Ester Complexes Research Articles

Zein and 3-Aminophenyl Boronic Acid Conjugated Polyvinylpyrrolidone Polymer Blend: Electrospinning, Characterization, and Mucoadhesive Drug Delivery.

The era of mucoadhesive polymers has advanced to the next generation, focusing on targeted adhesion of chemical functional groups with mucosa. This work aims to develop boronic acid functionalized polymers, which could facilitate reversible binding with the mucin in the mucosa. Pendant groups of boronic acid were conjugated on the chains of polyvinylpyrrolidone (PVP) via C═N bonding. The evidence from FTIR spectroscopy, XPS analysis, and UV spectroscopy has been used for the confirmation of the chemical conjugation of 3-aminophenyl boronic acid (APBA) to PVP. Boronate ester formation is a pH-dependent process. High pKa values of APBA preferably cause the binding of trigonal-shaped boronic acid with sialic acid groups of mucin. Boronic acid moieties additionally benefited in mucoadhesion in comparison to PVP alone, which is a result of the formation of a five-membered boronate ester complex. The presence of boronic acid moieties enhanced the force of adhesion on porcine buccal mucosal tissue from 13.12 ± 1.52 to 19.04 ± 1.97 g force. Specific binding of the polymer to the mucosal surface caused prolonged adhesion of the polymer to the mucosal surface. A polymer blend of boronic acid functionalized PVP and zein has been explored for its potential for mucoadhesive delivery of propranolol hydrochloride.

Polymer and micellar catalysis in d-fructose oxidation by imidazolium fluorochromate: A kinetic and mechanistic study

This work investigated the oxidation of d-fructose using imidazolium fluorochromate (IFC) as an oxidant and analyzed how sodium dodecyl sulfate (SDS) and polyethylene glycol (PEG-400) affected the reaction kinetics. The process exhibited a unit-order dependence on IFC, d-fructose, and perchloric acid concentration. Perchloric acid was the primary source of hydrogen ions in the reaction mixture. The stoichiometry of the reaction indicated that 3 mol of d-fructose requires 4 mol of IFC. Acrylonitrile, a radical-generating species, did not impact the reaction rate, indicating the absence of a free radical intermediate. The reaction rate decreases as the Mn (II) ions concentration increases, suggesting the involvement of Cr (IV) species in the reaction. The dielectric value of the reaction medium (D) had an inverse effect on the rate, and the outcomes were consistent with the Amis (log k1 and 1/D) and Kirkwood plots (log k1 and (D-1/2D+1)), indicating the presence of dipole-dipole interactions in the process. SDS and PEG-400 catalyzed the reaction. The reaction showed significant catalysis before reaching the critical micelle concentration (CMC). However, the observed rate constants stabilized at higher SDS concentrations exceeding the CMC. Piszkiewicz's cooperativity model was employed to describe the surfactant catalysis, while the Benesi-Hildebrand equation was utilized to explain polymer catalysis. The activation parameters are ΔH† = 44.3 ± 1.3 kJ mol−1, and ΔS† = −133.4 ± 4.3 J K−1 mol−1. The products of the reaction have been identified by spectral analysis as d-arabinoniclactone and formic acid. The formation of an ester complex followed by its decomposition was proposed as the rate-limiting step in the proposed mechanistic reaction pathway.

Cross-linking affecting properties and in-vitro digestibility of starch-sucrose ester complexes

This study investigated the effects of cross-linking on the characteristics and in-vitro digestibility of starch-sucrose ester (SE) complexes. To achieve this, corn starch (CS) was cross-linked with various concentrations of sodium trimetaphosphate /sodium tripolyphosphate (5 %, 10 %, and 15 %). Subsequently, cross-linked starches (CLS) were complexed with SE through hydrothermal treatment. X-ray diffraction analysis revealed that V-type amylose-lipid complexes formed by the interaction between CS and SE. The resultant CS-SE complex significantly reduced CS digestibility, increasing its resistant starch (RS) content from 10.19 % to 22.71 %. The cross-linking modification did not alter the crystalline pattern of the CS-SE complex. Several CLS-SE complexes demonstrated higher enzymatic resistance compared to the CS-SE complex. The CLS10-SE complex exhibited the highest RS content of 39.37 % when the cross-linking agent concentration was 10 %. This phenomenon may be attributable to the cross-linking reaction having enhanced the interaction between starch molecular chains, reducing the solubility and swelling power, thereby hindering the accessibility of starch chains to digestive enzymes. These findings indicate that cross-linking modification is a practical approach to improving the anti-digestion performance of starch-lipid complexes.

