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Cao W, Yu P, Yang K, Cao D. Aflatoxin B1: metabolism, toxicology, and its involvement in oxidative stress and cancer development. Toxicol Mech Methods 2021; 32:395-419. [PMID: 34930097 DOI: 10.1080/15376516.2021.2021339] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Aflatoxins are a class of carcinogenic mycotoxins produced by Aspergillus fungi, which are widely distributed in nature. Aflatoxin B1 (AFB1) is the most toxic of these compounds and its metabolites have a variety of biological activities, including acute toxicity, teratogenicity, mutagenicity and carcinogenicity, which has been well-characterized to lead to the development of hepatocellular carcinoma (HCC) in humans and animals. This review focuses on the metabolism of AFB1, including epoxidation and DNA adduction, as it concerns the initiation of cancer and the underlying mechanisms. In addition to DNA adduction, inflammation and oxidative stress caused by AFB1 can also participate in the occurrence of cancer. Therefore, the main carcinogenic mechanism of AFB1 related ROS is summarized. This review also describes recent reports of AFB1 exposures in occupational settings. It is hoped that people will pay more attention to occupational health, in order to reduce the incidence of cancer caused by occupational exposure.
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Affiliation(s)
- Weiya Cao
- Medical school, Anhui University of Science & Technology, Huainan 232001, China
| | - Pan Yu
- Medical school, Anhui University of Science & Technology, Huainan 232001, China
| | - KePeng Yang
- Medical school, Anhui University of Science & Technology, Huainan 232001, China
| | - Dongli Cao
- Medical school, Anhui University of Science & Technology, Huainan 232001, China
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2
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Harris CM, Zamperoni KE, Sernoskie SC, Chow NSM, Massey TE. Effects of in vivo treatment of mice with sulforaphane on repair of DNA pyridyloxylbutylation. Toxicology 2021; 454:152753. [PMID: 33741493 DOI: 10.1016/j.tox.2021.152753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/08/2021] [Accepted: 03/12/2021] [Indexed: 01/08/2023]
Abstract
The phytochemical sulforaphane (SF) has gained interest for its apparent association with reduced cancer risk and other cytoprotective properties, at least some of which are attributed to activation of the transcription factor Nrf2. Repair of bulky DNA adducts is important for mitigating carcinogenesis from exogenous DNA damaging agents, but it is unknown whether in vivo treatment with SF affects adduct repair. At 12 h following a single oral dose of 100 mg/kg SF, an almost doubling in activity for repair of pyridyloxobutylated DNA was observed in CD-1 mouse liver nuclear extracts, but not in lung extracts. This change at 12 h in repair activity was preceded by the induction of Nrf2-regulated genes but not accompanied by changes in levels of the specific nucleotide excision repair (NER) proteins XPC, XPA, XPB and p53 or in binding of hepatic XPC, XPA and XPB to damaged DNA. SF also did not significantly alter histone deacetylase activity as measured by acetylated histone H3 levels, or stimulate formation of γ-H2A.X, a marker of DNA damage. A significant reduction in oxidative DNA damage, as measured by 8-OHdG (a biomarker of oxidative DNA damage), was observed only in DNA from the lungs of SF-treated mice 3 h post-dosing. These results suggest that the ability of SF to increase bulky adduct repair activity is organ-selective and is consistent with activation of the Nrf2 signaling pathway.
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Affiliation(s)
- Christopher M Harris
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Kristen E Zamperoni
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Samantha C Sernoskie
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Natalie S M Chow
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Thomas E Massey
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
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3
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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Vleminckx C, Marko D, Oswald IP, Piersma A, Routledge M, Schlatter J, Baert K, Gergelova P, Wallace H. Risk assessment of aflatoxins in food. EFSA J 2020; 18:e06040. [PMID: 32874256 PMCID: PMC7447885 DOI: 10.2903/j.efsa.2020.6040] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
EFSA was asked to deliver a scientific opinion on the risks to public health related to the presence of aflatoxins in food. The risk assessment was confined to aflatoxin B1 (AFB1), AFB2, AFG1, AFG2 and AFM1. More than 200,000 analytical results on the occurrence of aflatoxins were used in the evaluation. Grains and grain-based products made the largest contribution to the mean chronic dietary exposure to AFB1 in all age classes, while 'liquid milk' and 'fermented milk products' were the main contributors to the AFM1 mean exposure. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans. The CONTAM Panel selected a benchmark dose lower confidence limit (BMDL) for a benchmark response of 10% of 0.4 μg/kg body weight (bw) per day for the incidence of HCC in male rats following AFB1 exposure to be used in a margin of exposure (MOE) approach. The calculation of a BMDL from the human data was not appropriate; instead, the cancer potencies estimated by the Joint FAO/WHO Expert Committee on Food Additives in 2016 were used. For AFM1, a potency factor of 0.1 relative to AFB1 was used. For AFG1, AFB2 and AFG2, the in vivo data are not sufficient to derive potency factors and equal potency to AFB1 was assumed as in previous assessments. MOE values for AFB1 exposure ranged from 5,000 to 29 and for AFM1 from 100,000 to 508. The calculated MOEs are below 10,000 for AFB1 and also for AFM1 where some surveys, particularly for the younger age groups, have an MOE below 10,000. This raises a health concern. The estimated cancer risks in humans following exposure to AFB1 and AFM1 are in-line with the conclusion drawn from the MOEs. The conclusions also apply to the combined exposure to all five aflatoxins.
