snacks like dasik improves plasma lipid profiles; this may be useful information for individuals who cannot refrain from snacking.

Oligonol, a low-molecular-weight polyphenol derived from lychee fruit, attenuates gluco-lipotoxicity-mediated renal disorder in type 2 diabetic db/db mice

Oligonol is a phenolic product derived from lychee fruit extract containing catechin-type monomers and oligomers of proanthocyanidins, produced by a manufacturing process which converts polyphenol polymers into oligomers. These proanthocyanidins have been reported to exhibit beneficial bioactivities in many studies, and so oligonol, a rich source of polyphenol, is expected to show favorable effects on various chronic diseases. This article summarizes recent work whether oligonol has an ameliorative effect on diabetic indices and renal disorders associated with gluco-lipotoxicity-mediated oxidative stress, inflammation, and apoptosis in db/db mice with diabetes. Oligonol was able to improve diabetic indices, prevent the development of diabetic renal disease, and preserve renal cells and the renal morphological structure via the attenuation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-induced oxidative stress, inhibition of advanced glycation endproduct (AGE) generation, and prevention of apoptosis-induced cell death in db/db mice, being independent of changes in the body weight or serum glucose levels. The present study provides important evidence that oligonol exhibits a pleiotropic effect, representing renoprotective effects against the development of diabetic complications in type 2 diabetic db/db mice.

Astaxanthin and Corni Fructus protect against diabetes-induced oxidative stress, inflammation, and advanced glycation end product in livers of streptozotocin-induced diabetic rats

This study was conducted to compare the protective effects of astaxanthin (ASX) with Corni Fructus (CF) against diabetes-induced pathologies such as oxidative stress-induced inflammation and advanced glycation end product (AGE) formation in the liver of type 1 diabetic rats. ASX (50 mg/kg body weight/day) or CF (200 mg/kg body weight/day) was orally administered every day for 18 days to streptozotocin (STZ)-induced diabetic rats, and their effects were compared with nondiabetic and diabetic control rats. The administration of CF, but not ASX, decreased both the elevated serum and hepatic glucose concentration in diabetic rats. In diabetic rats, increased levels of AGE, reactive oxygen species, and lipid peroxidation were significantly decreased by treatment with both ASX and CF in the liver of diabetic rats. STZ treatment markedly augmented the protein expressions of AGE, and both ASX and CF efficiently attenuated these increases in hepatic protein expressions. In addition, oxidative stress and proinflammatory protein expressions were upregulated in the diabetic rats. On the contrary, these upregulations of protein expressions were decreased by the administration of ASX or CF. These results suggest that the inhibitory effect of ASX on diabetes-induced hepatic dysfunction could be derived from the blocking of AGE formation and further anti-inflammation and that CF exhibited beneficial effects through the attenuation of hyperglycemia, and thus the inhibition of AGE formation and the inflammatory responses. Therefore, ASX as well as CF may help prevent ongoing diabetes-induced hepatic injury.

Polyphenol isolated from Corni Fructus, 7-O-galloyl-D-sedoheptulose, modulates advanced glycation endproduct-related pathway in type 2 diabetic db/db mice

7-O-Galloyl-D-sedoheptulose (GS) is the bioactive polyphenol isolated from the low-molecular-weight fraction of Corni Fructus (Cornus officinalis Sieb. et Zucc.). The present study was conducted to examine whether GS has an ameliorative effect on the liver of type 2 diabetic db/db mice. GS (20 or 100 mg/kg body weight/day, per os) was administered every day for 6 weeks to db/db mice, and its effect was compared with vehicle-treated db/db and m/m mice. The administration of GS decreased the elevated serum glucose, leptin, insulin, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), resistin, and hepatic functional parameters, and reduced the increased fluorescent advanced glycation endproducts (AGEs) and reactive oxygen species in the liver. The db/db mice exhibited the up-regulation of receptor for AGEs (RAGE) and AGE-related proteins; however, GS treatment significantly reduced those expressions. Moreover, the augmented expressions of oxidative stress- and inflammation-related proteins, phospho-extracellular-signal regulated kinase 1/2, phospho-c-Jun N-terminal kinase, nuclear factor-kappa B, activator protein-1, monocyte chemotactic protein-1, intracellular adhesion molecule-1, TNF-α, and IL-6, were down-regulated by GS administration. Hematoxylin-eosin staining showed that the increased hepatocellular damage in the liver of db/db mice improved with GS administration. The present results support the evidence for GS ameliorating hepatic damage through the RAGE-mediated inflammation pathway.

