Review: Biodegradation of tributyltins (organotins) by marine bacteria

Many marine bacterial strains have an inherent capability to degrade toxic organotin compounds, especially tributyltins (TBTs), that enter into the environment in the form of insecticides, fungicides and antifouling paints as a result of anthropogenic and industrial activities. Significant degradation of these compounds in the ambient environment may take several years, and it is necessary to consider methods or strategies that can accelerate the degradation process. There have been few demonstrations of biological degradation of these organotin biocides exclusively in laboratory‐scale experiments. Compared with the few bench‐scale degradation processes, there are no reports of field‐scale processes for TBT bioremediation, in spite of its serious environmental threat to non‐target organisms in the aquatic environment. Implementation of field‐scale biodegradation of TBT requires inputs from biology, hydrology, geology, chemistry and civil engineering. A framework is emerging that can be adapted to develop new processes for bioremediation of toxic environmental wastes. In the case of TBT bioremediation, this framework incorporates screening and identification of natural bacterial strains, determination of optimal conditions for growth of isolates and TBT degradation, establishment of new metabolic pathways involved in TBT degradation, identification, localization and cloning of genes involved in degradation and in TBT resistance, development of suitable microbial strains using genetic manipulation techniques for practical applications and optimization of practical engineering processes for bioremediation of organotin‐contaminated sites. The present review mainly addresses the aspect of TBT biodegradation with special reference to environmental sources of TBT, chemical structure and biological activity, resistant and degrading bacterial strains, possible mechanisms of resistance and degradation and the genetic and biochemical basis of TBT degradation and resistance. It also evaluates the feasibility and potential of natural and genetically modified TBT‐degrading bacterial strains in field‐scale experiments to bioremediate TBT‐contaminated marine sites, and makes recommendations for more intensive and focused research in the area of TBT bioremediation mediated by marine bacterial strains. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and cytotoxic activity of silacycloalkyl‐substituted heterocyclic aldehydes and their thiosemicarbazones

A series of 5‐[1‐methylsilacyclo‐pentyl/‐hexyl]‐2‐furfural, 5‐[1‐methylsilacyclo‐pentyl/‐hexyl]‐2‐thiophene carbaldehyde and 1,1‐bis(5‐formyl‐2‐furyl)silacyclo‐pentane/‐hexane and their thiosemicarbazones has been synthesized and subjected to antitumour assay. The effects of the substituents and the heterocycle were examined to establish structure–activity relationships. Thiosemicarbazones of 5‐(1‐methylsilacyclohexyl)furfural and 5‐(1‐methylsilacyclopentyl)furfural were very active (1.0–4.0 µg ml^?1) in vitro against human fibrosarcoma HT‐1080 and mouse hepatoma MG‐22A cells. At the same time, they were less toxic for normal fibroblasts 3T3. All compounds synthesized exhibited low or moderate toxicity (LD₅₀ 152–1904 mg kg^?1). Copyright © 2005 John Wiley & Sons, Ltd.     

An Environmentally Friendly and Flexible Aqueous Zinc Battery Using an Organic Cathode

Rechargeable batteries have been used to power various electric devices and store energy from renewables, but their toxic components (namely, electrode materials, electrolyte, and separator) generally cause serious environment issues when disused. Such toxicity characteristic makes them difficult to power future wearable electronic devices. Now an environmentally friendly and highly safe rechargeable battery, based on a pyrene‐4,5,9,10‐tetraone (PTO) cathode and zinc anode in mild aqueous electrolyte is presented. The PTO‐cathode shows a high specific capacity (336 mAh g^?1) for Zn²⁺ storage with fast kinetics and high reversibility. Thus, the PTO//Zn full cell exhibits a high energy density (186.7 Wh kg^?1), supercapacitor‐like power behavior and long‐term lifespan (over 1000 cycles). Moreover, a belt‐shaped PTO//Zn battery with robust mechanical durability and remarkable flexibility is first fabricated to clarify its potential application in wearable electronic devices.     

Characterization of Cinnamic Acid-Attached Nonionic Amphiphiles in UV Extinction,Emulsification, and In Vitro Toxicity

Cinnamic acid (CA) was covalently attached to nonionic surfactants by condensation reaction. The mass and the molar extinction coefficient of CA residue of each conjugate did not markedly deviate from those of free CA, indicating CA could absorb the UV light after being conjugated to the surfactants. When the concentration of the conjugates in aqueous phase was 0.1% and 1.0%, mineral oil could readily be emulsified by polyoxyehtylene(20) cetyl ether–CA conjugate (CE20–CA), polyoxyethylene(20) oleyl ether–CA conjugate (OE20–CA), and polyoxyehtylene(20) sorbitan monolaurate–CA conjugate (Tween 20–CA). The extinction coefficients of the surfactant–CA conjugates contained in O/W emulsion did not markedly deviate from those of the conjugates dissolved in water, suggesting that the conjugate could maintain their extinction coefficients when they coexisted with oil droplets. According to the result of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, the viability of cell (BALB/c 3T3 clone A31) was greater than 80% for all the surfactant–CA conjugates tested when the conjugate concentration was 0.2%. It is believed that CE20–CA, OE20–CA, and Tween 20–CA could be used as an emulsifier which absorbs UV light effectively.     

Binding of Chromium(III) to Transferrin Could Be Involved in Detoxification of Dietary Chromium(III) Rather than Transport of an Essential Trace Element

Cr^III binding to transferrin (Tf; the main Fe^III transport protein) has been postulated to mediate cellular uptake of Cr^III to facilitate a purported essential role for this element. Experiments using HepG2 (human hepatoma) cells, which were chosen because of high levels of the transferrin receptor, showed that Cr^III binding to vacant Fe^III‐binding sites of human Tf effectively blocks cellular Cr^III uptake. Through bio‐layer interferometry studies of the Tf cycle, it was found that both exclusion and efflux of Cr₂^IIITf from cells was caused by 1) relatively low Cr₂Tf affinity to cell‐surface Tf receptors compared to Fe₂Tf, and 2) disruption of metal release under endosomal conditions and post‐endosomal Tf dissociation from the receptor. These data support mounting evidence that Cr^III is not essential and that Tf binding is likely to be a natural protective mechanism against the toxicity and potential genotoxicity of dietary Cr through blocking Cr^III cellular accumulation.     

Systematic characterization of components of Makyo-kanseki-to granule and serum metabolomics for exploring its protective mechanism against acute lung injury in lipopolysaccharide-induced rats

Makyo-kanseki-to has been used for the treatment of pneumonia, becoming a basic formula for coronavirus disease 2019. However, the chemical profile of Makyo-kanseki-to granule and its possible mechanism against acute lung injury from terminal metabolic regulation have been unclear. The aim of this study was to characterize the constituents in Makyo-kanseki-to granule and reveal the potential related mechanism of Makyo-kanseki-to granule treatment for acute lung injury using a rat model of lipopolysaccharide-induced acute lung injury. Totally, 78 constituents were characterized based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Makyo-kanseki-to granule could alleviate acute lung injury through modulating rectal temperature, pulmonary edema, histopathology, and processes of inflammatory and oxidative stress. Twenty-two potential biomarkers in acute lung injury rats were identified by metabolomics based on ultra-performance liquid chromatography coupled with quadrupole exactive high-field mass spectrometry. They were mainly involved in amino acids and glycerophospholipid metabolism, which were regulated by Makyo-kanseki-to granule. The present results not only increase the understanding of the chemical profile and molecular mechanism of Makyo-kanseki-to granule mediated protection against acute lung injury but also provide an experimental basis and new ideas for further development and clinical application of Makyo-kanseki-to granule.