Biomass-derived chemical substitutes for bisphenol A: recent advancements in catalytic synthesis

Catalytic Transformation of Carbohydrates into Renewable Organic Chemicals by Revering the Principles of Green Chemistry

Adherence to the principles of green chemistry in a biorefinery setting ensures energy efficiency, reduces the consumption of materials, simplifies reactor design, and rationalizes the process parameters for synthesizing affordable organic chemicals of desired functional efficacy and ingrained sustainability. The green chemistry metrics facilitate assessing the relative merits and demerits of alternative synthetic pathways for the targeted product(s). This work elaborates on how green chemistry has emerged as a transformative framework and inspired innovations toward the catalytic conversion of biomass-derived carbohydrates into fuels, chemicals, and synthetic polymers. Specific discussions have been incorporated on the judicious selection of feedstock, reaction parameters, reagents (stoichiometric or catalytic), and other synthetic auxiliaries to obtain the targeted product(s) in desired selectivity and yield. The prospects of a carbohydrate-centric biorefinery have been emphasized and research avenues have been proposed to eliminate the remaining roadblocks. The analyses presented in this review will steer to developing superior synthetic strategies and processes for envisaging a sustainable bioeconomy centered on biomass-derived carbohydrates.

Enhancing the Catalytic Activity of Laccase@Copper-Metal-Organic Framework Nanofractal Microspheres: Synergistic Contribution of the Mass Transfer and Electron Transfer Pathway

Metal-organic frameworks (MOFs) are limited by small pores and buried active sites, and their enzyme-like catalytic activity is still very low. Herein, laccase was employed as the organic component to construct laccase@Cu3(BTC)2 nanofractal microspheres. During the preparation process, laccase adsorbed Cu2+ by electrostatic attractive interaction, then combined with Cu2+ by coordination interaction, and finally induced the in situ growth of H3BTC2 in multiple directions by electrostatic repulsion. Interestingly, electrostatic repulsion was tuned efficiently by adjusting the Cu2+ concentration to obtain laccase@Cu3(BTC)2 nanofractal microspheres (nanosheet microspheres, nanorod microspheres, and nanoneedle microspheres). Laccase@Cu3(BTC)2 nanorod microspheres exhibited the highest catalytic efficiency, which was 14-fold higher than that of smooth microspheres. The mechanism of the improvement of catalytic activity in the degradation of BPA was proposed for the first time. The enhanced catalytic activity depended on the adsorption effect of the nanorod framework and dual cycle synergistic catalysis of Cu+/Cu2+ active sites, which accelerated substrate diffusion and electron transfer. The catalytic mechanism of enzyme@MOF nanofractal microspheres not only deepens our understanding of enzyme and MOF synergistic catalysis but also provides new insights into the design of catalysts.

NeuTox: A weighted ensemble model for screening potential neuronal cytotoxicity of chemicals based on various types of molecular representations

Chemical-induced neurotoxicity has been widely brought into focus in the risk assessment of chemical safety. However, the traditional in vivo animal models to evaluate neurotoxicity are time-consuming and expensive, which cannot completely represent the pathophysiology of neurotoxicity in humans. Cytotoxicity to human neuroblastoma cell line (SH-SY5Y) is commonly used as an alternative to animal testing for the assessment of neurotoxicity, yet it is still not appropriate for high throughput screening of potential neuronal cytotoxicity of chemicals. In this study, we constructed an ensemble prediction model, termed NeuTox, by combining multiple machine learning algorithms with molecular representations based on the weighted score of Particle Swarm Optimization. For the test set, NeuTox shows excellent performance with an accuracy of 0.9064, which are superior to the top-performing individual models. The subsequent experimental verifications reveal that 5,5'-isopropylidenedi-2-biphenylol and 4,4'-cyclo-hexylidenebisphenol exhibited stronger SH-SY5Y-based cytotoxicity compared to bisphenol A, suggesting that NeuTox has good generalization ability in the first-tier assessment of neuronal cytotoxicity of BPA analogs. For ease of use, NeuTox is presented as an online web server that can be freely accessed via http://www.iehneutox-predictor.cn/NeuToxPredict/Predict.

Screening of the Antagonistic Activity of Potential Bisphenol A Alternatives toward the Androgen Receptor Using Machine Learning and Molecular Dynamics Simulation

Over the past few decades, extensive research has indicated that exposure to bisphenol A (BPA) increases the health risks in humans. Toxicological studies have demonstrated that BPA can bind to the androgen receptor (AR), resulting in endocrine-disrupting effects. In recent investigations, many alternatives to BPA have been detected in various environmental media as major pollutants. However, related experimental evaluations of BPA alternatives have not been systematically implemented for the assessment of chemical safety and the effects of structural characteristics on the antagonistic activity of the AR. To promote the green development of BPA alternatives, high-throughput toxicological screening is fundamental for prioritizing chemical tests. Therefore, we proposed a hybrid deep learning architecture that combines molecular descriptors and molecular graphs to predict AR antagonistic activity. Compared to previous models, this hybrid architecture can extract substantial chemical information from various molecular representations to improve the model's generalization ability for BPA alternatives. Our predictions suggest that lignin-derivable bisguaiacols, as alternatives to BPA, are likely to be nonantagonist for AR compared to bisphenol analogues. Additionally, molecular dynamics (MD) simulations identified the dihydrotestosterone-bound pocket, rather than the surface, as the major binding site of bisphenol analogues. The conformational changes of key helix H12 from an agonistic to an antagonistic conformation can be evaluated qualitatively by accelerated MD simulations to explain the underlying mechanism. Overall, our computational study is helpful for toxicological screening of BPA alternatives and the design of environmentally friendly BPA alternatives.

