• Toxicological Research
• /
• v.30 no.3
• /
• pp.211-220
• /
• 2014

Resveratrol has received considerable attention as a polyphenol with various biological effects such as anti-inflammatory, anti-oxidant, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. As part of the overall safety assessment of HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, we assessed genotoxicity in three in vitro assays: a bacterial mutation assay, a comet assay, and a chromosomal aberration assay. In the bacterial reverse mutation assay, HS-1793 did not increase revertant colony numbers in S. typhimurium strains (TA98, TA100, TA1535 and TA1537) or an E. coli strain (WP2 uvrA) regardless of metabolic activation. HS-1793 showed no evidence of genotoxic activity such as DNA damage on L5178Y $Tk^{+/-}$ mouse lymphoma cells with or without the S9 mix in the in vitro comet assay. No statistically significant differences in the incidence of chromosomal aberrations following HS-1793 treatment was observed on Chinese hamster lung cells exposed with or without the S9 mix. These results provide additional evidence that HS-1793 is non-genotoxic at the dose tested in three standard tests and further supports the generally recognized as safe determination of HS-1793 during early drug development.

• Biomolecules & Therapeutics
• /
• v.10 no.4
• /
• pp.268-273
• /
• 2002

Mutagenic potential of HM10411 (recombinant human granulocyte colony stimulating factor) was evaluated by bacterial reverse mutation test, in vitro chromosome aberration test and in vivo micronucleus test. The bacterial reverse mutation test was performed using the histidine auxotroph strains of Salmonella typhimurium TA100, TA1535, TA98, TA1537 and tryptophan auxotroph strain of Escherichia coli WP2 uvrA. The negative results of the bacterial reverse mutation test suggest that HM10411 does not induce mutation, in the genome of Salmonella typhimurium and E. coli under the conditions used. In addition, it has little clastogenicity either in vitro chromosome aberration test or in vivo micronucleus test. For in vitro chromosomal aberration test, Chinese hamster lung(CHL) cells were exposed to HM10411 of 23, 46 or 92 $\mu\textrm{g}$/ml for 6 or 24 hours in the absence and for 6 hours in the presence of metabolic activation system. There was no significant increase in the number of aberrant metaphase in HM 10411-treated groups at any dose levels both in the presence and absence of metabolic activation system. The micronucleus test was carried out using specific pathogen free(SPF) 7-week old male ICR mice, The test item, HM10411 was intraperitoneally administered at 1150, 2300 or 4600 $\mu\textrm{g}$/kg once a day for 2 consecutive days. There was no significant increase in the frequencies of micronucleated polychromatic erythrocytes(PCEs) at any treated groups compared with negative control group. Therefore, these results demonstrate that the test item, HM10411, was not mutagenic under the condition of these studies.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.2
• /
• pp.290-297
• /
• 2021

Leptolyngbya sp. KIOST-1 (LK1) is a newly isolated cyanobacterium that shows no obvious cytotoxicity and contains high protein content for both human and animal diets. However, only limited information is available on its toxic effects. The purpose of this study was to validate the safety of LK1 powder. Following Organisation for Economic Co-operation and Development (OECD) guidelines, a single-dose oral toxicity test in Sprague Dawley rats was performed. Genotoxicity was assessed using a bacterial reverse mutation test with Salmonella typhimurium (strains TA98, TA100, TA1535, and TA1537) and Escherichia coli WP2 uvrA, an in vitro mammalian chromosome aberration test using Chinese hamster lung cells, and an in vivo mammalian erythrocyte micronucleus test using Hsd:ICR (CD-1) SPF mouse bone marrow. After LK1 administration (2,500 mg/kg), there were no LK1-related body weight changes or necropsy findings. The reverse mutation test showed no increased reverse mutation upon exposure to 5,000 ㎍/plate of the LK1 powder, the maximum tested amount. The chromosome aberration test and micronucleus assay demonstrated no chromosomal abnormalities and genotoxicity, respectively, in the presence of the LK1 powder. The absence of physiological findings and genetic abnormalities suggests that LK1 powder is appropriate as a candidate biomass to be used as a safe food ingredient.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.7
• /
• pp.912-920
• /
• 2021

