Evaluation of Phenolic Compound Toxicity Using a Bioluminescent Assay with the Fungus Gerronema viridilucens

Detrimental impacts and QSAR baseline toxicity assessment of Japanese medaka embryos exposed to methylparaben and its halogenated byproducts

Despite the theoretical risk of forming halogenated methylparabens (halo-MePs) during water chlorination in the absence or presence of bromide ions, there remains a lack of in vivo toxicological assessments on vertebrate organisms for halo-MePs. This research addresses these gaps by investigating the lethal (assessed by embryo coagulation) or sub-lethal (assessed by hatching success/heartbeat rate) toxicity and teratogenicity (assessed by deformity rate) of MeP and its mono- and di-halogen derivatives (Cl- or Br-) using Japanese medaka embryos. In assessing selected apical endpoints to discern patterns in physiological or biochemical alterations, heightened toxic impacts were observed for halo-MePs compared to MeP. These include a higher incidence of embryo coagulation (4-36 fold), heartbeat rate decrement (11-36 fold), deformity rate increment (32-223 fold), hatching success decrement (11-59 fold), and an increase in Reactive Oxygen Species (ROS) level (1.2-7.4 fold)/Catalase (CAT) activity (1.7-2.8 fold). Experimentally determined LC50 values are correlated and predicted using a Quantitative Structure Activity Relationship (QSAR) based on the speciation-corrected liposome-water distribution ratio (Dlipw, pH 7.5). The QSAR baseline toxicity aligns well with (sub)lethal toxicity and teratogenicity, as evidenced by toxic ratio (TR) analysis showing TR < 10 for MeP exposure in all cases, while significant specific or reactive toxicity was found for halo-MeP exposure, with TR > 10 observed (excepting three values). Our extensive findings contribute novel insights into the intricate interplay of embryonic toxicity during the early-life-stage of Japanese medaka, with a specific focus on highlighting the potential hazards associated with halo-MePs compared to the parent compound MeP.

Biodegradation of phenolic pollutants and bioaugmentation strategies: A review of current knowledge and future perspectives

The widespread use of phenolic compounds renders their occurrence in various environmental matrices, posing ecological risks especially the endocrine disruption effects. Biodegradation-based techniques are efficient and cost-effective in degrading phenolic pollutants with less production of secondary pollution. This review focuses on phenol, 4-nonylphenol, 4-nitrophenol, bisphenol A and tetrabromobisphenol A as the representatives, and summarizes the current knowledge and future perspectives of their biodegradation and the enhancement strategy of bioaugmentation. Biodegradation and isolation of degrading microorganisms were mainly investigated under oxic conditions, where phenolic pollutants are typically hydroxylated to 4-hydroxybenzoate or hydroquinone prior to ring opening. Bioaugmentation efficiencies of phenolic pollutants significantly vary under different application conditions (e.g., increased degradation by 10-95% in soil and sediment). To optimize degradation of phenolic pollutants in different matrices, the factors that influence biodegradation capacity of microorganisms and performance of bioaugmentation are discussed. The use of immobilization strategy, indigenous degrading bacteria, and highly competent exogenous bacteria are proposed to facilitate the bioaugmentation process. Further studies are suggested to illustrate 1) biodegradation of phenolic pollutants under anoxic conditions, 2) application of microbial consortia with synergistic effects for phenolic pollutant degradation, and 3) assessment on the uncertain ecological risks associated with bioaugmentation, resulting from changes in degradation pathway of phenolic pollutants and alterations in structure and function of indigenous microbial community.

Effects of Endohedral Gd-Containing Fullerenols with a Different Number of Oxygen Substituents on Bacterial Bioluminescence

Gadolinium (Gd)-containing fullerenols are perspective agents for magnetic resonance imaging and cancer research. They combine the unique paramagnetic properties of Gd with solubility in water, low toxicity and antiradical activity of fullerenols. We compared the bioeffects of two Gd-containing fullerenols with a different number of oxygen groups-20 and 42: Gd@C82O20H14 and Gd@C82O42H32. The bioluminescent bacteria-based assay was applied to monitor the toxicity of fullerenols, bioluminescence was applied as a signal physiological parameter, and bacterial enzyme-based assay was used to evaluate the fullerenol effects on enzymatic intracellular processes. Chemiluminescence luminol assay was applied to monitor the content of reactive oxygen species (ROS) in bacterial and enzymatic media. It was shown that Gd@C82O42H32 and Gd@C82O20H14 inhibited bacterial bioluminescence at >10-1 and >10-2 gL-1, respectively, revealing a lower toxicity of Gd@C82O42H32. Low-concentration (10-3-10-1 gL-1) bacterial bioluminescence activation by Gd@C82O42H32 was observed, while this activation was not found under exposure to Gd@C82O20H14. Additional carboxyl groups in the structure of Gd@C82O42H32 were determined by infrared spectroscopy and confirmed by quantum chemical calculations. The groups were supposed to endow Gd@C82O42H32 with higher penetration ability through the cellular membrane, activation ability, lower toxicity, balancing of the ROS content in the bacterial suspensions, and lower aggregation in aqueous media.