The Role of Endocrine Disruptors Bisphenols and Phthalates in Obesity: Current Evidence, Perspectives and Controversies

Excess body weight constitutes one of the major health challenges for societies and healthcare systems worldwide. Besides the type of diet, calorie intake and the lack of physical exercise, recent data have highlighted a possible association between endocrine-disrupting chemicals (EDCs), such as bisphenol A, phthalates and their analogs, and obesity. EDCs represent a heterogeneous group of chemicals that may influence the hormonal regulation of body mass and adipose tissue morphology. Based on the available data from mechanistic, animal and epidemiological studies including meta-analyses, the weight of evidence points towards the contribution of EDCs to the development of obesity, associated disorders and obesity-related adipose tissue dysfunction by (1) impacting adipogenesis; (2) modulating epigenetic pathways during development, enhancing susceptibility to obesity; (3) influencing neuroendocrine signals responsible for appetite and satiety; (4) promoting a proinflammatory milieu in adipose tissue and inducing a state of chronic subclinical inflammation; (5) dysregulating gut microbiome and immune homeostasis; and (6) inducing dysfunction in thermogenic adipose tissue. Critical periods of exposure to obesogenic EDCs are the prenatal, neonatal, pubertal and reproductive periods. Interestingly, EDCs even at low doses may promote epigenetic transgenerational inheritance of adult obesity in subsequent generations. The aim of this review is to summarize the available evidence on the role of obesogenic EDCs, specifically BPA and phthalate plasticizers, in the development of obesity, taking into account in vitro, animal and epidemiologic studies; discuss mechanisms linking EDCs to obesity; analyze the effects of EDCs on obesity in critical chronic periods of exposure; and present interesting perspectives, challenges and preventive measures in this research area.

Challenges and Opportunities in the Catalytic Synthesis of Diphenolic Acid and Evaluation of Its Application Potential

Diphenolic acid, or 4,4-bis(4-hydroxyphenyl)pentanoic acid, represents one of the potentially most interesting bio-products obtainable from the levulinic acid supply-chain. It represents a valuable candidate for the replacement of bisphenol A, which is strongly questioned for its toxicological issues. Diphenolic acid synthesis involves the condensation reaction between phenol and levulinic acid and requires the presence of a Brønsted acid as a catalyst. In this review, the state of the art related to the catalytic issues of its synthesis have been critically discussed, with particular attention to the heterogeneous systems, the reference benchmark being represented by the homogeneous acids. The main opportunities in the field of heterogeneous catalysis are deeply discussed, as well as the bottlenecks to be overcome to facilitate diphenolic acid production on an industrial scale. The regioselectivity of the reaction is a critical point because only the p,p'-isomer is of industrial interest; thus, several strategies aiming at the improvement of the selectivity towards this isomer are considered. The future potential of adopting alkyl levulinates, instead of levulinic acid, as starting materials for the synthesis of new classes of biopolymers, such as new epoxy and phenolic resins and polycarbonates, is also briefly considered.

Urea Hydrogen Peroxide and Ethyl Lactate, an Eco-Friendly Combo System in the Direct C(sp2)-H Bond Selenylation of Imidazo[2,1-b]thiazole and Related Structures

Herein, we describe a urea hydrogen peroxide-mediated sustainable protocol for the synthesis of selenylated imidazo[2,1-b]thiazole by using half molar equivalent diorganyl diselenides in ethyl lactate as a greener solvent. The reaction features high yields, easy performance on gram scale, metal-free conditions, as well as applicability to imidazopyridine and imidazopyrimidine.

Survey on the Environmental Risks of Bisphenol A and Its Relevant Regulations in Taiwan: An Environmental Endocrine-Disrupting Chemical of Increasing Concern

Bisphenol A (BPA) has been identified as one of the endocrine disruptors or endocrine disrupting chemicals (EDCs). Due to its massive production (over 700,000 tons per year) and the extensive use of BPA-based plastics (i.e., polycarbonate and epoxy resin) in Taiwan, it was thus included as a toxic substance by the Ministry of Environment. This work surveyed the updated information about the production of BPA and its environmental distribution in Taiwan over the past decade. Furthermore, the regulatory strategies and countermeasures for managing the environmental risks of BPA by the Taiwan government were summarized to show the cross-ministerial efforts under the relevant acts, including the Toxic and Concerned Chemical Substances Control Act (TCCSCA), the Food Sanitation Management Act (FSMA) and the Commodity Inspection Act (CIA). The findings showed that most monitoring data were far below the acceptable risks. However, people may pose an adverse threat to the aquatic environment and human health via ecological and food chains. In addition, some countermeasures were further recommended to echo the international actions on environmental endocrine disruptors in recent years.