Oligonol, a low-molecular-weight polyphenol derived from lychee fruit, attenuates diabetes-induced renal damage through the advanced glycation end product-related pathway in db/db mice

This study was conducted to examine whether oligonol, a low-molecular-weight polyphenol derived from lychee fruit, has an ameliorative effect on diabetes-induced alterations, such as advanced glycation end product (AGE) formation or apoptosis in the kidneys of db/db mice with type 2 diabetes. Oligonol [10 or 20 mg/(kg body weight · d), orally] was administered every day for 8 wk to prediabetic db/db mice, and its effect was compared with vehicle-treated db/db and normal control mice (m/m). The administration of oligonol decreased the elevated renal glucose concentrations and reactive oxygen species in db/db mice (P < 0.05). The increased serum urea nitrogen and creatinine concentrations, which reflect renal dysfunction in db/db mice, were substantially lowered by oligonol. Oligonol reduced renal protein expression of NAD(P)H oxidase subunits (p22 phagocytic oxidase and NAD(P)H oxidase-4), AGEs (except for pentosidine), and c-Jun N-terminal kinase B-targeting proinflammatory tumor necrosis factor-α (P < 0.05). Oligonol improved the expressions of antiapoptotic [B-cell lymphoma protein 2 (Bcl-2) and survivin] and proapoptotic [Bcl-2-associated X protein, cytochrome c, and caspase-3] proteins in the kidneys of db/db mice (P < 0.05). In conclusion, these results provide important evidence that oligonol exhibits a pleiotropic effect on AGE formation and apoptosis-related variables, representing renoprotective effects against the development of diabetic complications in db/db mice with type 2 diabetes.

Effectiveness of Chinese prescription Kangen-karyu for dyslipi-demia, using 3T3-L1 adipocytes and type 2 diabetic mice

The Chinese prescription Kangen-karyu, comprised of six crude drugs, has received much attention due to its numerous biological activities. The present study was conducted to examine whether Kangen-karyu has an ameliorative effect on dyslipidemia. The effect of Kangen-karyu was evaluated using 3T3-L1 adipocytes, and also db/db mice as an experimental model for diabetic dyslipidemia. Kangen-karyu significantly inhibited adipocyte differentiation and lipid accumulation. Kangen-karyu also down-regulated the mRNA levels of peroxisome proliferator-activated receptor (PPAR)γ, sterol regulatory element-binding protein (SREBP)-1c, and fatty acid synthase, and the protein levels of aP2 and PPARγ, which indicates that Kangen-karyu inhibited adipogenesis during adipocyte differentiation, and may have potential anti-dyslipidemia effects. In addition, the administration of Kangen-karyu reduced hyperlipidemia in db/db type 2 diabetic mice through a decline in the serum levels of lipids, and an improvement of lipoprotein profiles. The enhanced hepatic triglyceride level of the db/db mice was significantly reduced by Kangen-karyu administration through the down-regulation of SREBP-1 and lipogenic enzymes in the liver. These findings indicate that Kangen-karyu exerts anti-dyslipidemia effects in adipocytes and type 2 diabetic db/db mice.

Role of oligomeric proanthocyanidins derived from an extract of persimmon fruits in the oxidative stress-related aging process

Many researchers have focused on the oligomeric form of proanthocyanidins with a lower level of polymerization found in foodstuffs such as grape seeds and blackberries. The present study indicated that the oral administration of oligomers isolated from persimmon fruits extended the lifespan of senescence-accelerated mouse prone/8 (SAMP8), a murine model of accelerated senescence. On the other hand, oligomer-treated SAMP8 did not show stereotypical behavior. We also revealed that the oral administration of oligomers improved spatial and object recognition memory in SAMP8. The density of axons in the hippocampal CA1 was significantly increased by oligomer administration. Moreover, the administration of oligomers increased the phosphorylation of vascular endothelial growth factor receptor (VEGFR)-2 in the hippocampal CA3, hypothalamus, and choroid plexus. We speculate that memory improvement accompanied by histological changes may be induced directly in the hippocampus and indirectly in the hypothalamus and choroid plexus through VEGFR-2 signaling. In the present study, we elucidated the protective effect of oligomers against memory impairment with aging. VEGFR-2 signaling may provide a new insight into ways to protect against memory deficit in the aging brain.

