Hydroquinone Derivatives Research Articles

Mechanisms Associated with Superoxide Radical Scavenging Reactions Involving Phenolic Compounds Deduced Based on the Correlation between Oxidation Peak Potentials and Second-Order Rate Constants Determined Using Flow-Injection Spin-Trapping EPR Methods.

Flow-injection spin-trapping electron paramagnetic resonance (FI-EPR) methods that involve the use of 5,5-dimethyl-pyrroline-N-oxide (DMPO) as a spin-trapping reagent have been developed for the kinetic study of the O2•- radical scavenging reactions occurring in the presence of various plant-derived and synthetic phenolic antioxidants (Aox), such as flavonoid, pyrogallol, catechol, hydroquinone, resorcinol, and phenol derivatives in aqueous media (pH 7.4 at 25 °C). The systematically estimated second-order rate constants (ks) of these phenolic compounds span a wide range (from 4.5 × 10 to 1.0 × 106 M-1 s-1). The semilogarithm plots presenting the relationship between ks values and oxidation peak potential (Ep) values of phenolic Aox are divided into three groups (A1, A2, and B). The ks-Ep plots of phenolic Aox bearing two or three OH moieties, such as pyrogallol, catechol, and hydroquinone derivatives, belonged to Groups A1 and A2. These molecules are potent O2•- radical scavengers with ks values above 3.8 × 104 (M-1 s-1). The ks-Ep plots of all phenol and resorcinol derivatives, and a few catechol and hydroquinone derivatives containing carboxyl groups adjacent to the OH groups, were categorized into the group poor scavengers (ks < 1.6 × 103 M-1 s-1). The ks values of each group correlated negatively with Ep values, supporting the hypothesis that the O2•- radical scavenging reaction proceeds via one-electron and two-proton processes. The processes were accompanied by the production of hydrogen peroxide at pH 7.4. Furthermore, the correlation between the plots of ks and the OH proton dissociation constant (pKa•) of the intermediate aroxyl radicals (ks-pKa• plots) revealed that the second proton transfer process could potentially be the rate-determining step of the O2•- radical scavenging reaction of phenolic compounds. The ks-Ep plots provide practical information to predict the O2•- radical scavenging activity of plant-derived phenolic compounds based on those molecular structures.

Oxidative Coupling of Hydroquinone Derivatives with Olefins to Dihydrobenzofurans.

Dihydrobenzofuran is an important skeleton for bioactive compounds and natural products. Hydroquinones can be easily modified into substituted hydroquinones, which effectively undergo oxidation to produce the corresponding benzoquinone derivatives. Benzoquinones are reactive electrophiles that are frequently utilized in coupling with olefins to dihydrobenzofurans. Herein, we report the one-pot oxidative coupling of hydroquinones bearing an electron-withdrawing group at the C2 position with olefins to dihydrobenzofurans in the presence of the Lewis acidic FeCl3 and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) oxidant. Furthermore, this method was applied to the oxidative coupling of N-electron-withdrawing group-substituted 4-aminophenol.

Electronic inductive and resonance effects of substituents on concerted two-proton-coupled electron transfer between electrogenerated superoxide and hydroquinone derivatives in N,N-dimethylformamide

Improving energy conversion technologies is pivotal for reducing the effects of global warming. The use of electron transfer catalysts based on electron carriers found in organisms, such as redox biomimetic quinone systems, is a promising route for truly efficient energy conversion. Herein, we report the density functional theory (DFT)-based analysis of the reaction between electrogenerated superoxide radical anion (O2•−) and methyl- or chloro-substituted benzene-1,4-diol (hydroquinone) derivatives in N,N-dimethylformamide. We investigate the electrochemical scavenging of O2•− by hydroquinone derivatives involving two proton transfers (PTs) and one electron transfer (ET). We show that chloro and methyl substituents promote a proton-coupled electron transfer (PCET) reaction with the effect increasing with the number of substituent groups. Our DFT results demonstrate that the substituent effect promotes either of the PT or ET processes, along a sequential PCET pathway. The electrochemical and DFT analyses of the substituent effect indicate that the concerted two-proton-coupled electron transfer (2PCET) promoted by an increasing number of the substituents is a plausible pathway for the reaction between electrogenerated O2•− and hydroquinone derivatives. In addition, our findings show that the resonance effect is the main driving force for the promotion of 2PCET.

