Complex Formation Research Articles

Immobilization of Pb(II) by Bacillus megaterium-based microbial-induced phosphate precipitation (MIPP) considering bacterial phosphorolysis ability and Ca-mediated alleviation of lead toxicity

Inappropriate handling of lead (Pb)-containing wastewater that is produced as a result of smelting activities threatens the surrounding environment and human health. The microbial-induced phosphate precipitation (MIPP) technology was applied to immobilize Pb2+ in an aqueous solution considering bacterial phosphorolysis ability and Ca-mediated alleviation of lead toxicity. Pb immobilization was accompanied by sample characterization in order to explore the inherent mechanism that affected the immobilization efficiency. Results showed that Ca2+ use elevated the immobilization efficiency through the prevention of bacterial physisorption and chemisorption, an enhancement to the phosphatase activity and the degree of SGP hydrolysis, and the provision of nucleation sites for Pb2+ to attach. The formation of the Pb-GP complex helped the bacteria to maintain its activity at the commencement of catalyzing SGP hydrolysis. The nucleated minerals that were precipitated in a columnar shape through a directional stacking manner under MIPP featured higher chemical stability compared to non-nucleated minerals. As a result, there were three pathways, namely, bacterial physisorption, bacterial chemisorption, and substrate chelation, applied for Pb immobilization. The immobilization efficiency of 99.6% is achieved by precipitating bioprecipitates including Pb5(PO4)3Cl, Pb10(PO4)6Cl2, and Ca2Pb3(PO4)3Cl. The findings accentuate the potential of applying the MIPP technology to Pb-containing wastewater remediation.

Reducing the oil absorption and tailoring starch properties in banana slices by integrated ultrasound in infrared frying

The reduction of oil absorption and modifications of starch properties in infrared fried (IF) banana slices by integrated ultrasound was investigated with power levels ranged 600–1000 W. Results showed that the internal moisture migration in IF banana slices were enhanced by ultrasonication, the crust development was delayed and finally formed with a thinner layer and higher uniformity. Both the pore volume and the porosity of IF samples were reduced by the integrated ultrasound, while the accounts of pores with diameters 100–250 μm and 0.02–1 μm has been increased. The total oil uptake in IF samples was reduced by 1.5%–9.4% and both the surface and structural oil was decreased by the ultrasound. The order of starch in long range and short range in IF banana slices were reduced by the integrated ultrasound, while the formation of starch-lipid complex was increased, which leading to the prolonged starch digestion time.

Imaging Rovibrational Excitation of Scattered YO Molecules in Inelastic Collisions with Kr and Ne.

Energy transfer between atoms and molecules is fundamental to many physical and chemical processes, and understanding the mechanisms and outcomes of energy transfer is crucial for various applications in physics and chemistry. Here, the rovibrational excitation of YO(X 2Σ+) molecules with the collision of Kr and Ne has been studied in the laser-ablation crossed beam and time-sliced ion velocity map imaging setup in combination with the resonance enhanced multiphoton ionization scheme. Significant changes in the angular distribution for different rovibrational excitations of YO molecules are observed with the collision of Kr. The sharp forward distribution for low rovibrational excitation of YO(v' = 0, 1) molecules suggest that the weak attractive potential between Kr and YO is dominant at large impact parameters. Comparatively, the strong sideway distribution for highly rovibrationally excited YO(v' = 1, 2, 3, and 5) is due to rainbow scattering from the stronger attractive potential of Kr···YO at relatively small impact parameters. The more isotropic angular distribution in the highly rovibrationally excited YO(v' = 11) indicates the formation of a short-lived complex. A change in the angular distribution of scattered YO with different rovibrational excitations was also observed in the collisions of Ne. For YO as a heteronuclear diatomic molecule, collisions of the Y- and the O-end of YO with rare gases would affect the contribution of inelastic processes at different impact parameters.