Synthesis of Rupestonic Acid L-Ephedrine Derivatives with Preliminary In vitro Anti-influenza Viral Activity.

Influenza virus is a kind of RNA virus. Nowadays, the high incidence of influenza and the morbidity and mortality of epidemic influenza are substantial. It has been reported that one hundred million people in the world are infected with influenza viruses, and two hundred and fifty thousand to five hundred thousand people die from the flu per year. In 2021, the number of infected persons in China was reported to be 654,700, and 0.07% of the infected persons died. The flu has caused a serious threat to human survival. Although several drugs, such as Zanamivir, Oseltamivir, Peramivir, and Laninamivir, have been used in clinics for the treatment of the influenza virus, there are some shortcomings of these drugs. The strain of influenza H5N1 (avian influenza) has been found to resist the effective drug Oseltamivir. Thus, there is an urgent demand to discover new influenza virus inhibitors to overcome the emergence of influenza antigens. This study aimed to develop new influenza virus inhibitors based on the rupestonic acid parent core. The rupestonic acid L-ephedrine ester (A) and rupestonic acid L-ephedrine complex (B) were synthesized in this work for the development of influenza virus inhibitors. The target compounds were synthesized using rupestonic acid and L-ephedrine as starting materials. Their structures were characterized by 1H NMR and 13C NMR, and the purity was determined by HPLC. Then, their preliminary in vitro influenza activity was evaluated using Oseltamivir as a reference drug. The results showed that the synthesized rupestonic acid L-ephedrine derivatives A and B were more potent influenza virus inhibitors against the strains of A/PR/8/34 (H1N1) and A/FM/1/47 (H1N1) with the IC50 values of 51.0, 51.0 μM and 441.0, 441.0 μM, respectively, than that of rupestonic acid. By comparing the IC50 of compounds A and B, compound A can be regarded as a very promising lead compound for the development of influenza virus inhibitors. The rupestonic acid L-ephedrine ester (A) and rupestonic acid L-ephedrine complex (B) were synthesized and characterized using 1H NMR and 13C NMR. Moreover, their purity was determined by HPLC. Both compounds A and B exhibited more potent activities against the strains of A/PR/8/34 (H1N1) and A/FM/1/47 (H1N1) than rupestonic acid. Compound A can be regarded as a very promising lead compound for the development of influenza virus inhibitors. Based on these results, more rupestonic acid derivatives will be designed and synthesized in the future for the development of influenza virus inhibitors.

Revolutionizing the capture efficiency of ultrasensitive digital ELISA via an antibody oriented-immobilization strategy.

Bead-based digital ELISA, the most sensitive protein quantification method, has drawn much attention to exploring ultra-low abundance biomarkers in the life sciences and clinical applications. However, its major challenge refers to the low antigen capture efficiency in the immunoreaction process due to the low probability of collision between the deficient concentration of the analytes and the captured antibody-immobilized on the beads. Here, we achieved significantly improved reaction efficiency in the digital signal formation by fixing the orientation of antibodies and revealed the kinetic mechanism for the first time. A facile and fast antibody conjugation strategy that formed boronate ester complexes was designed to retain the uniform orientation of antibodies with controllable antibody density. Remarkably, the oriented immobilized antibody exhibited stronger antigen-binding capacity and faster antigen-binding speed compared to randomly immobilized antibodies, with capture efficiency increasing approximately 14-fold at 15 μg of antibody per 1 mg microbeads (0.035 antibody nm-2) under 0.5 h incubation. Combined with theoretical analysis, we verified that the improved capture efficiency of the oriented antibodies mainly originated from the considerable rise in the binding rate constant (kon) rather than the increase in antigen-binding sites, which further prominently decreased the limit of detection (LoD) in a shorter incubation time compared with the randomly immobilized antibody. In conclusion, the antibody oriented conjugation method effectively overcomes the low capture efficiency challenge of bead-based digital ELISA. It paves a promising way for further improving the digital immunoassay performance and promotes the early diagnosis of diseases by recognizing more ultra-low abundance significant biomarkers.