Versatile Biaryls and Fused Aromatics through Oxidative Coupling of Hydroquinones with (Hetero)Arenes

AbstractHydroquinones bearing an electron‐withdrawing group at the C2‐position can effectively underwent oxidative coupling with (hetero)arenes (e. g., indoles, electron‐rich benzene derivatives) in the presence of 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) and FeCl3 to produce the corresponding biaryl products. In the present reactions, the DDQ‐mediated oxidation of hydroquinone derivatives produce benzoquinone intermediate, which subsequently underwent FeCl3‐catalyzed nucleophilic addition of (hetero)arenes to the α,β‐unsaturated carbonyl moiety to give the biaryl product in a one‐pot manner. Especially, the indole‐based biaryl products were further converted into tetracyclic aromatics through DDQ‐mediated oxidation followed by FeCl3‐catalyzed intramolecular cyclization. Thiophene derivatives were also applicable to give the tetracyclic aromatics. Moreover, the photophysical properties of the indole‐ and thiophene‐based tetracyclic aromatics in the solution and the solid states were investigated.

Post-inflammatory hyperpigmentation post-acne: possibilities of topical therapy

Post-inflammatory hyperpigmentation (PIH) is one of the most significant problems in patients with acne. The prevalence of PIH among patients with acne varies from 45 to 87%. Post-acne, including PIH, has an extremely negative impact on the quality of life and psychological well-being of patients, as it is often resistant to therapy and can persist for even several years. Successful acne treatment does not guarantee complete elimination of PIH and other post-acne symptoms. In the development of PIH, a key role is played by the mechanism associated with the production and distribution of melanin, which is activated by inflammation and the release of cytokines that promote an increase in the level of immunoreactive tyrosinase, which stimulates melanocytes, activation of melanogenesis and further transfer of melanosomes to surrounding keratinocytes. It is important for clinicians to recognize the psychosocial impact of PIH and manage inflammation, as well as proactively address residual PIH with appropriate treatment. Thus, prevention and correction of PIH should be one of the goals of acne treatment. Topical therapy for PIH in acne is considered the most acceptable and can be prescribed both as monotherapy and as part of combined methods. Tyrosinase is a target for topical anti-pigmentation agents, including hydroquinone, kojic acid, and resorcinyl thiazole derivatives. The latter includes isobutylamidothiazolyl resorcinol – thiamidol. The article provides a brief overview of data on the epidemiology of PIH, its pathogenesis, impact on the quality of life of patients and the perception of their image by people around them. Clinical experience with the use of anti-hyperpigmentation serum with thiamidol, licochalcone A and sodium hyaluronate is presented, which confirms the effectiveness, safety and feasibility of prescribing products with thiamidol for the treatment of PIH caused by acne.

Artificial Photosynthesis for Regioselective Reduction of NAD(P)+ to NAD(P)H Using Water as an Electron and Proton Source.

In photosynthesis, four electrons and four protons taken from water in photosystem II (PSII) are used to reduce NAD(P)+ to produce NAD(P)H in photosystem I (PSI), which is the most important reductant to reduce CO2. Despite extensive efforts to mimic photosynthesis, artificial photosynthesis to produce NAD(P)H using water electron and proton sources has yet to be achieved. Herein, we report the photocatalytic reduction of NAD(P)+ to NAD(P)H and its analogues in a molecular model of PSI, which is combined with water oxidation in a molecular model of PSII. Photoirradiation of a toluene/trifluoroethanol (TFE)/borate buffer aqueous solution of hydroquinone derivatives (X-QH2), 9-mesityl-10-methylacridinium ion, cobaloxime, and NAD(P)+ (PSI model) resulted in the quantitative and regioselective formation of NAD(P)H and p-benzoquinone derivatives (X-Q). X-Q was reduced to X-QH2, accompanied by the oxidation of water to dioxygen under the photoirradiation of a toluene/TFE/borate buffer aqueous solution of [(N4Py)FeII]2+ (PSII model). The PSI and PSII models were combined using two glass membranes and two liquid membranes to produce NAD(P)H using water as an electron and proton source with the turnover number (TON) of 54. To the best of our knowledge, this is the first time to achieve the stoichiometry of photosynthesis, photocatalytic reduction of NAD(P)+ by water to produce NAD(P)H and O2.

