Search Results (50)

The Portuguese Atlantic coast harbors a remarkably diverse macroalgal flora, shaped by the intersection of Lusitanian, Mediterranean, and boreal biogeographic influences. This diversity is reflected in the rich repertoire of secondary metabolites produced by local seaweeds, including halogenated compounds, terpenoids, phlorotannins, mycosporine like amino acids, sulfated polysaccharides, and unique phenolic structures. These metabolites exhibit a wide range of bioactivities, antioxidant, anti-inflammatory, antimicrobial, antiviral, antifouling, antitumoral, and neuroprotective, positioning Portuguese seaweeds as promising sources of novel bioactive agents. This review synthesizes the current state of knowledge on the chemical diversity and biological properties of metabolites isolated from seaweeds along the Portuguese Atlantic coast. We examine species-specific metabolite profiles, ecological drivers of chemical variability, and advances in extraction, purification, and structural elucidation. Emerging applications in pharmaceuticals, nutraceuticals, cosmeceuticals, and sustainable biomaterials are discussed, alongside the potential of seaweed derived compounds to support blue bioeconomy development. Finally, we identify research gaps and propose future directions for bioprospecting, metabolomics, and biotechnological exploitation of this underexplored marine resource. Full article

Water pollution from phenols remains a critical concern due to their persistence, toxicity, and industrial prevalence. Graphene oxide (GOx), with its functional groups and large surface area, offers strong adsorption potential. Using density functional theory (DFT), reduced density gradient (RDG), and quantitative structure–activity relationship (QSAR), we examined how protonation and substituents influence phenol adsorption. Deprotonated phenolates bind more strongly to GO than neutral species via electrostatics and H-bonding. Substituents alter affinity: halogens enhance it, bulky alkyls hinder it, and nitro groups show electron-withdrawing effects. Bisphenolate A displayed multidentate binding. QSAR models reproduced DFT energies with R² > 0.99, enabling fast prediction. These results highlight how pH speciation and substituents govern adsorption on GO, guiding the design of efficient water treatment materials. Full article

Wastewater-derived microplastics (WW-MPs) are increasingly recognised as reactive vectors for aromatic organic contaminants (AOCs), yet their role in contaminant fate remains insufficiently constrained. This review synthesises current knowledge on the transformation of microplastics in wastewater treatment plants, including fragmentation, oxidative ageing, additive leaching, and biofilm formation, and links these processes to changes in sorption capacity toward phenols, PAHs and their derivatives, and organochlorine pesticides (OCPs). We summarise the dominant adsorption mechanisms-hydrophobic partitioning, π-π interactions, hydrogen bonding, and electrostatic and, in some cases, halogen bonding-and critically evaluate how wastewater-relevant parameters (pH, ionic strength, dissolved organic matter, temperature, and biofilms) can modulate these interactions. Evidence in the literature consistently shows that ageing and biofouling enhance WW-MP affinity for many AOCs, reinforcing their function as mobile carriers. However, major gaps persist, including limited data on real wastewater-aged MPs, lack of methodological standardisation, and incomplete representation of ageing, competitive sorption, and non-equilibrium diffusion in existing isotherm and kinetic models. We propose key descriptors that should be incorporated into future sorption and fate frameworks and discuss how WW-MP-AOC interactions may influence ecological exposure, bioavailability, and risk assessment. This critical analysis supports more realistic predictions of AOC behaviour in wastewater environments. Full article

