Gyo-Nam Kim

Mulberry Leaf Extract Reduces Postprandial Hyperglycemia with Few Side Effects by Inhibiting α-Glucosidase in Normal Rats

Mulberry (Morus alba L.) leaf extract (MLE) was investigated as a potent plant-derived α-glucosidase inhibitor with low α-amylase inhibitory activity. MLE was prepared by heating in an autoclave at 121 °C for 15 minutes, and its in vitro and in vivo antihyperglycemic activities were investigated. The adverse side effects of MLE were analyzed by measuring the weight and volume of the cecum, stool color, starch content in the cecum, and the integrity of intestinal transporting capacity. The in vitro inhibitory activity of MLE on intestinal α-glucosidase was potent and that on intestinal α-amylase was very weak compared with acarbose. Sugar loading tests with starch, maltose, and sucrose showed that MLE may reduce postprandial increases in blood glucose by acting as an intestinal α-glucosidase inhibitor. Feeding tests suggested that MLE may exhibit fewer adverse side effects than other α-glucosidase inhibitors, such as abdominal flatulence and meteorism, which are attributed to the impaired digestion of starch by strong inhibition of intestinal α-amylase. These results suggest that MLE could be used in the development of pharmaceutical foods to control the blood glucose levels of diabetic patients by inhibiting intestinal α-glucosidase with reduced side effects.

Heat processing decreases Amadori products and increases total phenolic content and antioxidant activity of Korean red ginseng.

The functional properties of Korean red ginseng (KRG) are known to be dependent upon the extent of heat processing. We demonstrated that repeated heat processing in the preparation of KRG decreased its arginyl-fructosyl-glucose (AFG) content and metal chelating capacity. On the other hand, the total phenolic compound content, in vitro peroxyl radical scavenging ability, and cellular peroxyl and hydroxyl radical scavenging ability increased with repeated heat processing. The peroxyl radical scavenging ability of KRG may be due to the total phenolic compound content. The hydroxyl radical scavenging ability of KRG seems to result mainly from the chelating ability of Amadori compounds such as arginyl-fructose and AFG. The protective ability of KRG against Cu²(+)-induced oxidative stress in hepatoma HepG2 cells may be due to permeability into the cell membrane rather than antioxidant activity. These results can be used to predict the physiological functions of KRG in in vivo models.

Curcumin ameliorates AAPH-induced oxidative stress in HepG2 cells by activating Nrf2

In this study, 3 major curcuminoids were analyzed and the cellular anti-oxidant activities of E-TE(K) and E-TE(M) were assessed in HepG2 cells. The contributions and molecular targets of the 3 curcuminoids in the anti-oxidant activities of E-TE(K) and E-TE(M) were revealed. The curcuminoids including curcumin (CCM) was the most abundant curcuminoid [10.7% of ETE( K) and 17.5% of E-TE(M)] and the curcuminoid content, particularly CCM, was crucial for anti-oxidant activities of E-TE(K) and E-TE(M). The anti-oxidant activity of CCM involved the regulation of Nrf2, the central transcriptional factor for expression of phase II detoxifying enzymes such as heme oxygenase-1. The CCM-activated Nrf2 was shown to be regulated by the PI3K/Akt signaling pathway. Taken together, the results indicate that the activation of Nrf2 through PI3K/Akt signaling pathway is required for anti-oxidant activity of CCM. These findings provide the scientific evidence for the development of Nrf2 targeted dietary anti-oxidant.

Antioxidant and Anti-Inflammatory Effects of Rhei Rhizoma and Coptidis Rhizoma Mixture on Reflux Esophagitis in Rats

The purpose of this study was to investigate the antioxidant and anti-inflammatory effects of the combined extract of Rhei rhizoma and Coptidis rhizoma (RC-mix) in experimental model of acute reflux esophagitis. The antioxidant activity was assessed by in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. RC-mix was given at 100, 200, and 400 mg/kg body weight 2 h prior to induction of reflux esophagitis (RE). After 5 h, the effects of RC-mix treated rats were compared with those of normal and control rats. The representative flavonoid contents of RC-mix, such as sennoside A, epiberberine, coptisine, palmatine, and berberine, were detected using HPLC. The elevated esophageal mucosa damage was markedly ameliorated by RC-mix treatment in a dose-dependent manner. Furthermore, the administration of RC-mix reduced the increase of serum reactive oxygen species (ROS) and peroxynitrite (ONOO−). The improvement of superoxide dismutase (SOD) and heme oxygenase-1 (HO-1) levels were marked in the group given RC-mix. Moreover, the elevation of inflammatory mediators and cytokines by nuclear factor-kappa B (NF-κB) activation in control rats decreased by RC-mix pretreatment. These results indicate that RC-mix treatment reduces the pathological states of esophagitis via regulating NF-κB mediated inflammation related to oxidative stress.

