Molecular interaction of sulfonamides and ovalbumin, an allergenic egg protein, exploring biophysical, theoretical and biological studies

Interactions of novel 1,3-diaryltriazene-sulfamethazines with carbonic anhydrases: Kinetic studies and in silico simulations

Sulfonamides, recognized as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, are crucial in treating diverse diseases, including epilepsy, glaucoma, bacterial infections, and various pathological processes, e.g., high blood pressure, rheumatoid arthritis, ulcerative colitis, pain, and inflammation. Additionally, therapeutically, 1,3-diaryl-substituted triazenes and sulphamethazines (SM) are integral components in various drug structures, and the synthesis of novel compounds within these two categories holds substantial significance. Herein, ten 1,3-diaryltriazene-substituted sulphamethazine derivatives SM(1-10), which were created by reacting the diazonium salt of sulphamethazine with substituted aromatic amines, were synthesized and the physiologically and pharmacologically relevant human (h) isoforms hCA I and II, cytosolic isozymes, were included in the study. The synthesized compounds showed excellent inhibition versus hCAs; the 4-butoxy (SM7, KI of 5.69 ± 0.59 nM) compound exhibited a potent inhibitory effect against the hCA I compared with the reference drug acetazolamide (AAZ, KI of 116.00 ± 8.48 nM). The 4-cyano (SM4, KI of 5.87 ± 0.57 nM) compound displayed higher potency than AAZ (KI of 57.25 ± 4.15 nM) towards hCA II. Meanwhile, among the synthesized molecules, the 3,4-dimethoxy (SM9, KI of 74.98 ± 10.49 nM, SI of 9.94) compound (over hCA I) displayed a noticeable selectivity for hCA isoform II. The target compounds in the molecular docking investigation were determined to take part in various hydrophilic and hydrophobic interactions with nearby amino acids and fit nicely into the active sites of the hCAs. This research has yielded compounds displaying varying affinity toward hCA isoenzymes, ultimately serving as potent and selective hCA inhibitors. Given its substantial biological inhibitory potency, this particular derivative series is determined to hold the potential to serve as a promising lead compound against these hCAs.

Shedding light on the interaction of ovalbumin and resveratrol: structure, digestibility, transport, and allergenicity assessment of OVA-RES complexes

BACKGROUND

The interaction between food allergens and plant polyphenols has become a safe and effective management strategy to prevent food allergies. Ovalbumin (OVA) is the most abundant allergen in egg whites. Resveratrol (RES) is a plant polyphenol that is abundant in red grapes, berries, and peanuts, and has an anti-allergic effect on allergy-related immune cells. However, there is little information about the effect of RES on the allergenicity of OVA. In this study, the effect of RES on the allergenicity of OVA was investigated.

RESULTS

Molecular docking and spectroscopic studies indicated that the addition of RES changed the structure of OVA. The digestion and transfer rate of OVA-RES were effectively improved with an in vitro gastrointestinal digestion model and Caco-2 cell model, especially when the molar ratio of OVA-RES was 1:20. Meanwhile, the KU812 cell degranulation assay proved that the potential allergenicity was remarkably decreased while the molar ratios of OVA-RES were increased to 1:20. Furthermore, hydrogen bonds and van der Waals forces were the dominating forces to stabilize the OVA-RES complexes.

CONCLUSION

All the findings demonstrated that the potential allergenicity of OVA was reduced when interacting with RES, and RES can be a potential food material for preparing a hypoallergenic protein, especially for egg allergy. © 2023 Society of Chemical Industry.

Unleashing the binding interaction of chrysin-Cu(II) complex with the biomacromolecular targets: further studies of cell cytotoxicity and radical scavenging properties

Flavonoids are significant dietary components and have ability to coordinate with metal ions to produce novel drug discovery leads that are superior to those of the parent flavonoids. Here, in this report, we have synthesized chrysin-Cu(II) complex (as per reported article) and characterized it further with different analytical techniques. The synthesized complex was evaluated for radical scavenging and cell cytotoxicity studies where it exhibited enhanced activity as compared to bare chrysin. The interaction studies of the complex with ct-DNA (Kb ⁓ 105 M-1), human serum albumin (HSA) and ovalbumin (Kb ⁓ 104 M-1) were evaluated using multi-spectroscopic and molecular docking studies. Groove binding mode with ct-DNA was observed as confirmed from competitive displacement studies, viscosity measurement, melting temperature estimation and docking analyses. The complex exhibited comparatively higher affinity towards ct-DNA which indicated it efficient transportation by the carrier proteins and controlled release in the target DNA.Communicated by Ramaswamy H. Sarma.

