Phenol Derivatives Research Articles

Nickel-Catalyzed Cross-Electrophile Coupling of Aryl Triflates with Alkyl Halides: Mechanism-Informed Design of More General Conditions.

Aryl triflates make up a class of aryl electrophiles that are available in a single step from the corresponding phenol. Despite the known reactivity of nickel complexes for aryl C-O bond activation of phenol derivatives, nickel-catalyzed cross-electrophile coupling using aryl triflates has proven challenging. Herein, we report a method to form C(sp2)-C(sp3) bonds by coupling aryl triflates with alkyl bromides and chlorides using phenanthroline (phen) or pyridine-2,6-bis(N-cyanocarboxamidine) (PyBCamCN)-ligated nickel catalysts. The scope of the reaction is demonstrated with 38 examples (61 ± 14% average yield). Mechanistic studies provide a rationale for the conditions used and a roadmap for further applications of cross-electrophile coupling. First, the rate of alkyl radical generation is controlled by maintaining the majority of alkyl halide as the alkyl chloride, which is unreactive, and utilizing a dynamic halide exchange process to adjust the concentration of reactive alkyl bromide or iodide. Second, the challenge of using electron-rich aryl triflates appears to be due to off-cycle transmetalation to form unproductive aryl zinc reagents. The optimal PyBCamCN ligand together with LiCl avoids this deleterious transmetalation step.

Undescribed and known phenolic acid derivatives with significant antioxidant activity from the Scorzonera parviflora Jacq. roots.

The antioxidant activity of Scorzonera parviflora Jacq. roots were assessed by measuring their ability to scavenge ABTS and DPPH radicals. Bioactivity-guided fractionation was utilized to identify the compound(s) responsible for this activity. The most active phase, ethyl acetate, was isolated using column chromatography. The resulting fractions were then purified using preparative TLC on reverse phase and semi-preparative HPLC. The structures of the pure compounds were elucidated by spectral analysis (MS and 1H, 13C, 2D-NMR). Three undescribed phenolic acid derivatives, namely parvifloric acid A (1), B (2), and C (3), and one new sesquiterpene lactone, parviflorin (4) together with seven known compounds were isolated and identified as scopolin (5), scopoletin (6), caffeic acid (7), protocatechuic acid (8), 4,5-O-dicaffeoylquinic acid (9) 3,5-O-dicaffeoylquinic acid (10), and 3,5-O-dicaffeoylquinic acid methyl ester (11). Finally, the pure compounds obtained were tested to evaluate their antioxidant capacities, using ABTS and DPPH radical scavenging potencies. The highest activity was observed with 3,5-O-dicaffeoylquinic acid (10), followed by its methyl ester.

Imino and Thioureidic Derivatives as New Tools for Alzheimer's Disease: Preliminary Studies.

Alzheimer's disease is a neurodegenerative chronic disease with a severe social and economic impact in the societies, which still lacks an efficient therapy. Several pathophysiological events (β-amyloid [Aβ] deposits, τ-protein aggregation, loss of cholinergic activity, and oxidative stress) occurs in the progression of the disease. Therefore, the search for efficient multi-targeted agents for the treatment of Alzheimer's disease becomes indispensable. In this paper we evaluated the AChE inhibition by Ellman's method and antioxidant activity by DPPH assay of nine synthetic compounds: two hydroxy-benzene derivatives (1 and 2), three bis-thioureidic derivatives (3-5), two imidazole derivatives (6 and 7), and two phenylacetamide derivatives (8 and 9). The compound 2, (3s,5s,7s)-adamantan-1-yl 4-(((E)-2,5-dihydroxybenzylidene)amino)benzoate, exhibited the best antioxidant activity (30.00 ± 1.05 μM eq Trolox) and compound 4 showed the highest AChE inhibition value (IC50 [μM] 8.40 ± 0.32). In the search for a compound showing combined activities (antioxidant and AChE inhibition), the compound 4, octane-1,8-diyl-bis-S-amidinothiourea dihydrobromide, (19.02 ± 1.52 μM eq Trolox; IC50 [μM] 8.40 ± 0.32) was chosen to carry out a molecular docking study. The results showed that compound 4 has the ability to bind the active site of acetylcholinesterase with considerable affinity (estimated binding energies of -8.5 kcal/mol). All data indicate that compound 4 has the potential to be further investigated as a possible candidate in the Alzheimer's disease treatment.