Rokumi-jio-gan-containing prescriptions regulate oxidative stress through improving dyslipidemia in a subtotal nephrectomized rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Rokumi-jio-gan-containing prescriptions, traditional medicine, are widely used to treat renal dysfunction in Japan.

AIM OF THE STUDY

The present study was conducted to examine whether two Rokumi-jio-gan-containing prescriptions (Hachimi-jio-gan and Bakumi-jio-gan) have an ameliorative effect on dyslipidemia in nephrectomized rats.

MATERIALS AND METHODS

Each prescription was orally administered to nephrectomized rats at 150mg/kg body weight per day for 10 weeks, and its effect was compared with vehicle-treated nephrectomized rats.

RESULTS

Rats given Hachimi-jio-gan and Bakumi-jio-gan showed an improvement of renal functional parameters such as serum urea nitrogen, creatinine, creatinine clearance, and urinary protein. The increased triglyceride, total cholesterol, non-esterified fatty acid, high-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol/low-density lipoprotein cholesterol levels in serum, and triglyceride and total cholesterol contents in the kidney of nephrectomized rats were significantly decreased by Hachimi-jio-gan and Bakumi-jio-gan administration. Furthermore, Hachimi-jio-gan acts as a regulator of peroxisome proliferator-activated receptor α, sterol regulatory element binding protein (SREBP)-1, and SREBP-2. On the contrary, the increased reactive oxygen species and thiobarbituric acid-reactive substance were decreased, while superoxide dismutase and the reduced glutathione/oxidized glutathione ratio were augmented by Hachimi-jio-gan rather than Bakumi-jio-gan. The improvement of nuclear factor-kappa Bp65, cyclooxygenase-2, inducible nitric oxide synthase, NF-E2-related factor 2, and heme oxygenase-1 was marked in the group administered Bakumi-jio-gan. However, oil red O staining showed that the increased lipid deposition in the kidney of nephrectomized rats improved on Hachimi-jio-gan and Bakumi-jio-gan administration.

CONCLUSION

This study provides scientific evidence that two Rokumi-jio-gan-containing prescriptions (Hachimi-jio-gan and Bakumi-jio-gan) improve oxidative stress via dyslipidemia in the remnant kidney of nephrectomized rats.

Kimchi, a fermented vegetable, improves serum lipid profiles in healthy young adults: randomized clinical trial

Vegetable-based diets have generally focused on their health benefits including negative associations with the serum cholesterol concentrations. The aim of this study was to investigate whether serum lipid concentrations are influenced by the amount of kimchi intake. For the study, 100 volunteers were assigned to 2 dietary groups, low (15 g/day, n=50) and high (210 g/day, n=50) kimchi intake, and were housed together in a dormitory for 7 days. Identical meals except with different amount of kimchi were provided and subjects were instructed to maintain their normal physical activity. Concentrations of fasting blood glucose (FBG), total glucose, total cholesterol and low density lipoprotein (LDL)-C significantly decreased in both groups after 7 days of kimchi intake, but the effects were dose dependent. Lipid lowering effects of kimchi were more profound in the subjects with total cholesterol and LDL-C level over 190 and 130 mg/dL, respectively, in both groups. FBG was significantly decreased in the high kimchi intake as compared to the low intake group (P=.003). In conclusion, greater consumption of kimchi improved FBG and serum total cholesterol in young healthy adults.