Interaction between soy protein isolate/whey protein isolate and sucrose ester during microencapsulation: Multi-spectroscopy and molecular docking

Proteins serve as commonly utilized wall materials in the process of spray drying microencapsulation. However, proteins exhibit increased sensitivity to the environment, thereby impacting the stability of microcapsules. In this work, to improve the functional properties of proteins, whey protein isolate (WPI)/soy protein isolate (SPI) were combined with sucrose esters (SE) to investigate their interaction during spray drying. Spectroscopic studies revealed that SE is capable of inducing conformational changes in SPI and WPI, resulting in a decrease in their fluorescence through a static quenching mechanism. The formation of protein-sucrose ester complexes was confirmed using SDS-PAGE electrophoresis. Increasing the SE ratio resulted in a decrease in particle sizes of the SPI–SE and WPI–SE complexes, damaging the particles. Molecular docking simulation experiments were conducted with SE using 7S, 11S, and β-LG proteins. The results revealed the presence of hydrogen bonds, salt bridges, and hydrophobic interactions between SE and the 7S protein; hydrogen bonds, cation–π interactions, and hydrophobic interactions between SE and the 11S protein; as well as hydrogen bonds and hydrophobic interactions between SE and β–LG. These findings offered valuable insights for the development of novel formulations for food microencapsulation through spray drying.

Blood biochemical parameters in mice under the action of polyphosphate esters and their complexes with antibiotics

Complexes of polyphosphate esters with antibiotics were developed in Lviv Polytechnic National University together with scientists of Institute of Animal Biology NAAS to reduce the negative impact of antibiotics on the animal body. The conducted experiments allow assessing the effect of antibiotics, polyphosphate esters and complexes of polyphosphate esters with antibiotics on the body of laboratory animals based on biochemical markers of hepato- and nephrotoxicity. The antibiotics were administered in average daily therapeutic doses. It was found that the physiological state of mice and their blood biochemical indicators were within physiological normal values after the administration of polyphosphate ester P4 and complexes of polyphosphate ester P4+antibiotics (amoxicillin, oxytetracycline, and doxycycline). At the same time, intramuscular administration of polyphosphate ester P6 and complexes of P6+antibiotics have a certain negative effect on mice, which is manifested by changes in the activity of marker enzymes: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP). We found an increase in AST and ALT activities. P6+amoxicillin and P6+oxytetracycline complexes increased ALP activity. Complexes P4+antibiotics decreased ALP. Blood urea content decreased after the administration of polyphosphate ester P6 by 38.5%, P6+oxytetracycline by 26.9%, P6+doxycillin by 21.8%. P6+amoxicillin complex caused a significant increase by 237% in the concentration of creatinine in the blood of mice. The changes of blood creatinine concentration of other experimental groups fell within normal physiological range. Conducted studies of blood biochemical characteristics of mice under the action of new complexes of nanobiopolymer transporters with antibiotics ensured the selection of antibacterial drugs with low toxicity.