Pyruvate:ferredoxin oxidoreductase (PFOR) is a key Achilles’ heel in anaerobic pathogens. We integrate electronic-structure calculations (DFT), cheminformatic QSAR metrics, and residue-resolved docking to distill a concise “recognition code” and translate it into practical design rules. Using nitazoxanide (Nita; ΔG_(bind) ≈ −10.0 kcal·mol⁻¹) as a well-established reference, productive binding requires a conserved triad: a hydrogen-bond donor addressing Thr-997 and Cys-840, a π–π stack with Phe-869, and a recurrent π–σ contact to Thr-997 that orients the scaffold. Deacetylation to tizoxanide unmasks the phenolic donor and raises local electrophilicity, yet it also slightly loosens pocket packing (−9.6 kcal·mol⁻¹). Strategic halogenation introduces a σ-hole interaction near Pro-29, tightening pose geometry without disrupting the donor network; the lead analogue yields −10.1 kcal·mol⁻¹, and two others match the reference by preserving the triad and hydrophobic belt. The result is a minimal, testable recipe—retain the phenolic donor, enforce Thr-997/Cys-840 and Phe-869, and add a calibrated halogen σ-hole—offering falsifiable predictions to surpass nitazoxanide and guiding synthesis and biophysical validation in targeted PFOR inhibition. Full article

Metal-free aminobenzoic acid-derived Schiff bases are attractive antimicrobial leads because their azomethine (–C=N–) functionality enables tunable electronic properties and target engagement. We investigated whether halogenation on the phenolic ring would modulate the redox behavior and enhance antibacterial potency, and hypothesized that heavier halogens would favorably tune physicochemical and electronic descriptors. We synthesized three derivatives (SB-3/Cl, SB-4/Br, and SB-5/I) and confirmed their structures using FTIR, ¹H- and ¹³C-NMR, UV-Vis, and HRMS. For SB-5, single-crystal X-ray diffraction and Hirshfeld analysis verified the intramolecular O–H⋯N hydrogen bond and key packing contacts. Cyclic voltammetry revealed an irreversible oxidation (aminobenzoic ring) and, for the halogenated series, a reversible reduction associated with the imine; peak positions and reversibility trends are consistent with halogen electronic effects and DFT-based MEP/LHS descriptors. Antimicrobial testing showed that SB-5 was selectively potent against Gram-positive aerobes, with low-to-mid micromolar MICs across the panel. Among anaerobes, activity was more substantial: Clostridioides difficile was inhibited at 0.1 µM, and SB-3/SB-5 reduced its sporulation at sub-MICs, while Blautia coccoides was highly susceptible (MIC 0.01 µM). No activity was detected against Gram-negative bacteria at the tested concentrations. In the fungal assay, Botrytis cinerea displayed only a transient fungistatic response without complete growth inhibition. In mammalian cells (HeLa), the compounds displayed clear concentration-dependent behavior. Overall, halogenation, particularly iodination, emerges as a powerful tool to couple redox tuning with selective Gram-positive activity and a favorable cellular tolerance window, nominating SB-5 as a promising scaffold for further antimicrobial optimization. Full article

Nineteen previously and newly synthesized amphoteric 8-[(dialkylamino)methyl]-7-hydroxy-4-(2-oxo-2H-chromen-3-yl)-2H-chromen-2-ones were assayed as inhibitors of monoamine oxidases (MAO-A and B) and cholinesterases (AChE and BChE). Five of the tested compounds (2b, 2c, 3c, 5b, and 5c), namely those bearing the less bulky alkyls in the Mannich base 8-CH₂NR₂ (R = Me, Et) and the halogens (Cl, Br) at C6 of the 4-coumarin-3-yl moiety, showed moderate inhibitory potencies toward human MAO-A in the single-digit micromolar range (IC₅₀s from 1.49 to 3.04 µM). In particular, the 6′-Cl derivatives 2b and 5b proved to be reversible competitive inhibitors of human MAO-A with K_i values of 0.272 and 0.326 µM. Among the tested compounds, 3c proved to also be a moderate inhibitor of human AChE (IC₅₀ 4.27 µM). Molecular docking calculations suggested binding modes of the most active compounds to MAO-A and AChE binding sites consistent enough with the experimental data. Chemoinformatic tools suggest for the most active compounds, including the dual MAO-A/AChE inhibitor 3c, full compliance with Lipinski’s rule of five, high probability of gastrointestinal absorption, but low blood–brain barrier (BBB) permeability. While further efforts are required to improve their CNS distribution, herein new phenolic Mannich bases have been identified that may have potential for treating neurodegenerative syndromes. Full article