Beneficial effects of the active principle component of Korean cabbage kimchi via increasing nitric oxide production and suppressing inflammation in the aorta of apoE knockout mice

The present study investigated the effects of 3'-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA), the active principle compound of kimchi, on vascular damage in the experimental atherosclerotic animal. HDMPPA was administrated by an intraperitoneal injection of 10 mg/kg per d for 8 weeks to apoE knockout (KO) mice with an atherogenic diet containing 1 % cholesterol, and its effects were compared with vehicle-treated control mice. HDMPPA increased NO content in the aorta, accompanied by a decrease in reactive oxygen species (ROS) concentration. Furthermore, in the HDMPPA-treated group, aortic endothelial NO synthase (eNOS) expression was up-regulated compared with the control group. These results suggested that HDMPPA could maintain NO bioavailability through an increasing eNOS expression and preventing NO degradation by ROS. Furthermore, HDMPPA treatment in apoE KO mice inhibited eNOS uncoupling through an increase in vascular tetrahydrobiopterin content and a decrease in serum asymmetric dimethylarginine levels. Moreover, HDMPPA ameliorates inflammatory-related protein expression in the aorta of apoE KO mice. Therefore, the present study suggests that HDMPPA, the active compound of kimchi, a Korean functional food, may exert its vascular protective effect through the preservation of NO bioavailability and suppression of the inflammatory response.

7-O-galloyl-D-sedoheptulose attenuates oxidative stress-induced diabetic injury via decreasing expression of nuclear factor-κB- and apoptosis-related protein in the liver

The present study was conducted to examine whether 7-O-galloyl-D-sedoheptulose (GS) has an ameliorative effect on diabetic alterations such as oxidative stress, inflammation, and apoptosis in the liver of type 2 diabetic db/db mice. GS was administered at 20 or 100 mg/kg body weight per day for 6 weeks to db/db mice, and its effect was compared with vehicle-treated db/db and m/m mice. In the serum and hepatic tissue, biochemical factors and protein expressions associated with nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, inflammation, and apoptosis were examined. As a result, GS administration to type 2 diabetic mice lowered serum and hepatic oxidative stress through the reduction of reactive oxygen species and lipid peroxidation. These results were derived, at least in part, from attenuating the expression of NADPH oxidase subunit proteins, Nox-4 and p22(phox). In the diabetic condition, augmented nuclear factor (NF)-E2-related factor 2 and heme oxygenase-1 were reduced with a decrease in oxidative stress on GS treatment. Furthermore, in the GS-treated group, NF-kappa B-related pro-inflammatory factors and pro-apoptotic protein expressions were alleviated in the hepatic tissue. Taking these into consideration, our findings support the therapeutic evidence for GS ameliorating the development of diabetic complications via regulating oxidative stress, inflammation, and apoptosis.

7-O-Galloyl-d-sedoheptulose ameliorates renal damage triggered by reactive oxygen species-sensitive pathway of inflammation and apoptosis

Objectives

This study was carried out to verify the preventive effects of 7-O-galloyl-d-sedoheptulose (GS), a phenolic compound isolated from Corni Fructus, underlying diabetic renal damage in type 2 diabetes.

Methods

GS was orally administered to db/db mice at doses of 20 and 100 mg/kg body weight per day for six weeks, and its effects were compared with those of the vehicle in db/db and m/m mice.

Key findings

In the serum and kidney, biochemical factors and expression of protein related to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, apoptosis and inflammation were examined. GS treatment attenuated serum and renal oxidative stress through reduction of reactive oxygen species and lipid peroxidation and increase in the ratio of glutathione and its oxidised form. Importantly, GS reduced renal protein expression of Nox-4 and p22phox (one of the subunits of NADPH oxidase), pro-apoptotic factors (such as Bax and cytochrome c) and nuclear factor-kappa B-targeting pro-inflammatory inducible nitric oxide synthase and cyclooxygenase-2.

Conclusions

These renoprotective effects of GS were achieved through attenuation of diabetes-induced oxidative stress and its sensitive protein expression associated with inflammation and apoptosis in db/db mice.