Investigating sulfonamides - Human serum albumin interactions: A comprehensive approach using multi-spectroscopy, DFT calculations, and molecular docking

The environmental and health risks associated with sulfonamide antibiotics (SAs) are receiving increasing attention. Through multi-spectroscopy, density functional theory (DFT), and molecular docking, this study investigated the interaction features and mechanisms between six representative SAs and human serum albumin (HSA). Multi-spectroscopy analysis showed that the six SAs had significant binding capabilities with HSA. The order of binding constants at 298 K was as follows: sulfadoxine (SDX): 7.18 × 105 L mol-1 > sulfamethizole (SMT): 6.28 × 105 L mol-1 > sulfamerazine (SMR): 2.70 × 104 L mol-1 > sulfamonomethoxine (SMM): 2.54 × 104 L mol-1 > sulfamethazine (SMZ): 3.06 × 104 L mol-1 > sulfadimethoxine (SDM): 2.50 × 104 L mol-1. During the molecular docking process of the six SAs with HSA, the binding affinity range is from -7.4 kcal mol-1 to -8.6 kcal mol-1. Notably, the docking result of HSA-SDX reached the maximum of -8.6 kcal mol-1, indicating that SDX may possess the highest binding capacity to HSA. HSA-SDX binding, identified as a static quenching and exothermic process, is primarily driven by hydrogen bonds (H bonds) or van der Waals (vdW) interactions. The quenching processes of SMR/SMZ/SMM/SDX/SMT to HSA are a combination of dynamic and static quenching, indicating an endothermic reaction. Hydrophobic interactions are primarily accountable for SMR/SMZ/SMM/SDX/SMT and HSA binding. Competition binding results revealed that the primary HSA-SAs binding sites are in the subdomain IB of the HAS structure, consistent with the results of molecule docking. The correlation analysis based on DFT calculations revealed an inherent relationship between the structural chemical features of SAs and the binding performance of HSA-SAs. The dual descriptor (DD) and the electrophilic Fukui function were found to have a significant relationship (0.71 and -0.71, respectively) with the binding constants of HSA-SAs, predicting the binding performance of SAs and HSA. These insights have substantial scientific value for evaluating the environmental risks of SAs as well as understanding their impact on biological life activities.

Spectroscopic studies on noncovalent binding of nicotinamide-modified BRCA1 (856-871) analogs to calf thymus DNA

Various peptide drugs have entered the market with the development of molecular biology. Peptide drugs are used for treat diseases such as diabetes, breast cancer, and HIV infection. In this study, three nicotinamide-modified peptides were synthesized by modifying the N-terminus of BRCA1 (856-871, Y856R, K862Y, R866W) peptide with three nicotinic acid derivatives using solid-phase peptide synthesis. The results of calf thymus DNA (ctDNA) binding activity indicated that binding constants of BRCA1 (856-871, Y856R, K862Y, R866W) (P0) and three nicotinamide-modified peptides (P1, P2, and P3) to ctDNA were 1.89 × 10³, 2.97 × 10⁴, 7.61 × 10⁴, and 8.09 × 10⁴ L·mol^-1, respectively. The binding affinity of the modified peptides was superior to that of BRCA1 (856-871, Y856R, K862Y, R866W). ΔH^θ < 0 and ΔS^θ < 0 indicated that van der Waals force and hydrogen bond contributed most to peptide-ctDNA binding. Results obtained by Circular dichroism (CD) indicated that peptide binding interaction led to conformational changes in ctDNA. Ultraviolet-visible (UV) spectroscopy, ethidium bromide (EB) competition experiments, DNA melting experiments, and viscosity measurements verified that peptides interacted with ctDNA via groove binding. Ionic strength experiments manifested that electrostatic binding was also involved in peptide-ctDNA binding.

The influence of N-alkyl chains in benzoyl-thiourea derivatives on urease inhibition: Soil studies and biophysical and theoretical investigations on the mechanism of interaction

