• Toxicological Research
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• v.15 no.1
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• pp.95-101
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• 1999

Cytochrome P450 (CYP) 3A4 metabolizes aflatoxin B1 (AFB1) to AFB1-exo-8,9-epoxide (8,9-epoxidation) and aflatoxin Q1 (AFQ1; 3$\alpha$-hydroxylation) simultaneously. We investigated whether each metabolite was formed via its own binding site of CAP3A4 active site. Kinetics of the formation of the two metabolites were sigmoidal and consistent with the kinetics of substrate activation. The HIll model predicted that two substrate binding wites are involved in the oxidationof AFB1 by CYP3A4. Dehydronifedipine, a metabolite of nifedipine generated by CYP3A4, inhibited the formation of AFQ1 without any inhibition in the formation of AFB1-exo-8,9-epoxidation. Dehydronifedipine was found to act as a reversible competitive inhibitor against 3$\alpha$-hydroxylation of AFB1. Vmax and S0.5 of the 8,9-epoxidation were not changed in the presence of 0, 50, or 100 $\mu\textrm{M}$ dehydronifedipine. S0.5 of 3$\alpha$-hydroxylation was increased from 58$\pm$4 $\mu\textrm{M}$ to 111$\pm$8 $\mu\textrm{M}$ in the presence of 100 $\mu\textrm{M}$ nifedipine whereas Vmax was not changed. These results suggest that there exist two independent binding sites in the active site of CAP3A4 . One binding site is responsible for AFB1-exo-8,9-epoxidation and the other is involved in 3$\alpha$-hydroxylation of AFB1. Dehydronifedipine might selectively bind to the site which is responsible for the formation of AFQ1 in the active site of CYP3A4.

• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.487-495
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• 1998

The mycotoxins, $Aflatoxin\;B_1(B)$ and Ochratoxin A(A), were measured from the various mejus manufactured under the artificial or natural conditions by the indirect competitive ELISA; The various fungi isolated from the Korean traditional home (KTH) made meju collected were observed to produce each mycotoxin mentioned above in the toxin producing broth, but only few in the sterilized cereals of soybean under the artificial conditions. Thus, the isolated fungi were not found to produce both A and B toxins in the artificial conditions. Particularly, the any mycotoxin was not determined at the range of 0.01 to 100 ng per gm of the mejus made under the conditions of KTH widely collected in Korea. The mycotoxins produced by the meju-fermenting fungi were seemed or speculated to be degraded in KTH's mejus under the natural conditions. The species of Mucor involved in the initial stage of fermentation were discussed to be important in the fermentations of KTH mejus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.2
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• pp.156-161
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• 1991

The mutagenic, comutagenic and antimutagenic effects of red pepper powder were studied by using Ames mutagenicity test. extracts(3 fractions) of the red pepper powder did not show any mutagenicity with or without S9 mix in Salmonella typhimurium strains of TA100 and TA98. These extracts did not show any comutagenicity on N-methyl-N'-nitro-N-nitrosoguanidine(MNNG). Capsaicin also did not exhibit any mutagenicity in the absence or presence of S9 mix prepared from rat or hamster livers. However, the red pepper powder showed antimutagenicity aganist aflatoxin $B_1(AFB_1)$ mediatdd mutagenicity. Especially first fraction of the pepper powder inhibited strongly the mutagenicity of $AFB_1$. There was no difference of these activities between hotter tasted pepper powder and plain hot tasted pepper powder.

• Korean Journal of Veterinary Service
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• v.42 no.3
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• pp.127-133
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• 2019