Antioxidant and anti-adipogenic activities of persimmon tannins

Soluble and insoluble tannins from 5 different types of persimmon-unripe, astringent Cheongdobansi (CU); red-ripe Cheongdobansi (CR); unripe, astringent Daebong (DU); red-ripe Daebong (DR); and unripe, non-astringent Fuyu (FU)-were prepared. The antioxidant activity of the tannins was determined by measuring the DPPH radical scavenging activity (RSA), ABTS RSA, and reducing power. The strongest DPPH RSA and reducing power were found in the soluble tannins from CU. Soluble tannins from CR, CU, and DU at a concentration of 1,000 μg/mL scavenged most of the ABTS radicals. Approximately 83 and 42% suppression of adipogenesis in 3T3-L1 cells were observed in the 100 μg/mL treatments of the soluble tannins from CU and CR, respectively. Soluble tannins showed relatively higher antioxidant and anti-adipogenic activities than insoluble tannins. These results demonstrate that soluble and insoluble persimmon tannins showed different antioxidant and anti-adipogenic activities according to persimmon types.

Anti-Oxidant and Anti-Adipogenic Effects of Ethanol Extracts from Wheat Germ and Wheat Germ Fermented with Aspergillus oryzae

Most of the wheat germ in cereal grains is removed during the milling process. Various physiological effects have been reported for bioactive substances in wheat germ such as phenolic acids and flavonoids. In this study, the anti-oxidant and anti-adipogenic effects of ethanol extracts from wheat germ (WGE) and wheat germ fermented with Aspergillus oryzae (F-WGE) were investigated in HepG2 and 3T3-L1 cells. The anti-oxidant activity of F-WGE was demonstrated by a dose-dependent increase in the enhanced scavenging capacity of hydroxyl radicals and Cu2+-chelating activity compared to WGE. WGE and F-WGE treatment at doses between 10 and 400 μg/mL did not affect the viability of HepG2 and 3T3-L1 cells. Intracellular ROS levels from Cu2+-induced oxidative stress were significantly decreased by F-WGE treatment in HepG2 cells compared to WGE. Lipid accumulation was increased in 3T3-L1 adipocytes by 100 μM Fe2+ treatment, but the accumulation was strongly inhibited by 100 μg/mL of WGE and F-WGE treatment. These results suggest that changes in bioactive substances during the fermentation of wheat germ can potentiate scavenging activities against transition metal-induced oxidative stress and lipid accumulation in 3T3-L1 adipocytes. Therefore, we propose that F-WGE is a novel food materials and provided scientific evidences for its efficacy in the development of functional foods.

Anti-aging Potential of Extracts Prepared from Fruits and Medicinal Herbs Cultivated in the Gyeongnam Area of Korea

Many recent studies have focused on maintaining a healthy life by preventing and/or postponing the aging process. Numerous studies have reported that continuous exposure to reactive oxygen species can stimulate skin aging and that excessive accumulation of fat can cause an impaired skin barrier and tissue structure alterations. Thus, the maintenance of antioxidant homeostasis and the suppression of adipose accumulation are important strategies for skin anti-aging. Here, we prepared three types of extracts [whole juice, acetone-perchloric acid (PCA), and ethanol] from 20 fruits and medicinal herbs native to the Gyeongnam area of Korea. The total phenolic content of each extract was analyzed, and we observed higher total phenolic contents in the medicinal herbs. Consistent with this, the results of the oxygen radical absorbance activity capacity assay indicated that the in vitro antioxidant activities of the medicinal herb extracts were stronger than those of the fruit extracts. The fruits and medicinal herbs had strong effects on cell-based systems, including H2O2-induced oxidative stress in human keratinocytes and 3T3-L1 lipid accumulation. Nishimura Wase persimmon, Taishu persimmon, wrinkled giant hyssop, sweet wormwood, Chinese cedar, red perilla, tan shen, hiyodori-jogo, and cramp bark may be natural anti-aging materials with effective antioxidant and anti-adipogenic activities. Taken together, our findings may provide scientific evidence supporting the development of functional foods and nutraceuticals from fruits and medicinal herbs.