Ajwa date extract (Phoenix dactylifera L.): Phytochemical analysis, antiviral activity against herpes simplex virus-I and coxsackie B4 virus, and in silico study.

To investigate the phytochemical composition of Ajwa date extract and evaluate its antiviral activity and mechanism of action. High perfomance liquid chromatography, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry were used to analyze the phytochemical profile of Ajwa date extract. The antiviral activity was assessed using the MTT colorimetric assay against herpes simplex virus type I (HSV-I) and coxsackievirus B4 (CVB-4). Assessment of the mechanism of action against HSV-I was carried out using 3 protocols. Molecular docking and quantum chemical calculations were carried out to predict the binding affinities of the identified compounds to viral glycoprotein D. A total of 17 metabolites belonging to different classes of metabolites, mainly flavonoids, phenolic acid derivatives, fatty acids, and sugar derivatives. Ajwa extract exhibited antiviral activity against HSV-I with an IC: 50 of 113.99±4.67 μg/mL, whereas it showed limited activity against CVB-4. The antiviral activity of Ajwa extract was mainly attributed to its cell protectant activity by preventing adherence of viral to host cell with an IC: 50 equal to 57.82±1.37μg/mL. Molecular docking studies indicated that chlorogenic acid had the strongest binding affinity to viral glycoprotein D, which suggests its potential role in inhibiting viral entry into host cells. The Ajwa date extract demonstrated promising antiviral activity, especially against HSV-I. Integrating in vitro and in silico analyses provided valuable insights into the mechanisms of action.

Phenolic Derivatives Isolated from Chamaecrista hildebrandtii (Vatke) Lock and Their Biological Activities

Chamaecrista hildebrandtii is used to prepare herbal medicines as laxative and purgative agents to treat diseases such as diarrhea, stomach ulcers, healing wounds and skin infections. Thus, this plant has shown great interest to researchers, but the chemical constituent of this plant has not been determined. The objective of the study was the extraction and purification of phytochemicals from C. hildebrandtii crude leaf extracts and to determine their antioxidant and antimicrobial ability. Extraction of the C. hildebrandtii leaves was done by macerating shade-dried and milled leaves in methanol that was further partitioned using water, hexane and ethyl acetate. Ethyl acetate fraction underwent further TLC analysis and repeated column chromatography with various solvent combinations to give a total of twelve fractions. Spectroscopic analysis was done using 1H NMR, 13C NMR, 1H-1H COSY, 2D-HSQC and 13C DEPT-135 and carefully compared with the literature available. Two phenolic compounds emodin (1,3,8-trihydroxy-6-methylanthraquinone) and chrysophanol (1,2-dihydroxy-6-methylanthrquinone) were isolated and identified. The antimicrobial activity was tested by disc diffusion method using Mueller Hinton agar growth medium. Emodin exhibited comparatively higher inhibitory activity against microbes in comparison with chrysophanol. Emodin showed a 55.1% DPPH inhibition while chrysophanol recorded a 58.2% inhibition. Emodin showed a desirable IC50 of 7.3 mg/mL compared to chrysophanol with an IC50 value of 12.3 mg/mL. The IC50 values of the two isolates were slightly higher than that of ascorbic acid (IC50 = 3.24 mg/mL). The outcome revealed that C. hildebrandtii leaf extracts may represent a promising natural source of polyphenols, which can be used as antimicrobial and antioxidant agents.

Foeniculum vulgare Miller bracts, revalorization of a local food waste

This research aims at the valorization of fennel by-products from the Campania region (Southern Italy). A phytochemical characterization of the hydroalcoholic extracts (HEs) and of the essential oils (EOs) from edible and non-edible parts (waste) of Foeniculum vulgare Mill. was carried out using HRESIMS and GC-MS. The analysis led to the identification in the extracts of flavonoids, phenolic acid derivatives, amino acids and fatty acids and essential amino acids and the presence of trans-anethole and limonene as main components of the EOs. Their antioxidant activity was investigated by DPPH e ABTS assays, showing moderate antioxidant activity for the HEs and no activity for the EOs. Antimicrobial activity was evaluated by disk diffusion method against some common bacterial food contaminants: Acinetobacter baumannii, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Salmonella sp., Shigella sp., Staphylococcus aureus. The EOs resulted active on almost all bacterial strains while HEs were found inactive. This study demonstrated that the waste obtained from fennel harvesting should t be considered as a valuable and reusable product.