SOS response is a conserved response to DNA damage in prokaryotes and is negatively regulated by LexA protein, which recognizes specifically an "SOS-box" motif present in the promoter region of SOS genes. Myxococcus xanthus DK1622 possesses a lexA gene, and while the deletion of lexA had no significant effect on either bacterial morphology, UV-C resistance, or sporulation, it did delay growth. UV-C radiation resulted in 651 upregulated genes in M. xanthus, including the typical SOS genes lexA, recA, uvrA, recN and so on, mostly enriched in the pathways of DNA replication and repair, secondary metabolism, and signal transduction. The UV-irradiated lexA mutant also showed the induced expression of SOS genes and these SOS genes enriched into a similar pathway profile to that of wild-type strain. Without irradiation treatment, the absence of LexA enhanced the expression of 122 genes that were not enriched in any pathway. Further analysis of the promoter sequence revealed that in the 122 genes, only the promoters of recA2, lexA and an operon composed of three genes (pafB, pafC and cyaA) had SOS box sequence to which the LexA protein is bound directly. These results update our current understanding of SOS response in M. xanthus and show that UV induces more genes involved in secondary metabolism and signal transduction in addition to DNA replication and repair; and while the canonical LexA-dependent regulation on SOS response has shrunk, only 5 SOS genes are directly repressed by LexA.

• Korean Journal of Food Science and Technology
• /
• v.30 no.6
• /
• pp.1464-1469
• /
• 1998

SOS Chromotest and Ames test were carried out to evaluate the mutagenicity of three chloropropanols. In the SOS Chromotest, 3-monochloro-l,2-propanediol (3-MCPD) and 2,3-dichloro-1-propanol (2,3-DCP) except for 1,3-dichloro-2-propanol (1,3-DCP) induced SOS response in Escherichia coli PQ37 with dose-response relationship and 2,3-DCP was far more genotoxic than 3-MCPD. The genotoxic activities of both compounds, however, were very lower in E. coli PQ35 (PQ37 $uvrA^+)$ as compared to them in E. coli PQ37, whereas much higher in E. coli PQ243 (PQ37 tagA alkA). These results indicate that there are at least two types of DNA lesions caused by these compounds; one is a excision-repairable and the other is 3-methyladenine or any similar lesion which is excision-unrepairable and can induce adaptive response. In Salmonella typhimurium TA100, all the compounds showed strong mutagenicities, establishing the following genotoxic order: 2,3-DCP>3-MCPD>1,3-DCP. But the mutagenic activities were very low in S. typhimurium TA98 and TA97a. These results suggest that the mutation by chloropropanols can be induced by the DNA lesions causing base-pair substitutions. From the result that the mutagenicities of 3-MCPD and 2,3-DCP in S. typhimurium TA1535 were very low as compared to those in S. typhimurium TA100, it was appeared that the mutations by both compounds necessitate error-prone SOS repair.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.12
• /
• pp.2125-2134
• /
• 2015

IrrE is a highly conserved global regulator in the Deinococcus genus and contributes to survival from high doses of UV radiation, ionizing radiation, and desiccation. Drad-IrrE and Dgob-IrrE from Deinococcus radiodurans and Deinococcus gobiensis I-0 each share 66% sequence identity. However, Dgob-IrrE showed a stronger protection phenotype against UV radiation than Drad-IrrE in the D. radiodurans irrE-deletion mutant (ΔirrE), which may be due to amino acid residues differences around the DNA-binding HTH domain. Site-directed mutagenesis was used to generate a Drad-IrrE A184S single mutant, which has been characterized and compared with the ΔirrE mutant complemented strain with Drad-irrE, designated ΔirrE-E. The effects of the A184S mutation following UV radiation and mitomycin C (MMC) shock were determined. The A184S mutant displayed significantly increased resistance to UV radiation and MMC shock. The corresponding A184 site in Dgob-IrrE was inversely mutated, generating the S131A mutant, which exhibited a loss of resistance against UV radiation, MMC shock, and desiccation. qPCR analysis revealed that critical genes in the DNA repair system, such as recA, pprA, uvrA, and ddrB, were remarkably induced after UV radiation and MMC shock in the ΔirrE-IE and A184S mutants. These data suggested that A184S improves the ability against UV radiation and MMC shock, providing new insights into the modification of IrrE. We speculated that the serine residue may determine the efficiency of DNA binding, leading to the increased expression of IrrE-dependent genes important for protection against DNA damage.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.38 no.1
• /
• pp.91-101
• /
• 2012