The structure of the archaeal nuclease RecJ2 implicates its catalytic mechanism and inability to interact with GINS

Bacterial RecJ exhibits 5'→3' exonuclease activity that is specific to single-stranded DNA (ssDNA); however, archaeal RecJs show 5’ or 3’ exonuclease activity. The hyperthermophilic archaea Methanocaldococcus jannaschii encodes the 5’-exonuclease MjRecJ1 and the 3’-exonuclease MjRecJ2. In addition to nuclease activity, archaeal RecJ interacts with GINS, a structural subcomplex of the replicative DNA helicase complex. However, MjRecJ1 and MjRecJ2 do not interact with MjGINS. Here, we report the structural basis for the inability of the MjRecJ2 homologous dimer to interact with MjGINS and its efficient 3' hydrolysis polarity for short dinucleotides. Based on the crystal structure of MjRecJ2, we propose that the interaction surface of the MjRecJ2 dimer overlaps the potential interaction surface for MjGINS and blocks the formation of the MjRecJ2-GINS complex. Exposing the interaction surface of the MjRecJ2 dimer restores its interaction with MjGINS. The cocrystal structures of MjRecJ2 with substrate dideoxynucleotides or product dCMP/CMP show that MjRecJ2 has a short substrate binding patch, which is perpendicular to the longer patch of bacterial RecJ. Our results provide new insights into the function and diversification of archaeal RecJ/Cdc45 proteins.

N‒N hydrazonyl bond cleavage in benzothiazolyl-hydrazino-phenathrenequinone mediated by ruthenium(II) via an anion radical intermediate

The complexes [Ru(LBenz)H(CO)(PPh3)2] 2, [Ru(LBenz)Cl(CO)(PPh3)2] 3, (ligand behaving as bidentate monoanionic) and [Ru(LBenz)Cl(CO)(PPh3)] 4, (ligand is tridentate monoanionic) have been synthesized starting from benzothiazolyl-hydrazino-phenathrenequinone (HL) 1 and [RuH(CO)Cl(PPh3)3]. These are characterized by electrochemical and spectral methods as well as single crystal X-ray diffractometry (SCXRD). Upon treating with NaBH4, 3 accepts an electron within the coordinated ligand framework and the anionic hydrazonyl-N takes up a proton to be transformed to meta-stable hydrazinoquinone anion radical complex of ruthenium(II) [Ru(HLBenz•‒)Cl(CO)(PPh3)2] 5, possibly via concerted proton electron transfer process (CPET). Thus, the redox non-innocent character of the ligand upon complexation with ruthenium(II), has been disclosed and it is attributed to presence of low lying π* orbitals of almost entirely of phenanthraquinone and hydrazone character. In 5, the π‒acceptor ability of the ligand donor centres are reduced due to the existence of an odd electron in SOMO and hence the M-L distances around the coordination sphere are altered. The N‒N (hydrazonyl bond length increases from 1.296(6) Å in 3 to 1.429 Å in 5, leading to lesser thermodynamic stability of the latter and upon standing, the N‒N bond is cleaved to be transformed to 6+, possibly via the formation of iminoquinone anion radical complex, [6] (reported elsewhere). Also, it is via the dissociation of N‒N (hydrazonyl) bond, the biologically important molecule 2-aminobenzothiazole is formed along with 6+, so as to provide a novel route for its synthesis.

Efficient degradation of vulcanized natural rubber into liquid rubber by catalytic oxidation

Waste tire rubber based on natural rubber (NR) represents an abundant feedstock for the production of valuable products. This study investigated an efficient approach to convert NR vulcanizates into liquid rubber with the number-average molar masses of 1.3 × 104 g/mol. Compared to the anaerobic liquefaction at 300°C for 3 min, NR vulcanizates were liquefied efficiently at 210°C for 3 min by thermo-oxidative degradation catalyzed by manganese (II) stearate. The apparent activation energy of the NR degradation reaction decreased from 470.8 kJ/mol to 208.2 kJ/mol with catalysis, which was attributed to the formation of a coordination complex between catalysts and peroxides via the single-electron transfer redox reaction, leading to the catalytic oxidative degradation of NR vulcanizates. The main chain scission and crosslink scission occurred simultaneously during the degradation process, and the main chain scission was the primary catalytic oxidation reaction according to the Horikx theory. In addition, the obtained liquid rubber contained carbonyls, ether linkages, and sulfoxide groups, as proved by FTIR and 13C-NMR. The catalytic oxidative degradation mechanism of NR vulcanizates was proposed based on the chemical structure of products and simulation results. The efficient method was proposed to highly facilitate the recycling and valorization of NR-based waste tire rubber.