Boronate ester-based pH stimulated bactericide armoring for efficient fouling control of LNF membranes

Membrane fabricated with a method of ingenious simplicity to be equipped with antibacterial function is the key to address the biofouling issue in separation applications. Herein, we proposed an innovative approach to armor abundant antibiotics on the membrane with minimal loss of the active functional groups of the antibiotics. Boronate ester-based membrane was first fabricated with non-solvent induced phase separation (NIPS) method. A loose nanofiltration (LNF) membrane with unique trinity structure was then constructed through the cross-linking between boronate ester complexes and trimesoyl chloride (TMC) on the top layer. Due to the pH responsive and dynamic nature of boronate ester complexes, boronic acid groups can be released under acidic conditions, acting as binding sites for diol-bearing antibiotics. This not only allows the sufficient anchoring of antibiotics (here kanamycin (KM) was chosen as model antibiotics), but also minimizes the consumption of active groups of KM molecules. The resultant membrane delivers excellent biocidal effect against both Gram-negative and positive bacteria, while also exhibiting superior water permeance of 134.86 ± 5.62 L m−2 h−1 bar−1. This work reveals the great potential of boronate esters complexes for the development of high-flux antibacterial membranes.

A Boronate Ester Driven Rechargeable Antibacterial Membrane for Fast Molecular Sieving

AbstractMembrane decorated with biocides is an effective way to suppress biofilm growth. However, their immediate biocidal effect usually suffers from a significant decline due to the irreversible consumption of the biocides. Here, a smart nanofiltration membrane is reported with rechargeable antibacterial capability that is fabricated by a facile interfacial polymerization via 3‐aminophenylboronic acid and trimesoyl chloride on a polysulfone substrate. Biocides bearing diol groups can be grafted onto the membrane surface under neutral/alkaline condition and then released from the surface under acidic environment, due to the pH‐responsive feature of boronate ester complexes. The resultant membrane exhibits integrated properties of fast bacterial inactivating efficiency, rechargeable antibacterial capability, and impressive stability. In addition, the achieved membrane shows remarkable separation efficiency to dye/monovalent salt system. The successful fabrication of the membrane with rechargeable anti‐bacterial property provides new insights into the development of pH‐responsive and sustainable antibacterial membranes.

Catalytic Asymmetric Diels-Alder Reaction of 2'-Hydroxychalcone as a Dienophile with a VANOL-Borate Ester Complex.

Numerous flavonoid Diels-Alder-type natural products have been isolated and received great attention from the synthetic community. Herein, we reported a catalytic strategy for an asymmetric Diels-Alder reaction of 2'-hydroxychalcone with a range of diene substrates using a chiral ligand-boron Lewis acid complex. This method enables the convenient synthesis of a wide range of cyclohexene skeletons in excellent yields with moderate to good enantioselectivities, which is critical to prepare natural product congeners for further biological studies.

Novel Homoleptic and Heteroleptic Pt(II) β‐oxodithiocinnamic ester Complexes: Synthesis, Characterization, Interactions with 9‐methylguanine and Antiproliferative Activity

AbstractThree new series of homoleptic and heteroleptic platinum(II) β‐oxodithiocinnamic ester complexes, [Pt(L1–L9)2], [Pt(L1–L9)(DMS)Cl] and [Pt(L1–L9)(DMSO)Cl], were synthesized and characterized using elemental analysis, mass spectrometry, and different NMR spectroscopy (1H, 13C{1H} and 195Pt). The β‐oxodithiocinnamic esters coordinate towards the platinum(II) centre as O,S‐bidentate chelating ligands. The structures of HL3, [Pt(L2)2], [Pt(L6)(DMS)Cl] as well as [Pt(L2)(DMSO)Cl] have been confirmed through the X‐ray crystallography, where the platinum(II) complexes exhibit a slightly distorted square planar geometry. In this article, we also investigated the solvolysis of three representative Pt(II) complexes, as well as the interaction with 9‐methylguanine as a DNA model system, by utilizing the LC‐ESI‐MS technique. A selection of the complexes was assessed for their use as anticancer agents, and cytotoxicity assays with these complexes showed modest toxicity on both Cisplatin sensitive and resistant ovarian cancer cell lines. However, the compounds cytotoxicity was not affected by the Cisplatin resistance mechanisms and a specific selection of the ligands may modify the cell line specificity.

