Mixed-type Inhibitor Research Articles

Assessment of New Imidazol Derivatives and Investigation of Their Corrosion-Reducing Characteristics for Carbon Steel in HCl Acid Solution

This study assessed the corrosion inhibitory and adsorption properties of two imidazol derivatives, namely 5-((2,4,5-triphenyl-1H-imidazol-1-yl)methyl)quinolin-8-ol (TIMQ) and 5-((2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)quinolin-8-ol (CDIQ), on carbon steel (CS) in 1 M of HCl using electrochemical methods, including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP), UV–visible spectroscopy (UV–v), scanning electron microscopy (SEM), and molecular modeling. The findings showed that TIMQ and CDIQ were potent inhibitors with inhibition efficiencies of 94.8% and 95.8%, respectively. The potentiodynamic polarization experiments showed that the inhibitors worked as mixed-type inhibitors, and the impedance investigations supported the improvement of a protective layer for the inhibitor on the metal surface. Each inhibitor was adsorbed onto the carbon steel surfaces, according to the Langmuir adsorption method. The steel was shielded from acidic ions by an adsorbed coating of the inhibitor molecules, according to SEM. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations were used to inspect the results, and a good correlation was found between these results and those of the study. This information can be applied to determine the effectiveness of inhibitors in a HCl acid solution.

Fish processing discards extract as an eco-friendly corrosion inhibitor for carbon steel in hydrochloric acid

The objective of this study is to extract amino acids from fish processing discards for the preparation of highly effective and degradable corrosion inhibitors. The composition of fish processing discards extract (FPDE) was characterized by HPLC and FTIR. The results showed that the main components of FPDE are amino acids and contain a large number of unsaturated functional groups. Electrochemical techniques (electrochemical impedance spectroscopy (EIS) and Tafel), surface analysis (XPS and AFM), and molecular dynamics simulations (MDS) were conducted to investigate the corrosion inhibition mechanism of FPDE for carbon steel in 1 mol/L HCl. As shown by electrochemical tests, FPDE exhibits mixed-type corrosion inhibition with a maximum inhibition efficiency of 93.3%. FPDE exhibits excellent corrosion inhibition properties on carbon steel surfaces by forming a high coverage film through chemisorption and physisorption. Indeed, the advantages of remarkable inhibition efficiency and facile extraction methods allow FPDE to become a promising corrosion inhibitor for practical applications.

Electrochemical Investigation of C-Steel Corrosion Inhibition, In Silico, and Sulfate-Reducing Bacteria Investigations Using Pyrazole Derivatives.

The inhibitory impact of the two synthesized pyrazole derivatives (3 and 4) toward metallic and microbial corrosion was investigated. Using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, it was possible to determine their ability to prevent the corrosion of C-steel in 1 M HCl, which was significantly enhanced with increasing concentration (ex. 93%). They act as mixed-type inhibitors, according to polarization curves. The compounds under investigation were adsorbed on a C-steel surface in 1 M HCl following the Langmuir isotherm model. The double-layer capacitance was decreased, and the charge transfer resistance (Rct) was raised due to the examined inhibitors' adsorption. Investigating changes in the surface morphology and confirming the corrosion inhibition mechanism are done using scanning electron microscopy. Density functional theory calculations and Monte Carlo simulations were also conducted to show the adsorption affinity of the understudied compounds over the steel substrate in neutral and protonated forms. Furthermore, the antimicrobial performance of the two synthesized pyrazoles against sulfate-reducing bacteria was evaluated, and the recorded inhibition efficiency was 100%. The current research shows important developments in producing highly effective anticorrosion and antimicrobial pyrazole derivatives.

Synthesis, Anti-Tyrosinase Activity, and Spectroscopic Inhibition Mechanism of Cinnamic Acid-Eugenol Esters.