Influence of para-substituted benzaldehyde derivatives with different push/pull electron strength groups on the conformation of human serum albumin and toxicological effects in zebrafish

Excessive intake of benzaldehyde and its derivatives can cause irreversible damage to living organisms. Hence, benzaldehyde derivatives with different para-substitutions of push/pull electronic groups were chosen to investigate the effect of different substituent properties on the structure of human serum albumin (HSA). The binding constants, number of binding sites, major interaction forces, protein structural changes, and binding sites of benzaldehyde (BzH) and its derivatives (4-BzHD) with HSA in serum proteins were obtained based on multispectral and molecular docking techniques. The mechanism of BzH/4-BzHD interaction on HSA is mainly static quenching and is accompanied by the formation of a ground state complex. BzH/4-BzHD is bound to HSA in a 1:1 stoichiometric ratio. The interaction forces for the binding of BzH/4-BzHD to HSA are mainly hydrogen bonding and hydrophobic interaction, which are also accompanied by a small amount of electrostatic interactions. The effect of BzH/4-BzHD on HSA conformation follows: 4-Diethylaminobenzaldehyde (4-DBzH) > 4-Nitrobenzaldehyde (4-NBzH) > 4-Hydroxybenzaldehyde (4-HBzH) > 4-Acetaminobenzaldehyde (4-ABzH) > BzH, which means that the stronger push/pull electronic strength of the para-substituted benzaldehyde derivatives has a greater effect on HSA conformation. Furthermore, the concentration-lethality curves of different concentrations for BzH/4-BzHD on zebrafish verified above conclusion. This work provides a scientific basis for the risk assessment of benzaldehyde and its derivatives to the ecological environment and human health and for the environmental toxicological studies of benzaldehyde derivatives with different strengths of push/pull electron substitution.

Update on chiral recognition mechanisms in separation science.

The stereospecific analysis of chiral molecules is an important issue in many scientific fields. In separation sciences, this is achieved via the formation of transient diastereomeric complexes between a chiral selector and the selectand enantiomers driven by molecular interactions including electrostatic, ion-dipole, dipole-dipole, van der Waals or π-π interactions as well as hydrogen or halogen bonds depending on the nature of selector and selectand. Nuclear magnetic resonance spectroscopy and molecular modeling methods are currently the most frequently applied techniques to understand the selector-selectand interactions at a molecular level and to draw conclusions on the chiral separation mechanism. The present short review summarizes some of the recent achievements for the understanding of the chiral recognition of the most important chiral selectors combining separation techniques with molecular modeling and/or spectroscopic techniques dating between 2020 and early 2024. The selectors include polysaccharide derivatives, cyclodextrins, macrocyclic glycopeptides, proteins, donor-acceptor type selectors, ion-exchangers, crown ethers, and molecular micelles. The application of chiral ionic liquids and chiral deep eutectic solvents, as well as further selectors, are also briefly addressed. A compilation of all published literature on chiral selectors has not been attempted.

Synthesis and computational study of metal complex of α-mangostin as an anticancer candidate

Context: The number of breast cancer patients from year to year is increasing, accompanied by an increase in global mortality; the position in Indonesia has reached 60-70% with end-stage conditions. ERα antiproliferative activity exists in α-mangostin compounds, but this compound still has several physicochemical problems, including its solubility. Therefore, efforts are needed to increase the activity of α-mangostin and its affinity as an alpha estrogen receptor antagonist through a structure-based design method. Aims: To obtain new compounds derived from α-mangostin in the form of a metal complex with cobalt (AM-Co), platinum (AM-Pt), and iron (AM-Fe) as medicinal ingredients that can be used as breast cancer therapeutic agents. Methods: The research methods include in silico studies (pharmacokinetic and toxicity prediction, molecular docking, and molecular dynamics), semi-synthesis to form a complex compound, and testing cytotoxic activity against MCF-7 and T-47D human breast cancer cells. Results: From the in vitro test results, it can be seen that the AM-Pt compound showed the best anticancer activity on MCF-7 cells compared to others from IC50 and SI values; this was supported by the results of in silico studies either through molecular docking or molecular dynamics, where this compound was more effective. Conclusions: Furthermore, it can be used as an anticancer candidate; particularly, its activity is predicted to be more potent as an ER antagonist than -mangostin and cisplatin.