Bisphenol A has a sex-dependent disruptive effect on hepatic lipid metabolism in zebrafish

Bisphenol A (BPA) is an endocrine disruptor that has adverse effects on lipid metabolism. However, most of the current studies on the effects of BPA on lipid metabolism in fish have focused on middle- and short-term exposure tests. The aim of this study was to investigate the effects of long-term BPA exposure on liver lipid metabolism in zebrafish. Post-fertilization embryos were exposed to environmentally relevant concentrations of BPA for 120 days, and the changes in triglyceride (TG), total cholesterol (TC) levels, and gene expression related to liver lipid metabolism were investigated in both male and female fish. The results showed that long-term exposure to BPA led to lipid deposition in liver, and there was a sex difference. In the liver of female fish, there was higher lipid transport and synthesis at low concentration of BPA, while overall metabolic levels were increased at high concentration of BPA. In contrast, BPA showed a dose-dependent effect on the lipid deposition in male fish. The expression of mRNA of TG transport-related and lipid synthesis-related genes was significantly up-regulated and the expression of genes related to lipid catabolism, was significantly down-regulated with increasing BPA dose. Taken together, our results indicate that long-term exposure to BPA can increase lipid deposition in a gender-specific manner. This may be due to the different responses of lipid metabolism related genes to BPA in male and female zebrafish. These results will provide a new reference for a deeper understanding of the ecotoxicological effects of BPA on aquatic animals.

Potential effects of bisphenol A on diabetes mellitus and its chronic complications: A narrative review

Diabetes mellitus (DM) is a metabolic disease caused by multiple factors such as genetics, environment, and lifestyle. Bisphenol A (BPA), as one of the most common endocrine-disrupting chemicals (EDCs), has been strongly implicated in the development of type 2 diabetes mellitus (T2DM). BPA exposure is associated with target organ damage in DM and may exacerbate the progression of some chronic complications of DM. This paper reviews relevant epidemiological, in vivo, and in vitro studies to better understand BPA's potential risk associations and pathological mechanisms in several chronic diabetic complications.

Catalytic disconnection of C-O bonds in epoxy resins and composites

Fibre-reinforced epoxy composites are well established in regard to load-bearing applications in the aerospace, automotive and wind power industries, owing to their light weight and high durability. These composites are based on thermoset resins embedding glass or carbon fibres¹. In lieu of viable recycling strategies, end-of-use composite-based structures such as wind turbine blades are commonly landfilled^1-4. Because of the negative environmental impact of plastic waste^5,6, the need for circular economies of plastics has become more pressing^7,8. However, recycling thermoset plastics is no trivial matter^1-4. Here we report a transition-metal-catalysed protocol for recovery of the polymer building block bisphenol A and intact fibres from epoxy composites. A Ru-catalysed, dehydrogenation/bond, cleavage/reduction cascade disconnects the C(alkyl)-O bonds of the most common linkages of the polymer. We showcase the application of this methodology to relevant unmodified amine-cured epoxy resins as well as commercial composites, including the shell of a wind turbine blade. Our results demonstrate that chemical recycling approaches for thermoset epoxy resins and composites are achievable.

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

Access to a wide range of plastic materials has been rationalized by the increased demand from growing populations and the development of high-throughput production systems. Plastic materials at low costs with reliable properties have been utilized in many everyday products. Multibillion-dollar companies are established around these plastic materials, and each polymer takes years to optimize, secure intellectual property, comply with the regulatory bodies such as the Registration, Evaluation, Authorisation and Restriction of Chemicals and the Environmental Protection Agency and develop consumer confidence. Therefore, developing a fully sustainable new plastic material with even a slightly different chemical structure is a costly and long process. Hence, the production of the common plastic materials with exactly the same chemical structures that does not require any new registration processes better reflects the reality of how to address the critical future of sustainable plastics. In this review, we have highlighted the very recent examples on the synthesis of common monomers using chemicals from sustainable feedstocks that can be used as a like-for-like substitute to prepare conventional petrochemical-free thermoplastics.

