Sung Yong Yang

The hepatoprotection of caffeic acid and rosmarinic acid, major compounds of Perilla frutescens, against t-BHP-induced oxidative liver damage

Perilla frutescens leaves are often used in East Asian gourmet food. In this study, we investigated the hepatoprotective effects of caffeic acid (CA), rosmarinic acid (RA), and their combination. P. frutescens contains 1.32μg CA/mg dry material (DM) and 26.84μg RA/mg DM analyzed by HPLC-DAD and HPLC-MS. CA remarkably reduced the oxidative damage than rosmarinic acid in an in vitro study. Oral intubation with CA or RA alone for five days was conducted prior to treatment with a single dose of tert-butyl hydroperoxide (0.5mmol/kg b.w., i.p.), which led to a significant reduction of indicators of hepatic toxicity, such as aspartate aminotransferase, alanine aminotransferase, oxidized glutathione, lipid peroxidation and enzyme activities related to antioxidant such as catalase, glutathione peroxidase and superoxide dismutase. Interestingly, compared to treatment with CA or RA alone, a combination of both compounds more increased the endogenous antioxidant enzymes and glutathione (GSH) and decreased lipid peroxidation in livers. These results suggest that CA from perilla leaves plays a role in the increased hepatic GSH concentration, and shows an additive hepatic protection with RA against oxidative hepatic damage.

Protective effect of extracts of Perilla frutescens treated with sucrose on tert-butyl hydroperoxide-induced oxidative hepatotoxicity in vitro and in vivo

Perilla frutescens leaves are often used in East Asian gourmet food. In this study, we investigated the hepatoprotective effects of P. frutescens leaves grown in different concentrations of sucrose (0, 115, 175 and 235 mM sucrose) leading to four samples of perilla leaf extracts (PLEs). Based on caffeic acid level and antioxidant activities, further experiments were conducted using perilla leaf extracts treated with 6% sucrose compared with non-treated perilla leaf extracts as a control. Oral intubation with non-treated perilla leaf extracts or perilla leaf extracts treated with 6% sucrose (1000 mg/kg b.w. rat) for 5 days was conducted before treatment with a single dose of tert-butyl hydroperoxide (0.5 mmol/kg b.w., i.p.) led to a significant reduction of hepatic toxicity in the perilla leaf extracts treated with 6% sucrose. We demonstrated that P. frutescens with higher contents of caffeic acid was produced, and that sucrose could play a role in the induction of this secondary metabolite. Sucrose-treated perilla leaves, which had better antioxidant activities than untreated leaves, can be used as a potential dietary source.

Mutagenicity and Oral Toxicity Studies of Terminalia chebula

The fruit of Terminalia chebula Retz. (T. chebula), which is a member of the Combfreetaceae family, is used widely in Asian countries as a traditional folk medicine, and its extract has been reported to be an anticancer, antidiabetic and anticaries agent. In our previous study, chebulic acid isolated from T. chebula extract was confirmed to show antioxidant activity and protective action against endothelial cell dysfunction. In order to support the safety‐in‐use of the ethyl acetate (EtOAc)‐soluble portion of a T. chebula ethanol extract containing 29.4% chebulic acid content, the prepared portion was tested in an in vitro mutagenicity assay, and a single‐ and 14‐day repeated dose oral toxicity study. In the bacterial mutation assay, up to 5000 µg/mL concentration of the EtOAc‐soluble portion, the numbers of colonies did not increase whether with or without metabolic activation. In the oral toxicity study, the single oral dose of the extract at 2000 mg/kg did not produce mortality or abnormal lesions in the internal organs of rats. The results of a 14‐day orally repeated dose showed that the EtOAc‐soluble portion of T. chebula ethanol extracts gave no adverse effects at dosages of 2000 mg/kg in rats in the study. Copyright

Optimization of Maillard reaction with ribose for enhancing anti-allergy effect of fish protein hydrolysates using response surface methodology