Bicyclol mitigates lipopolysaccharide-induced acute lung injury through myeloid differentiation factor 88 inhibition

Acute lung injury (ALI) remains a significant clinical challenge due to the absence of effective treatment alternatives. This study presents a new method that employs a screening platform focusing on MyD88 affinity, anti-inflammatory properties, and toxicity. This platform was used to evaluate a 300-compound library known for its anti-inflammatory potential. Among the screened compounds, Bicyclol emerged as a standout, exhibiting MyD88 binding and a significant reduction in LPS-stimulated pro-inflammatory factors production in mouse primary peritoneal macrophages. By targeting MyD88, Bicyclol disrupts the MyD88/TLR4 complex and MyD88 polymer formation, thereby mitigating the MAPKs and NF-κB signaling pathways. In vivo experiments further confirmed Bicyclol's efficacy, demonstrating alleviated ALI symptoms, decreased inflammatory cytokines level, and reduced inflammatory cells presence in lung tissues. These findings were associated with a decrease in mortality in LPS-challenged mice. Overall, Bicyclol represents a promising treatment option for ALI by specifically targeting MyD88 and limiting inflammatory responses.

Quercetin, a natural flavonoid, protects against hepatic ischemia–reperfusion injury via inhibiting Caspase-8/ASC dependent macrophage pyroptosis

IntroductionHepatic ischemia–reperfusion injury (IRI) is an inevitable adverse event following liver surgery, leading to liver damage and potential organ failure. Despite advancements, effective interventions for hepatic IRI remain elusive, posing a significant clinical challenge. The innate immune response significantly contributes to the pathogenesis of hepatic IRI by promoting an inflammatory cytotoxic cycle. We have reported that blocking GSDMD-induced pyroptosis in innate immunity cells protected hepatic IRI from inflammatory injury. However, the search for effective pyroptosis inhibitors continues. ObjectivesThis study aims to evaluate whether quercetin, a natural flavonoid, can inhibit GSDMD-induced pyroptosis and mitigate hepatic IRI. MethodsWe established the hepatic IRI murine model and cellular pyroptosis model to evaluate the efficacy of quercetin. ResultsQuercetin effectively alleviated hepatic IRI-induced tissue necrosis and inflammation. We found that during hepatic IRI, the cleavage of GSDMD occurred in hepatic macrophages, but not in other non-parenchymal cells. Quercetin inhibited the cleavage of GSDMD in macrophages. Moreover, we found that quercetin blocked the ASC assembly to inhibit the formation of NLRP3 inflammasomes and AIM2 inflammasomes, suppressing macrophage pyroptosis. Co-immunoprecipitation experiments confirmed that quercetin inhibited the interaction between ASC and Caspase-8, which is the mechanism of ASC complex and inflammasome formation. Overexpression of Caspase-8 abolished the anti-pyroptosis effect of quercetin in NLRP3 and AIM2 inflammasome signaling. Furthermore, we found that the hepatoprotective activity of quercetin was reduced in myelocytic GSDMD-deficient mice. ConclusionOur findings suggest that quercetin has beneficial effects on hepatic IRI. Quercetin could attenuate hepatic IRI and target inhibition of macrophage pyroptosis via blocking Caspase-8/ASC interaction. We recommend that quercetin might serve as a targeted approach for the prevention and personalized treatment of hepatic IRI in perioperative patients.