Ni- and Ni/Pd-Catalyzed Reductive Coupling of Lignin-Derived Aromatics to Access Biobased Plasticizers

Lignin-derived aromatic chemicals offer a compelling alternative to petrochemical feedstocks, and new applications are the focus of extensive interest. 4-Hydroxybenzoic acid (H), vanillic acid (G), and syringic acid (S) are readily obtained via oxidative depolymerization of hardwood lignin substrates. Here, we explore the use of these compounds to access biaryl dicarboxylate esters that represent biobased, less toxic alternatives to phthalate plasticizers. Chemical and electrochemical methods are developed for catalytic reductive coupling of sulfonate derivatives of H, G, and S to access all possible homo- and cross-coupling products. A conventional NiCl₂/bipyridine catalyst is able to access the H-H and G-G products, but new catalysts are identified to afford the more challenging coupling products, including a NiCl₂/bisphosphine catalyst for S-S and a NiCl₂/phenanthroline/PdCl₂/phosphine cocatalyst system for H-G, H-S, and G-S. High-throughput experimentation methods with a chemical reductant (Zn powder) are shown to provide an efficient screening platform for identification of new catalysts, while electrochemical methods can access improved yields and/or facilitate implementation on larger scale. Plasticizer tests are performed with poly(vinyl chloride), using esters of the 4,4'-biaryl dicarboxylate products. The H-G and G-G derivatives, in particular, exhibit performance advantages relative to an established petroleum-based phthalate ester plasticizer.

Novel stereoisomeric lignin-derived polycarbonates: towards the creation of bisphenol polycarbonate mimics

In this work, we have described a family of bio-based polycarbonates (PC-MBC) based on the unique lignin-derived aliphatic diol 4,4'-methylenebiscyclohexanol (MBC) that was sustainably sourced from lignin oxidation mixture. The detailed structure analysis of these polycarbonates has been confirmed by a series of 2D NMR (HSQC and COSY) characterizations. Depending on the stereoisomerism of MBC, the PC-MBC displayed a wide achievable T _g range of 117-174 °C and high T _d5% of >310 °C by variation of the ratio of the stereoisomers of MBC, offering great substitution perspectives towards a bisphenol-containing polycarbonates. Nonetheless, the most here presented PC-MBC polycarbonates were film-forming and transparent.

Construction of dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots composites for effective bisphenol A degradation

In this work, a novel dual Z-scheme Bi₂WO₆/g-C₃N₄/black phosphorus quantum dots (Bi₂WO₆/g-C₃N₄/BPQDs) composites were fabricated and utilized towards photocatalytic degradation of bisphenol A (BPA) under visible-light irradiation. Optimizing the content of g-C₃N₄ and BPQDs in Bi₂WO₆/g-C₃N₄/BPQDs composites to a suitable mass ratio can enhance the visible-light harvesting capacity and increase the charge separation efficiency and the transfer rate of excited-state electrons and holes, resulting in much higher photocatalytic activity for BPA degradation (95.6%, at 20 mg/L in 120 min) than that of Bi₂WO₆ (63.7%), g-C₃N₄ (25.0%), BPQDs (8.5%), and Bi₂WO₆/g-C₃N₄ (79.6%), respectively. Radical trapping experiments indicated that photogenerated holes (h⁺) and superoxide radicals (•O₂^-) played crucial roles in photocatalytic BPA degradation. Further, the possible degradation pathway and photocatalytic mechanism was proposed by analyzing the BPA intermediates. This work also demonstrated that the Bi₂WO₆/g-C₃N₄/BPQDs as effective photocatalysts was stable and have promising potential to remove environmental contaminants from real water samples.

Zaki M, M. Al-Qahtani S, Fayad E, T. Salem E, K. Abdulsahib W, Emam H, M. Hassan H. Integration of Ultrastructural and Computational Approaches Reveals the Protective Effect of Astaxanthin against BPA-Induced Nephrotoxicity

BACKGROUND

Bisphenol A (BPA) is an environmental contaminant that can induce deleterious organ effects. Human Cytochrome P450 CYP2C9 enzyme belongs to the essential xenobiotic-metabolizing enzymes, producing ROS as a byproduct. Astaxanthin (ATX) is a powerful antioxidant that protects organs and tissues from the damaging effects of oxidative stress caused by various diseases.

AIM OF THE STUDY

This study investigated the possible protective impacts of ATX against BPA-induced nephrotoxicity and its underlying mechanism.

MATERIALS AND METHODS

Kidney tissues were isolated and examined microscopically from control, protected, and unprotected groups of rats to examine the potential protective effect of ATX against nephrotoxicity. Moreover, a molecular dynamic (MD) simulation was conducted to predict the performance of ATX upon binding to the active site of P450 CYP2C9 protein receptor as a potential mechanism of ATX protective effect.

RESULTS

Implemented computational methods revealed the possible underlying mechanism of ATX protection; the protective impact of ATX is mediated by inhibiting P450 CYP2C9 through binding to its dimeric state where the RMSF value for apo-protein and ATX-complex system were 5.720.57 and 1.040.41, respectively, implicating the ATX-complex system to have lesser variance in its residues, leading to the prevention of ROS excess production, maintaining the oxidant-antioxidant balance and re-establishing the proper mitochondrial functionality. Furthermore, the experimental methods validated in silico outcomes and revealed that ATX therapy effectively restored the typical histological architecture of pathological kidney tissues.

CONCLUSIONS

ATX prevents BPA-induced nephrotoxicity by controlling oxidative imbalance and reversing mitochondrial dysfunction. These outcomes shed new light on the appropriate use of ATX as a treatment or prophylactic agent for these severe conditions.