As one kind of renewable aromatic polymer, lignin is severely underused due to its chemical recalcitrance. Lignin can endure demethylation modification to improve its activation by releasing more active functional groups. However, the process suffers from expensive, corrosive, and toxic issues by employing halogen-containing reagents, which has become an obstacle to industrial applications. Herein, a series of dicarboxylic acid-based protic ionic liquids (DAPILs) systems composed of ethanolamine and dibasic organic acids (e.g., aspartic acid (Asp), glutamic acid (Glu), succinic acid (SA), and glutaric acid (GA)) with 1~2:1 stoichiometric ratio, have been finely designed for the demethylation of industrial lignin. With [EOA][GA] treatment, the polyphenol content in lignin was favorably increased beyond 1.58 times. The structural tailoring and variation were fully characterized by 2D HSQC and ¹H NMR. The analysis results indicated that, with the increase of phenolic hydroxyl content in lignin, the β-O-4′ bond was broken and the content of structural units (S, G) and the S/G ratio of lignin decreased accordingly. After the treatment, the used IL and tailored lignin can be recovered over 95%. This novel, halogen-free and environmentally friendly lignin-cutting strategy not only opens avenues for high-value utilization of lignin but also expands the field of application of dicarboxylic acid-based protic ionic liquids. Full article

Thyroid hormones, biosynthesized in the follicular cells in the thyroid gland, play a crucial role in regulating various important biological processes. The thyroid hormone is synthesized as pro-hormone L-thyroxine (T4), while the active form is primarily produced through the phenolic ring deiodination of T4 by iodothyronine deiodinase enzymes (DIOs). Three distinct isoforms of the enzyme are known, which, despite having almost similar amino acid sequences in their active site, differ in their regioselectivity of deiodination towards T4 and its metabolites. However, the precise mechanism and the origin of the differences in the regioselectivity of deiodination by DIOs are still not fully understood. Over the years, several research groups have attempted to mimic this system with small molecules to gain some insight into the reactivity and mechanism. In this review, we will explore the recent developments on the biomimetic deiodination of T4 and its derivatives by using selenium-based enzyme mimetics. For example, naphthalene-based molecules, featuring a 1,8-dichalcogen atom, have been shown to perform tyrosyl ring deiodination of T4 and T3, producing rT3 and 3,3′-T2, respectively. The modification of the electron density around the phenolic ring through substitutions in the 4′-hydroxyl group can alter the regioselectivity of the deiodination by deiodinase mimics. Additionally, we will highlight the recent progress in the development of a dipeptide-based DIO1 mimic, as well as the deiodination of other halogenated thyronine derivatives by mimics. Full article

The use of CO₂ as a C1 carbon source for the synthesis of valuable chemicals through biotechnology methods represents an effective strategy to fix carbon dioxide. Phenolic acid decarboxylases possess the capability to introduce a carboxyl group into para-hydroxystyrenes for the regionally selective synthesis of (E)-para-hydroxycinnamic acids, utilizing bicarbonate as a CO₂ source. It is difficult to achieve this reaction with traditional chemical methods, and only a few enzymes have been isolated and characterized. Here, we mined which low amino acid sequence shared its identity with those of related decarboxylases and which heterologously expressed phenolic acid decarboxylase PAD_Cs from Clostridium sp. DSM 8431 in E. coli. The recombinant PAD_Cs displayed maximum activity at 50 °C, and pH 5.0. PAD_Cs showed distinct carboxylation ability. The carboxylated substrates have a wide range of substitution modes on aromatic systems, including alkyl and alkoxy groups as well as halogens. Furthermore, the carboxylation conversion rates were impressive: para-hydroxystyrene exceeded 20% and 2-methoxy-4-vinylphenol surpassed 26%. This study indicated that PAD_Cs might serve as a potential enzyme source in biotechnological CO₂ fixation. Full article