Rigidity results on totally real submanifolds in complex space forms

Rigidity results on totally real submanifolds in complex space forms

Understanding arsenic-ulexite interactions in evaporite environments: Evidence from XRPD, micro-XRF, micro-FT-IR, and XPS studies

World-class borate deposits often form from As-rich waters, this study addresses the understudied association of arsenic (As) species with evaporite borates, focusing on the Puna region's borate deposits (Central Andes of Argentina). The research aims to characterize the association between borate minerals and high As concentrations in brines and thermal waters. To achieve this, five borate samples were collected from the Olaroz salt flat nucleus and thermal springs, alongside associated water samples. Comprehensive analytical techniques, including ICP-MS, ICP-OES, synchrotron-based micro-XRF, XRPD, Rietveld analysis, micro-FT-IR, and XPS, were employed to determine bulk and surface chemical compositions, mineral identification, and solid speciation of As and boron. The study reveals that under oxidizing conditions and in absence of organic matter, aqueous arsenic species interact with ulexite through a stepwise process involving charge neutralization, cationic bridge formation, and surface complex formation with polyborate and As(V) oxyanions. However, in environments associated with microbial mats or organic-rich sediments, the dissolved As(V) is reduced to As(III), which forms complexes with functional groups of organic matter. The coexistence of As(III) and As(V) in specific layers suggests potential remediation strategies targeting organic matter for the removal of the more toxic As(III) in similar geological settings.

HMGA2 promotes platelet-neutrophil complex formation and pulmonary tissue damage in myelodysplastic syndromes

High mobility group AT-hook 2 (HMGA2) is an architectural transcription factor that functions as an oncogene in various cancers. Although overexpression of HMGA2 has been reported in several myeloid malignancies, its role varies considerably in different disease contexts. Here, we identified a distinct role of HMGA2 as a mediator of noninfectious pneumonia in myelodysplastic syndrome (MDS). The expression level of HMGA2 in CD34+ hematopoietic stem cells and progenitors (HSC/Ps) was significantly associated with the incidence of noninfectious pneumonia, a common systemic complication in patients with MDS. Consistent with this clinical investigation, HMGA2 overexpression in a mouse model of an MDS-associated mutation led to the development of lethal noninfectious pneumonia. Mechanistically, HMGA2 overexpression conferred a megakaryocytic lineage bias to HSC/Ps and contributed to platelet activation in MDS mice. P-selectin+-activated platelets interacted with MDS clone-derived neutrophils that exhibit increased susceptibility to cell death and formed platelet-neutrophil complexes (PNCs). Both the frequency of PNCs and neutrophil cell death within the lung microenvironment increased in MDS mice overexpressing HMGA2. Genetic inhibition of P-selectin attenuated pulmonary tissue damage in MDS mice. These findings indicate that PNCs could be a new therapeutic target for noninfectious pneumonia in patients with MDS and provide new insights into the mechanistic basis of the systemic complications of MDS.

Nuclear-penetrating scleroderma autoantibody inhibits topoisomerase 1 cleavage complex formation

The contributions of anti-Topoisomerase 1 (Top1) autoantibodies to the pathophysiology of diffuse cutaneous systemic sclerosis (dcSSc), the most aggressive scleroderma subtype, are unknown. Top1 catalyzes DNA relaxation and unwinding in cell nuclei, a site previously considered inaccessible to antibodies. The discovery of autoantibodies in systemic lupus erythematosus that penetrate nuclei and inhibit DNA repair raised the possibility that nuclear-penetrating autoantibodies contribute to mechanisms of autoimmunity. Here we show that an anti-Top1 autoantibody produced by a single B cell clone from a patient with dcSSc penetrates live cells and localizes into nuclei. Functionally, the autoantibody inhibits formation of the Top1 cleavage complex necessary for DNA nicking, which distinguishes it from cytotoxic camptothecin Top1 inhibitors used in cancer therapy that trap the cleavage complex rather than preventing its formation. Discovery of a patient-derived cell-penetrating scleroderma anti-Top1 autoantibody that inhibits Top1 cleavage complex formation supports the hypothesis that anti-Top1 autoantibodies contribute to cellular dysfunction in dcSSc and offers a valuable antibody reagent resource for future studies on anti-Top1 autoantibody contributions to scleroderma pathophysiology.