Tyrosinase plays crucial roles in mediating the production of melanin pigment; thus, its inhibitors could be useful in preventing melanin-related diseases. To find potential tyrosinase inhibitors, a series of cinnamic acid-eugenol esters (c1~c29) was synthesized and their chemical structures were confirmed by 1H NMR, 13C NMR, HRMS, and FT-IR, respectively. The biological evaluation results showed that all compounds c1~c29 exhibited definite tyrosinase inhibitory activity; especially, compound c27 was the strongest tyrosinase inhibitor (IC50: 3.07 ± 0.26 μM), being ~4.6-fold stronger than the positive control, kojic acid (IC50: 14.15 ± 0.46 μM). Inhibition kinetic studies validated compound c27 as a reversible mixed-type inhibitor against tyrosinase. Three-dimensional fluorescence and circular dichroism (CD) spectra results indicated that compound c27 could change the conformation and secondary structure of tyrosinase. Fluorescence-quenching results showed that compound c27 quenched tyrosinase fluorescence in the static manner with one binding site. Molecular docking results also revealed the binding interactions between compound c27 and tyrosinase. Therefore, cinnamic acid-eugenol esters, especially c27, could be used as lead compounds to find potential tyrosinase inhibitors.

Triazolothiadiazoles and triazolothiadiazines as potent α-glucosidase inhibitors: Mechanistic insights from kinetics studies, molecular docking and dynamics simulations

Diabetes mellitus has been considered as a serious health problem worldwide due its high prevalence rate and associated complications. In this context, the current research work aims at exploring new structural leads for the treatment of a major metabolic disorder, diabetes mellitus type 2. The outcomes of our prior studies on a diverse set of triazolothiadiazole and triazolothiadiazine derivatives and their therapeutic potential, encouraged us to explore their anti-diabetic competency by targeting the key carbohydrate catabolic enzyme, α-glucosidase. Therefore, all these analogues were examined to reveal their contribution towards this severe metabolic issue. Interestingly, all the tested compounds (2a-2l and 3a-3p) exhibited several times more potent α-glucosidase inhibitory activities (IC50 in the range of 2.44–219.93 μM) as compared to marketed drug, acarbose (IC50 = 873.34 ± 1.67 μM). Furthermore, their mechanism of action was investigated through in vitro kinetics studies which revealed compounds 3a, 3d, 3o, and 2k as competitive inhibitors, and 3f as a mixed type inhibitor of α-glucosidase. In addition, in silico molecular docking and molecular dynamics simulations were applied to observe the mode of interaction of the active hits within the binding pocket of α-glucosidase. Both docking and simulation results favored our in vitro mechanistic analysis.

Investigation of the corrosion inhibition performance of snail slime on the exposed surface of mild steel in acidic environment

Corrosion of metals is a major issue in various industries and the use of organic materials, especially plant extracts, as alternatives to toxic chemicals in corrosion inhibitors is gaining attention. However, the potential of animal products as corrosion inhibitors has not been fully explored. This study investigates the corrosion inhibiting potential of snail slime (SS) for mild steel in 0.5 M H2SO4 solution using Gravimetric and electrochemical methods, including open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used for material characterization. The results indicate that snail slime has a high inhibition efficiency of up to 92.75%, with inhibition efficiency decreasing as temperature and immersion time increase but it increased with higher inhibitor concentrations. Adsorption studies showed that snail slime exhibited strong adherence to the Langmuir and Temkin adsorption isotherms, indicating spontaneous adsorption on mild steel. The inhibition mechanism shows typical physical adsorption and follows first-order kinetics. While the EIS analysis indicated a charge transfer-controlled corrosion process with the highest inhibition efficiency of 81.74%, the PDP analysis revealed that snail slime acted as a mixed-type inhibitor with the highest inhibition efficiency of 81.98%. FTIR reveals the functional groups responsible for the inhibition exhibited by snail slime inhibitors, including CH, OH, CO-O, CCl, and NH. SEM shows that the inhibition of corrosion is due to the formation of an insoluble stable protective film on the sample surface by an adsorption process. These findings suggest that snail slime has significant potential as an eco-friendly alternative to synthetic corrosion inhibitors in industrial applications.