Photocatalysis offers a powerful approach for water purification from toxic organics, hydrogen production, biosolids processing, and the conversion of CO₂ into useful products. Further advancements in photocatalytic technologies depend on the development of novel, highly efficient catalysts and optimized synthesis methods. This study aimed to develop a laser synthesis technique for bismuth oxyhalide nanoparticles (NPs) as efficient and multifunctional photocatalysts. Laser ablation of a Bi target in a solution containing halogen salt precursors, followed by laser plasma treatment of the resulting colloid, yielded crystalline bismuth oxyhalides (Bi_xO_yX_z, where X = Cl, Br, or I) NPs without the need for additional annealing. The composition, structure, morphology, and optical properties of the synthesized Bi_xO_yX_z (X = Cl, Br, I) NPs were characterized using XRD analysis, electron microscopy, Raman spectroscopy, and UV-Vis spectroscopy. The effect of the halogen on the photocatalytic activity of the double oxides was investigated. The materials exhibited high photocatalytic activity in the degradation of persistent model pollutants like Rhodamine B, tetracycline, and phenol. Furthermore, the Bi_xO_yX_z NPs demonstrated good efficiency and high yield in the selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-furandicarboxylic acid (FDCA). The obtained results highlight the promising potential of this laser synthesis approach for producing high-performance bismuth oxyhalide photocatalysts. Full article

Bromophenols, which belong to the family of phenolic compounds, are halogenated secondary metabolites characterized by the incorporation of bromine atoms into the phenol ring structure, resulting in unique chemical properties. These compounds, synthesized as secondary metabolites by algae, exhibit different isomeric forms due to bromine substitution at different positions within the phenol ring, showing variability among species. Bromine substitution not only confers specific chemical properties but also plays an important role in the ecological functions of bromophenols by inducing increased lipophilicity, which affects solubility and reactivity, an adaptive response to external conditions. Certain genera of red algae, such as Gracilaria and Rhodomela, have been identified as important sources of bromophenols. Research on bromophenols involves extraction, commonly using solvents such as methanol or methanol-dichloromethane, and identification and structural elucidation using advanced analytical techniques such as mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy for the precise determination of structure and configuration. Bromophenols display diverse biological activities, highlighting antimicrobial, antidiabetic, antiviral and antioxidant properties, which are closely related to their specific chemical structure. The importance of understanding the chemical group of bromophenols is underlined by their role in chemical defense mechanisms, contributing to potential biotechnological applications and broader contributions to the marine ecosystem. Therefore, this study is aimed to review the chemical characteristics and biological properties of bromophenols in red algae. Full article

Acne vulgaris, a high-prevalence skin condition afflicting people, persists as a significant challenge in the absence of effective treatments and emerging antibiotic resistance. To address this pressing concern, exploration of innovative approaches is of the utmost importance. Asparagopsis armata, an invasive red seaweed renowned for its diverse array of bioactive compounds, emerges as a promising candidate. This study seeks to elucidate the potential utility of A. armata biomass in the treatment of acne vulgaris. Crude extracts were obtained through solid–liquid extraction, and fractions were obtained using liquid–liquid extraction. The analyzed bioactivities included antioxidant, antimicrobial, and anti-inflammatory. Also, chemical characterization was performed to identify free fatty acids and compounds through LC-MS and elements. The present findings unveil compelling attributes, including anti-Cutibacterium acnes activity, cytotoxic and non-cytotoxic effects, antioxidant properties, and its ability to reduce nitric oxide production with consequent anti-inflammatory potential. Additionally, chemical characterization provides insights into its mineral elements, free fatty acids, and diverse compounds. The observed antimicrobial efficacy may be linked to halogenated compounds and fatty acids. Cytoprotection appears to be associated with the presence of glycerolipids and glycosylated metabolites. Furthermore, its antioxidant activity, coupled with anti-inflammatory properties, can be attributed to phenolic compounds, such as flavonoids. This study underscores the potential of A. armata as a natural ingredient in skincare formulations, offering an important contribution to the ongoing battle against acne vulgaris. Full article