Effect of lipase addition on inhibition of starch retrogradation in rice

We investigated whether the production of the free fatty acids (FFAs) by the addition of lipase during rice cooking inhibits starch retrogradation, and to examine whether proteins are involved in this process. Rice milled with milling ratios of 90%, 80%, 70%, and 60% and alkaline-soaked raw rice (AS) were prepared to obtain samples with different protein content. The protein content decreased from 8.24% to 5.83% as the milling ratio decreased from 90% to 60%, and AS contains 4.58% of protein. The prepared rice was cooked with and without lipase, and then treated with two freeze-thaw cycles to accelerate starch retrogradation. The addition of lipase increased the FFAs content and the peroxide value form 1.65 meq/kg to 4.75 meq/kg and decreased the free thiol (SH) content in cooked rice. The degree of swelling was reduced by 0.14 during cooking with the addition of lipase in cooked rice with a milling ratio of 90%. The degree of starch retrogradation (Dr) tended to increase as the milling ratios decreased from 90% to 60% and AS showed Dr similar to milling ratio of 60%. The degree of amylose-lipid complexes formation, which is involved in the inhibition of starch retrogradation, did not change with or without lipase, suggesting that the inhibitory effect of lipase became smaller as protein decreased. These results suggest that the FFAs produced by lipase converted the free SH of the protein into disulfide bonds, which altered the swelling characteristics of the starch and eventually inhibited the starch retrogradation.

Research of saccharides and related biocomplexes: A review with recent techniques and applications.

Saccharides and biocompounds as saccharide (sugar) complexes have various roles and biological functions in living organisms due to modifications via nucleophilic substitution, polymerization, and complex formation reactions. Mostly, mono-, di-, oligo-, and polysaccharides are stabilized to inactive glycosides, which are formed in metabolic pathways. Natural saccharides are important in food and environmental monitoring. Glycosides with various functionalities are significant in clinical and medical research. Saccharides are often studied with the chromatographic methods of hydrophilic interaction liquid chromatography and anion exchange chromatograpy, but also with capillary electrophoresis and mass spectrometry with their on-line coupling systems. Sample preparation is important in the identification of saccharide compounds. The cases discussed here focus on bioscience, clinical, and food applications.

Technical transformation of heavy/ultra-heavy oil production in China driven by low carbon goals: A review

With the growing global energy demand and limited production of conventional crude oil, the extraction of unconventional heavy and extra-heavy oil is receiving unprecedented attention. China is the fourth largest producer of heavy oil. High viscosity and complex formation environments increase the difficulty of exploiting heavy oil. To alleviate the economic cost and environmental pollution pressure brought by heavy oil production, China has achieved significant advancement in the innovation of heavy oil recovery, including accelerating the transformation of thermal technology to non-thermal technology and the use of new energy technology to achieve the goal of low-carbon economy and green environmental protection. Based on the background of heavy oil in China, this paper recharacterizes the high-viscosity mechanism of heavy oil. From different aspects, including basic principles, main characteristics, applicability, limitations, and challenges, this paper comprehensively reviews existing heavy oil recovery technologies, including thermal recovery, in-situ upgrading, cold recovery, and new energy technologies.Currently, in China, the main target of heavy oil recovery is achieving the “carbon peaking and carbon neutrality” goals, which can be described as low energy consumption, low emission, and low pollution. To facilitate the low-carbon transition in the extraction of heavy/extra-heavy oil and attain environmental sustainability goals, it is essential to increase the proportion of non-thermal factors in thermal recovery technologies, develop efficient in-situ catalysts, adopt clean cold extraction techniques, and advance the development of new energy technologies.