Electrochemical sensor based on confined synthesis of gold nanoparticles @ covalent organic frameworks for the detection of bisphenol A

Covalent-organic frameworks (COFs), a kind of conjugate crystalline polymers, has great potential for high performance electrochemical sensors due to high porosity, controllable pores and structure, and large specific surface area, etc. Herein, we developed an electrochemical sensor based on confined synthesis of gold nanoparticles @ 1,3,5-triformylphloroglucinol (Tp) and benzidine (BD) connected COFs (Au NPs@TpBD-COFs) for electrochemical detection of bisphenol A (BPA). Firstly, Au NPs were grown on the surface and in the pores of COFs by confinement synthesis strategy, which aimed to improve the conductivity and catalytic activity of COFs. Then, this composite was used to constitute electrochemical sensor for the oxidation of BPA, resulting a good electrocatalytic activity in the phosphate buffer solution (pH 7.4). Due to high conductivity of Au NPs and TpBD-COFs recognize BPA via π-π stacking interactions and hydrogen bonds, the proposed sensor for the detection of BPA has the linear range of 5-1000 μM and the detection limit of 1 μM. Finally, the proposed sensor was used to measure the content of BPA in real water samples with a satisfactory recovery from 98.6 to 106.9%. Those good results confirmed that the proposed electrochemical sensors for monitoring of BPA in the application of COFs provided a significant guidance.

Reduced genotoxicity of lignin-derivable replacements to bisphenol A studied using in silico, in vitro, and in vivo methods

Bisguaiacols, lignin-derivable bisphenols, are considered promising and possibly safer alternatives to bisphenol A (BPA), but comprehensive toxicity investigations are needed to ensure safety. Most toxicity studies of BPA and its analogues have focused on potential estrogenic activity, and only limited toxicological data are available on other toxicity aspects, such as genotoxicity at low exposure levels. In this study, the genotoxicity of six lignin-derivable bisguaiacols with varying regioisomer contents and degrees of methoxy substitution was investigated using a multi-tiered method, consisting of in silico simulations, in vitro Ames tests, and in vivo comet tests. The toxicity estimation software tool, an application that predicts toxicity of chemicals using quantitative structure-activity relationships, calculated that the majority of the lignin-derivable bisguaiacols were non-mutagenic. These results were supported by Ames tests using five tester strains (TA98, TA100, TA102, TA1535, and TA1537) at concentrations ranging from 0.5 pmol/plate to 5 nmol/plate. The potential genotoxicity of bisguaiacols was further evaluated using in vivo comet testing in fetal chicken livers, and in addition to the standard alkaline comet assay, the formamidopyrimidine DNA glycosylase enzyme-modified comet assay was employed to investigate oxidative DNA damage in the liver samples. The oxidative stress analyses indicated that the majority of lignin-derivable analogues showed no signs of mutagenicity (mutagenic index < 1.5) or genotoxicity, in comparison to BPA and bisphenol F, likely due to the methoxy groups on the lignin-derivable aromatics. These findings reinforce the potential of lignin-derivable bisphenols as safer alternatives to BPA.

An insight into bisphenol A, food exposure and its adverse effects on health: A review

Bisphenol A (BPA) is a synthetic chemical widely employed to synthesize epoxy resins, polymer materials, and polycarbonate plastics. BPA is abundant in the environment, i.e., in food containers, water bottles, thermal papers, toys, medical devices, etc., and is incorporated into soil/water through leaching. Being a potent endocrine disrupter, and has the potential to alter several body mechanisms. Studies confirmed its anti-androgen action and estrogen-like effects, which impart many negative health impacts, especially on the immune system, neuroendocrine process, and reproductive mechanism. Moreover, it can also induce mutagenesis and carcinogenesis, as per recent scientific research. This review focuses on BPA's presence and concentrations in different environments, food sources and the basic mechanisms of BPA-induced toxicity and health disruptions. It is a unique review of its type because it focuses on the association of cancer, hormonal disruption, immunosuppression, and infertility with BPA. These issues are widespread today, and BPA significantly contributes to their incidence because of its wide usage in daily life utensils and other accessories. The review also discusses researched-based measures to cope with the toxic chemical.

Inhibition mechanisms of Fe2+/Fe3+ and Mn2+ on fungal laccase-enabled bisphenol a polyreaction