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Moore MM, Schoeny RS, Becker RA, White K, Pottenger LH. Development of an adverse outcome pathway for chemically induced hepatocellular carcinoma: case study of AFB1, a human carcinogen with a mutagenic mode of action. Crit Rev Toxicol 2018; 48:312-337. [PMID: 29431554 DOI: 10.1080/10408444.2017.1423462] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adverse outcome pathways (AOPs) are frameworks starting with a molecular initiating event (MIE), followed by key events (KEs) linked by KE relationships (KERs), ultimately resulting in a specific adverse outcome. Relevant data for the pathway and each KE/KER are evaluated to assess biological plausibility, weight-of-evidence, and confidence. We aimed to describe an AOP relevant to chemicals directly inducing mutation in cancer critical gene(s), via the formation of chemical-specific pro-mutagenic DNA adduct(s), as an early critical step in tumor etiology. Such chemicals have mutagenic modes-of-action (MOA) for tumor induction. To assist with developing this AOP, Aflatoxin B1 (AFB1) was selected as a case study because it has a rich database and is considered to have a mutagenic MOA. AFB1 information was used to define specific KEs, KERs, and to inform development of a generic AOP for mutagen-induced hepatocellular carcinoma (HCC). In assessing the AFB1 information, it became clear that existing data are, in fact, not optimal and for some KEs/KERs, the definitive data are not available. In particular, while there is substantial information that AFB1 can induce mutations (based on a number of mutation assays), the definitive evidence - the ability to induce mutation in the cancer critical gene(s) in the tumor target tissue - is not available. Thus, it is necessary to consider the patterns of results in the weight-of-evidence for KEs and KERs. It was important to determine whether there was sufficient evidence that AFB1 can induce the necessary critical mutations early in the carcinogenic process, which was the case.
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Affiliation(s)
- Martha M Moore
- a Ramboll Environ US Corporation , Little Rock , AR , USA
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5
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Xu F, Yu K, Yu H, Wang P, Song M, Xiu C, Li Y. Lycopene relieves AFB 1 -induced liver injury through enhancing hepatic antioxidation and detoxification potential with Nrf2 activation. J Funct Foods 2017. [DOI: 10.1016/j.jff.2017.10.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Wang G, Miao Y, Sun Z, Zheng S. Simultaneous adsorption of aflatoxin B 1 and zearalenone by mono- and di-alkyl cationic surfactants modified montmorillonites. J Colloid Interface Sci 2017; 511:67-76. [PMID: 28972897 DOI: 10.1016/j.jcis.2017.09.074] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/15/2017] [Accepted: 09/20/2017] [Indexed: 11/28/2022]
Abstract
Organo-montmorillonites (OMts) modified with mono- and di-alkyl cationic surfactants were prepared to remove polar mycotoxin aflatoxin B1 (AFB1) and weak polar, hydrophobic mycotoxin zearalenone (ZER) simultaneously. The structural and surface properties of the prepared OMts were investigated. In vitro adsorption experiments were carried out to simulate the in vivo conditions of gastrointestinal tract of animals by a batch mode. The adsorption of AFB1 and ZER in both single and binary-contaminate systems were investigated systematically. Both OMts showed super enhanced adsorption capacities towards AFB1 and ZER whenever in single and binary-contaminate systems compared with raw Mt, indicating the effectiveness of the prepared OMts acted as mycotoxins adsorbents. DODAC-Mt showed a higher adsorption capacity towards AFB1 and ZER than OTAB-Mt. The equilibrium data of AFB1 on OMts were fitted satisfactorily with Freundlich and Linear models, suggesting the co-existence of different adsorption mechanism which were proposed to be ion-dipole interactions (between surfactant cations and carbonyl groups of AFB1) and adsorption/partition mechanisms. The adsorption isotherms of OMts to ZER matched best with Linear models, implying the adsorption/partition mechanism. For simultaneous adsorption, the adsorption process of one mycotoxin was slightly affected by the presence of the other mycotoxin due to the requirement of partial same sorption sites. In addition, the solution pH had negligible influence on the adsorption process of OMts, meaning no desorption occurred when the adsorbents pass through from stomach to intestine as animal feed.