The effects of corni fructus extract and its fractions against α-glucosidase inhibitory activities in vitro and sucrose tolerance in normal rats

Corni fructus (Cornus officinalis Sieb. et Zucc.) is a traditional medicine exerting multifaceted protective effects against diabetes and its complications. In this study, to further identify the physiological effects of corni fructus against diabetes and its complications, we investigated α-glucosidase inhibitory activities in vitro and employed the sucrose tolerance test as an indicator of the control of the postprandial blood glucose level. In vitro assays showed that corni fructus extract has a higher inhibitory activity than its major components. Then, corni fructus extract was fractionated again to screen the fractions showing a strong inhibitory activity against α-glucosidase. Of the tested fractions, five showed a rate of α-glucosidase inhibition of over 80%. Next, the four abundant fractions were evaluated their IC(50) values, as well as the inhibition mode in vitro and plasma glucose level after sucrose loading in normal Wistar rats. As a result, the IC(50) values of these fractions were between 1.1-2.1 μg/ml. Among the four fractions, three showed mixed inhibition, while one (Fr. 4-9) showed the competition-independent inhibition of α-glucosidase. In addition, Fr. 4S-1 significantly inhibited the rise in the plasma glucose levels at a dose of 20 mg/kg body weight after sucrose loading. These results indicate that Fr. 4S-1 from corni fructus has a potential to control postprandial hyperglycemia by α-glucosidase inhibition.

Hepato-/reno-protective activity of Chinese prescription Kangen-karyu through inhibition of AGE formation and fibrosis-related protein expression in type 2 diabetes

OBJECTIVES

This study was conducted to examine whether Kangen-karyu, a Chinese prescription, has an ameliorative effect on diabetes-induced alterations such as advanced glycation endproduct (AGE) formation or the fibrotic response in liver and kidney of type 2 diabetic db/db mice.

METHODS

Kangen-karyu (100 or 200 mg/kg body weight/day, p.o.) was administered every day for 18 weeks to db/db mice, and its effect was compared with vehicle-treated db/db and m/m mice.

KEY FINDINGS

The administration of Kangen-karyu decreased the elevated serum glucose concentration in db/db mice. The increased serum creatinine and urea nitrogen levels, which reflect renal dysfunction in db/db mice, were significantly lowered by Kangen-karyu administration. The db/db mice exhibited the up-regulation of AGEs and its receptor expression in liver and kidney; however, Kangen-karyu treatment significantly reduced expression except for the receptor. Moreover, the augmented expressions of fibrosis-related proteins, transforming growth factor (TGF)-β1, fibronectin and collagen IV were down-regulated by Kangen-karyu administration.

CONCLUSIONS

These results provide important evidence that Kangen-karyu exhibits a pleiotropic effect on AGE formation and fibrosis-related parameters, representing hepatoprotective and renoprotective effects against the development of diabetic complications in type 2 diabetic db/db mice.

Chinese prescription Kangen-karyu prevents dyslipidaemia and oxidative stress in mouse model of type 2 diabetes

Objectives

We have investigated the effects of Kangen-karyu, a Chinese prescription, on the lipid metabolism and oxidative stress in a type 2 diabetes model.

Methods

Male db/db mice were divided into three groups: control (vehicle), Kangen-karyu 100 or 200 mg/kg body weight/day orally administered mice. Age-matched non-diabetic m/m mice were used as a normal group.

Key findings

The administration of Kangen-karyu reduced hyperglycaemia and hyperlipidaemia in db/db type 2 diabetic mice through a decline in the serum levels of glucose and lipids, and an improvement of lipoprotein profiles. The increased oxidative stress in db/db mice was attenuated by the administration of Kangen-karyu through inhibiting the generation of reactive oxygen species and lipid peroxidation. The enhanced hepatic triglyceride and total cholesterol levels of the db/db mice were significantly reduced by Kangen-karyu administration through down-regulation of sterol regulatory element-binding protein-1 and lipogenic enzymes in liver. Furthermore, the expressions of hepatic nuclear factor-kappa B (NF-κB) and cyclooxygenase-2 and inducible nitric oxide synthase protein levels were also augmented in db/db mice. However, Kangen-karyu reduced the expressions of these inflammatory proteins by inhibiting NF-κB activation in db/db type 2 diabetes.