Bisphenol A (BPA) is regarded as an endocrine disruptor associated with negative health effects in animals and humans. Laccase from white-rot fungus can enable BPA oxidation and auto-polymerization to circumvent its biotoxicity, but the work concerning the effect mechanisms of divalent and trivalent metal ions (MIs) on BPA polyreaction have rarely been reported. Herein, Trametes versicolor laccase-started BPA conversion within 1 h followed pseudo-first order kinetics, and the rate constant (k_prcs) and half-life were respectively 0.61 h^-1 and 1.14 h. The presence of Ca²⁺, Mg²⁺, Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Al³⁺ exhibited insignificant impact on BPA removal, whereas Fe²⁺, Fe³⁺ and Mn²⁺ had a strong inhibiting effect. Compared with MI-free, the k_prcs values of BPA respectively lowered 34.4%, 44.3% and 98.4% in the presence of Fe²⁺, Fe³⁺ and Mn²⁺. Enzymatic activity and differential absorption spectrum disclosed that the inhibitory actions were accomplished by two different mechanisms. One is Fe²⁺ was preferentially oxidized into Fe³⁺ that restrained laccase activity at the initial stage of reaction, and subsequently, the formed Fe³⁺ complex bound with laccase T1-Cu site and thus impeded the single-electron transfer system. The other is Mn²⁺ was instantly oxidized by laccase to generate Mn³⁺-citrate complex, which completely consumed the dissolved O₂ in solution and consequently terminated BPA removal. Considering environmental bioremediation, T. versicolor laccase-enabled auto-polymerization is a simple and convenient candidate to eliminate BPA in enzymatic wastewater treatment, however the effects of Fe²⁺/Fe³⁺ and Mn²⁺ on BPA decontamination should be cautiously assessed.

Design of highly active Ni catalysts supported on carbon nanofibers for the hydrolytic hydrogenation of cellobiose

The direct transformation of cellulose into sugar alcohols (one-pot conversion) over supported nickel catalysts represents an attractive chemical route for biomass valorization, allowing the use of subcritical water in the hydrolysis step. The effectiveness of this process is substantially conditioned by the hydrogenation ability of the catalyst, determined by design parameters such as the active phase loading and particle size. Herein, mechanistic insights into catalyst design to produce superior activity were outlined using the hydrolytic hydrogenation of cellobiose as a model reaction. Variations in the impregnation technique (precipitation in basic media, incipient wetness impregnation, and the use of colloidal-deposition approaches) endowed carbon-nanofiber-supported catalysts within a wide range of Ni crystal sizes (5.8–20.4 nm) and loadings (5–14 wt%). The link between the properties of these catalysts and their reactivity has been established using characterization techniques such as X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma-optical emission spectroscopy (ICP-OES). A fair compromise was found between the Ni surface area (3.89 m²/g) and its resistance against oxidation for intermediate crystallite sizes (∼11.3 nm) loaded at 10.7 wt%, affording the hydrogenation of 81.2% cellobiose to sorbitol after 3 h reaction at 190°C and 4.0 MPa H₂ (measured at room temperature). The facile oxidation of smaller Ni particle sizes impeded the use of highly dispersed catalysts to reduce the metal content requirements.

Critical review of the toxicity mechanisms of bisphenol F in zebrafish (Danio rerio): Knowledge gaps and future directions

Replacement chemicals for bisphenol A, such as bisphenol F (BPF), are detected in aquatic environments worldwide and can potentially exert negative effects on aquatic organisms. We synthesized peer-reviewed literature reporting molecular and physiological responses in zebrafish following exposure to BPF, as BPF is closely related to BPA structure and is a dominant replacement chemical in the marketplace. Global concentrations of BPF in aquatic environments were compiled and compared to physiological and behavioral impacts reported in zebrafish (e.g., developmental abnormalities, oxidative stress, immunotoxicity, endocrine disruption, and neurotoxicity). Using computational approaches, we elucidate BPF-mediated molecular networks and reveal novel biomarkers associated with BPF exposure. Functional classes of proteins including inflammatory cytokines, ATPases, peroxidases, and aromatic l-amino decarboxylases represent novel, underexplored targets of toxicity. Most revealing of this critical review is that few studies report biological responses to BPF at levels present in aquatic environments. Recommendations for future investigations based on knowledge gaps include: (1) Mechanistic studies in the central nervous system of zebrafish to address neurotoxicity; (2) Behavioral assays in zebrafish that assess the effects of BPF on anxiolytic, social, and fear-related behaviors; (3) Studies that broaden understanding of potential endocrine disrupting effects of BPF, for example insulin signaling is predicted to be sensitive to BPF exposure; (4) Studies into metabolic disruption with a focus on glutathione and aromatic amino acids, based upon pathway analysis data; (5) Studies utilizing mixture exposures with other BPA analogs to reflect environmental conditions more accurately.

Endocrine Disruptors and Prostate Cancer

The role of endocrine disruptors (EDs) in the human prostate gland is an overlooked issue even though the prostate is essential for male fertility. From experimental models, it is known that EDs can influence several molecular mechanisms involved in prostate homeostasis and diseases, including prostate cancer (PCa), one of the most common cancers in the male, whose onset and progression is characterized by the deregulation of several cellular pathways including androgen receptor (AR) signaling. The prostate gland essentiality relies on its function to produce and secrete the prostatic fluid, a component of the seminal fluid, needed to keep alive and functional sperms upon ejaculation. In physiological condition, in the prostate epithelium the more-active androgen, the 5α-dihydrotestosterone (DHT), formed from testosterone (T) by the 5α-reductase enzyme (SRD5A), binds to AR and, upon homodimerization and nuclear translocation, recognizes the promoter of target genes modulating them. In pathological conditions, AR mutations and/or less specific AR binding by ligands modulate differently targeted genes leading to an altered regulation of cell proliferation and triggering PCa onset and development. EDs acting on the AR-dependent signaling within the prostate gland can contribute to the PCa onset and to exacerbating its development.