Insights on Microsomal Prostaglandin E2 Synthase 1 (mPGES-1) Inhibitors using Molecular Dynamics and MM/PBSA Calculations

Background: Despite being a normal body response against invading agents, inflammation, when exaggerated, needs to be controlled to minimize damage to the body. There are several drugs in clinical use against inflammation and other inflammatory conditions. Still, side effects often limit the use of these drugs, such as gastrointestinal effects generated by COX-1 inhibitors and cardiovascular effects by COX-2 inhibitors. Thus, exploring new targets such as mPGES-1 may lead to discovering agents that are more selective against inflammation and generate fewer side effects. Objectives: Here, docking, molecular dynamics, and MM-PBSA studies were performed on a dataset of known mPGES-1 inhibitors to identify helpful information and discover new mPGES-1 inhibitors. Methods: Molecular docking in GOLD software was used to obtain the complexes used in Molecular dynamics simulations (GROMACS software), performed to generate the RMSD, RMSF, Rg, SASA, and H-bond plots to predict the complexes' stability. The most stable conformation was analyzed regarding the most important interactions of the compounds. Finally, MM-PBSA calculations using the tool g_mmpbsa in GROMACS software were performed to determine de-binding affinity, interaction parameters, and per-residue contribution. Results: The main findings of this work were that the molecular dynamics simulation was able to find the open conformation of mPGES-1, which showed a greater preference on compounds in this region, consisting of residues known as "gateways". All compounds showed stability and stable complex formation with mPGES-1, as demonstrated by the results of RMSD, RMSF, Rg, SASA, and H-bond plots generated in a molecular dynamics simulation at 100 ns. The molecular dynamics identified three preferential sites of interaction for the compounds. Thus, the docking and dynamics protocols showed greater affinity of these compounds for cavity-02, interacting with Leu85, Pro81, Gln134, Cys137, Ala138, and Ala141. On the other hand, compound 09 preferred the cavity-03 of the protein, interacting mainly with His72 through Hbond. In addition, MM-PBSA calculations showed binding energies of up to -220,113 KJ/mol for compound 04. Furthermore, MM-PBSA could identify which electrostatic interactions are the most prevalent in the complex formation of the compounds with the highest affinity (04 and 07). Still, the van der Waals interactions are the most important for the others. Finally, the energy contribution per-residue revealed Lys120, Arg122, Arg126, and Tyr130 as the most important for the formation of the complexes. Conclusion: Design mPGES-1 inhibitors based on the residues Leu85, Pro81, Gln134, Cys137, Ala138, and Ala141, in addition to Lys120, Arg122, Arg126, and Tyr130 can provide new promising drugs useful against diseases involving inflammatory conditions.

ENHANCING BIOAVAILABILITY OF RESVERATROL THROUGH COMPLEXATION WITH π-ACCEPTORS: A SPECTROSCOPIC INVESTIGATION

Polyphenols, including the highly effective resveratrol, have garnered attention due to their potential as drug candidates for COVID-19 prevention and treatment, as well as their diverse biological activities. However, clinical application is hindered by limited bioavailability. To address this, complexation of resveratrol (RES) with electron-accepting compounds, such as TCNE and DDQ, was investigated. A spectroscopic and thermodynamic study of these charge transfer complexes was conducted in methanol and ethanol using UV-visible spectrophotometry. The composition of the charge transfer complexes (CTC) were determined using molar ratio method and Job's continuous variation method. Benesi-Hildbrand equation was used to calculate the formation constants KCT and the molar extinction coefficient ɛCT of the formed complexes. Thermodynamic parameters (∆G°), (∆H°), (∆S°) and other physical factors, transition energy (ECT), ionization potential (IP), resonance energy (RN), oscillator strength (ƒ) and dipole moment (μ) were determined too.Solid CTC were characterized by FT-IR and NMR spectroscopy. CTC formed in the reaction of resveratrol with both π -acceptors have high formation constants KCT indicating the high stability of these complexes. The solvent nature was identified as a factor influencing KCT values. Specifically, the KCT values for [RES-DDQ] CTC formed in ethanol surpassed those of the same complex formed in methanol. Conversely, the KCT values of [RES-TCNE] CTC formed in methanol were higher than those of the same complex formed in ethanol.This research offers insights into enhancing the properties of resveratrol through charge transfer complex formation, paving the way for potential applications in anticancer therapeutics.