• Proceedings of the PSK Conference
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• 2003.10b
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• pp.172.2-173
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• 2003

3-Alkoxy-6-allylthiopyridazine derivatives showed the strongest protective effect against oxidative stress and their anticancer effect determined on the growth of SK-Hep-l hepatocellular carcinomar cells. The allythio group as a pharmacologically active group was introduced into pyridazine nucleus and a substituent such as halogen or alkoxy was also introduced into paraposition of allylthio group. Five kinds of 3-alkoxy-6-allylthiopyridazine derivatives were synthesized and their chemoprotective activities examined in rats exposed to aflatoxin $B_1$-toxicant. (omitted)

• Toxicological Research
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• v.3 no.1
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• pp.1-8
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• 1987

In vitro induction of cytochrome 450 associated monooxygenase activities by phenobarbital (PB) and 3-methylcholanthrene (MC) was investigated in primary cultures of adult rat hepatocytes. PB and MC were added to the culture 24 hr after the initial plating of hepatocytes. A signiftcant increase of the activities of 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase were observed in MC and PB treated culture. MC caused about 500% induction of the initial oxidation rates of both enzymes in 48 hr. However the PB maintained both enzyme activities close to the level of freshly isolated hepatocytes. Biphenyl 4-hydroxylase and aminopyrine N-demethylase activities were also induced by MC and PB. But the level of induction was less than that occuring with 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase. When aflatoxin $B_1$ was added to the hepatocyte cultures which have been treated with MC or PB, it caused a significant increase of the unscheduled DNA synthesis at higher dose of aflatoxin $B_1$ as compared to those of untreated control hepatocyte cultures. The results suggest that microsomal enzyme activities can be selectively controlled preferably in hepatocyte cultures by the in vitro induction method. This principle may be useful for studying the metabolism and other toxicological studies.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.181-186
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• 2000

This study was conducted to investigate various components and aflatoxin of sigumjang during fermentation time. The contents of moisture were decreased during fermentation time. The contents of protein, fat and ash were $19.8{\sim}20.8%,\;1.3{\sim}1.6%$ and $3.1{\sim}3.2%$, respectively. The pH was gradually acidized. The result of measurement of surface color showed: L-value, $29.45{\sim}30.94\;a-value,\;+3.01{\sim}+3.63;\;b-value,\;+5.39{\sim}+6.34$. Aflatoxin was not detected during fermentation. Among 81 kinds of flavor components identified in sigumjang, esters was most in number followed by acids, aldehydes, alcohols and phenols.

• Mycobiology
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• v.50 no.6
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• pp.408-419
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• 2022

Filamentous fungi that could be classified into Aspergillus flavus/oryzae were isolated from traditionally fermented meju commercially available in Korea. The samples were analyzed for aflatoxin B1 and ochratoxin A contamination by HPLC; however, no toxin was detected. In addition, fungal and bacterial metagenomic sequencing were performed to analyze the microbial distribution in the samples. The results revealed that the distribution and abundance of fungi and bacteria differed considerably depending on the production regions and fermentation conditions of the meju samples. Through morphological analysis, ITS region sequencing, and assessment of the aflatoxin-producing ability, a total of 32 A. flavus/oryzae strains were identified. PCR analysis of six regions with a high mutation frequency in the aflatoxin gene cluster (AGC) revealed a total of six types of AGC breaking point patterns. The A. flavus/oryzae strains did not exhibit the high amylase activity detected in the commercial yellow koji strain (starter mold). However, their peptidase and lipase activities were generally higher than that of the koji isolates. We verified the safety of the traditionally fermented meju samples by analyzing the AGC breaking point pattern and the enzyme activities of A. flavus/oryzae strains isolated from the samples. The isolated strains could possibly be used as starter molds for soybean fermentation.

• Preventive Nutrition and Food Science
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• v.5 no.4
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• pp.189-193
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• 2000