Sensitive Electrochemical Sensor Modified by Hydroquinone Derivative and Magnesium Oxide Nanoparticles for Simultaneous Determination of Hydroxylamine and Phenol

Sensitive Electrochemical Sensor Modified by Hydroquinone Derivative and Magnesium Oxide Nanoparticles for Simultaneous Determination of Hydroxylamine and Phenol

Characterization of a novel sucrose phosphorylase from Paenibacillus elgii and its use in biosynthesis of α-arbutin.

α-Arbutin, a naturally occurring glycosylated derivative of hydroquinone (HQ), effectively inhibits melanin biosynthesis in epidermal cells. It is widely recognized as a fourth-generation whitening agent within the cosmetic industry. Currently, enzymatic catalysis is universally deemed the safest and most efficient method for α-arbutin synthesis. Sucrose phosphorylase (SPase), one of the most frequently employed glycosyltransferases, has been extensively reported for α-arbutin synthesis. In this study, a previously reported SPase known for its effectiveness in synthesizing α-arbutin, was used as a probe sequence to identify a novel SPase from Paenibacillus elgii (PeSP) in the protein database. The sequence similarity between PeSP and the probe was 39.71%, indicating a degree of novelty. Subsequently, the gene encoding PeSP was coexpressed with the molecular chaperone pG-Tf2 in Escherichia coli, significantly improving PeSP's solubility. Following this, PeSP was characterized and employed for α-arbutin biosynthesis. The specific activity of co-expressed PeSP reached 169.72 U/mg, exhibited optimal activity at 35℃ and pH 7.0, with a half-life of 3.6h under the condition of 35℃. PeSP demonstrated excellent stability at pH 6.5-8.5 and sensitivity to high concentrations of metal ions. The kinetic parameters Km and kcat/Km were determined to be 14.50 mM and 9.79min- 1·mM- 1, respectively.The reaction conditions for α-arbutin biosynthesis using recombinant PeSP were optimized, resulting in a maximum α-arbutin concentration of 52.60g/L and a HQ conversion rate of 60.9%. The optimal conditions were achieved at 30℃ and pH 7.0 with 200 U/mL of PeSP, and by combining sucrose and hydroquinone at a molar ratio of 5:1 for a duration of 25h.

Evaluation of the Antiplatelet Activity of Tricyclic Acyl Hydroquinone Derivatives

Evaluation of the Antiplatelet Activity of Tricyclic Acyl Hydroquinone Derivatives

Acid-Catalyzed [4+1]-Dearomatization Spiroannulation of Hydroquinones and Naphthols

AbstractAcid-catalyzed [4+1]-dearomatization spiroannulation reactions of electron-rich hydroquinone and naphthol derivatives were demonstrated as convenient methods to access spirocyclic cyclohexadienone derivatives. The Lewis acid Bi(OTf)3 exhibited the best catalytic performance when a 1,2-dialkynylbenzene was used as the electrophile for the spiroannulation, whereas the Brønsted acid benzene-1,2-disulfonic acid was the best catalyst when 2-ethynylbenzylic esters were used as electrophiles. Most of the reaction conditions are mild, efficient, and simple to operate.

