Characterizing the binding interaction of astilbin with bovine serum albumin: a spectroscopic study in combination with molecular docking technology

Astilbin (ASN) is a flavonoid compound isolated from the rhizome of Smilax china L. (Smilacaceae). It has many bioactivities, such as selective immunosuppression, antioxidant, anti-hepatic injury, etc., and is widely used in traditional Chinese medical treatments. The interaction of ASN with bovine serum albumin (BSA) was studied in a physiological buffer (pH = 7.40) using multi-spectroscopic techniques in combination with molecular docking methods. UV-vis absorption measurements proved that a ASN–BSA complex could be formed. Fluorescence data revealed that ASN could strongly quench the intrinsic fluorescence of BSA in terms of a static quenching procedure. The process of binding was spontaneous and the binding occurred mainly through hydrogen bonding and van der Waals forces. The distance r between donor (BSA) and acceptor (ASN) was calculated to be 4.80 nm based on Förster''s non-radiative energy transfer theory. The binding constant (K_a = 7.31 × 10⁴ mol L⁻¹) and the number of binding sites (n ≈ 1) at 298 K suggested that ASN only occupied one site in BSA with high affinity. Moreover, the results of molecular docking indicated that ASN was more likely to be located in site I (sub-domain IIA) of BSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that ASN induced conformational changes of BSA. The findings would be beneficial for research on the transportation, distribution and some important bioactivities of ASN in the human body.

The interaction of astilbin with bovine serum albumin was confirmed by multi-spectroscopic techniques and molecular docking methods.     

In vitro anticancer activity of parent and nano-encapsulated samarium(iii) complex towards antimicrobial activity studies and FS-DNA/BSA binding affinity

Based on the potential anticancer properties of lanthanide complexes, the anticancer activity of the Sm(iii) complex containing a 2,2′-bipyridine ligand (bpy) and its interaction with FS-DNA (Fish-Salmon DNA) and BSA (Bovine Serum Albumin) were examined experimentally and by molecular docking in this paper. Absorption and fluorescence spectroscopic methods were used to define the thermodynamic parameters, binding constant (K_b), and the probable binding mechanism. It was concluded that the Sm complex interacts with FS-DNA through a minor groove with a K_b of 10⁵ M⁻¹. Also, the K_b for the BSA binding at 298 K was found to be 5.89 × 10⁵ M⁻¹, showing relatively a high tendency of the Sm complex to DNA and BSA. Besides, the Sm complex was docked to BSA and DNA by the autodock program. The results of the docking calculations were in good agreement with the experimental examinations. Additionally, the antifungal and antibacterial properties of this complex were investigated. The anticancer tests on the effect of the Sm complex, starch nano-encapsulation, and lipid nano-encapsulation in MCF-7 and A-549 cell lines were performed by the MTT method. It can be observed that the Sm complex and its nanocarriers presented a selective inhibitory effect on various cancer cell growths.

The biological properties of the Sm-complex, such as its interaction with FS-DNA and BSA, anticancer, and antimicrobial activities were studied.     

Synthesis of novel genistein amino acid derivatives and investigation on their interactions with bovine serum albumin by spectroscopy and molecular docking

Genistein amino acid derivatives 4a–4d were synthesized and evaluated for their cytotoxic activities against MCF-7, Hela, MGC-803 and HCT-116 cell lines by MTT assays in vitro. The results revealed that compounds 4a–4d showed better activity than the parent compound genistein. Particularly, compound 4b displayed the most significant anticancer activity against MGC-803 with an IC₅₀ value of 12.08 μM. In addition, the mechanisms of interaction between genistein, compounds 4a–4d and BSA were investigated via multi-spectroscopic techniques such as ultraviolet (UV) spectroscopy, fluorescence, circular dichroism (CD), and molecular docking under physiological conditions. The results suggested that endogenous fluorescence of BSA could be quenched by genistein and compounds 4a–4dvia forming BSA-compound complex, which meant a static quenching mechanism was involved. The negative values of enthalpy (ΔH) and entropy (ΔS) indicated that interactions between BSA and the ligands were spontaneous, and hydrogen bonding and van der Waals interactions were involved in the BSA-compound complexion formation. The UV, synchronous and 3D fluorescence results revealed that the micro-environment of tryptophan and conformation of BSA were changed after binding to ligands. CD analysis demonstrated the variation in the secondary structure and that the α-helix content of BSA decreased. Eventually, molecular docking was executed to forecast the binding forces and binding sites between BSA and compounds 4a–4d.

Introducing amino acid into genistein can not only improve its antitumor activity, but also enhance its binding affinity to BSA.     

Parent and nano-encapsulated ytterbium(iii) complex toward binding with biological macromolecules,in vitro cytotoxicity,cleavage and antimicrobial activity studies

To determine the chemotherapeutic and pharmacokinetic aspects of an ytterbium complex containing 2,9-dimethyl-1,10-phenanthroline (Me₂Phen), in vitro binding studies were carried out with FS-DNA/BSA by employing multiple biophysical methods and a molecular modeling study. There are different techniques including absorption spectroscopy, fluorescence spectroscopy, circular dichroism studies, viscosity experiments (only in the case of DNA), and competitive experiments used to determine the interaction mode between DNA/BSA and the ytterbium-complex. The results showed that the Yb-complex exhibited a high propensity for the interaction of BSA and DNA via hydrophobic interactions and van der Waals forces. Further, a competitive examination and docking study showed that the interaction site of the ytterbium complex on BSA is site III. The results of docking calculations for DNA/BSA were in good agreement with experimental findings. The complex displays efficient DNA cleavage in the presence of hydrogen peroxide. Moreover, antimicrobial studies of different bacteria and fungi indicated its promising antibacterial activity. In vitro cytotoxicity studies of the Yb-complex, starch nano-encapsulated, and lipid nano-encapsulated were carried out in MCF-7 and A-549 cell lines, which revealed significantly good activity. The results of anticancer activity studies showed that the cytotoxic activity of the Yb-complex was increased when encapsulated with nanocarriers. Based on biological applications of the Yb-complex, it can be concluded that this complex and its nanocarriers can act as novel anticancer and antimicrobial candidates.