Preservative and antimutagenic effects of green tea leaves added Chinese cabbage kimchi (GK1, GK2, GK3, and GK4 : 1, 2, 3 and 4 of green tea leaves (GTL) in proportion of 100 of salted Chinese cabbage were added to kimchi) were compared to those of the Chinese cabbage kimchi without GTL (control kimchi, CK). Fermentation period of GKs was further delayed than that of CK. The initial pH and acidity between GKs an CK were similar, but the time reach optimally ripened status of kimchi (pH 4.3) was different. CK took 6 days, while GK1, GK2, GK3 and GK4 took 6, 10, 12 and 14 days at 10℃, respectively. The growth of Leuconostoc sp. and Lactobacilus sp. in GKs delayed comparing to those in FCK. Among GKs, as the added amount of green tea leaves increased, the growth of lactic acid bacteria was retarded. The antimutagenic effects of juices from GKs and CK were studied against aflatoxin B₁(AFB₁) in the Ames test on Salmonella typehimurium TA100 and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the SOS chromotest using E. coli PQ37. Juices from optimally ripened GKs (pH 4.3) showed 52∼76% inhibition rates against the indirect mutagen, aflatoxin B₁ induced mutagenicity while 49% inhibition rate by CK in the Ames test. Juices from GKs and CK showed 44∼67% and 36% inhibition rate against direct mutagen, MNNG (70 ng/assay) induce mutagenicity in the SOS chromotest. Thus GKs delayed fermentation period of kimchi and exhibited higher antimutagenic activity than CK.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.545-546
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• 2008

• Proceedings of the PSK Conference
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• 2002.04a
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• pp.188.2-189
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• 2002

• Journal of Food Hygiene and Safety
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• v.4 no.3
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• pp.165-170
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• 1989

To isolate the aflatoxin producing strains from agricultural products in Youngnam districts, rice(59), meju(30), corn(32), barley(58), soil(33), peanut(30), soybean(45), and unhulled barley(60) were collected from markets or homes. From 342 sample sources, 280 strains of Aspergillus spp. were isolated. As a result of screening by TLC, 29 strains expressed fluorescent spot and four strains have a same Rf value of standard aflatoxins, and the percentage of contamination from aflatoxin producing strains was 1.3%, and those strains were estimated as Aspergillus flavus group by the examine of characteristics and morphology.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.143-148
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• 1992

The antimutagenic effects of green-yellow vegetables toward aflatoxin B$_1$(AFB$_1$) and 4-nitroquinoline-1-ox-ide (4-NQO) using the Ames assay system with Salmonella typhimurium TA98 and TA100 were studied. Forty six to fifty percent of the methanol extracts of the vegetable samples inhibited the mutagenicity induced by AFB$_1$in TA98 and TA100. Perilla leaf, lettuce, broccoli, crown daisy, water dropwort, small water dropwort, red pepper, red pepper leaves, amaranth, spinach and radish root were significantly reduced the mutagenicity of AFB$_1$(p< 0.01). Whereas 25 out of 27 samples (93%) exhibited antimutagenicity toward a direct mutagen of 4-NQO (p< 0.01. 0.05). The samples which showed the strong antimutagenicity (>60%) were cabbage, kale, lettuce, broccoli, mustard leaf, green red pepper, green sweet pepper, spinach, amaranth, soybean sprout and immature pumpkin. The juices from the several samples also showed antimu-tagenic activity toward AFB$_1$. Cabbage, perilla leaf, small water dropwort and spinach reduced TAT100 revertants dose dependently in the range of 50-500$m\ell$/plate, however, cucumber and carrot showed little effect.

• Food Science and Preservation
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• v.22 no.5
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• pp.758-767
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• 2015

Red pepper powder sensitive to aflatoxins contamination is major ingredients of kimchi. This study was conducted to investigate the effect of lactic acid bacteria (LAB) on the changes in aflatoxin levels during kimchi fermentation. Baechu kimchi was contaminated with aflatoxins ($B_1$, $B_2$, $G_1$, and $G_2$) and inoculated with LAB (Lactobacillus plantarum and Leuconostoc mesenteroides), and the following characteristics were investigated for 8 weeks: pH, titratable acidity, salinity, microbial properties, and aflatoxin levels. The pH decreased rapidly during storage, and the titratable acidity was increased. The salinity of the samples was shown to increase from 2.30 to 2.40%. The total number of aerobic bacteria and lactic acid bacteria in kimchi inoculated with LAB was significantly higher than that of the others. Yeast and molds were detected at approximately 1~3 log CFU/g during storage. Coliforms were detected in the control after 4 weeks, whereas in other samples they were not detected until after 2 weeks. The aflatoxin levels reduced during kimchi fermentation. The average reduction rate of aflatoxin levels during kimchi fermentation was 8.39%, but in kimchi inoculated with Lac. plantarum and Leu. mesenteroides, the rate were 25.16 % and 27.86%, respectively. These results showed that aflatoxins can be removed by LAB during kimchi fermentation.