In vitro inhibition of human cytochrome P450 enzymes by licoisoflavone B from Glycyrrhiza uralensis Fisch. ex DC.

Glycyrrhiza uralensis Fisch. ex DC, one of the 3 pharmacopeial species of licorice and widely used in dietary supplements, can inhibit certain cytochrome P450 (CYP) enzymes. Thereby, G. uralensis preparations have the potential to cause pharmacokinetic drug interactions when consumed along with prescription medicines. One compound (1.34 mg dry weight) responsible for inhibiting CYP2B6, CYP2C8, and CYP2C9 was isolated using bioactivity-guided fractionation from 250 g dried roots, stolons, and rhizomes. The enzyme kinetics and mechanisms of inhibition were determined using human liver microsomes, recombinant enzymes, and UHPLC-MS/MS-based assays. Identified as licoisoflavone B, this compound displayed reversible inhibition of CYP2C8 with an IC50 value of 7.4 ± 1.1 µM and reversible inhibition of CYP2C9 with an IC50 value of 4.9 ± 0.4 µM. The enzyme kinetics indicated that the mechanism of inhibition was competitive for recombinant CYP2C8, with a Ki value of 7.0 ± 0.7 μM, and mixed-type inhibition for recombinant CYP2C9, with a Ki value of 1.2 ± 0.2 μM. Licoisoflavone B moderately inhibited CYP2B6 through a combination of irreversible and reversible mechanisms with an IC50 value of 16.0 ± 3.9 µM.

Comparative study of the performance and inhibitory efficiency of two new organic heterocyclic in the chemical industry

In this study, two inhibitors namely 6-Chloro −2-phenylimidazo[1,2-a]pyridine (Pyr1) and 6-Chloro-2-(4- Chlorophenyl)imidazo[1,2-a]pyridine (Pyr2) were used to investigate their inhibition ability toward mild steel corrosion in 1 M HCl using electrochemical techniques and quantum approaches. The two inhibitors show corrosion inhibition efficiency of 98.35% and 97.57% for Pyr2 and Pyr1 respectively at the optimum concentration 10-3 M. This is due to the features of the substituent group and the effect of its emplacement in the phenyl ring. The electrochemical measurements reveal that both anodic and cathodic current are affected by these organic compounds so they are classified as mixed-type inhibitors with predominance cathodic character. The inhibited solution was analysed using UV spectrometer, which indicates a tendency to develop a complex between inhibitors and ferrous ions. The computational approaches were performed in order to examine the correlation between inhibition efficiency and molecular structure of the inhibitors Pyr1 and Pyr2.

Physicochemical characterizations, α-amylase inhibitory activities and inhibitory mechanisms of five bacterial exopolysaccharides

Inhibiting pancreatic α-amylase activity can decrease the release rate of glucose, thereby delaying postprandial blood glucose. This study aimed to investigate the physicochemical properties and porcine pancreatic α-amylase (PPA) inhibitory activities of five bacterial exopolysaccharides (EPSs). We also aimed to analyze the differences of their inhibitory activities, exploring the inhibition mechanism between EPSs and PPA. Five EPSs had a low molecular weight (55–66 kDa), which were mainly composed of mannose and glucose with total content exceeding 86 %. The IC50 values of five EPSs (0.162–0.431 mg/mL) were significantly lower than that of acarbose (0.763 mg/mL), indicating that the inhibitory effects of five EPSs on PPA were stronger than acarbose, especially the EPS from Bacillus subtilis STB22 (BS–EPS). Moreover, BS–EPS was a mixed-type inhibitor, whereas other EPSs were noncompetitive inhibitors of PPA. Five EPSs quenched the fluorophore of PPA by the mixed quenching or apparent static quenching. Interestingly, BS–EPS showed stronger binding affinity to PPA than other EPSs. It can be speculated that EPSs with low molecular weight, high carboxylic acid content, and α-glycosidic bond exhibited high PPA inhibitory activity. These results suggest that BS-EPS can effectively inhibit PPA activity and has potential applications in reducing postprandial hyperglycemia.