Halibut is served on sushi and as sliced raw fish fillets. We investigated the optimal conditions of the Maillard reaction (MR) with ribose using response surface methodology to reduce the allergenicity of its protein. A 3-factored and 5-leveled central composite design was used, where the independent variables were substrate (ribose) concentration (X1, %), reaction time (X2, min), and pH (X3), while the dependent variables were browning index (Y1, absorbance at 420nm), DPPH scavenging (Y2, EC50 mg/mL), FRAP (Y3, mM FeSO4/mg extract) and β-hexosaminidase release (Y4, %). The optimal conditions were obtained as follows: X1, 28.36%; X2, 38.09min; X3, 8.26. Maillard reaction products of fish protein hydrolysate (MFPH) reduced the amount of nitric oxide synthesis compared to the untreated FPH, and had a significant anti-allergy effect on β-hexosaminidase and histamine release, compared with that of the FPH control. We concluded that MFPH, which had better antioxidant and anti-allergy activities than untreated FPH, can be used as an improved dietary source.

Chebulic acid prevents hepatic fibrosis induced by advanced glycation end-products in LX-2 cell by modulating Nrf2 translocation via ERK pathway

Advanced glycation end-products (AGEs) are formed during normal aging, and at an accelerated rate in metabolic syndrome patients. Nonalcoholic steatohepatitis (NASH) can be caused by the AGEs in plasma, while glyceraldehyde-derived AGEs (glycer-AGEs) are significantly higher in the serum of NASH patients. In this study, we investigated the molecular mechanisms of chebulic acid, isolated from Terminalia chebula Retz., in the inhibition of glycer-AGEs induced production of reactive oxygen species (ROS) and collagen accumulation using the LX-2 cell line. Chebulic acid significantly inhibited the induction of ROS and accumulation of collagen proteins by glycer-AGEs. ERK phosphorylation and total nuclear factor E2-related factor 2 (Nrf2) protein expression were induced by chebulic acid in a dose-dependent manner. Chebulic acid was also found to induce translocation of Nrf2 into the nucleus, which was attenuated by inhibition of ERK phosphorylation through treatment with PD98059. Following translocation of Nrf2, chebulic acid induced the protein expressions of catalytic subunit of γ-glutamylcysteine synthetase and glutathione synthesis. Collagen accumulation was also significantly reduced by chebulic acid treatment. The observed effects of chebulic acid were all inhibited by PD98059 treatment. Taken together, these results suggest that chebulic acid prevents the glycer-AGEs-induced ROS formation of LX-2 cells and collagen accumulation by ERK-phosphorylation-mediated Nrf2 nuclear translocation, which causes upregulation of antioxidant protein production.

Nephroprotection of plantamajoside in rats treated with cadmium.

Cadmium (Cd), an environmental and industrial pollutant, generates free radicals responsible for oxidative stress. Cd can also lead to various renal toxic damage such as the proximal tubules and glomerulus dysfunction. Plantamajoside (PMS), a major compound of Plantago asiatica (PA), was reported to have the antioxidant effects. In this study, we investigated the protective effects of PMS on Cd-induced renal damage in the NRK-52E cell and rat kidney tissue. Cd exposure increased the ROS generation, lipid peroxidation, serum biochemical values of renal damage, and mRNA and protein expressions of KIM-1 in vitro and in vivo. The significant reduction in glutathione (GSH)/glutathione disulfide (GSSG) ratio and activities of antioxidant enzymes were also observed in the rats treated with Cd. PMS significantly decreased the ROS generation and lipid peroxidation, thus enhancing GSH/GSSG ratio, antioxidant enzyme activities in the cells and rats, and improved histochemical appearances, indicating that PMS has protective activities against Cd-induced renal injury.