Weakly-Activated Phenol Derivatives as New Green Electrophilic Partners in Suzuki–Miyaura and Related C-C Couplings

In recent years, there has been growing interest in the development of greener alternatives to traditional reagents used in carbon–carbon coupling reactions, particularly in response to environmental concerns. The commonly used aryl halides, despite being highly reactive in the Suzuki–Miyaura coupling (SMC), pose significant environmental risks. As a result, research has shifted towards exploring the use of phenols, which are widely accessible and environmentally benign. However, phenols are considerably less reactive due to the poor leaving group properties of the hydroxyl group, necessitating prior activation to facilitate their use in coupling reactions. This work aims to review the recent investigations on the activation strategies for phenols, focusing on their application in the Suzuki–Miyaura and related C-C couplings. In addition, the exploration of the potential of conducting the activation step “in situ” will also be discussed. We hope that this article will pave the way for the development of more sustainable and efficient coupling methodologies, addressing both ecological and practical challenges in organic synthesis.

Antioxidant activity and protective effect of hydroxy derivatives of chalcones for sterlet (Acipenser ruthenus, Linnaeus, 1758) sperm.

The aim of this work is to study the effect of adding hydroxy derivatives of chalcones to the basic cryomedium on the ability of sterlet sperm to utilize superoxide and hydrogen peroxide, the intensity of lipid peroxidation of male fish germ cells, and their viability both before cryopreservation and after 3 days of freezing at liquid nitrogen temperature. The ability of phenolic derivatives of chalcones to increase the superoxide dismutase and catalase activities of sterlet sperm and to reduce the intensity of lipid peroxidation has been established. The antioxidant activity of the derivatives exceeds the effect of Trolox, which inhibits the functioning of the enzyme component of the antioxidant protection of fish sperm and promotes lipid peroxidation of fish sperm before cryopreservation. A beneficial effect of hydroxy derivatives of chalcones on the motility parameters of thawed sperm has been shown, indicating their ability to increase the cryoresistance of sperm in such a promising aquaculture species as sterlet.

Biosynthesis of Depsides, Depsidones, and Diphenyl Ethers from Fungi and Lichens

Depsides are a class of natural products in which two or more (poly)phenolic acid derivatives are linked by an ester bond. Depsides and related natural products, such as depsidones and diphenyl ethers, are widespread in nature and exhibit a wide range of biological activities. Although their biosynthesis has attracted considerable research interest for many decades, it remained largely elusive until recently. Recent studies have revealed the molecular mechanisms underlying the biosynthesis of several depsides and related natural products, uncovering unique enzymatic chemistry in their biosynthetic pathways. This review summarizes the biosynthetic pathways and mechanisms for depsides, depsidones, and diphenyl ethers, focusing on fungi and lichens, which are the primary producers of these compounds.

Chemical Characterization and Antimicrobial Activity of Green Propolis from the Brazilian Caatinga Biome.

Green propolis, particularly from the unique flora of the Brazilian Caatinga biome, has gained significant interest due to its diverse chemical composition and biological activities. This study focuses on the chemical characterization and antimicrobial evaluation of Caatinga green propolis. Twelve compounds were isolated through different chromatographic techniques, including flavanones (naringenin, 7-O-methyleriodictyol, sakuranetin), flavones (hispidulin, cirsimaritin), flavonols (quercetin, quercetin-3-methyl ether, kaempferol, 6-methoxykaempferol, viscosine, penduletin), and one chalcone (kukulkanin B). Using liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QToF-MS), a total of 55 compounds excluding reference standards were tentatively identified, which include flavonoids, phenolic acids derivatives, and alkaloids, with flavonols, flavanones, and flavones being predominant. Antimicrobial testing against pathogens revealed that the crude extract exhibited low inhibitory activity, against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) (IC50: 148.4 and 120.98 µg/mL, respectively). Although the isolated compounds showed limited individual activity, a fraction containing sakuranetin and penduletin (Fraction 8) exhibited moderated activity against Cryptococcus neoformans (IC50: 47.86 µg/mL), while a fraction containing quercetin and hispidulin showed moderated activity against VRE (IC50: 16.99 µg/mL). These findings highlight the potential application of Caatinga green propolis as an antimicrobial agent, particularly against resistant bacterial strains, and underscore the importance of synergistic interactions between compounds in enhancing biological effects.