Tunable Anticorrosive Effects of Newly Synthesized Benzothiazole Azo Dyes by Potassium Iodide Synergism for Carbon Steel in 1 M HCl: Combined Experimental and Theoretical Studies.

Herein, we synthesized three novel benzothiazole azo dyes, including 4-chloro-2-(4-methyl-benzothiazol-2-ylazo)-phenol (CMBTAP), 1-(6-chloro-benzothiazol-2-ylazo)-naphthalen-2-ol (CBAN), and 2-(6-chloro-benzothiazol-2-ylazo)-4-methyl-phenol (CBAMP), and investigated their corrosion inhibition effect on carbon steel. The dyes were characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR, and mass spectroscopy. Weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements were performed to investigate the corrosion inhibition effect of the dyes on carbon steel in a 1.0 M HCl solution. The synergistic effects of the dyes with potassium iodide (KI) were also investigated. The inhibition efficiency (IE%) was enhanced by increasing the dose of the dyes (1 × 10-5 to 2 × 10-4 M) and decreased as the temperature increased from 25 to 45 °C. The addition of KI to a 1.0 M HCl solution containing the dyes improved the performance and efficiency as iodide ions promoted the formation of inhibition films on the surface of carbon steel. The dyes are mixed-type inhibitors, according to Tafel polarization. Scanning electron microscopy and energy dispersive X-ray analysis were used to evaluate the surface morphology of carbon steel sheets. Quantum theory calculations were utilized to evaluate the relationship between the dyes' chemical structures and their inhibitory efficiency, which confirmed the experimental results. The calculations revealed that the dyes have low energy gap and Milliken and Fukui indices. Among all of the dyes, CMBTAP showed the highest adsorption energy. The corrosion IE was in the order CMBTAP > CBAMP > CBAN.

Insight into the corrosion inhibition performance of Jasmine flower extract on copper in sulfuric acid medium using experimental and theoretical calculation methods

BackgroundCopper is widely used in all areas of society, but it is easy to be corroded in corrosive media, which causes certain economic losses. Among many anti-corrosion methods, adding corrosion inhibitors is an efficient, convenient and common method. However, there are some shortcomings in traditional corrosion inhibitors, so it is urgent to develop an efficient corrosion inhibitor with no toxicity and low cost as well as no harm to the environment. MethodsThe corrosion performance of Jasmine flower extract (JFE) for copper in 0.5 mol/L sulfuric acid medium was studied by electrochemical test, and the microstructure and chemical composition of copper surface were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscope (AFM). The interaction mechanism between corrosion inhibitor molecules and copper was analyzed based on theoretical calculation. Significant findingsThe results show that JFE is an efficient and environment-friendly corrosion inhibitor. In a certain temperature range (298 ∼ 308 K), when the concentration of JFE is 500 mg/L, the corrosion inhibition efficiency (η) is not less than 94.0%. According to Langmuir adsorption model, the JFE adsorbs on the copper surface as a mixed type of inhibitor.

Discovery and biological evaluation of a new type of dual inhibitors of indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase from ethnomedicinal plant Dactylicapnos scandens

The root of Dactylicapnos scandens (D.Don.) Hutch (Papaveraceae), one of the most famous ethno-medicinal plants from the Bai communities in P. R. China, is used to treat various inflammations and tumours. Bioassay-guided phytochemical research on D. scandens followed by semi-synthesis led to a series of undescribed tetrahydroisoquinoline alkaloids with dual inhibitory activities against indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). The previously undescribed dark-green alkaloid dactycapnine A exhibited the best dual inhibitor effects among the identified compounds. Structure-activity relationship analysis revealed the importance of the base skeleton with a hyperconjugation system. The performed semi-synthesis further yielded bioactive dimeric and trimeric compounds with hyperconjugated systems. Performed STD NMR experiments disclosed direct interactions between dactycapnine A and IDO1/TDO. Inhibition kinetics indicated dactycapnine A as a mixed-type dual inhibitor. These findings provided a possible explanation for the anticancer properties of the ethno-medicinal plant species D. scandens.