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Affiliation(s)
- Gaofeng Wang
- School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
| | - Yushan Miao
- School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
| | - Zhiming Sun
- School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.
| | - Shuilin Zheng
- School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.
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Li L, Brown KL, Ma R, Stone MP. DNA Sequence Modulates Geometrical Isomerism of the trans-8,9- Dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)- 9-hydroxy Aflatoxin B1 Adduct. Chem Res Toxicol 2016; 28:225-37. [PMID: 25587868 PMCID: PMC4332041 DOI: 10.1021/tx5003832] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Aflatoxin
B1 (AFB1), a mycotoxin produced
by Aspergillus flavus, is oxidized
by cytochrome P450 enzymes to aflatoxin B1-8,9-epoxide,
which alkylates DNA at N7-dG. Under basic conditions,
this N7-dG adduct rearranges to yield the trans-8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxy
aflatoxin B1 (AFB1–FAPY) adduct. The
AFB1–FAPY adduct exhibits geometrical isomerism
involving the formamide moiety. NMR analyses of duplex oligodeoxynucleotides
containing the 5′-XA-3′, 5′-XC-3′, 5′-XT-3′,
and 5′-XY-3′ sequences (X = AFB1–FAPY;
Y = 7-deaza-dG) demonstrate that the equilibrium between E and Z isomers is controlled by major groove hydrogen
bonding interactions. Structural analysis of the adduct in the 5′-XA-3′
sequence indicates the preference of the E isomer
of the formamide group, attributed to formation of a hydrogen bond
between the formyl oxygen and the N6 exocyclic amino group
of the 3′-neighbor adenine. While the 5′-XA-3′
sequence exhibits the E isomer, the 5′-XC-3′
sequence exhibits a 7:3 E:Z ratio
at equilibrium at 283 K. The E isomer is favored
by a hydrogen bond between the formyl oxygen and the N4-dC exocyclic amino group of the 3′-neighbor cytosine. The
5′-XT-3′ and 5′-XY-3′ sequences cannot
form such a hydrogen bond between the formyl oxygen and the 3′-neighbor
T or Y, respectively, and in these sequence contexts the Z isomer is favored. Additional equilibria between α and β
anomers and the potential to exhibit atropisomers about the C5–N5 bond do not depend upon sequence. In each
of the four DNA sequences, the AFB1–FAPY adduct
maintains the β deoxyribose configuration. Each of these four
sequences feature the atropisomer of the AFB1 moiety that
is intercalated above the 5′-face of the damaged guanine. This
enforces the Ra axial conformation for
the C5–N5 bond.
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8
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Lee RJ, Workman AD, Carey RM, Chen B, Rosen PL, Doghramji L, Adappa ND, Palmer JN, Kennedy DW, Cohen NA. Fungal Aflatoxins Reduce Respiratory Mucosal Ciliary Function. Sci Rep 2016; 6:33221. [PMID: 27623953 PMCID: PMC5021939 DOI: 10.1038/srep33221] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/23/2016] [Indexed: 11/29/2022] Open
Abstract
Aflatoxins are mycotoxins secreted by Aspergillus flavus, which can colonize the respiratory tract and cause fungal rhinosinusitis or bronchopulmonary aspergillosis. A. flavus is the second leading cause of invasive aspergillosis worldwide. Because many respiratory pathogens secrete toxins to impair mucociliary immunity, we examined the effects of acute exposure to aflatoxins on airway cell physiology. Using air-liquid interface cultures of primary human sinonasal and bronchial cells, we imaged ciliary beat frequency (CBF), intracellular calcium, and nitric oxide (NO). Exposure to aflatoxins (0.1 to 10 μM; 5 to 10 minutes) reduced baseline (~6-12%) and agonist-stimulated CBF. Conditioned media (CM) from A. fumigatus, A. niger, and A. flavus cultures also reduced CBF by ~10% after 60 min exposure, but effects were blocked by an anti-aflatoxin antibody only with A. flavus CM. CBF reduction required protein kinase C but was not associated with changes in calcium or NO. However, AFB2 reduced NO production by ~50% during stimulation of the ciliary-localized T2R38 receptor. Using a fluorescent reporter construct expressed in A549 cells, we directly observed activation of PKC activity by AFB2. Aflatoxins secreted by respiratory A. flavus may impair motile and chemosensory functions of airway cilia, contributing to pathogenesis of fungal airway diseases.