Protective effects of maillard reaction products of whey protein concentrate against oxidative stress through an Nrf2-Dependent Pathway in HepG2 Cells

Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

Caffeic Acid Inhibits the Uptake of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) by Inducing the Efflux Transporters Expression in Caco-2 Cells

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is formed as a by-product of the Maillard reaction during cooking and frying of protein-rich foods at high temperatures. PhIP is metabolized in the liver by cytochrome P450 1A1/2 to carcinogenic metabolite N-hydroxy PhIP, which can form DNA adduct. The ATP binding cassette (ABC) transporters, P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP) are capable of transporting the food-borne procarcinogen PhIP back to the intestinal lumen. In the present study, the uptake and efflux of PhIP were assessed by determining apparent bidirectional permeability coefficients and efflux ratio. The efflux ratio of PhIP with 10 µM caffeic acid was significantly increased compared with control. The mRNA levels of efflux transporters were measured to evaluate the effect of caffeic acid in the presence of PhIP on efflux-mediated transport of PhIP. Caco-2 cells exposed to 10 µM caffeic acid for 3 and 6 h also exhibited higher mRNA levels of P-gp and BCRP than those of control. In contrast, the mRNA level of MRP2 was only slightly induced after 3 h and 6 h. Therefore, caffeic acid at low concentration is expected to be used not only as an antioxidant, but also as an inhibitor of the absorption of food borne carcinogen heterocyclic amines. However, further studies, especially in vivo studies, are required to confirm these results.

In vivo study of the renal protective effects of Capsosiphon fulvescens against streptozotocin-induced oxidative stress

Mi-Hyun Nam, Yun-Chang Koo, Chung-Oui Hong, Sung-Yong Yang, Se-Wook Kim, Hye-Lim Jung, Hwa Lee, Ji-Yeon Kim, Ah-Ram Han, Won-rak Son, Min-Cheol Pyo, and Kwang-Won Lee*Division of Food Bioscience and Technology, College of Life Science & Biotechnology, Korea UniversityAbstract In this study, we evaluated the effect of Capsosiphon fulvescens extract (CFE) and its active compound,pheophorbide A (PhA), on diabetic kidney failure. Diabetes mellitus (DM) was induced by a single intraperitoneal injectionof streptozotocin (STZ; 40 mg/kg body weight (BW)). After a week, the rats were orally administered CFE (4 and 20 mg/kg BW) or PhA (0.2 mg/kg BW) once a day for 9 weeks. After scarification, renal tissue samples were collected forbiochemical and histochemical analyses. Our study showed that the treatment with CFE and PhA significantly decreasedlipid peroxidation level and the activities of glutathione peroxidase and glutathione-S-transferase (p<0.05), but it increasedglutathione level and the activities of glutathione reductase, superoxide dismutase, and catalase in the renal tissues(p<0.05). The CFE- and PhA-treated rats with DM showed improved histochemical appearance and decreased abnormalglycogen accumulation. Therefore, we suggest that PhA-containing CFE could exert renal protective effects against STZ-induced oxidative stress.Keywords: Capsosiphon fulvescens , streptozotocin, diabetic rats, oxidative stress, antioxidant enzyme, renal protective effects

Improved physicochemical properties and hepatic protection of Maillard reaction products derived from fish protein hydrolysates and ribose

High amounts of waste products generated from fish-processing need to be disposed of despite their potential nutritional value. A variety of methods, such as enzymatic hydrolysis, have been developed for these byproducts. In the current study, we investigated the physicochemical, biological and antioxidative properties of fish protein hydrolysates (FPH) conjugated with ribose through the Maillard reaction. These glycated conjugates of FPH (GFPH) had more viscous rheological properties than FPH and exhibited higher heat, emulsification and foaming stability. They also protected liver HepG2 cells against t-BHP-induced oxidative stress with enhanced glutathione synthesis in vitro. Furthermore, it was shown that GFPH induced upregulation of phase II enzyme expression, such as that of HO-1 and γ-GCL, via nuclear translocation of Nrf2 and phosphorylation of ERK. Taken together, these results demonstrate the potential of GFPH for use as a functional food ingredient with improved rheological and antioxidative properties.