Sustainable Routes for the Synthesis of Renewable Adipic Acid from Biomass Derivatives

Adipic acid (AA) is a key industrial dicarboxylic acid intermediate used in nylon manufacturing. Unfortunately, the traditional process technology is accompanied by serious environmental pollution. Given the growing demand for adipic acid and the desire to reduce its negative impact on the environment, considerable efforts have been devoted to developing more green and friendly routes. This Review is focused on the latest advances in the sustainable preparation of AA from biomass-based platform molecules, including 5-hydroxymethylfufural, glucose, γ-valerolactone, and phenolic compounds, through biocatalysis, chemocatalysis, and the combination of both. Additionally, the development of state-of-the-art catalysts for different catalytic systems systematically is discussed and summarized, as well as their reaction mechanisms. Finally, the prospects for all preparation routes are critically evaluated and key technical challenges in the development of green and sustainable processes for the manufacture of AA are highlighted. It is hoped that the green adipic acid synthesis pathways presented can provide insights and guidance for further research into other industrial processes for the production of nylon precursors in the future.

Synthesis of renewable diesel and jet fuel range alkanes using 2-methylfuran and cyclohexanone

New solid acid catalysts were prepared by bisphenol A, paraformaldehyde and chlorosulfonic acid, and applied to hydroxylalkylation/alkylation (HAA) of 2-methylfuran (2-MF) and cyclohexanone. After optimizing the reaction conditions, the conversion of 2-MF reached 99% and the yield of 5,5′-(cyclohexane-1,1-diyl)bis(2-methylfuran) acquired 98%. The activity and catalytic efficiency were higher than those of Amberlyst 15 and Amberlyst 36 resins, which could be rationalized by high acid strength. At the same time, the catalysts were characterized by acid–base titration and FTIR. Hydrodeoxygenation (HDO) of HAA products of 2-methylfuran and cyclopentanone were processed on the Ni/SiO₂ catalyst prepared by wet impregnation method to further convert into aviation kerosene, and the yield reached 93%.

New solid acid catalysts were prepared by bisphenol A, paraformaldehyde, and applied to HAA of 2-methylfuran (2-MF) and cyclohexanone. Hydrodeoxygenation (HDO) of HAA products of 2-MF and cyclopentanone were processed on Ni/SiO₂ catalyst.

Highly efficient Ni–NiO/carbon nanotubes catalysts for the selective transfer hydrogenation of 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)furan

Ni–NiO/CNTs showed an excellent activity towards the catalytic transfer hydrogenation of 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)furan.

Preparation and properties of novel bio-based epoxy resin thermosets from lignin oligomers and cardanol

A series of lignin-based epoxy resins (LEPs) were prepared by the reaction of epichlorohydrin with lignin oligomers derived from partial reductive depolymerization of lignin. To overcome the high viscosity and brittleness defects in practical applications, the LEPs were blended with renewable epoxied cardanol glycidyl ether (ECGE) and then cured with methyltetrahydrophthalic anhydride (MeTHPA) to form high-performance epoxy thermosets. The effects of degree of lignin depolymerization, chemical composition of lignin oligomers and dosage of ECGE on thermal and mechanical properties of the cured products were investigated. The LEP/MeTHPA thermosets exhibited good thermal and mechanical properties. Especially, by separating monomer-rich fractions from lignin oligomers, the thermal and mechanical properties of the cured product were improved obviously. Notably, the incorporation of ECGE also possessed a positive effect on reinforcing and toughening the cured products. With 20 wt% ECGE loadings, the tensile, flexural and impact strength of the cured product reached the maximum value of 77 MPa, 115 MPa and 14 kJ/m², respectively, which were equivalent to the commercial bisphenol A epoxy resins thermosets. These findings indicated that the novel bio-based epoxy resins from lignin oligomers and cardanol could be utilized as renewable alternatives for BPA epoxy resins.

An In-Situ Self-regeneration Catalyst for the Production of Renewable Penta-1,3-diene

Catalyst deactivation is a problem of great concern for many heterogeneous reactions. Here, an urchin-like LaPO₄ catalyst was easily developed for pentane-2,3-diol dehydration; it has an impressive ability to restore the activity in situ by itself during the reaction, accounting for its high stability. This facilitates the efficient production of renewable penta-1,3-diene from pentane-2,3-dione via a novel approach, where penta-2,3-diol was obtained as an intermediate in 95 % yield under mild conditions.