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Affiliation(s)
- Robert J. Lee
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Alan D. Workman
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ryan M. Carey
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Bei Chen
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Phillip L. Rosen
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Laurel Doghramji
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nithin D. Adappa
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - James N. Palmer
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - David W. Kennedy
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Noam A. Cohen
- Department of Otorhinolaryngology – Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Philadelphia VA Medical Center Surgical Services, Philadelphia, Pennsylvania, USA
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
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9
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Yang Y, Wen J, Kong W, Liu Q, Luo H, Wang J, Yang M. Simultaneous determination of four aflatoxins and ochratoxin A in ginger after inoculation with fungi by ultra-fast liquid chromatography-tandem mass spectrometry. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:4160-7. [PMID: 26762953 DOI: 10.1002/jsfa.7618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/09/2015] [Accepted: 01/05/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Aflatoxins (AFs) and ochratoxin A (OTA) have been detected frequently in food, agricultural products and traditional Chinese medicines, and their presence poses serious health and economic problems worldwide. Ginger can easily be polluted with mycotoxins. In this study, ginger samples were cultivated for 15 days after inoculation with fungi and were prepared based on ultrasound-assisted solid-liquid extraction using methanol/water followed by immunoaffinity column clean-up and analysed by ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) for AFs and OTA. RESULTS The limits of detection and quantification of AFs and OTA were 0.04-0.30 µg mL(-1) and 0.125-1.0 µg mL(-1) , respectively. The recoveries were 82.0-100.2%. After 15 days' cultivation, no macroscopic mildew was found in ginger. But, the content of AFB1 expressed an increasing trend in ginger, peel [less than the limit of quantification (LOQ)] to the innermost layer (51.86 µ mL(-1) ), AFB2 was only detected in the innermost layer at the level of 0.87 µ mL(-1) . A small amount ( CONCLUSION The developed method was successfully applied to analyse five mycotoxins, and has many advantages including rapid determination and high sensitivity. Meanwhile, in practice, more attention should be paid to the safety and quality of ginger. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Ying Yang
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jing Wen
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Weijun Kong
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Qiutao Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
- Pharmacy College, Liaoning Medical University, Jinzhou, Liaoning 121001, China
| | - Hongli Luo
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
| | - Jian Wang
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Meihua Yang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
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10
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Nones J, Nones J, Poli A, Trentin AG, Riella HG, Kuhnen NC. Organophilic treatments of bentonite increase the adsorption of aflatoxin B1 and protect stem cells against cellular damage. Colloids Surf B Biointerfaces 2016; 145:555-561. [PMID: 27281241 DOI: 10.1016/j.colsurfb.2016.05.061] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/18/2016] [Accepted: 05/24/2016] [Indexed: 11/24/2022]
Abstract
Bentonite clays exhibit high adsorptive capacity for contaminants, including aflatoxin B1 (AFB1), a mycotoxin responsible for causing severe toxicity in several species including pigs, poultry and man. Organophilic treatments is known to increase the adsorption capacity of bentonites, and the primary aim of this study was to evaluate the ability of Brazilian bentonite and two organic salts - benzalkonium chloride (BAC) and cetyltrimethylammonium bromide (CTAB) to adsorb AFB1. For this end, 2(2) factorial designs were used in order to analyze if BAC or CTAB was able to increase AFB1 adsorption when submitted in different temperature and concentration. Both BAC and CTAB treatment (at 30°C and 2% of salt concentration) were found to increase the adsorption of AFB1 significantly compared with untreated bentonite. After organophilic bentonite treatments with BAC or CTAB, a vibration of CH stretch (2850 and 2920cm(-1)) were detected. A frequency of the SiO stretch (1020 and 1090cm(-1)) was changed by intercalation of organic cation. Furthermore, the interlayer spacing of bentonite increases to 1.23nm (d001 reflection at 2θ=7.16) and 1.22 (d001 reflection at 2θ=7.22) after the addition of BAC and CTAB, respectively. Another aim of the study was to observe the effects of these two bentonite salts in neural crest stem cell cultures. The two materials that were created by organophilic treatments were not found to be toxic to stem cells. Furthermore the results indicate that the two materials tested may protect the neural crest stem cells against damage caused by AFB1.