Electrochemistry and electrochemical assessment of host–guest complexation of substituted pillar[m]arene[n]quinones

Electrochemical behavior of pillar[n]arene[m]quinone (n + m = 5, n = 2–4) has been for the first time investigated in aqueous media on the glassy carbon electrode. All the compounds studied showed quasi-reversible redox conversion to hydroquinone derivatives. The reaction was not complicated with ionization of hydroxy groups or by the formation of intramolecular hydrogen bonds. In the whole pH region tested (2.0 – 9.0) the stoichiometry of electron and hydrogen ions transfer was found the same (1:1). The peak currents changed with no respect of the number of quinone units in the macrocycle molecule and were probably more affected by steric factors and self-aggregation confirmed by scanning electron microscopy. Adsorption of the macrocycles on the electrode covered with carbon black resulted in remarkable improvement of the conditions of electron exchange and of the peak currents on voltammograms. Screening of possible guest molecules showed that among amino acids, tyrosine formed complexes with pillarquinones both in solution and on the electrode interface. Complexation resulted in decrease of the peak currents on voltammograms due to steric hindrance of electric wiring. This made it possible to determine 5–100 µM tyrosine in the solution and 1–100 µM tyrosine with pillar[3]arene[2]quinone adsorbed in the carbon black layer. No interferences were established in normal human serum and Ringer-Locke’s solution. The approach to supramolecular detection of small molecules by intrinsic redox activity of the macrocyclic hosts can be extended to other analytes by modification of the macrocyclic components of the reaction.

All-organic aqueous batteries consisting of quinone-hydroquinone derivatives with proton/aluminum-ion co-insertion mechanism

All-organic aqueous batteries are deemed attractive energy storage systems for some application scenarios demanding recyclability or wearability. The efficient redox activity of quinone/hydroquinone-derived couples in biosystems inspires us to develop advanced batteries based on them. However, designing such an all-organic aqueous battery is challenging in selecting suitable electrolytes and active materials. A possible battery configuration consisting of the 9, 10-anthraquinone (AQ) anode, hydroquinone derivatives cathode, and weak acid metal-ion aqueous electrolyte is demonstrated herein. The molecular configuration of quinones and ionic type of electrolytes affect the redox behaviors of electrodes. Gratifyingly, a combination of AQ-tetrachlorohydroquinone-Al2(SO4)3 exhibits optimal performance. The underlying work mechanism of this full-battery configuration is disclosed by electrochemical and structural characterizations, finding that H+ and Al3+ are jointly involved in the redox reaction of quinone electrodes, and Al3+ plays a crucial role. This work inaugurates a new framework for designing an all-organic aqueous battery.

An efficient strategy based on polyelectrolyte of constructing a sequential energy transfer artificial light-harvesting system for photocatalysis

In this work, an efficient artificial light-harvesting system with a two-step sequential energy transfer process was first constructed based on the polyelectrolyte material sodium carboxymethyl cellulose (CMC) and AIE molecule cyano-substituted amphiphilic hydroquinone derivative (PPTA) in an aqueous solution. The energy harvested by the two fluorescent dyes EY and SR101 from the supramolecular assembly PPTA-CMC was fully used for photochemical catalysis for the dehalogenation of α-bromoacetophenone, cross dehydrogenation coupling reaction (CDC), and alkylation of C–H bonds of phenyl vinyl sulfone (PVS) and tetrahydrofuran (THF) in the aqueous medium.

Tandem mass spectrometry analysis reveals changes in metabolome profile in Triticosecale seeds based on harvesting time

Triticosecale "Bilinda" (cultivar was bred in the laboratories of the Leningrad Research Agriculture Institute, Branch of Russian Potato Research Centre, Leningrad Province) contains a large number of polyphenolic compounds which are biologically active components. The purpose of this work was to conduct a comparative metabolomic study of extracts of Triticosecale cultivar "Bilinda" seeds harvested at different stages of maturation. To identify target analytes in extracts HPLC was used in combination with an ion trap. The results showed the presence of 93 target compounds corresponding to Triticosecale. In addition to the reported polyphenol constituents, 28 polyphenols were newly annotated in grains of Triticosecale. There were 9 flavones, 7 flavonols, 2 flavan-3-ols, 1 flavanone, 5 hydroxybenzoic acids, 1 hydroxycinnamic acid, 1 anthocyanidin, 1 condensed tannin, 1 hydroxycoumarin, 2 triterpenoids; 1 diterpenoid, 6 sterols, 2 isoquinoline alkaloids, 4 carotenoids, 1 hydroquinone derivative and others bioactive compounds. Metabolic analysis showed a significant difference in the classes and amounts of polyphenolic substances identified in the seeds, depending on the time of seed collection.

