• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.1970-1975
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• 2007

Squalene synthase plays an important role in the cholesterol biosynthetic pathway. Inhibiting this enzyme in hypercholesterolemia can lower not only plasma cholesterol but also plasma triglyceride levels. A squalene synthase inhibitor was screened from Prunus mume fruit, and then purified via sequential processes of ethanol extraction, HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, and crystallization. The squalene synthase inhibitor was identified as chlorogenic acid with a molecular mass of 354 Da and a molecular formula of $C_{16}H_{18}O_9$ based on UV spectrophotometry, $^1H$ and $^{13}C$ NMRs, and mass spectrometry. Chlorogenic acid inhibited the squalene synthase of pig liver with an $IC_{50}$ level of 100 nM. Since chlorogenic acid was an effective inhibitor against the squalene synthase of an animal source, it may be a potential therapeutic agent for hypercholesterolemia.

• Applied Biological Chemistry
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• v.30 no.2
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• pp.192-197
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• 1987

Natto was produced by fermenting local soybeans Bacillus subtilis S.N.U. 816. The changes of chemical composition, enzyme activity and texture of NATTO during the fermentation were investigated. The amount of amino type and watr soluble nitrogens were increased as the fermentation progressed, although the former seemed to reach a plateau at about 20 hours of the fermentation, of the protease activity were increased until 16 hours of fermentation at which time they tended to reach plateaus. Among the inspected free sugars (fructose, glucose, sucrose, maltose), remarkable increases in the levels of fructose and glucose were observe3 after 4 hours of the fermentation. Since then their contents, however, were reduced very low as the processing went on, and sucrose contents dropped drastically to about 10% level and stayed low thereafter. Free amino acid contents of natto during 20 hours of the fermentation were or 2 times greater than those of the unfermented steamed soybean, the 24 hours ferment, respectively. Sensory evaluation revealed that 20 hours of fermentation produced the best quality products based on taste, odor, and color, considering all the data, it seems possible to conclude that the optimum of time for fermentation of natto at $42^{\circ}C$ is 20 hours.

• Korean Journal of Plant Resources
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• v.26 no.3
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• pp.374-382
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• 2013

The objective of this study was determined to evaluate ${\alpha}$-amylase, ${\alpha}$-glucosidase, pancreatic lipase inhibition in vitro and DPPH radical scavenging activity of the several Korean resources plants. The ${\alpha}$-amylase inhibitory activity of Salicornia herbacea, Erythronium japonicum (flower) and Phragmites communis (root) in water extract showed relatively high 62.8%, 66.5% and 69.3%, respectively. The ${\alpha}$-amylase inhibitory activity of Citrus junos (pericarp) and Cornus officinalis in methanol extract was found to have an effect with 32.8% in Citrus junos (pericarp) and 60.9% in Cornus officinalis. Corylopsis coreana in both water and methanol extract had the highest ${\alpha}$-glucosidase inhibitory activity of 81.7% and 89.5%, while the extract of Portulaca oleracea, Ficus carica and Citrus junos was not measured ${\alpha}$-glucosidase inhibitory activity at given experiment concentration. Depending on the extraction solvent and the plant species, it was observed that there was a significant difference in ${\alpha}$-glucosidase inhibitory activity. The pancreatic lipase inhibitory activity showed relatively higher in the methanol extract than water extract except pericarp of Citrus junos. The DPPH radical scavenging activity of selected plants was much difference between measured plant species, and showed that the increase was proportional to the concentration. These results suggested that selected plants had the potent biological activity on carbohydrate, lipid Inhibitory activity and antioxidant activity, therefore these plant resources could be a good materials to develop medicinal preparations, nutraceuticals or health functional foods for diabetes or obesity.