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Affiliation(s)
- Janaína Nones
- Department of Chemical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Jader Nones
- Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
| | - Anicleto Poli
- Department of Pharmacology, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Andrea Gonçalves Trentin
- Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Humberto Gracher Riella
- Department of Chemical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Nivaldo Cabral Kuhnen
- Department of Chemical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
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11
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Abstract
The cells in the human body are continuously challenged by a variety of genotoxic attacks. Erroneous repair of the DNA can lead to mutations and chromosomal aberrations that can alter the functions of tumor suppressor genes or oncogenes, thus causing cancer development. As a central tumor suppressor, p53 guards the genome by orchestrating a variety of DNA-damage-response (DDR) mechanisms. Already early in metazoan evolution, p53 started controlling the apoptotic demise of genomically compromised cells. p53 plays a prominent role as a facilitator of DNA repair by halting the cell cycle to allow time for the repair machineries to restore genome stability. In addition, p53 took on diverse roles to also directly impact the activity of various DNA-repair systems. It thus appears as if p53 is multitasking in providing protection from cancer development by maintaining genome stability.
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Affiliation(s)
- Ashley B Williams
- Medical Faculty, Institute for Genome Stability in Ageing and Disease, University of Cologne, 50931 Cologne, Germany Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Systems Biology of Ageing Cologne, University of Cologne, 50931 Cologne, Germany
| | - Björn Schumacher
- Medical Faculty, Institute for Genome Stability in Ageing and Disease, University of Cologne, 50931 Cologne, Germany Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Systems Biology of Ageing Cologne, University of Cologne, 50931 Cologne, Germany
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12
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Mulder JE, Bondy GS, Mehta R, Massey TE. The impact of chronic Aflatoxin B1 exposure and p53 genotype on base excision repair in mouse lung and liver. Mutat Res 2015; 773:63-8. [PMID: 25847422 DOI: 10.1016/j.mrfmmm.2015.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 12/05/2014] [Accepted: 01/18/2015] [Indexed: 12/15/2022]
Abstract
Aflatoxin B1 (AFB1) is produced by species of Aspergillus, and is a known human carcinogen. AFB1-induced oxidative DNA damage, specifically 8-hydroxy-2-deoxyguanosine (8-OHdG) lesions, has been demonstrated in both animal models and in humans, and is repaired by base excision repair (BER). The tumour suppressor gene p53 is implicated in the regulation of DNA repair, and heterozygous p53 knockouts have an attenuated nucleotide excision repair response to AFB1. Male heterozygous p53 knockout mice and their wild-type controls were exposed to 0, 0.2 or 1.0ppm AFB1 for 26 weeks in their diet. BER activity of lung and liver was assessed with an in vitro assay, using 8-OHdG-damaged plasmid DNA as a substrate. BER activity did not differ between livers or lungs from untreated wild-type versus heterozygous p53 knockout mice. In wild-type mice, repair was 65% lower in liver extracts from mice exposed to 1.0ppm AFB1 than in liver extracts from mice exposed to 0.2ppm AFB1 (p<0.05), but not significantly lower than that in liver extracts from control mice. AFB1 did not affect BER in lung extracts from wild-type mice, or in lung and liver extracts from heterozygous p53 knockout mice. In liver and lung, AFB1 exposure did not alter levels of 8-oxoguanine glycosylase protein, a key enzyme in the repair of 8-OHdG, and did not cause hepatotoxicity, as indicated by plasma alanine aminotransferase levels. In conclusion, chronic exposure to AFB1 did not affect BER in lungs or livers of heterozygous p53 knockout mice. BER activity was lower in livers from p53 wild type mice exposed to 1.0ppm AFB1 versus those exposed to 0.2ppm AFB1, an effect that was not attributable to liver cell death or altered levels of 8-oxoguanine glycosylase.
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Affiliation(s)
- Jeanne E Mulder
- Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen's University Kingston, Ontario, Canada K7L 3N6
| | - Genevieve S Bondy
- Toxicology Research Division, 2202D, Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9 Canada
| | - Rekha Mehta
- Toxicology Research Division, 2202D, Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9 Canada
| | - Thomas E Massey
- Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen's University Kingston, Ontario, Canada K7L 3N6.
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