Effects of acidic non-steroidal anti-inflammatory drugs on human cytochrome P450 4A11 activity: Roles of carboxylic acid and a sulfur atom in potent inhibition by sulindac sulfide

Cytochrome P450 4A11 (CYP4A11) has many endogenous and exogenous compounds containing a carboxyl group in their structure as substrates. If drugs with this characteristic potently attenuate the catalytic function of CYP4A11, drug-drug interactions may occur. Acidic non-steroidal anti-inflammatory drugs (NSAIDs) possess a carboxylic acid in their structure. However, it remains unclear whether these drugs inhibit CYP4A11 activity. The present study examined the inhibitory effects of acidic NSAIDs on CYP4A11 activity using human liver microsomes (HLMs) and recombinant CYP4A11. Sulindac sulfide, ibuprofen, and flurbiprofen effectively decreased the luciferin-4A O-demethylase activity of HLMs and recombinant CYP4A11 (inhibition rates of 30–96% at an inhibitor concentration of 100 μM), while salicylic acid, aspirin, diclofenac, mefenamic acid, indomethacin, etodolac, ketoprofen, loxoprofen, S-naproxen, pranoprofen, zaltoprofen, and oxaprozin exhibited weaker inhibitory activity (inhibition rates up to 23%). Among the drugs tested, sulindac sulfide was the most potent inhibitor of CYP4A11 activity. A kinetic analysis of the inhibition of CYP4A11 by sulindac sulfide revealed mixed-type inhibition for HLMs (Ki = 3.38 μM) and recombinant CYP4A11 (Ki = 4.19 μM). Sulindac sulfide is a pharmacologically active metabolite of sulindac (sulfoxide form), which is also oxidized to sulindac sulfone. To elucidate the role of a sulfur atom of sulindac sulfide in the inhibition of CYP4A11, the inhibitory effects of sulindac sulfide and its oxidized forms on CYP4A11 activity were examined. The potency of inhibition against HLMs was greater in the order of sulindac sulfide, sulindac, and sulindac sulfone; IC50 values were 6.16, 52.7, and 71.6 μM, respectively. The present results indicate that sulindac sulfide is a potent inhibitor of CYP4A11. These results and the molecular modeling of CYP4A11 with sulindac sulfide and its oxidized forms suggest that a sulfur atom of sulindac sulfide as well as its carboxylic acid play important roles in the inhibition of CYP4A11.

Perspectives on Corrosion Inhibition Features of Novel Synthesized Gemini-Fluorinated Cationic Surfactants Bearing Varied Spacers for Acid Pickling of X60-Steel: Practical, and In Silico Calculations.

Through our present study, three novel Gemini-fluorinated cationic surfactants bearing different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity of the as-prepared surfactants was examined. The inhibiting influence of FSG6 molecules on the X60 steel corrosion in the pickling solution (HCl) was examined by diverse methods comprising electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and X-ray photoelectron spectroscopy (XPS) experimentations, and computational calculations. The inhibition effectiveness of FSG6 surfactants followed the order of 93.37% (FSG6-2) < 96.74% (FSG6-4) < 98.37% (FSG6-6) at 2.0 × 10-4 M. The FSG6 surfactants function as mixed-type inhibitors, according to PDP investigations. The H2O molecules that adsorbed on the steel interface were substituted with surfactant molecules, and the surfactant's inhibitory activity is likely caused by the improvement in an adsorptive layer on the steel substrate, as specified by the EIS results. The Langmuir isotherm describes the absorption of FSG6 molecules on the metal surface. The XPS investigations validate the steel interface's extremely protective nature. The mechanism of interaction between FSG6 molecules with an X60-steel employing the DFT calculations and MC simulations methods was also examined and discussed.