Synthesis and antioxidant properties of (dodecylsulfanyl)methyl derivatives of hydroquinone

Synthesis and antioxidant properties of (dodecylsulfanyl)methyl derivatives of hydroquinone

Hydroquinone derivatives attenuate biofilm formation and virulence factor production in Vibrio spp

Gram-negative Vibrio parahaemolyticus is a halophilic human pathogen known to be the leading cause of food poisoning associated with consuming uncooked or undercooked seafood. The increasing presence and contamination of seafood have caused serious safety concerns in food facilities. Notably, it can form biofilms on food surfaces that confer resistance to antimicrobial treatments. Therefore, in the present study, the antibacterial, antibiofilm, and antivirulence activities of hydroquinone (HQ) and its 16 derivatives were investigated against V. parahaemolyticus and V. harveyi. Representative active antibacterial and antibiofilm compounds, 2,3-dimethylhydroquinone (2,3-DMHQ) and 2,5-ditert-butylhydroquinone (DBHQ), were further examined using a crystal violet assay, biochemical reactions, live cell imaging, and scanning electron microscopy. 2,3-DMHQ with a minimum inhibitory concentration (MIC) of 20 μg/mL completely inhibited biofilm formation at a sub-MIC of 15 μg/mL. And, DBHQ with an MIC of ˃1000 μg/mL reduced biofilm formation by 70 % at sub-MIC of 25 μg/mL. Both 2,3-DMHQ and DBHQ inhibited protease and indole production as well as motility phenotypes. 2,3-DMHQ decreased fimbriae production and hydrophobicity whereas DBHQ did not. Transcriptomic studies revealed that genes related to biofilm, quorum sensing (QS), and hemolysin were downregulated. In addition, 2,3-DMHQ and DBHQ prevented biofilm formation of V. parahaemolyticus on squid surfaces and 2,3-DMHQ reduced the presence of V. parahaemolyticus in a boiled shrimp model. Toxicity assays using the Caenorhabditis elegans and seed germinations models showed that they were non-to-mildly toxic. These results suggest that 2,3-DMHQ and DBHQ possess the antimicrobial properties required to control V. parahaemolyticus planktonic and biofilm states in food production facilities.

Palladium-Catalyzed C-H Functionalization of Aryl Acetamides and Benzoquinones: Synthesis of Substituted Aryl Quinones.

An efficient synthesis of aryl-substituted quinones via Pd(II)-catalyzed C-H functionalization of less expensive and abundant benzoquinones with aryl acetamides is demonstrated. An auxiliary ligand N,N-bidentate-directing group 8-aminoquinoline plays a crucial role in the success of the reaction. A broad range of substituted phenyl acetamides including commercially available drug molecules were examined and also found to be highly compatible with quinones. The aryl-substituted quinones were also easily converted into aryl-substituted hydroquinone derivatives. A plausible reaction mechanism was proposed to account for the selective distal C-H bond functionalization.

