Yoo Seok Jeong

Grape skin and loquat leaf extracts and acai puree have potent anti-atherosclerotic and anti-diabetic activity in vitro and in vivo in hypercholesterolemic zebrafish.

Three major sources of flavonoids and phenolic compounds, which are commonly used in food industry, namely loquat leaf (LL), grape skin (GS) and acai puree, were tested in regard to their potential anti-atherosclerotic and anti-diabetic activity. The compounds were evaluated by in vitro antioxidant assay using a macrophage model and for in vivo hypolipidemic activity using zebrafish. In assays in vitro, all extracts demonstrated potent ferric ion reductive capacity, radical-scavenging activity and inhibition of low-density lipoprotein (LDL) oxidation at a final concentration of 0.1 mg/ml. Extracts could also abrogate fructose-mediated protein glycation and mildly inhibit cholesteryl ester transfer protein (CETP). Cellular uptake of oxidized or acetylated LDL into macrophages was inhibited by acai treatment (final concentration, 0.1 mg/ml) and moderately diminished by GS and LL extracts. After 4 weeks of feeding on a high cholesterol diet (HCD), zebrafish exhibited serum total cholesterol (TC) and triglyceride (TG) levels 2.5-fold higher than those fed a normal diet (ND). Within the experimental group, those fed acai demonstrated the lowest serum TC and CETP activity, while the LL-consuming group showed a reduction in serum TC and TG relative to HCD-fed fish. Serum glucose levels also increased in the HCD group, to threefold above the ND group; GS and LL feeding elicited the greatest reduction in hyperglycemia. The groups consuming acai and LL showed much less hepatic inflammation, as well as attenuation of fatty liver and a reduced content of oxidized species. In conclusion, extracts of LL, GS, and acai shared antioxidant, anti-inflammatory and anti-atherosclerotic activity in cellular assays and in a hypercholesterolemic zebrafish model.

Grape skin extract reduces adipogenesis- and lipogenesis-related gene expression in 3T3-L1 adipocytes through the peroxisome proliferator-activated receptor-γ signaling pathway.

We previously reported that grape skin ethanol extract (GSE) decreases adipogenic transcription factor gene expression, inhibiting triglyceride accumulation in 3T3-L1 adipocytes. In this study, we hypothesized that GSE may induce differential expression profiles in adipocytes, thus providing protection against obesity. Thirty-five genes involved in the peroxisome proliferator-activated receptor-γ (PPARγ) signaling pathway, lipid metabolism, or adipogenesis were identified through microarray analysis of adipocytes treated with GSE. Expression of the genes involved in PPARγ signaling, Adipoq, Scd1, Nr1h3, Fabp5, Scd2, and Pparg decreased with GSE treatment, whereas expression of Ppargc1a increased. Lipid metabolism-associated genes Mlxp1, Stat5a, Hsl, Plin1, and Vdr were down-regulated. Interestingly, GSE also affected expression of genes related to the mitogen-activated protein kinases pathway. GSE extract treatment decreased expression of aP2, Fas, and Tnfa, known markers of adipogenesis, as measured by real-time polymerase reaction. These findings demonstrate the antiadipogenic effects of GSE on 3T3-L1 adipocytes at the genetic level, primarily on the PPARγ signaling pathway.

Evaluation of two Bacillus subtilis strains isolated from Korean fermented food as probiotics against loperamide-induced constipation in mice

Probiotics are live microbes that confer health benefits on the host when administered in adequate amounts. To evaluate the probiotic potential of Bacillus subtilis isolated from Korean fermented foods, we investigated the resistance to biological barriers and improvement of loperamide-induced constipation. The values of resistance to gastric acidity of B. subtilis CBD2 and KMKW4 strains were 55.34±2.12 and 64.58±2.95%, respectively, whereas the survival rate of B. subtilis KMKW4 (31.17±5.78%) in bile acids was superior to that of CBD2 (8.62±2.09%). These strains also demonstrated adhesiveness to intestinal epithelial HT-29 cells and an inhibitory activity against pathogenic microflora. Furthermore, B. subtilis CBD2 and KMKW4 strains improved gastrointestinal activity when tested in a loperamide-induced mouse model of constipation. Pre-treatment with CBD2 and KMKW4 strains before the onset of constipation improved fecal output and gastrointestinal transit in loperamide-treated mice. These strains also showed inhibitory effects on the activity of β-glucosidase and tryptophanase, harmful enzymes of intestinal microflora. Taken together, these finding show that B. subtilis CBD2 and KMKW4 have high adaptability to gastrointestinal environment, and the ability to inhibit pathogenic microflora and prevent constipation, suggesting their activity as potential probiotics.

Multiplex real-time polymerase chain reaction for rapid detection of Staphylococcus aureus, Vibrio parahaemolyticus , and Salmonella typhimurium in milk and kimbap

This study presented a multiplex, single-tube, realtime polymerase chain reaction (RTi-PCR) approach for detecting Staphylococcus aureus, Vibrio parahaemolyticus, and Salmonella typhimurium, three of the more frequent foodborne pathogenic bacteria typically investigated in a variety of foods. New primer sequences were designed for detection of specific gene fragments in the 23s ribosomal RNA, transmembrane transcription regulator, and replication origin sequences of S. aureus, V. parahaemolyticus, and S. typhimurium. Simultaneous amplifications were performed under the optimized reaction conditions. Melting curve analysis using SYBR Green I RTi-PCR analysis produced characteristic Tm values for each target amplicon, demonstrating specific and efficient amplification of the three fragments. Addition of an internal amplification control did not affect detection sensitivity for the target pathogen. The analysis of frequent foodborne pathogenic bacteria in artificially inoculated food demonstrated analytical sensitivity for direct detection of each pathogen using the Chelex method rather than a commercial DNA extraction kit. The assay was sensitive to 103 colony-forming units (CFU)/reaction. With enrichment (2 or 4 h), each species could be detected at 101 CFU/g. These results provided that RTi-PCR is a rapid and costeffective procedure to detect foodborne pathogens. This assay could become a valuable tool for routine microbiological analysis in the food industry.