Ureases are enzymes produced by fungi, plants, and bacteria associated with agricultural and clinical problems. The urea hydrolysis in NH₃ and CO₂ leads to the loss of N-urea fertilizers in soils and changes the human stomach microenvironment, favoring the colonization of H. pylori. In this sense, it is necessary to evaluate potential enzyme inhibitors to mitigate the effects of their activities and respond to scientific and market demands to produce fertilizers with enhanced efficiency. Thus, biophysical and theoretical studies were carried out to evaluate the influence of the N-alkyl chain in benzoyl-thiourea derivatives on urease enzyme inhibition. A screening based on IC₅₀, binding constants, and theoretical studies demonstrated that BTU1 without the N-alkyl chain (R = H) was more active than other compounds, so the magnitude of the interaction was determined as BTU1 > BTU2 > BTU3 > BTU4 > BTU5, corresponding to progressively increased chain length. Thus, BTU1 was selected for interaction and soil application essays. The binding constants (K_b) for the supramolecular urease-BTU1 complex ranged from 7.95 to 5.71 × 10³ M^-1 at different temperatures (22, 30, and 38 °C), indicating that the preferential forces responsible for the stabilization of the complex are hydrogen bonds and van der Waals forces (ΔH = -15.84 kJ mol^-1 and ΔS = -36.61 J mol^-1 K^-1). Theoretical and experimental results (thermodynamics, synchronous fluorescence, and competition assay) agree and indicate that BTU1 is a mixed inhibitor. Finally, urease inhibition was evaluated in the four soil samples, where BTU1 was as efficient as NBPT (based on ANOVA two-way and Tukey test with 95% confidence), with an average inhibition of 20% of urease activity. Thus, the biophysics and theoretical studies are strategies for evaluating potential inhibitors and showed that increasing the N-alkyl chain in benzoyl-thiourea derivatives did not favor urease inhibition.

Deciphering the interactions of phytochemicals with ovalbumin, the major food allergen from egg white: spectroscopic and computational studies

Ovalbumin (OVA), the major component of egg white, has been used as a model carrier protein to study the interaction of four bioactive phytochemicals 6-hydroxyflavone, chrysin, naringin, and naringenin. A static quenching mechanism was primarily associated with the complexation of the flavonoids with OVA. Hydrophobic forces play a major part in the stability of the complexes. The structural changes within the protein in response to flavonoid binding revealed a decrease in OVA's α-helical content. The hypothesized binding site for flavonoids in OVA overlaps with one or more immunoglobulin E-binding epitopes that may have some effect in the immunoglobulin E response pathway. The flavonoids remain in the same binding site throughout the simulation time and impart protein stability by forming different noncovalent interactions. This study presents comprehensive information about the interaction of the flavonoids with OVA and the associated structural variations after the binding, which might help researchers better comprehend similar medication pharmacodynamics and provide critical information for future therapeutic development.

Role of Ovalbumin/β-Cyclodextrin in Improving Structural and Gelling Properties of Culter alburnus Myofibrillar Proteins during Frozen Storage

This study aimed to analyze the cryoprotective effect of a ovalbumin (OVA) and β-cyclodextrin (βCD) mixture (3:1, OVA/βCD) on the structure, rheology and gelling properties of myofibrillar proteins (MPs) during 90 days of frozen storage. A mixture of OVA/βCD at different concentrations (0, 2, 4, and 6%) was added to MPs and stored at −18 °C for 90 days. The addition of OVA/βCD significantly decreased the sulfhydryl contents while it increased the surface hydrophobicity, which was closely connected with tertiary structural changes. Circular dichroism analysis showed that the addition of OVA/βCD enhanced the stability of the secondary structure by inhibiting the decline in the α-helix. Rheological properties analysis indicated that 6% OVA/βCD treatment showed better storage modulus (G’) and loss modulus (G”). In addition, treatment of OVA/βCD showed better gel forming properties than the control group (0%), helping to form a homogeneous and denser gel network. The results proved that 6% OVA/βCD could be act as a promising cryoprotectant, which can improve the structure and gel behavior of Culter alburnus MPs during frozen storage. Moreover, OVA/βCD could be a potential alternative to conventional cryoprotectants at the industrial level to increase the economic and commercial values of seafood products.

Sulfonamide drugs: structure, antibacterial property, toxicity, and biophysical interactions

Sulfonamide (or sulphonamide) functional group chemistry (SN) forms the basis of several groups of drug. In vivo sulfonamides exhibit a range of pharmacological activities, such as anti-carbonic anhydrase and anti-t dihydropteroate synthetase allowing them to play a role in treating a diverse range of disease states such as diuresis, hypoglycemia, thyroiditis, inflammation, and glaucoma. Sulfamethazine (SMZ) is a commonly used sulphonamide drug in veterinary medicine that acts as an antibacterial compound to treat livestock diseases such as gastrointestinal and respiratory tract infections. Sulfadiazine (SDZ) is another frequently employed sulphonamide drug that is used in combination with the anti-malarial drug pyrimethamine to treat toxoplasmosis in warm-blooded animals. This study explores the research findings and the work behaviours of SN (SMZ and SDZ) drugs. The areas covered include SN drug structure, SN drug antibacterial activity, SN drug toxicity, and SN environmental toxicity.