Abundant oxygen vacancies promote bond breaking of hydrogen peroxide on 3D urchin-like Pd/W18O49 surface to achieve high-performance catalysis of hydroquinone oxidation

As a typical carcinogenic phenolic environmental pollutant, hydroquinone (HQ), its effective catalytic conversion is particularly urgent for environmental protection. However, the development of low-cost, high-efficiency catalysts still faces many challenges. Furthermore, the mechanism for efficient catalysis has not been established. In this paper, a trace amount of Pd-supported 3D urchin-like Pd/W18O49 composite in an aqueous solution was reported as a high-quality catalyst for the H2O2 catalytic oxidation of hydroquinone (HQ) to benzoquinone (BQ) with a turnover frequency (TOF) of 1750 h−1, exceeding commercial catalyst. Through experiments combined with density functional theory (DFT) calculations analysis, this excellent catalytic effect is mainly attributed to the existence of an electronic induction effect between W18O49 and Pd nanoparticles (NPs). Meanwhile, the abundant oxygen vacancies on the surface of W18O49 can stabilize the·OH radicals generated from the decomposition of H2O2, thus promoting the breakage of O-O bonds to generate more·OH radicals and achieve an effective oxidation reaction. In addition, the influencing factors such as catalyst and HQ concentration, solution pH, solvent, various inorganic and organic interferences were comprehensively investigated. The 3D urchin-like Pd/W18O49 catalyst also showed an excellent effect on the catalytic oxidation of HQ derivatives with high TOFs.

Bioassay-Guided Isolation of 2-[p-(2-Carboxyhydrazino)phenoxy]-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol from Oroxylum indicum and the Investigation of Its Molecular Mechanism Action of Apoptosis Induction.

The leaf crude extract of Oroxylum indicum (L.) Kurz induces genomic DNA fragmentation, comet formation, and the inhibition of cell proliferation in the prostate cancer cell line PC3, as assessed by agarose gel electrophoresis, comet assay and MTT assay, respectively. The bioactive compound was purified through bioassay-guided fractionation using preparative HPLC and MTT assay. The light brown and water-soluble compound was characterized using 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), and electrospray ionization (ESI) mass spectrometry. The compound was identified as a glycosylated hydroquinone derivative, 2-[p-(2-Carboxyhydrazino)phenoxy]-6-(hydroxymethyl) tetrahy-dro-2H-pyran-3,4,5-triol (molecular formula, C13H18N2O8; molecular mass = 330). The identified phytocompound has not been reported earlier elsewhere. Therefore, the common name of the novel anticancer phytocompound isolated from Oroxylum indicum in this current study is oroxyquinone. The half-maximal inhibitory concentration (IC50) of oroxyquinone on PC3 cells was 58.9 µM (95% CI = 54.5 to 63.7 µM). Treatment of PC3 cells with oroxyquinone induced genomic DNA fragmentation and chromatin condensation, increased in the annexin-V positive cells, arrested the cell cycle at S phases, and inhibited the cell migration; as assessed by comet assay, DAPI staining, flow cytometry and a wound healing assay, respectively. On the investigation of the molecular mechanism of the induction of apoptosis, the results indicated that oroxyquinone induced caspase-3 and PARP independent apoptosis but through the p38 pathway and the localization of AIF into the nucleus. The present study identifies a novel anticancer molecule and provides scientific evidence supporting the therapeutic potency of Oroxylum indicum for ethnomedicinal uses.

Electrochemical Acid-Catalyzed Desorption and Regeneration of MDEA CO2-Rich Liquid by Hydroquinone Derivatives (Tiron)

The acid-catalyzed desorption of the MDEA CO2-rich liquid under the electrochemical reaction can lower the desorption temperature, thereby reducing the energy consumption for regeneration. In this work, disodium 4,5-dihydroxy-1,3-benzenedisulfonate (tiron) was used as an acidic medium for the electrocatalytic regeneration of the MDEA CO2-rich solution. The results show that the CO2 desorption efficiency reaches more than 90% at 25 °C for the 0.3 M MDEA (0.1 M tiron) system. At 50 °C, compared with 3 M MDEA (without tiron), the maximum CO2 desorption rate and desorption efficiency of the 3 M MDEA (with 0.1 M tiron) CO2-rich solution increased by 27.4 and 18.3%, respectively. Elevating the temperature can increase the quantity of CO2 desorption and the degree of MDEAH+ deprotonation as well as the reactivity of tiron on the electrode, so the desorption rate of CO2 can be further improved by the oxidation of tiron releasing H+ in coordination with thermal desorption.