• Journal of Nutrition and Health
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• v.44 no.6
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• pp.488-497
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• 2011

Oxygen is necessary to sustain life, yet cellular oxygen metabolism creates destructive elements called free radicals. Free radicals are chemically unbalanced and carrying free electrons that can damage molecules, potentially damaging the cell itself. For this reason, many antioxidant products, including supplements and functional foods, are being developed. In particular, natural products are rich sources of pharmacologically active compounds. The purpose of this study was to investigate the antioxidant effects of target biomaterials in Korean traditional spices such as diallyl sulfide (DAS), capsaicin (CAP), and gingerol (GGR), and to investigate the response of the antioxidant defense system to oxidative stress by hydrogen peroxide ($H_2O_2$) compared to sulforaphane (SFN) in HepG2 cells. After the analysis of the cell viability using Cell Counting kit-8 (CCK-8) assay, we determined that the optimum levels were $200{\mu}M$ DAS, $25{\mu}M$ CAP, $50{\mu}M$ GGR, and $12.5{\mu}M$ SFN. Antioxidant enzymes were measured and protein expression was detected by Western blotting. All treatments showed a significant decrease in antioxidant enzyme activity such as superoxide dismutase, catalse, and glutathione peroxidase in HepG2 cells. Additionally, DAS, CAP, GGR and SFN increased the antioxidant system-related transcription factor Nrf2 which was found to be regulated by the activation of MAPK-JNK in this study. In conclusion, these results indicate the protective effects of DAS CAP, GGR, and SFN against $H_2O_2$-induced oxidative stress.

• Journal of Applied Biological Chemistry
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• v.55 no.3
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• pp.141-148
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• 2012

Recently, concerns about the volatile hazardous compounds including acetaldehyde, methanol, and fusel oils in alcoholic beverages, which cause hangover such as headache and dizziness after consumption, have been raised. The volatile hazardous compounds might also lead to an increased incidence of liver diseases and even cancers with a high consumption of alcoholic beverages. Acetaldehyde is a volatile compound naturally found in alcoholic beverages and used as flavor in many foods. However this is also regarded as possibly being carcinogenic to humans. Furthermore, acetaldehyde with alcoholic consumption is recently classified as Group 1, carcinogenic to humans. On the other hand, methanol is generated from demethoxylation of pectin by pectinolytic enzyme during alcoholic fermentation. Higher alcohols occur naturally in alcoholic beverages as by-products of alcoholic fermentation and are generally regarded as important flavor compounds. In the current study, we reviewed on the health concern, maximum levels, analytical methods, and current levels of hazardous volatile compounds in alcoholic beverages.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.153-159
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• 2000

A 4.4 kb DNA fragment encompassing lacA (galactoside acetyltransferase) and lacZ($\beta$-galactosidase) genes from Lactococus lactis ssp. lactis ATCC 7962 (L. lactis 7962) was introduced ito a Lac strain, Lactococcus lactis ssp. lactis MG1363 (L. lactis MG1363) by using a lactococcal expression vector, pMG36e and expression level of lacZ was examined. Growth rates and $\beta$-galactosidase ($\beta$-gal) activities of MG1363 cells carrying recombinant plasmid, pMLZ3, on M17 broth containing different carbon sources (1%, w/v) were examined. Contrary to the expectations, MG1363 [pMLZ3] grown on lactose showed the lowest enzyme activity (17 units) and cells grown on galactose had the highest $\beta$-gal activity (41 units). Cells grown on glucose had intermediate activity (33 units). These activities are about one tenth of the values observed in L. lactis 7962 where lacZ is present as a single-copy gene in the chromosome. When the cellular concentrations of lacZ transcript were examined using slot blot hybridization, it was found that MG1363[pMLZ3] produced sufficient amounts of transcript. These results indicate that either proteolytic degradation of $\beta$-gal or other regulatory mechanism prevent the translation or accumulation of $\beta$-gal in L. lactis MG1363 cells. In regard to regulation, the presence of the ccpA gene in L. lactis MG1363 was confirmed by Southern blot.

• Journal of Microbiology
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• v.42 no.3
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• pp.216-222
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• 2004

In a previous paper, the ogdH gene that encodes 2-oxoglutarat dehydrogenase was isolated from Salmonella typhimurium. The catalytic N-terminal region in the enzyme was found to be very specific for the Salmonella species. Therefore, the aim of the present study was to detect S. typhimurium in food sources using primers designed for OGDH-l and OGDH-2 which were based on the salmonella-specific region of the ogdH gene. A simple polymerase chain reaction (PCR) detection method was developed to detect low numbers of S. typhimurium in a chicken meat microbial consortium. Using the ogdH-specific primers under stringent amplification conditions and for gene probe analysis, fewer than 100 colony-forming units (CFUs) were detectable when pure cultures were employed. When the PCR assay was run on S. typhimurium-contaminated meat contents, only the positive meat samples containing as few as 200 CFUs reacted to the assay. The method employed for sample processing is simple and it was determined to provide a sensitive means of detecting trace amounts of S. typhimurium-specific sequences in the presence of mixed meat microbial populations. When compared with six representative intestinal gram-negative bacterial strains in foods, including Vibrio parahaemolyticus, V. vulnificus, Enterobacter cloacae, E. coli O157:H7, Pseudomonas aeruginosa, and Proteus sp., S. typhimurium had a unique and distinct PCR product (796 bp). In conclusion, the two OGDH primers were found to be rapid and sensitive detectors of Salmonella spp for the PCR method.