Влияние пирролидиновых производных 2,6-ди-трет-бутилфенола на супероксид- и пероксид водорода-утилизирующую активность спермы сибирского осетра

The effect of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives on the ability of Siberian sturgeon (Acipenser baerii, Brandt, 1869) sperm to utilize superoxide anion radical (O2–•) generated in a model system of adrenaline oxidation in an alkaline medium, as well as exogenous hydrogen peroxide (H2O2) before and after freezing at liquid nitrogen temperature for 3 days was studied. The study of this activity of phenolic derivatives was carried out in comparison with the reference antioxidant Trolox, a water-soluble analogue of vitamin E. When phenolic derivatives were added at a concentration of 0.1 mM to the basic Stein cryomedium containing 12.5% egg yolk, 12.5% DMSO, 5 mM KCl, 130 mM NaCl, 20 mM NaHCO3 and 5.5 mM glucose, a multidirectional effect of the compounds on the ability of Siberian sturgeon sperm to utilize superoxide anion radical and hydrogen peroxide before and after the freezing-defrosting process was established. The studied compounds increase the H2O2-utilizing activity of reproductive cells, while reducing their superoxide-utilizing activity. Pyrrolidine derivatives of phenol were found to be more effective in stimulating the H2O2-utilizing activity of defrosted sperm of the Siberian sturgeon than Trolox. A decrease in the rate of O2– • and H2O2 utilization by fish sperm was found after cryopreservation in the control and in the presence of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives. A protective effect of new phenolic derivatives on the enzymatic link of antioxidant protection of Siberian sturgeon sperm during cryopreservation was shown. The obtained results indicate the prospects for further studies of the protective activity of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives in the process of cryopreservation of reproductive cells of rare, endangered and commercially valuable fish species.

Phosphonamidates of Camphorsultam: Versatile Building Blocks for the Synthesis of P‐Chiral Phosphorous(V) Compounds

AbstractCamphorsultam was utilized for the optical resolution of P‐chiral phosphorous compounds. After chromatographic separation of diastereomeric RP‐ and SP‐phosphonamidate intermediates, subsequent substitution reactions with phenol derivatives yielded P‐chiral phosphonic acid aryl esters with excellent enantioselectivities. In these processes, chiral sulfonamide of camphorsultam demonstrated superior abilities as an optical‐resolving agent and a good leaving group. This method was applied to the synthesis of P‐chiral phosphinic esters, phosphonamidates, and thiophosphonate diesters.

Assessment of the authenticity of horse chestnut (Aesculus hippocastanum L.) flowers by scanning electron microscopy

Introduction. Horse chestnut (Aesculus hippocastanum L.) is a plant widely used in official and folk medicine in many countries. Pharmacopoeia raw materials in the Russian Federation are only horse chestnut seeds. Flowers, due to the fraction of phenolic derivatives and triterpene saponins contained in them, are a promising medicinal plant raw material, presumably having a venotonizing and membrane-protective effect. To obtain medicinal herbal preparations based on horse chestnut flowers, it is required to have regulatory documentation containing a list of quality indicators, including a description of the signs of its authenticity (morphology and anatomy). Scanning electron microscopy is one of the advanced methods that have recently been increasingly used in medicine and pharmacognostic analysis. Unlike light microscopy, the method provides a three-dimensional spatial representation of diagnostically significant signs of medicinal plant raw materials.Aim. The aim of the study was to study the morphology of the surface of horse chestnut flowers by scanning electron microscopy.Materials and methods. The object of the study was dried whole flowers of horse chestnut (Aesculus hippocastanum L.), collected in the Voronezh region in 2023 at the beginning of flowering. The pieces of flowers were pre-sprayed with silicon on an automatic spraying unit Q150R ES (Quorum Technologies Ltd., Great Britain). Micrographs were obtained using the JSM-6510LV electron microscope (JEOL Ltd., Japan).Results and discussion. The micrographs obtained during the analysis showed diagnostically significant features of the flower structure: the epidermal cells of the corolla petals are polygonal, irregularly shaped, some elongated with sinuous folds. Pollen grains can be collected in cluster-like clusters, located separately or found singly. The surface of the corolla petal is covered with numerous often twisting hairs having a rough-warped structure and a cone-shaped base with a clearly defined attachment point. The surface of the staminate filaments is striated, with longitudinal folds with single unicellular hairs. The anther has a folded shape, its surface is lined with scaly epidermal cells with rough and thickened walls. The surface of the calyx, including the pedicel, is also densely pubescent with numerous trichomes.Conclusion. The scanning electron microscopy method was used for the first time to study the morphological and anatomical features of horse chestnut flowers. The structure of the main diagnostically significant structures of this LRS has been clarified. The morphology of the epidermis surface of the petals of the corolla and calyx, trichomes, pollen filaments, anthers and pollen grains of flowers has been determined. It has been established that carbon and oxygen are the predominant elements of the raw materials.