Enantiodiscriminating Lipophilic Liquid Membrane-Based Assay for High-Throughput Nanomolar Enantioenrichment of Chiral Building Blocks.

The reported optical resolution method was designed to support high-throughput enantioseparation of molecular building blocks obtained by automated small-scale synthetic methods. Lipophilic esters of common resolving agents were prepared and used as liquid membranes on the indifferent polymer surface of a microtiter assay. Chiral model compounds were enriched in one of the enantiomers starting from the aqueous solutions of their racemic mixture. Enantiodiscrimination was provided by forming diastereomeric coordination complexes of lipophilic enantiopure esters with the enantiomers of the chiral building blocks inside the liquid membranes. This enantiomeric recognition resulted in a greater distribution ratio of the preferred isomer in the membrane phase, thus the process enables a simultaneous enantioenrichment of the solutions outside the membrane. This paper reports a novel microplate-integrated stereoselective membrane enrichment technique satisfying the need for automatable enantioseparation on a subpreparative scale.

Acoplanarity, Aromaticity, Chirality, and Helical Twisting Power of Chlorin e6 13(N)-Methylamide-15,17-dimethyl Ester Complexes: Effect of a Metal

The experimental and theoretical study of the influence of metal complexing on geometry, aromaticity, chirality, and the ability to twist the nematic phase by complexes based on modified natural chlorin e6 was carried out. The geometry optimization of the chlorin e6 13(N)-methylamide-15,17-dimethyl ester (MADMECl) and its Zn, Cu, and Ni complexes by DFT (CAM-B3LYP/6–31 G(d,p) functional) method was performed. Based on these calculations, the acoplanarity degree of the macrocyclic ligand and the distortion energy of its dianion were estimated, which allowed the arrangement of the MADMECl complexes in the series Ni > Cu > Zn. Aromaticity was evaluated using the NICS criterion (nuclear independent chemical shift). An increase in the degree of aromaticity of the macrocycle upon complex formation was established. At the same time, the aromaticity of the inner conjugation contour corresponds to the same series as the acoplanarity, while the outer π-delocalization is characterized by the reverse sequence. An experimental evaluation of the electron circular dichroism of the Soret and the Q-bands, as well as the g-factor of dissymmetry, was carried out. The growth of these parameters with an increase in the degree of acoplanarity and aromaticity of the internal conjugation contour was determined. The induction of helical phases in mixtures of nematic liquid crystals (LCs) based on cyanobiphenyls and MADMECl macrocyclic metal complexes was studied by polarization microscopy, and the clearance temperatures and helix pitch of the mesophases were measured. A strong effect of the metal on the phase transition temperature and helical twisting power was established.

Lanthanide Complexes (Ln=La, Nd, Dy) of Octaethyl propane‐1,1,3,3‐tetrayltetrakis(phosphonate): Multidentate Binding Competing with Monodentate DMSO Complexes

AbstractThe preparation of lanthanide nitrate complexes [Ln(NO3)3{L}]n (Ln3+=La, Nd, Dy) supported by the octaethyl propane‐1,1,3,3‐tetrayltetrakis(phosphonate) (L) chelate ligand platform is presented. Re‐crystallization of these compounds from DMSO/THF led to a complete replacement of the multidentate phosphonate ester ligand and the formation of exclusively DMSO‐supported lanthanide nitrate species [Ln(NO3)3(DMSO)4]. The relative basicity of a model phosphonate ester vs. DMSO is explored with theoretical means, pointing out the relevance of solvation in this case in line with the experimentally observed exchange process. The optical properties of the dysprosium(III) derivatives are examined in the visible region indicating a significantly higher quantum yield for its tetraphosphonic ester complex than for the DMSO coordinated analog.