• Korean Journal of Pharmacognosy
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• v.29 no.4
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• pp.338-346
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• 1998

In order to elucidate the relationship between anti-HIV-1 enzyme activity and inhibition of HIV-1 replication by natural sources, extracts from some plants using the foods and oriental medicines were tested for inhibitory effects on the viral replication, reverse transcriptase (RT), protease and ${\alpha}-glucosidase$. In the anti-RT test, water extracts of Ficus carica (leaf), Houttuynia cordata (aerial part) and Ixeris tamagawaensis (aerial part) showed more than 79% inhitibion at a concentration of $100\;{\mu}g/ml$. The protease and ${\alpha}-glucosidase-inhibiting$ samples in the screening were water extract of Syringa dilatata (leaf) and methanol extract of Hibiscus syriacus (leaf and stem), which showed more than 40% inhibition at a concentration of $100\;{\mu}g/ml$. In the primary anti-HIV-1 test, water extracts of Equisetum arvense (aerial part), Hibiscus syriacus (leaf), Ixeris tamagawaensis (aerial part) and Pueraira thunbergiana (leaf) showed the potent inhibition against HIV-1 induced cytopathic effects.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1064-1069
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• 2008

Levan fructotransferase (LFTase) preferentially catalyzes the transfructosylation reaction in addition to levan hydrolysis, whereas other levan-degrading enzymes hydrolyze levan into a levan-oligosaccharide and fructose. Based on sequence comparisons and enzymatic properties, the fructosyl transfer activity of LFTase is proposed to have evolved from levanase. In order to probe the residues that are critical to the intramolecular fructosyl transfer reaction of the Microbacterium sp. AL-210 LFTase, an error-prone PCR mutagenesis process was carried out, and the mutants that led to a shift in activity from transfructosylation towards hydrolysis of levan were screened by the DNS method. After two rounds of mutagenesis, TLC and HPLC analyses of the reaction products by the selected mutants revealed two major products; one is a di-D-fructose-2,6':6,2'-dianhydride (DFAIV) and the other is a levanbiose. The newly detected levanbiose corresponds to the reaction product from LFTase lacking transferring activity. Two mutants (2-F8 and 2-G9) showed a high yield of levanbiose (38-40%) compared with the wild-type enzyme, and thus behaved as levanases. Sequence analysis of the individual mutants responsible for the enhanced hydrolytic activity indicated that Asn-85 was highly involved in the transfructosylation activity of LFTase.

• Journal of Applied Biological Chemistry
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• v.60 no.2
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• pp.133-136
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• 2017

Fermentation plays a vital role in the nutritional enrichment of food. Korea has a long tradition of adding fermented food to the daily diet and jeotgal is one of the common fermented and salted foods in Korean cuisine. In our study, we added soymilk as an additive to squid jeotgal to improve its functionality. We mixed different concentrations of soymilk (2, 5, and 10 mg/g) with squid jeotgal samples, fermented them for one week, and then tested their antioxidant and anticancer activities to compare with those of squid jeotgal samples without soymilk additive. To investigate the anticancer characteristics, glutathione-S-transferase (GST)-pi enzyme assay was used. To test the antioxidant activities, various assays were performed, including 2,2-diphenyl-1-picryl hydrazyl free radical scavenging activity, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium saltradical cation scavenging assay, and reducing power assay. Samples fermented with a small amount of soymilk showed excellent anticancer activity. The addition of only 2 mg/g of soymilk to squid jeotgal inhibited the activity of GST-pi by almost 50% when compared with the sample with no addition. Moreover, no undesirable bitterness or astringency was noticed. Our results could help to improve the current food status of squid jeotgal and it could be used to reduce the risk of chronic disease along with its basic nutritional function.