Corrosion inhibitory characteristics, thermodynamics, and theoretical studies of N-((2-aminoethyl) carbamothioyl) acrylamide for carbon steel in 1 M HCl

Green synthesis has become very significant for sustainable development and health concern. The multicomponent is applied as an eco-friendly procedure to synthesize N-((2-aminoethyl) carbamothioyl) acrylamide (ACA). The structure of ACA is verified using FTIR and 1HNMR spectroscopy. The inhibitory effect of ACA for carbon steel in 1 M HCl is assessed using electrochemical measurements and weight loss. The Langmuir adsorption isotherm model fits the inhibitive effect caused by adsorption on the metal surface. Additionally, the surface morphology is examined using SEM and AFM. The photos demonstrate a smoothing of the protective surface and a 0.45 nm reduction in average roughness. Different quantum descriptors using DFT theory were calculated and found to be corroborated with the experimental results. By creating successive resistive adsorption films, the ACA, at a concentration of 10−3 M, protects the carbon steel in 1MHCl with a 97% efficiency as a mixed-type inhibitor.

Inhibition Mechanism of Chitooligosaccharide-Polyphenol Conjugates toward Polyphenoloxidase from Shrimp Cephalothorax.

Crustaceans are perishable with a short shelf-life. They are prone to deterioration after capture, particularly during handling, processing, and storage due to melanosis caused by polyphenoloxidase (PPO). Therefore, inhibitory effects of chitooligosaccharide (CHOS) in comparison with CHOS-catechin (CHOS-CAT), CHOS-epigallocatechin gallate (CHOS-EGCG), and CHOS-gallic acid (CHOS-GAL) conjugates on Pacific white shrimp cephalothorax PPO were studied. IC50 of CHOS-CAT (0.32 mg/mL) toward PPO was less than those of all conjugates tested (p < 0.05). CHOS-CAT exhibited the mixed-type inhibition. Kic (0.58 mg/mL) and Kiu (0.02 mg/mL) of CHOS-CAT were lower than those of other conjugates (p < 0.05). CHOS-CAT showed static fluorescence-quenching, suggesting a change in micro-environment around the active site of PPO. Moreover, CHOS-CAT was linked with various amino acid residues, including Tyr208 or Tyr209 of proPPO via van der Waals, hydrophobic interaction, and hydrogen bonding as elucidated by the molecular docking of proPPO. Although CHOS-CAT had the highest PPO inhibitory activity, it showed a lower binding energy (-8.5 kcal/mol) than other samples, except for CHOS-EGCG (-10.2 kcal/mol). Therefore, CHOS-CAT could act as an anti-melanosis agent in shrimp and other crustaceans to prevent undesirable discoloration associated with quality losses.

Establishing a cell-based screening workflow for determining the efficiency of CYP2C9 metabolism: moving towards the use of breath volatiles in personalised medicine

The use of volatile biomarkers in exhaled breath as predictors to individual drug response would advance the field of personalised medicine by providing direct information on enzyme activity. This would result in enormous benefits, both for patients and for the healthcare sector. Non-invasive breath tests would also gain a high acceptance by patients. Towards this goal, differences in metabolism resulting from extensive polymorphisms in a major group of drug-metabolizing enzymes, the cytochrome P450 (CYP) family, need to be determined and quantified. CYP2C9 is responsible for metabolising many crucial drugs (e.g., diclofenac) and food ingredients (e.g., limonene). In this paper, we provide a proof-of-concept study that illustrates the in vitro bioconversion of diclofenac in recombinant HEK293T cells overexpressing CYP2C9 to 4ʹ-hydroxydiclofenac. This in vitro approach is a necessary and important first step in the development of breath tests to determine and monitor metabolic processes in the human body. By focusing on the metabolic conversion of diclofenac, we have been able to establish a workflow using a cell-based system for CYP2C9 activity. Furthermore, we illustrate how the bioconversion of diclofenac is limited in the presence of limonene, which is another CYP2C9 metabolising substrate. We show that increasing limonene levels continuously reduce the production of 4ʹ-hydroxydiclofenac. Michaelis-Menten kinetics were performed for the diclofenac 4ʹ-hydroxylation with and without limonene, giving a kinetic constant of the reaction, K M, of 103 µM and 94.1 µM, respectively, and a maximum reaction rate, V max, of 46.8 pmol min−1 106 cells−1 and 56.0 pmol min−1 106 cells−1 with and without the inhibitor, respectively, suggesting a non-competitive or mixed inhibition type. The half-maximal inhibitory concentration value (IC50) for the inhibition of the formation of 4ʹ-hydroxydiclofenace by limonene is determined to be 1413 µM.