Conclusions

This study suggests that Kangen-karyu may improve oxidative stress via the regulation of dyslipidaemia in type 2 diabetes.

Bioactive constituents of Corni Fructus: The therapeutic use of morroniside, loganin, and 7-O-galloyl-D-sedoheptulose as renoprotective agents in type 2 diabetes

Corni Fructus, the fruit of Cornus officinalis Sieb. et Zucc. (Cornaceae), is an important crude herb used in Chinese medicine to exhibit several biological activities, including hypoglycemic, antineoplastic, and antimicrobial effects, and to improve liver and kidney functions. We have been investigating the mechanism and bioactive constituents of Corni Fructus using diabetic animal models. Morroniside, loganin, and 7-O-galloyl-D-sedoheptulose, the main active compounds of Corni Fructus, exhibit the same lowering effects of elevated triglyceride, oxidative stress and advanced glycation endproduct (AGE) formation in the kidney of db/db mice. The effects of morroniside and 7-O-galloyl-D-sedoheptulose were mediated through modulation by renal sterol regulatory element binding proteins and nuclear factor-kappa B expression, but the effect of loganin was presumably mediated by hypoglycemic and antioxidant effects in the kidney, and also indirectly by the amelioration of metabolic disorders in other organs such as the liver. These findings led us to conclude that morroniside, loganin, and 7-O-galloyl-D-sedoheptulose would synergistically contribute to the inhibition of metabolic disorders (hyperglycemia and dyslipidemia), oxidative stress, inflammation, as well as AGE formation in the diabetic kidney.

Effects of morroniside isolated from Corni Fructus on renal lipids and inflammation in type 2 diabetic mice

Objectives

The effects of morroniside isolated from Corni Fructus on renal lipids and inflammation provoked by hyperglycaemia were investigated using type 2 diabetic mice.

Methods

Morroniside was administered orally to db/db mice at 20 or 100 mg/kg daily for 8 weeks, and its effects were compared with those in vehicle-treated db/db and m/m (non-diabetic) mice. Serum and renal biochemical factors and protein expression related to lipid homeostasis and inflammation were measured.

Key findings

Morroniside produced significant dose-dependent reductions in serum triglyceride and renal glucose and lipid levels. Morroniside altered the abnormal protein expression of sterol regulatory element binding proteins (SREBP-1 and SREBP-2). In addition, the formation of reactive oxygen species and lipid peroxidation were inhibited in the morroniside-treated db/db mouse group, and the ratio of reduced glutathione to the oxidised form was significantly elevated. These results suggest that morroniside alleviated oxidative stress in the kidneys of db/db mice. Furthermore, 100 mg/kg morroniside down-regulated the expression of nuclear factor-κBp65, cyclooxygenase-2 and inducible nitric oxide synthase augmented in db/db mice.

Conclusions

Morroniside may inhibit abnormal lipid metabolism and inflammation due to reactive oxygen species in the kidneys in type 2 diabetes.

Active principle of kimchi, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, retards fatty streak formation at aortic sinus of apolipoprotein E knockout mice

We examined the beneficial effects of an active principle in kimchi, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA), on atherogenesis in apolipoprotein E knockout (apoE KO) mice. ApoE KO mice were fed an atherogenic diet containing 1% cholesterol (control group) with an intraperitoneal injection of chemically synthesized HDMPPA (10 mg/kg/day) (HDMPPA group) for 8 weeks. The aortic sinus atherosclerotic lesion size in the HDMPPA group (n = 10) was significantly smaller (control vs. HDMPPA, 280,790 vs. 165,409 microm(2), P < .001). The level of reactive oxygen species (ROS) in the HDMPPA group was lower by 14%, compared with the control group (P < .05). Aortic NADPH oxidase activity was significantly lower in the HDMPPA group than in the control group. HDMPPA suppressed the mRNA expression of p47phox and rac-1 of NADPH oxidase by 27.2% and 46.0%, respectively, compared with values of the control group. In conclusion, HDMPPA in kimchi may attenuate atherosclerosis in apoE KO mice through retardation of ROS generation via down-regulating the mRNA expression of p47phox and rac-1, which are the components of NADPH oxidase.