Anti-Adipogenic Effects of Ethanol Extracts Prepared from Selected Medicinal Herbs in 3T3-L1 Cells

Obesity is a major risk factor for various metabolic diseases such as cardiovascular disease, hypertension, and type 2 diabetes mellitus. In this study, we prepared ethanol extracts from Agastache rugosa (ARE), Chrysanthemum zawadskii (CZE), Mentha arvensis (MAE), Perilla frutescens (PFE), Leonurus sibiricus (LSE), Gardenia jasminoides (GJE), and Lycopus coreanus (LCE). The anti-oxidant and anti-adipogenic effects were evaluated. The IC50 values for ascorbic acid and LCE against 2,2-diphenyl-1-picrylhydrazyl radicals were 246.2 μg/mL and 166.2 μg/mL, respectively, followed by ARE (186.6 μg/mL), CZE (198.6 μg/mL), MAE (337.1 μg/mL), PFE (415.3 μg/mL), LSE (548.2 μg/mL), and GJE (626.3 μg/mL). In non-toxic concentration ranges, CZE had a strong inhibitory effect against 3T3-L1 adipogenes (84.5%) than those of the other extracts. Furthermore, the anti-adipogenic effect of CZE is largely limited in the early stage of adipogenesis, and we revealed that the inhibitory role of CZE in adipogenesis is required for the activation of Wnt signaling. Our results provide scientific evidence that the anti-adipogenic effect of CZE can be applied as an ingredient for the development of functional foods and nutri-cosmetics for obesity prevention.

Anti-adipogenic activity of blue mussel (Mytilus edulis) extract by regulation of 3T3-L1 adipogenesis through Wnt/β-catenin signaling pathway

The blue mussel (Mytilus edulis) is widely distributed in European waters but it is little consumed. Although several studies have been reported biological activities of mussels, the anti-adipogenic activity of blue mussel and the molecular mechanism in anti-obese activity remain unknown. Here, we prepared a water extract of blue mussel (BME) and its anti-adipogenic activity was assessed in 3T3-L1 cells. BME treatment dose-dependently inhibited 3T3-L1 lipid accumulation, as judged by Oil Red O staining and microscopic analysis. Consistent with this, BME treatment markedly suppressed mRNA expression levels of adipogenic genes, such as C/EBPβ, PPARγ, C/EBPα, and FAS, in 3T3-L1 mature adipocytes. BME-inhibited lipid accumulation in 3T3-L1 adipocytes was limited with treatment after adipocyte differentiation, particularly in the early and intermediate stages. We also showed that the Wnt/β-catenin signaling pathway is required in BME-inhibited 3T3-L1 adipogenesis. These finding may provide scientific evidence for the development of functional foods against obesity.

Antioxidant and anti-adipogenic activities of chestnut (Castanea crenata) byproducts

The antioxidant and anti-adipogenic activities of chestnut byproducts were evaluated. At 100 μg/mL, the methanol extract (ME) scavenged 34.2% of DPPH and 78.8% of ABTS radicals. The DPPH and ABTS radical scavenging activity of the water extract (WE) was found to be low (13.7 and 33.1%, respectively) compared with controls. WE and ME dose-dependently inhibited lipid accumulation of 3T3-L1 adipocytes. WE and ME at 100 μg/mL suppressed 3T3-L1 adipogenesis by 71.0 and 96.5%, respectively, when compared with mature adipocytes. The results indicated that WE and ME inhibited adipocyte differentiation by down-regulating the mRNA expression levels of CCAAT/enhancer binding protein (C/EBP)-β, C/EBPα, and peroxisome proliferator-activated receptor (PPAR)-γ in 3T3-L1 cells. Our study also revealed that WE and ME inhibited pre- and early stage adipogenesis in 3T3-L1 cells. The results suggest that chestnut byproducts are a promising source of antioxidant and antiobesity molecules.