One-Step Regioselective Synthesis of N-1-Substituted Dihydrouracils: A Motif of Growing Popularity in the Targeted Protein Degradation Field.

The increasing popularity of the dihydrouracil motif in cereblon (CRBN) recruiting proteolysis-targeting chimeras (PROTACs) has necessitated the development of a facile, cost-effective, and high-yielding method for its introduction into molecules. To that end, we disclose herein an N-1 selective Pd-catalyzed cross-coupling of dihydrouracil with aryl electrophiles to provide access to medicinally relevant scaffolds in a single step. This approach exhibits excellent functional group tolerance and broad applicability to an abundance of (hetero)aryl halides and phenol derivatives and utilizes readily available catalyst/ligand systems. Thus, our strategy should find broad utility in the arena of PROTAC research, as it obviates the drawbacks of previous methodologies that rely on multistep synthetic routes and protecting group strategies to achieve N-1 selectivity.

Synthesis and antimicrobial activity of 5-aminoquinoline and 3-amino phenol derivatives

A series of 5-aminoquinoline derivatives 3a-f and 3-aminophenol derivatives 5a-f were synthesized in order to determine their in vitro antimicrobial activity. The chemical structures of the synthesized compounds were confirmed by FT-IR and 1H NMR spectral studies. Among the synthesized compounds, 3a, 3e, 3f, 5b, 5c and 5f showed good antimicrobial activity against tested microbial strains.

Photoinduced Regioselective Decarbonylative and Decarboxylative C-O Bond Functionalizations: Approach toward Chemoselective Scissions of Isatoic Anhydride and Unraveling the Enroutes through Control Experiments and DFT Studies.

Distinctive, green, innovative, and well-organized photoinduced (metal- or photocatalyst-free) regioselective decarbonylative and decarboxylative C-O bond functionalization protocols to access aryl 2-aminobenzoates and 2-substituted benzoxazinone derivatives in excellent yields have been devised. These are achieved through the chemoselective scission of isatoic anhydride with ketones, diaryliodonium triflate, nitroalkene, phthalazinone, and phenol derivatives, which, in turn, served as the representative "electrophilic and nucleophilic" coupling partners. Control experiments and DFT calculations reveal that electrophilic radical-bearing coupling partners specifically follow the decarbonylation pathway, while nucleophilic radical-bearing conjugates facilitate the decarboxylation process. Thus, the devised methods represent the chemoselective fragmentation of isatoic anhydride, which occurs due to the electronic nature of the coupling partners. Again, the regioselective C-O/O-C bond formation is also a novel outcome of this methodology. We have also devised a green method for synthesizing 2-aminobenzoate-subtituted paracetamol through a decarboxylation route. A fluorescence quenching study indicates that phenyl 2-aminobenzoate specifically detects Fe(II) ions, exhibiting no reactivity toward various other metal ions. Additionally, transition-metal-catalyzed C-H bond functionalization of 2-substituted benzoxazinone with phenyl vinyl sulfone was performed at ease with significant yields, which appreciated the strategy developed by us.

Effects of Sodium Selenite on Accumulations of Selenium and GABA, Phenolic Profiles, and Antioxidant Activity of Foxtail Millet During Germination.