This study's purpose is to research the antioxidant power of Calaguala (Polypodium leucotomos, PL) as an oral supplement: Calaguala, a native of Central America, is a fern which belongs to the family polypodiaceae protecting the skin from the ultraviolet and active oxygen free radicals. The total 14 volunteers, each female 7 & male 7, were divided into 2 groups, then exposed to UV for 30 min after taking Calaguala and placebo. The total antioxidant capacity (TAC) was analyzed by taking the blood samples from anticubital vein 3 hours after UV exposure. First, Calaguala siginifcantly decreased the concentration of active oxygen free radicals 4 weeks later. The concentration of active oxygen free radical in PL group declined more than placebo group, when measured 30 min and 3 hours after UV exposure. Second, Calaguala did not significantly increase TAC 4 weeks later, but significantly decreased TAC 3 hours after exposure, when compared with placebo group. Now days, the photo allergy and photo aging caused by air pollution and ozone destruction have drastically increased, and thus the amount of UV radiation reaching the earth's surface increased. The increase of active free oxygen radicals resulted in accelerating the diseases and aging. The first superficial protecting protection by reflection & dispersion and the second body internal protection by taking oral photo antioxidant such as Calaguala should be continuously researched.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.9
• /
• pp.1045-1052
• /
• 2017

In this study, a battery of genetic-toxicity studies on corn silk extract with high maysin content were performed according to internationally accepted protocols. In a mutation test using Salmonella Typhimurium TA1535, TA1537, TA98, and TA100, the number of mutant colonies did not significantly increase up to a maximum concentration of $5,000{\mu}g/plate$ in the presence or absence of the S9 metabolic activation system. In the chromosome aberration test using Chinese hamster lung fibroblasts, negative results were observed in the concentration up to $1,250{\mu}g/mL$ of corn silk extract. In the micronucleus test using ICR mice, incidence of polymorphonuclear erythrocytes with a maximum concentration of 2,000 mg/kg corn silk extract did not show any significant difference compared to the negative control group. Based on these results, the test substance, con silk extract, did not influence genotoxicity.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.1
• /
• pp.45-53
• /
• 2000

To analyze the photodegradation mechanism of materials for fisheries facilities which stand for considerable time immediately under or even partly above the water surface, such as cage collar, cage net, stationary fishing gear, egc. after 900 hours exposure, weathering experiments on 3 kinds of netting twines like dyed polyethylene(PE) and nylon, and non-treated high strength PE(Hi-PE) were carried out by using xenon light source. The results obtained are as follows : It was observed by scanning electron micrograph(SEM) that a good protection by pigments was obtained in PE and nylon specimen, while crack was rapidly progressed at the surface of Hi-PE one owing to etching by UVR. There was a little increase in density resulting from reorientation of polymer chain, chain scission, etc. in Hi-PE specimen. A wide angle X-ray diffraction showed that 3 kinds of specimens had no fundamental changes in polymer crystalline structure considering each 2$\theta$ of diffraction peak. Remaining tenacity of netting twines was in order of PE, nylon, and Hi-PE after having been exposed to the effect of 900 hours. PE and nylon treated with stuffs were shown to be more resilient than non-treated Hi-PE as confirmed by SEM.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.10
• /
• pp.1406-1413
• /
• 2016

This study was carried out to evaluate the toxicity of ethanolic extracts of Morus alba L. branch (ME). In the reverse mutation test, Salmonella Typhimurium TA98, TA100, TA1535, TA1357, and Escherichia coli WP2uvrA were used to estimate the mutagenic potential of ME. Sprague-Dawley rats were orally administered ME at levels of 1,250, 2,500, and 5,000 mg/kg for the single-dose toxicity test and 500, 1,000, and 2,000 mg/kg/d for the repeated-dose toxicity test for 28 consecutive days. As expected, reverse mutation was not detected at any concentration of ME, regardless of application of the metabolic activation system with or without S9 mix. In the single-dose toxicity test, ME caused neither significant visible signs of toxicity nor mortality in rats, and $LD_{50}$ was estimated to be over 5,000 mg/kg. In the repeated-dose toxicity test, ME administration at 500, 1,000, and 2,000 mg/kg for 28 days to male or female rats did not result in mortality. Similarly, no toxicologically significant treatment-related changes in body weight, food intake, or organ weights were noted. Several hematological and biochemical parameters in both genders showed significant differences, but these were within normal ranges. These results support the safe use of ME.