Advances in photocatalytic degradation of organic pollutants in wastewaters: harnessing the power of phthalocyanines and phthalocyanine-containing materials

Access to clean water is increasingly challenging worldwide due to human activities and climate change. Wastewater treatment and utilization offer a promising solution by reducing the reliance on pure underground water. However, it is crucial to develop efficient and sustainable methods for wastewater purification. Among the emerging wastewater treatment strategies, photocatalysis has gained significant attention for decomposing organic pollutants in water, especially when combined with sunlight and a recoverable photocatalyst. Heterogeneous photocatalysts have distinct advantages, as they can be recovered and reused without significant loss of activity over multiple cycles. Phthalocyanine dyes, with their exceptional photophysical properties, are particularly valuable for homogeneous and heterogeneous photocatalysis. By immobilizing these photosensitizers in various supports, hybrid materials extend their light absorption into the visible spectrum, complementing most supports' limited UV light absorption. The novelty and research importance of this review stems from its discussion of the multifaceted approach to treating contaminated wastewater with phthalocyanines and materials containing phthalocyanines. It highlights key aspects of each study, including photocatalytic efficiency, recyclability characteristics, investigation of the generation of oxygen species responsible for degradation, identification of the major degradation byproducts for each pollutant, and others. Moreover, the review includes tables that illustrate and compare the various phthalocyanines and supporting materials employed in each study for pollutant degradation. Additionally, almost all photocatalysts mentioned in this review could degrade at least 5% of the pollutant, and more than 50 photocatalysts showed photocatalytic rates above 50%. When immobilized in some support, the synergistic effect of the phthalocyanine was visible in the photocatalytic rate of the studied pollutant. However, when performing these types of works, it is necessary to understand the degradation products of each pollutant and their relative toxicities. Along with this, recyclability and stability studies are also necessary. Despite the good results presented in this review, some of the works lack those studies. Moreover, none of the works mentions any study in wastewater.

Fungal bioassays for environmental monitoring

Environmental pollutants are today a major concern and an intensely discussed topic on the global agenda for sustainable development. They include a wide range of organic compounds, such as pharmaceutical waste, pesticides, plastics, and volatile organic compounds that can be found in air, soil, water bodies, sewage, and industrial wastewater. In addition to impacting fauna, flora, and fungi, skin absorption, inhalation, and ingestion of some pollutants can also negatively affect human health. Fungi play a crucial role in the decomposition and cycle of natural and synthetic substances. They exhibit a variety of growth, metabolic, morphological, and reproductive strategies and can be found in association with animals, plants, algae, and cyanobacteria. There are fungal strains that occur naturally in soil, sediment, and water that have inherent abilities to survive with contaminants, making the organism important for bioassay applications. In this context, we reviewed the applications of fungal-based bioassays as a versatile tool for environmental monitoring.

Implicitly perturbed Hamiltonian as a class of versatile and general-purpose molecular representations for machine learning

Unraveling challenging problems by machine learning has recently become a hot topic in many scientific disciplines. For developing rigorous machine-learning models to study problems of interest in molecular sciences, translating molecular structures to quantitative representations as suitable machine-learning inputs play a central role. Many different molecular representations and the state-of-the-art ones, although efficient in studying numerous molecular features, still are suboptimal in many challenging cases, as discussed in the context of the present research. The main aim of the present study is to introduce the Implicitly Perturbed Hamiltonian (ImPerHam) as a class of versatile representations for more efficient machine learning of challenging problems in molecular sciences. ImPerHam representations are defined as energy attributes of the molecular Hamiltonian, implicitly perturbed by a number of hypothetic or real arbitrary solvents based on continuum solvation models. We demonstrate the outstanding performance of machine-learning models based on ImPerHam representations for three diverse and challenging cases of predicting inhibition of the CYP450 enzyme, high precision, and transferrable evaluation of non-covalent interaction energy of molecular systems, and accurately reproducing solvation free energies for large benchmark sets.

Molecular representations are fundamental tools for machine-learning models. The current work introduces a new set of molecular representations demonstrated to enable accurate predictions of molecular conformational energy and solvation free energy.

Revealing the heterogeneous activation mechanism of peroxydisulfate by CuO: the critical role of surface-binding organic substrates

Heterogeneous catalytic activation mechanisms of peroxydisulfate (PDS) by transition metal oxides are generally attributed to the interactions between catalysts and PDS, however, the role of the co-existed organic substrate was largely overlooked in the past studies. In this work, phenol was selected as the target organic pollutant in a CuO/PDS system to evaluate its deep-seated role in participating in the effective activation of PDS. First, optimized reaction conditions as pH of 6.0, CuO of 5.96 g·L^-1 and PDS of 2.5 mM were obtained by the response surface methodology (RSM) with a phenol degradation efficiency of 84.0%. It was further found that pre-adsorption of phenol or PDS led to obviously different performances in the phenol degradation with/without the radical scavengers. Two different activation pathways of PDS, i.e., the non-radical pathway mediated by surface deprotonated phenol to generate ¹O₂ and the radical pathway mediated by structural Cu(I)/Cu(II) to produce SO₄^-, were therefore proposed, and the former was predominant in the CuO/PDS/phenol system. In addition, HCO₃^- and HPO₄^2- could strongly inhibit the phenol degradation while Cl^- and NO₃^- only performed negligible effects. NaOH washing could regenerate the surface hydroxyl groups and recover the catalytic ability of CuO. The result of this study integrated the interactions among the catalyst, oxidant and substrate, providing new insights into environmental-friendly PDS activation processes.