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Enhanced degradation of pesticide dichlorophen by laccase immobilized on nanoporous materials: a cytotoxic and molecular simulation investigation Abraham Vidal, Patricia Concepción García-Suárez, Evarista Arellano-García, Oscar Edel Contreras, and Sergio Aguila Bioconjugate Chem., Just Accepted Manuscript • DOI: 10.1021/acs.bioconjchem.7b00739 • Publication Date (Web): 16 Jan 2018 Downloaded from http://pubs.acs.org on January 19, 2018
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Bioconjugate Chemistry
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Enhanced degradation of pesticide dichlorophen by laccase immobilized on
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nanoporous materials: a cytotoxic and molecular simulation investigation
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Abraham Vidal-Limon† ; Patricia Concepción García Suárez†‡ ; Evarista ArellanoGarcía‡; Oscar E. Contreras†; Sergio A. Aguila† *
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†Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de
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Mexico, km. 107 Carretera Tijuana-Ensenada, Pedregal Playitas, PO. 22860 Ensenada,
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Baja California, Mexico.
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‡Universidad Autonoma de Baja California, km. 105 Carretera Tijuana-Ensenada,
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Pedregal Playitas, PO. 22860. Ensenada, Baja California, Mexico.
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[email protected] 11
[email protected] 12
[email protected] 13
[email protected] 14
[email protected] *
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Highlights •
dichlorophen.
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•
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A reduction on apoptotic, cytotoxic and genotoxic effects were found after treatment of dichlorophen with laccase-MSU-F.
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A hybrid nanomaterial (laccase-MSU-F) readily oxidizes organochlorine pesticide
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Theoretical affinity of oxidized sub-products of dichlorophen was reduced on human steroid hormone nuclear receptors after laccase-MSU-F treatment.
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Abstract
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Use of pesticides is usually related to over-production of crops in order to overcome
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worldwide demand of food and alimentary safety. Nevertheless, pesticides are
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environmental persistent molecules, such as the organochlorine pesticides, which are
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often found in undesired places. In this work, we show that a hybrid nanomaterial
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(laccase – MSU-F) readily oxidizes the pesticide dichlorophen, reducing its acute
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genotoxicity and apoptotic effects. In order to predict chronic alterations related to
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endocrine disruption, we compared the calculated affinity of dichlorophen oxidized sub-
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products to steroid hormone nuclear receptors (NRs), using molecular simulation
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methods. We found a reduction in theoretical affinity of sub-products of oxidized
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dichlorophen for the ligand-binding pocket of NRs (~5 Kcal/mol) likewise of changes in
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binding modes that suggest a reduction in binding events (RMSD values < 10 Å).
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Keywords: Dichlorophen; laccase; molecular dynamics; MSU-F; Nanomaterials.
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Abbreviations
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CP, chlorophen.
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DCP, dichlorophen.
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DDT, dichlorodiphenyltrichloroethane..
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FEB, free energy of binding.
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oxDCP, laccase-oxidized dichlorophen.
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MD, molecular dynamics.
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MSU-F, mesoporous synthetic silica foam.
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NR, steroid hormone nuclear receptors.
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RMSD, root mean square deviation.
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Bioconjugate Chemistry
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Introduction
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Worldwide use of pesticides has drastically risen during the last 60 years, with a 15-20-
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fold increase related to agricultural and public health control areas
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pesticides are known to be persistent compounds, which often appear in undesired
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places (groundwater, agricultural soils or accumulated in trophic networks) 3. Exposure
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to organochlorines, among many others pesticides, has toxic effects on human health
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(Food and Environment Protection Act, 1985), from intense acute responses such as
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eye or skin irritation, and allergic sensitization
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disruption of endocrine hormone physiology or reproductive abnormalities
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1,2
. However,
to chronic immune suppression, 7–10
. At
11–13
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cellular scale, diverse injuries have been reported after pesticide exposure
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nuclear abnormalities, induction of pro-apoptotic signaling, high mutagenic rates and
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overall decrease of cellular proliferation. Thus, the effects of organochlorine pesticides
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have turned into a worldwide environmental and public health issue, with records of ~ 1
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x 106 annual intoxications and 2 x 104 annual deaths (WHO, 2014). Besides, a strong
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correlation between usage of pesticides and cancer has been found for at least 3.7 x
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104 cases annually 14,15. In the particular case of Mexico, an annual average of 3.5 x 105
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Tons of pesticides are administered to the registered 3.5 x 107 Ha agricultural areas
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(INEGI, 2014), leaving a very extensive and environmentally impacted landscape.
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Moreover, nearly 350 reports of intoxications due to acute exposure to pesticides are
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reported each year 16,17.
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Dichlorophen(2,2′-methylenebis(4-chlorophenol), DCP) is an environmentally persistent
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organochlorine pesticide, with fungicide, vermicide and bactericide activities
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its persistency, dichlorophen is commonly found on soils and effluents (~ 10-145 ng/L)
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19,20
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demonstrated that after acute exposure of rats to sub-lethal doses of dichlorophen,
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cellular abnormalities appeared such as chromosomal aberrations and loss of genetic
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material in bone marrow cells and erythrocytes. Chronic effects can be traced to a
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disruption of endocrine hormone physiology, since several studies suggest that
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organochlorine pesticides can act as antagonists of human nuclear receptors 21,22
, where it interacts preferably with lipidic cellular regions
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, i.e.
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. Due to
. Lone et al.
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Among the most efficient approaches, physicochemical strategies have been developed
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to tackle the persistence of organochlorine pesticides in the environment, with the aim
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of ameliorating their well-documented detrimental effects. Xiao et al. reported a mixed
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approach of UV irradiation and ozonation (UV/O3) to degrade chlorophen (CP) in
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aqueous media, enhancing in one order of magnitude the oxidation rate of CP and
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DCP. In this approach, the mechanism of degradation was mediated by HO, which was
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produced after photodecomposition of H2O2 (the latter was produced after UV irradiation
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