The purpose of this study was to investigate the contamination level of representative mycotoxins that have adverse effects on livestock by using LC-MS/MS method and to utilize the results as basic data for the establishment of quality control system for feed, and to provide information on production and storage. A total of nine mycotoxins, including aflatoxin $B_1$, aflatoxin $B_2$, aflatoxin $G_1$, aflatoxin $G_2$, ochratoxin A, fumonisin $B_1$, fumonisin $B_2$, deoxynivalenol (DON), zearalenone (ZEN) were simultaneously analyzed in LC-MS/MS under ESI positive mode. Fumonisin $B_1$ and fumonisin $B_2$ were detected from 3 cases of 75 forage produced in Incheon area, the detection rate was 4.0%. The detection concentration was 0.01~0.02 mg/kg, which was lower than the domestic recommended limit. Fumonisins were detected in a slightly different manner from the results of mycotoxin studies reported in Korea, which is attributed to the high temperature and dry summer weather of the year. The result of LC-MS/MS method performance of 9 mycotoxins, the recovery of DON was quite low as $41.53{\pm}3.91%$ that is not suitable for simultaneous analysis. This is probably due to that the extract solution used in this study was not suitable for the extraction of DON, along with the characteristics of a very dry forage. For the study of mycotoxins in Incheon area forage for the first time, further investigation is needed for the safe supply of livestock products.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.73-81
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• 2021

The current study investigated how Saccharomyces cerevisiae ameliorates the adverse effects of aflatoxin on in vitro rumen fermentation. In this study, five groups (T₁: Control [basal feed]; T₂: T₁ + 300 ppb aflatoxin B1 [AFB₁] and T₃, T₄, and T₅: T₂ with 0.05, 0.1, and 0.2% of S. cerevisiae, respectively) were prepared and incubated in vitro. The results revealed that truly degradable dry matter (TDDM), gas production (GP), microbial biomass production (MBP), truly degradable organic matter (TDOM), partitioning factor (PF), total volatile fatty acids (TVFA), acetate (A), propionate (P) and butyrate (B) values in the control group (T₁) were higher (p < 0.05) than those of the AFB₁ fed group (T₂). The A : P ratio in the control group (T₁) was reduced (p < 0.05) when compared to that of the T₂ group. The TDDM, TDOM, GP, TVFA, A, P, and B values of T₃, T₄, and T₅ improved with the increasing levels of S. cerevisiae; however, the values of group T₅ were lower (p < 0.05) than that of the control. The values of MBP, A : P ratio and PF in group T₅ were statistically similar to that of the control. It was concluded that the inclusion of S. cerevisiae (0.05 to 0.20%) to the AFB₁ (300 ppb) contaminated feed partially to completely ameliorated the adverse effects of AFB₁ on the in vitro rumen fermentation parameters.

• Korean Journal of Pharmacognosy
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• v.51 no.4
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• pp.270-277
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• 2020

This study analyzed mycotoxins, aflatoxin B1, B2, G1, G2, fumonisin B1, B2, ochratoxin A and zearalenone, using LC-MS/MS and conducted risk assessment on 54 samples of seeds distributed in SeoulYangnyeongsi and the management status of extramural herbal dispensary facility. The matched calibration showed a good linearity as observed in 6 concentration levels(r2>0.999) as a result of method validation applied with Arecae semen. Limits of detection(LOD) and quantification(LOQ) were in the range of 0.02-0.11 ㎍/kg and 0.08-0.34 ㎍/kg, respectively. Recoveries also estimated, ranging from 65.1-99.7% with relative standard deviation(RSD) 0.5-6.3%. As a result of the method on 54 samples, mycotoxins were detected in 16 samples. Among them, two Thujae semen showed a degree of concentration that exceeded the aflatoxin specification. In the risk assessment, the human exposure safety standard values were calculated as ADI(Acceptable Daily Intake) for aflatoxin B1, fumonisin and zearalenone. Ochratoxin A was calculated as PTWI(Provisional Tolerable Weekly Intake). The MOE(Margine of Exposure) of aflatoxin B1 was in the range of 40.36-3536.88. And no items exceeded 100% in %TDI(Tolerable Daily Intake) and %TWI(Tolerable Weekly Intake) of fumonisin, zearalenone and ochratoxin A.