Dopamine is a key neurotransmitter involved in a series of biologically relevant processes and its derivatives have sparked significant interest as intriguing synthetic targets. This class of compounds is indeed not only considerable for the potential biological activities but is also promising for diverse applications in material science. In light of this, our research was focused on the synthesis of 6-aryldopamine derivatives starting from 4-(2-aminoethyl)phenol through a sequential protocol, whose main steps are hydroxylation, halogenation, and Suzuki cross-coupling. Our method demonstrated versatility, efficiency, and compatibility with various functional groups, including aldehydes, ketones, esters, ethers, and fluorine. Full article

Dihydroxylated polybrominated diphenyl ethers (DiOH-PBDEs) could be the metabolites of PBDEs of some organisms or the natural products of certain marine bacteria and algae. OH-PBDEs may demonstrate binding affinity to thyroid hormone receptors (TRs) and can disrupt the functioning of the systems modulated by TRs. However, the thyroid hormone disruption mechanism of diOH-PBDEs remains elusive due to the absence of diOH-PBDEs standards. This investigation explores the potential disruptive effects of OH/diOH-PBDEs on thyroid hormones via competitive binding and coactivator recruitment with TRα and TRβ. At levels of 5000 nM and 25,000 nM, 6-OH-BDE-47 demonstrated significant recruitment of steroid receptor coactivator (SRC), whereas none of the diOH-PBDEs exhibited SRC recruitment within the range of 0.32–25,000 nM. AutoDock CrankPep (ADCP) simulations suggest that the conformation of SRC and TR–ligand complexes, particularly their interaction with Helix 12, rather than binding affinity, plays a pivotal role in ligand agonistic activity. 6,6′-diOH-BDE-47 displayed antagonistic activity towards both TRα and TRβ, while the antagonism of 3,5-diOH-BDE-100 for TRα and TRβ was concentration-dependent. 3,5-diOH-BDE-17 and 3,5-diOH-BDE-51 exhibited no discernible agonistic or antagonistic activities. Molecular docking analysis revealed that the binding energy of 3,3′,5-triiodo-L-thyronine (T3) surpassed that of OH/diOH-PBDEs. 3,5-diOH-BDE-100 exhibited the highest binding energy, whereas 6,6′-diOH-BDE-47 displayed the lowest. These findings suggest that the structural determinants influencing the agonistic and antagonistic activities of halogen phenols may be more intricate than previously proposed, involving factors beyond high-brominated PBDEs or hydroxyl group and bromine substitutions. It is likely that the agonistic or antagonistic propensities of OH/diOH-PBDEs are instigated by protein conformational changes rather than considerations of binding energy. Full article

The known oxygenated polyhalogenated diphenyl ether, 2-(2′,4′-dibromophenoxy)-3,5-dibromophenol (1), with previously reported activity in multiple cytotoxicity assays was isolated from the sponge Lamellodysidea sp. and proved to be an amenable scaffold for semisynthetic library generation. The phenol group of 1 was targeted to generate 12 ether analogues in low-to-excellent yields, and the new library was fully characterized by NMR, UV, and MS analyses. The chemical structures for 2, 8, and 9 were additionally determined via single-crystal X-ray diffraction analysis. All natural and semisynthetic compounds were evaluated for their ability to inhibit the growth of DU145, LNCaP, MCF-7, and MDA-MB-231 cancer cell lines. Compound 3 was shown to have near-equivalent activity compared to scaffold 1 in two in vitro assays, and the activity of the compounds with an additional benzyl ring appeared to be reliant on the presence and position of additional halogens. Full article