Dictamnine derivatives as a novel family of dual inhibitors for cholinesterase and β-amyloid aggregation

A novel series of dictamnine derivatives were synthesized and evaluated as dual inhibitors for cholinesterase and β-amyloid aggregation. These molecules exhibited potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities at the micromolar to sub-micromolar levels. Compound 7k exhibited the strongest inhibitory activity for both AChE and BChE, with IC50 values of 0.40 μM and 0.63 μM, respectively, improving results from its precursor dictamnine and the commercial inhibitor galanthamine. Kinetic analyses and molecular modeling results indicated a mixed-type inhibition of AChE by compound 7k. In addition, some of the derivatives revealed potent inhibitory activity of AChE induced β-amyloid (Aβ) aggregation. Moreover, 7k did not show toxicity against SH-SY5Y and HL-7702 cells at the tested concentration. Therefore, these dictamnine derivatives, and especially 7k, are suitable candidates for the treatment of Alzheimer's disease and should be further studied.

Modification of conducting arylidene copolymers by formation of inclusion complexes: synthesis, characterization, and applications as highly corrosion inhibitors for mild steel

Modifying the metal surface is one solution to the industry’s growing corrosion problem. Thus, via threading approach and insertion of copolymers (CoP5-7) containing polyarylidenes through the internal cavity beta-cyclodextrin β-CD, novel pseudopolyrotaxanes copolymers (PC5-7) are developed, resulting in mild steel corrosion inhibition. Inhibitors of corrosion based on β-CD molecules adsorb strongly to metal surfaces because of their many polar groups, adsorption centers, many linkages of side chains, and benzene rings. The corrosion inhibition efficiencies IE % statistics have been revised via the Tafel polarization method and Spectroscopy based on the electrochemical impedance (EIS), with PC7 achieving the highest 99.93% in 1.0 M H2SO4; they are mixed-type inhibitors. The chemical composition of the resulting PCs is determined with Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) is utilized to examine the morphological structure of the produced polymers, and X-ray diffraction is employed to identify crystallinity. Encapsulating CoP5-7 with β-CD changes the morphological structures and increases the generated PCs' crystallinity. The thermal stability of PCs is studied, indicating the presence of these CoPs within the β-CD cavities enhances their thermal stability. This research will be a stepping stone for developing high-efficiency anti-corrosion coatings and various industrial applications.

Natural polycitric acid-curcumin for highly efficient corrosion inhibition of aluminum alloys

A new inhibitor called poly(citric acid-curcumin) (Cur-PCA) was synthesized to mitigate the corrosion of aluminum alloy heat exchange tubes in a low-temperature multi-effect seawater desalination plant. The corrosion-inhibiting properties of Cur-PCA on 3105 aluminum alloy were studied in a pickling solution of 1 mol/L HCl prepared using a 3.5 % NaCl solution at 25 °C. The investigation utilized weight loss analysis, electrochemical techniques, scanning electron microscopy (SEM), molecular dynamics simulation, and quantum chemical calculations. The findings demonstrated that Cur-PCA acted as a mixed-type inhibitor, predominantly inhibiting the cathodic reaction. At a concentration of 500 ppm, Cur-PCA exhibited an inhibition efficiency of 94.19 %. The adsorption behavior of Cur-PCA conformed to the El-Awady model, and it could spontaneously adsorb onto the surface of the aluminum alloy. Molecular dynamics simulation and quantum chemical calculations confirmed the spontaneous adsorption of Cur-PCA molecules on the aluminum alloy surface and explored the relationship between the structure of Cur-PCA and its corrosion inhibition effect.