• Microbiology and Biotechnology Letters
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• v.50 no.2
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• pp.202-210
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• 2022

Aflatoxin contamination in rice has been documented in a number of studies, and has a high incidence in Asian countries, and as such, there has been a growing interest in alternative biocontrol strategies to address this issue. In this study, 147 strains of yeasts and yeast-like fungi were screened for their potential to produce volatile organic compounds (VOCs) active against Aspergillus flavus strains that produce aflatoxin B₁ (AFB₁). Five strains within four different genera showed greater than 50% growth inhibition of some strains of A. flavus. These were Anthracocystis sp. DMKU-PAL124, Aureobasidium sp. DMKU-PAL120, Aureobasidium sp. DMKU-PAL144, Rhodotorula sp. DMKU-PAL99, and Solicococcus keelungensis DMKU-PAL84. VOCs produced by these microorganisms ranged from 4 to 14 compounds and included alcohols, alkenes, aromatics, esters and furans. The major VOCs produced by the closely related Aureobasidium strains were found to bedistinct. Moreover, 2-phenylethanol was the most abundant compound generated by Aureobasidium sp. DMKU-PAL120, while methyl benzeneacetate was the major compound emitted from Aureobasidium sp. DMKU-PAL144. On the other hand, 2-methyl-1-butanol and 3-methyl-1-butanol were significant compounds produced by the other three genera. These antagonists apparently inhibited A. flavus sporulation and mycelial development. Additionally, the reduction of the AFB1 in the fungal-contaminated rice grains was observed after co-incubation with these VOC-producing strains and ranged from 37.7 ± 8.3% to 60.3 ± 3.4%. Our findings suggest that these same microorganisms are promising biological control agents for use against aflatoxin-producing fungi in rice and other agricultural products.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.27-32
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• 2010

This study was conducted to monitor aflatoxins in various medicinal herbs, providing available data for the safety of those products. To monitor aflatoxins in medicinal herbs, a total of 400 samples of 40 different herbs were collected in commercial retailers in Seoul, Daejeon, Gwangju, Daegu, and Busan from March to August, 2008. The samples that passed the sensory evaluation were tested for aflatoxins. Aflatoxins in samples were analyzed by HPLC-florescence coupled with photochemical enhancement. Samples were extracted with 70% methanol and then diluted to the appropriate concentration. A refining process was performed using an immunoaffinity column. The analytical method used in this study was validated. The $R^2$ value for aflatoxin $B_1$ was 0.99946, and the detection range was from 0.25 to 10.0 ng/mL. The accuracy of the analysis was ranged from 83.2% to 101.8%. The relative standard deviation (RSD) in the aflatoxin $B_1$ analysis was 3.4%, demonstrating the precision of this method. In addition, the detection limit and quantitative analysis limit of aflatoxin $B_1$ was $0.53\;{\mu}g/kg$ and $1.76\;{\mu}g/kg$, respectively. These results indicated that the analytical method used in this study was appropriate. The results of HPLC showed that 1% (4 samples) of the samples may contain aflatoxins. The concentration of quantified aflatoxin was $2.3\;{\mu}g/kg$ for both Quisqualis fructus and Remotiflori radix samples. The other samples were below the limit of quantification. Moreover, the concentration of aflatoxin $B_1$ which is made by specific fungi were below the level of regulation. Only 20% of aflatoxin $B_1$ were transferred to hot water. Therefore, the levels of aflatoxins in medicinal herbs were considered to be safe especially considering the aflatoxin transfer ratio.

• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.81-87
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• 1995

Daily exposure of aflatoxin B1 (AFB1) was estimated in foods (rice, barley, soybean, peanut, soysauce, soybean paste) by ELISA (enzyme linked immunosorbent assay) using polyclonal antibody R101. Before ELISA, a simple extraction method was applied for the quantitation of AFB1 in foods using chloroform which showed high recovery (70$\pm$12%). AFB1 levels in foods were 0.32 ng/ml (rice), 0.24ng/ml (barley), 0.22 ng/ml (peanut), 0.30~0.78 ng/ml (soysauce), and 0.2 ng/ml (soybean paste). Based on food consumption, we estimated that Koreans were exposed to AFB1 at the level of 1.86$\pm$0.46 ng/kg/day and liver cancer incidence attributed to AFB1 exposure (assuming that AFB1 as a single hepatocarcinogenic agent) might be calculated to be 13.1 per 100, 000 population. Our data demonstrate that AFB1 levels in foods were below the regulation of 10 ppb in foods and might not be the major risk factor for the high incidence of lover cancer in Korea.

• 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.