Study on the performance and mechanism of bio-electrochemical system to mitigate membrane fouling in bioreactors

To alleviate membrane fouling, a membrane of the membrane bioreactor was directly used as the anode of the bio-electrochemical system. On the 14th day, the control group had blocked, while the experimental group with a current of 0.44 mA, the increase in ΔTMP was only 2.2 kPa. The polysaccharide and protein concentrations in the open-circuit group were 4.2 and 2.9 times higher than those in the closed-circuit group, respectively. Three-dimensional fluorescence spectroscopy and gas chromatography mass spectrometry showed that most of the deposition in the control group contained high-molecular-weight compounds, especially long-chain ester derivatives, phenols, and complex hydrocarbons, whereas the experimental group was the opposite. Therefore, current (electrons) can change the composition of the cake layer. High-throughput sequencing indicated that a significantly higher abundance of electroactive microorganisms on the experimental than control group. Two-dimensional correlation spectroscopy showed that electrons promote the degradation of polysaccharides, thereby alleviating membrane fouling.

Novel Chloro-Substituted Salicylanilide Derivatives and Their β-Cyclodextrin Complexes: Synthesis, Characterization, and Antibacterial Activity.

The goal of this research was to design novel chloro-substituted salicylanilide derivatives and their β-cyclodextrin complexes in order to obtain efficient antibacterial compounds and to demonstrate the beneficial role of complexation on the efficiency of these compounds. Thus, salicylanilide derivatives, esters, and hydrazides were obtained by microwave-assisted synthesis and their structure proven based on FTIR and NMR spectra. In order to improve water solubility, chemical and physical stability, and drug distribution through biological membranes, the inclusion complexes of the ethyl esters in β-cyclodextrin were also obtained using kneading. Inclusion-complex characterization was accomplished by modern analytical methods, X-ray diffraction, SEM, TGA, FTIR, and UV-vis spectroscopy. The newly synthesized compounds were tested against some Gram-positive and Gram-negative bacteria. Antimicrobial tests revealed good activity on Gram-positive bacteria and no inhibition against Gram-negative strains. The MIC and MBC values for compounds derived from N-(2-chlorophenyl)-2-hydroxybenzamide were 0.125–1.0 mg/mL. N-(4-chlorophenyl)-2-hydroxybenzamide derivatives were found to be less active. The inclusion complexes generally behaved similarly to the guest compounds, and antibacterial activity was not been altered by complexation.

Dopamine Assisted Self-Cleaning, Antifouling, and Antibacterial Coating via Dynamic Covalent Interactions.

The rapid accumulation of dead bacteria or protein on a bactericidal surface can reduce the effectiveness of the modified surface and alter its biocidal activity by shielding the surface biocide functional groups, promoting microbial attachment and subsequent biofilm formation. Thus, the alteration of biocidal activity due to biofilm formation can cause serious trouble including severe infection or implant or medical device failure leading to death. Therefore, developing a smart self-cleaning surface is of great interest. Ideally, such a surface can not only kill the attached microbials but also release the dead cells and foulants from the surface under a particular incitement on demand. In this project, a sugar-responsive self-cleaning coating has been developed by forming covalent boronic ester bonds between catechol groups from polydopamine and a benzoxaborole pendant from zwitterionic and cationic polymers. To incorporate antifouling properties and enhance the biocompatibility of the coating, bioinspired zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC) was chosen and benzoxaborole pendant containing zwitterionic polymer poly(MPC-st-MAABO) (MAABO: 5-methacrylamido-1,2-benzoxaborole) was synthesized. Additionally to impart antibacterial properties to the surface, a quaternary ammonium containing cationic polymer poly(2-(methacryloyloxy)ethyl trimethylammonium (META)-st-MAABO)) was synthesized. These synthesized polymers were covalently grafted to a polydopamine (PDA) coated surface by forming a strong cyclic boronic ester complex with a catechol group of the PDA layer endowing the surface with bacteria contact-killing properties and capturing specific protein. After the addition of cis-diol containing competitive molecules, i.e., saccharides/sugars, this boronic ester complex with a catechol group of PDA was replaced and the attached polymer layer was cleaved from the surface, resulting in the release of both absorbed protein and live/killed bacteria electrostatically attached to the polymer layer. This dynamic self-cleaning surface can be a promising material for biomedical applications avoiding the gathering of dead cells and debris that are typically encountered on a traditional biocidal surface.

