• Journal of Life Science
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• v.25 no.2
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• pp.136-150
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• 2015

Pseudomonas syringae pathovar tabaci is a plant pathogenic bacterium that causes wildfire disease in tobacco plants. In P. syringae pv. tabaci, PsyI, a LuxI-type protein, acts as an AHL synthase, while primary and secondary sequence analysis of PsyR has revealed that it is a homolog of the LuxR-type transcriptional regulator that responds to AHL molecules. In this study, using phenotypic and genetic analyses in P. syringae pv. tabaci, we show the effect of PsyR protein as a quorum-sensing (QS) transcriptional regulator. Regulatory effects of PsyR on swarming motility and production of siderophores, tabtoxin, and N-acyl homoserine lactones were examined via phenotypic assays, and confirmed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Further qRT-PCR showed that PsyR regulates expression of these virulence genes in response to environmental signals. However, an upstream region of the gene was not bound with purified MBP-PsyR protein; rather, PsyR was only able to shift the upstream region of psyI. These results suggested that PsyR may be indirectly controlled via intermediate-regulatory systems and that auto-regulation by PsyR does not occur.

• Korean Journal of Food Science and Technology
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• v.20 no.2
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• pp.176-187
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• 1988

Volatile flavor components in the Chinese quince fruits were trapped by simultaneous steam distillation-extraction method, and these were fractionated into the neutral, the basic, the phenolic and the acidic fraction. In the identification of carboxylic acids, the acidic fraction was methylated with diazomethane. Volatile flavor components in these fractions were analyzed by the high-resolution GC and GC-MS equipped with a fused silica capillary column. The total of one hundred and forty-five compounds from the steam volatile concentrate of the Chinese quince fruits were identified: they were 3 aliphatic hydrocarbons, 1 cyclic hydrocarbon, 4 aromatic hydrocarbons, 9 terpene hydrocarbons, 17 alcohols, 3 terpene alcohols, 6 phenols, 21 aldehydes, 7 ketones, 28 esters, 27 acids, 3 furans, 2 thiazoles, 2 acetals, 3 lactones and 9 miscellaneous ones. The greater part of the components except for carboxylic acids were identified from the neutral fraction. The neutral fraction gave a much higher yield than others and was assumed to be indispensable for the reproduction of the aroma of the Chinese quince fruits in a sensory evaluation. According to the results of the GC-sniff evaluation, 1-hexanal, cis-3-hexenal, trans-2-hexenal, 2-methyl-2-hepten-6-one, 1-hexanol, cis-3-hexenol, trans, trans-2, 4-hexadienal and trans-2-hexenol were considered to be the key compounds of grassy odor. On the other hand, esters seemed to be the main constituents of a fruity aroma in the Chinese quince fruits.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1493-1501
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• 2012

The antioxidant activities of volatile aroma extracts from Cudrania tricuspidata (Carr.) Bureau were examined using two antioxidant assays. Ten volatile aroma compounds identified in this plant were also tested for antioxidant activity. The volatile aroma extracts of stem and root from C. tricuspidata exhibited antioxidant activities with a clear dose response relationship in both aldehyde/carboxylic acid and lipid/malonaldehyde assays. Antioxidant activities of volatile aroma extracts from C. tricuspidata at $500{\mu}g/mL$ were $77.02{\pm}8.12%$ (stem) and $74.19{\pm}6.82%$ (root) in the aldehyde/carboxylic acid assay. Antioxidant activities of volatile aroma extracts from C. tricuspidata at $160{\mu}g/mL$ were $76.17{\pm}4.25%$ (stem) and $61.43{\pm}2.11%$ (root) in the lipid/malonaldehyde assay. Positively identified volatile aroma components in extracts of stem and root from C. tricuspidata were seven terpenes and terpenoides, 14 alkyl compounds, 11 nitrogen containing heterocyclic compounds, three oxygen containing heterocyclic compounds, 12 aromatic compounds, nine lactones, and seven miscellaneous compounds (possible contaminants). Among the positively identified compounds, eugenol, isoeugenol, and 2,4-bis (1,1-dimethylethyl)phenol exhibited antioxidant activities comparable to those of BHT and ${\alpha}$-tocopherol. Vanillin and 2-acetylpyrrole showed moderate activities in the lipid/malonaldehyde assay. These results suggest that consumption of antioxidant-rich beverages prepared from C. tricuspidata could have beneficial effects on human health by preventing diseases caused by oxidative damage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.8-15
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• 2008

Saussurea lappa (SL) has been used to reduce abdominal pain and tenesmus in traditional oriental medicine. SL and major compounds of SL, sesquiterpene lactones, have been suggested to possess various biological effects, including anti-tumor, anti-ulcer, anti-inflammatory, anti-viral and cardiotonic activities. Recently, it has been reported that ethanol extracts from roots of SL have antiproliferative effects on gastric cancer cells. To explore the possibility that SL has chemopreventive effects on prostate cancer, we examined whether the hexane extract of SL (HESL) inhibits the growth of LNCaP human prostate cancer cells. Cells were incubated with various concentrations ($0{\sim}4$ mg/L) of HESL in DMEM/F12 containing 5% charcoal stripped fetal bovine serum. HESL substantially decreased viable cell numbers and induced apoptosis of LNCaP cells in dose-dependent manners. HESL increased the levels of cleaved caspase-8, -9, -7 and -3, and poly (ADP-ribose) polymerase. HESL increased the levels of the pro-apoptotic Bak and truncated-Bid proteins whereas it had no effect on the anti-apoptotic Bcl-2, Bcl-xL, or Mcl-1. The present results indicate that HESL inhibits the growth of human prostate cancer cells by inducing apoptosis, which involves the activation of the caspase cascades.