Chemical, Thermal and Antioxidant Properties of Lignins Solubilized during Soda/AQ Pulping of Orange and Olive Tree Pruning Residues

Some agroforestry residues such as orange and olive tree pruning have been extensively evaluated for their valorization due to its high carbohydrates content. However, lignin-enriched residues generated during carbohydrates valorization are normally incinerated to produce energy. In order to find alternative high added-value applications for these lignins, a depth characterization of them is required. In this study, lignins isolated from the black liquors produced during soda/anthraquinone (soda/AQ) pulping of orange and olive tree pruning residues were analyzed by analytical standard methods and Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (solid state 13C NMR and 2D NMR) and size exclusion chromatography (SEC). Thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and antioxidant capacity (Trolox equivalent antioxidant capacity) were also evaluated. Both lignins showed a high OH phenolic content as consequence of a wide breakdown of β-aryl ether linkages. This extensive degradation yielded lignins with low molecular weights and polydispersity values. Moreover, both lignins exhibited an enrichment of syringyl units together with different native as well as soda/AQ lignin derived units. Based on these chemical properties, orange and olive lignins showed relatively high thermal stability and good antioxidant activities. These results make them potential additives to enhance the thermo-oxidation stability of synthetic polymers.

Estrogenic activity of lignin-derivable alternatives to bisphenol A assessed via molecular docking simulations

Lignin-derivable bisphenols are potential alternatives to bisphenol A (BPA), a suspected endocrine disruptor; however, a greater understanding of structure–activity relationships (SARs) associated with such lignin-derivable building blocks is necessary to move replacement efforts forward. This study focuses on the prediction of bisphenol estrogenic activity (EA) to inform the design of potentially safer BPA alternatives. To achieve this goal, the binding affinities to estrogen receptor alpha (ERα) of lignin-derivable bisphenols were calculated via molecular docking simulations and correlated to median effective concentration (EC₅₀) values using an empirical correlation curve created from known EC₅₀ values and binding affinities of commercial (bis)phenols. Based on the correlation curve, lignin-derivable bisphenols with binding affinities weaker than ∼−6.0 kcal mol⁻¹ were expected to exhibit no EA, and further analysis suggested that having two methoxy groups on an aromatic ring of the bio-derivable bisphenol was largely responsible for the reduction in binding to ERα. Such dimethoxy aromatics are readily sourced from the depolymerization of hardwood biomass. Additionally, bulkier substituents on the bridging carbon of lignin-bisphenols, like diethyl or dimethoxy, were shown to weaken binding to ERα. And, as the bio-derivable aromatics maintain major structural similarities to BPA, the resultant polymeric materials should possess comparable/equivalent thermal (e.g., glass transition temperatures, thermal decomposition temperatures) and mechanical (e.g., tensile strength, modulus) properties to those of polymers derived from BPA. Hence, the SARs established in this work can facilitate the development of sustainable polymers that maintain the performance of existing BPA-based materials while simultaneously reducing estrogenic potential.

This article explores lignin-derivable bisphenols as alternatives to bisphenol A – a suspected endocrine disruptor – by investigating their structure-activity relationships with respect to estrogen receptor alpha via molecular docking.

Resin-supported iridium complex for low-temperature vanillin hydrogenation using formic acid in water

Biorefinery seeks to utilize biomass waste streams as a source of chemical precursors with which to feed the chemical industry. This goal seeks to replace petroleum as the main feedstock, however this task requires the development of efficient catalysts capable of transforming substances derived from biomass into useful chemical products. In this study, we demonstrate that a highly-active iridium complex can be solid-supported and used as a low-temperature catalyst for both the decomposition of formic acid (FA) to produce hydrogen, and as a hydrogenation catalyst to produce vanillyl alcohol (VA) and 2-methoxy-4-methylphenol (MMP) from vanillin (V); a lignin-derived feedstock. These hydrogenation products are promising precursors for epoxy resins and thus demonstrate an approach for their production without the need for petroleum. In contrast to other catalysts that require temperatures exceeding 100 °C, here we accomplish this at a temperature of <50 °C in water under autogenous pressure. This approach provides an avenue towards biorefinery with lower energy demands, which is central to the decentralization and broad implementation. We found that the high activity of the iridium complex transfers to the solid-support and is capable of accelerating the rate determining step; the decomposition of FA into hydrogen and carbon dioxide. The yield of both VA and MMP can be independently tuned depending on the temperature. The simplicity of this approach expands the utility of molecular metal complexes and provides new catalyst opportunities in biorefinery.

Solid-supported molecular catalysis for biorefinery. Hydrogenation using formic acid in water at low temperature.

Valorisation of plastic waste via metal-catalysed depolymerisation

Metal-catalysed depolymerisation of plastics to reusable building blocks, including monomers, oligomers or added-value chemicals, is an attractive tool for the recycling and valorisation of these materials. The present manuscript shortly reviews the most significant contributions that appeared in the field within the period January 2010–January 2020 describing selective depolymerisation methods of plastics. Achievements are broken down according to the plastic material, namely polyolefins, polyesters, polycarbonates and polyamides. The focus is on recent advancements targeting sustainable and environmentally friendly processes. Biocatalytic or unselective processes, acid–base treatments as well as the production of fuels are not discussed, nor are the methods for the further upgrade of the depolymerisation products.

Synthesis and anionic polymerization of isosorbide mono-epoxides for linear biobased polyethers

Different regioisomeric and diastereomeric isosorbide mono-epoxides are prepared and polymerized to thermally stable and relatively rigid biobased linear polyethers.