This study investigated the influence of soaking and spraying with a sodium selenite (Na2SeO3) solution on selenium accumulation, γ-aminobutyric acid (GABA) content, phenolic compositions, and the antioxidant activity of foxtail millet sprouts. The screening results showed that foxtail millet seeds soaked with 60 mg/L of Na2SeO3 solution and sprayed with 2 mg/L of Na2SeO3 solution were the appropriate concentrations for the germination process. Compared with the spraying method, a presoaking treatment presented far higher selenium content and significantly higher (p < 0.05) selenium enrichment rates in foxtail millet sprouts. The content of free and bound phenolics, as well as GABA, were significantly (p < 0.05) increased in foxtail millet sprouts through both soaking and spraying treatments. Correspondingly, most of the individual phenolic compounds were significantly (p < 0.05) increased, especially after germination for 3 days. Trans-ferulic acid and trans-p-coumaric acid were the predominate bound phenolic acids, feruloylquinic acid and 4-p-coumaroylquinic acid were the major free-form phenolic compounds, and N-feruloyl serotonin and N-(p-coumaroyl) serotonin were the new arising phenolic derivatives caused by germination. Both the soaking and spraying treatments induced the enrichment of these individual phenolic compositions, thus increasing the total phenolic content and in vitro antioxidant activity of foxtail millet sprouts. It was indicated that selenium-enriched germination treatment should be an effective method to produce functional selenium-enriched foxtail millet sprouts with more abundant GABA and polyphenols, thus enhancing the health benefits and added value of foxtail millet.

Co-valorisation of cassava peel and rice husk to biofuel precursor via intermediate pyrolysis: Kinetics, thermodynamic and pyrolytic oil characterisation

This study explored the co-valorisation of cassava peel and rice husk into biofuel precursors through pyrolysis. The research involved characterization of the biomass, and thermogravimetric analysis at heating rates of 5, 10, and 15 °C/min. An intermediate pyrolysis was conducted using a laboratory-scale setup with a stainless-steel reactor and a Swagelok double-ended tube, yielding pyrolytic oil for analysis. Proximate analysis revealed cassava peel (CP) contains 9.23 wt% ash, while rice husk (RH) has 16.50 wt% ash respectively, while the combined samples of cassava peel and rice husk (CS) had ash content of 74.27 wt%, fixed carbon of 70.07 wt%, and volatile matter of 75.72 wt%. The heating values for the samples were 17.15 MJ/kg, 15.22 MJ/kg, and 17.06 MJ/kg for cassava peel, rice husk, and combined sample respectively. Ultimate analysis indicated the following elemental compositions: CP (40.95 % C, 5.67 % H, 0.22 % N, 0.09 % S, 52.17 % O2), RH (40.15 % C, 5.98 % H, 0.41 % N, 0.78 % S, 52.68 % O2), and the CS (43.06 % C, 6.41 % H, 0.32 % N, 0.41 % S, 49.80 % O2). Kinetic and thermodynamic analysis from the distributed activation energy models revealed average activation energies of 184.95 kJ/mol (CP), 140.56 kJ/mol (RH), and 125.63 kJ/mol (CS). The pyrolysis products consist of 37.50 wt% pyrolytic oil, 11.12 wt% bio-char, and 51.38 wt% non-condensable gases. GC–MS analysis of the pyrolytic oil identified significant amounts of hydrocarbons, phenols, and phenol derivatives, suggesting potential for biofuel production. This study highlights the viability of combined biomass sources for biofuel production and waste to wealth utilization.

Peroxidase of Trametes hirsuta LE-BIN 072: Purification, Characteristics, and Application for Dye Decolorization

Lignin peroxidase (LiP9) from the basidiomycete Trametes hirsuta LE-BIN 072, an effective lignin destructor, was purified to a homogeneous state (with an RZ purity index of 1.8) and characterized for the first time. The molecular weight of LiP9 was 43 kDa and its pI was 3.2. The enzyme showed the highest activity at pH 2.5 and 35°C when veratryl alcohol was used as a substrate. The analysis of the substrate specificity showed that LiP9 oxidized phenol derivatives much faster than those of benzoic and cinnamic acids with the same substituents in the benzene ring. The highest specific activity of the enzyme was observed for catechol oxidation. The ability of LiP9 to decolorize recalcitrant dyes (reactive black 5, congo red, remazol brilliant blue R, phenol red, indigo carmine, and bromocresol green) was assessed. The highest decolorization efficiency was shown for indigo carmine (in the presence of veratryl alcohol) and bromocresol green (directly) up to 80 and 60%, respectively, in 1 hour.

Hydrodeoxygenation of Lignin Phenol Derivatives to Aromatic Hydrocarbons: A Mini-Review of Metal/Acid Bifunctional Catalysts

Hydrodeoxygenation of Lignin Phenol Derivatives to Aromatic Hydrocarbons: A Mini-Review of Metal/Acid Bifunctional Catalysts