Co-Delivery of p53 Restored and E7 Targeted Nucleic Acids by Poly (Beta-Amino Ester) Complex Nanoparticles for the Treatment of HPV Related Cervical Lesions.

The p53 gene has the highest mutation frequency in tumors, and its inactivation can lead to malignant transformation, such as cell cycle arrest and apoptotic inhibition. Persistent high-risk human papillomavirus (HR-HPV) infection is the leading cause of cervical cancer. P53 was inactivated by HPV oncoprotein E6, promoting abnormal cell proliferation and carcinogenesis. To study the treatment of cervical intraepithelial neoplasia (CIN) and cervical cancer by restoring p53 expression and inactivating HPV oncoprotein, and to verify the effectiveness of nano drugs based on nucleic acid delivery in cancer treatment, we developed poly (beta-amino ester)537, to form biocompatible and degradable nanoparticles with plasmids (expressing p53 and targeting E7). In vitro and in vivo experiments show that nanoparticles have low toxicity and high transfection efficiency. Nanoparticles inhibited the growth of xenograft tumors and successfully reversed HPV transgenic mice’s cervical intraepithelial neoplasia. Our work suggests that the restoration of p53 expression and the inactivation of HPV16 E7 are essential for blocking the development of cervical cancer. This study provides new insights into the precise treatment of HPV-related cervical lesions.

Semisolid formulations based on solid-in-oil-in-water systems containing proteins

In recent years, improvements have been made, through biotechnological processes, in the production and development of peptides capable of increasing collagen and elastin synthesis for anti-aging skin care. However, proteins have many limitations due to their structural, chemical and physical fragility to external aggressions, which may cause conformational changes, leading to loss of biological activity. Therefore, it is important to create delivery systems that protect these biomolecules from damage, allowing them to reach their target. This work aimed to develop a system able to carry bovine serum albumin (BSA), used as a model of a protein, and to incorporate this system in a semisolid formulation suitable for skin application. A microemulgel based on a solid-in-oil-in-water (S/O/W) microemulsion was prepared. Firstly, the association efficiency (AE) of lyophilized BSA-sucrose ester complex and the size of S/O nanodispersion were assessed; then, the characterization and stability evaluation of the final semisolid formulation through evaluation of pH, texture and rheological behavior were performed. The average value of AE was 54.74% ± 2.17. It was possible to develop an S/O/W microemulsion, which allowed the subsequent development of an S/O/W microemulgel that assured suitable pH, texture and rheological characteristics for skin application.

Separation and Identification of Resveratrol Butyrate Ester Complexes and Their Bioactivity in HepG2 Cell Models

Resveratrol butyrate ester (RBE) complexes have demonstrated higher antioxidant capacity and anti-fat accumulation activity in previous studies. In this study, silica gel, high-performance liquid chromatography, and 1H nuclear magnetic resonance were used for separation and identification of RBE complex components. With the exception of resveratrol, five different structures of ester derivatives were separated from silica gel: 3,4′-di-O-butanoylresveratrol (ED2, 18.8%), 3-O-butanoylresveratrol (ED4, 35.7%), 4′-O-butanoylresveratrol (ED5, 4.4%), 3,5,4′-tri-O-butanoylresveratrol (ED6, 1.5%), and 3,5-di-O-butanoylresveratrol (ED7, 0.7%). Among the ester derivatives obtained, ED2 and ED4 were the main ester derivatives in the RBE complex. Thus, the cellular antioxidant activities of the RBE mixture, ED2, and ED4 were evaluated. Results showed that the antioxidant capacity of ED2 and ED4 was higher than that of the RBE mixture, demonstrating that the number and position of butyrate esterification sites are related to cell survival rate and antioxidant capacity. This study is the first to report the successful isolation, structural identification, and cellular biological antioxidant activity of RBE complex derivatives, which are key characteristics for the potential practical application of RBE complexes.