The biological applications of Yb-complexes including anticancer, antimicrobial and DNA cleavage ability, and their interaction with FS-DNA and BSA were examined.     

Insights into the interaction of potent antimicrobial chalcone triazole analogs with human serum albumin: spectroscopy and molecular docking approaches

Mechanistic insights into the interaction of five previously chemically synthesized triazole-linked chalcone analogs (CTs) with human serum albumin (HSA) were sought using various spectroscopic techniques (UV-visible absorption, fluorescence, and circular dichroism) and molecular docking. The fluorescence quenching experiments performed at three different temperatures (288, 298 and 308 K) revealed the static mode of quenching and the binding constants (K_b ∼ 10^6–9) obtained indicated the strong affinity of these analogs for HSA. Furthermore, significant changes in the secondary structure of HSA in the presence of these analogs were also confirmed by far UV-CD spectroscopy. The thermodynamic properties such as the enthalpy change (ΔH°), Gibbs free energy change (ΔG°) and entropy change (ΔS°) revealed that the binding process was spontaneous and exothermic. Theoretical studies, viz., DFT and molecular docking corroborated the experimental results as these five analogs could bind with HSA through hydrogen bonding and hydrophobic interactions. The present study provides useful information regarding the interaction mechanism of these analogs with HSA, which can provide a new avenue to design more potent chalcone triazole analogs for use in the biomedical field.

Mechanistic insights into the interaction of five previously chemically synthesized triazole-linked chalcone analogs with human serum albumin were analyzed using UV-visible absorption, fluorescence quenching, circular dichroism and molecular docking studies.     

Comparative in vitro cytotoxicity and binding investigation of artemisinin and its biogenetic precursors with ctDNA

Artemisinin (ART) and its biogenetic precursors artemisinic acid (AA) and dihydroartemisinic acid (DHAA) are important traditional medicinal herb compounds with tumor growth inhibition properties. Herein, we have studied the cytotoxicity of ART, AA, and DHAA on different cancer cell lines (H1299, A431, and HCT 116) and investigated in detail their binding mechanisms with ctDNA by using spectroscopy, cyclic voltammetry, and computational methods. The UV absorbance, cyclic voltammetry, DNA helix melting, competition binding, and circular dichroism studies suggested that the complex formation of ART–ctDNA and AA–ctDNA occurs through groove binding. However, in the case of DHAA–ctDNA interaction, electrostatic interaction plays a major role. The thermodynamic parameters, viz., ΔG⁰, ΔH⁰, and ΔS⁰ were calculated, which showed the involvement of hydrogen bonds and van der Waals interactions for drug–ctDNA interaction. FTIR and molecular docking results suggested that ART, AA, and DHAA were bound to the A–T rich region in the minor groove of ctDNA.

Artemisinin (ART) and its biogenetic precursors artemisinic acid (AA) and dihydroartemisinic acid (DHAA) are important traditional medicinal herb compounds with tumor growth inhibition properties.     

Combined spectroscopy methods and molecular simulations for the binding properties of trametinib to human serum albumin

Trametinib is a novel anticancer drug for treating metastatic cutaneous melanoma. The present study probed into the binding of trametinib to human serum albumin (HSA) through spectroscopy methods and molecular simulations. Trametinib could quench the fluorescence of HSA through static quenching which could be probed via fluorescence spectroscopy and time-resolved fluorescence. Thermodynamic parameters and docking results indicated that hydrogen bonds and van der Waals forces play crucial roles in this binding process, which exerts almost no effect on the HSA conformation under synchronous fluorescence, three-dimensional fluorescence, circular dichroism spectra, and molecular dynamics simulations. Site marker displacement experiments and molecular docking reveal that trametinib primarily binds to Sudlow site I of HSA. In addition, the trametinib–HSA interaction was hardly influenced by varying amino acid (glutamine, alanine, glycine, and valine) concentrations. This study can provide useful information for the pharmacokinetic properties of trametinib.

Probing the binding properties of trametinib to human serum albumin.     

Novel quercetin and apigenin-acetamide derivatives: design,synthesis, characterization,biological evaluation and molecular docking studies

Flavonoids exhibit essential but limited biological properties which can be enhanced through chemical modifications. In this study, we designed, synthesized, and characterized two novel flavonoid derivatives, quercetin penta-acetamide (1S3) and apigenin tri-acetamide (2S3). These compounds were confirmed using (¹H, ¹³C) NMR, UV-Vis, and FT-IR characterizations. Their interaction with fish sperm DNA (FS-DNA) at physiological pH was investigated by UV-Vis and fluorescence spectrophotometry. The binding constant (K_b) for the UV-Vis experiment was found to be 1.43 ± 0.3 × 10⁴ M⁻¹ for 1S3 and 2.08 ± 0.2 × 10⁴ M⁻¹ for 2S3. The binding constants (K_SV) for the fluorescence quenching experiment were 1.83 × 10⁴ M⁻¹ and 1.96 × 10⁴ M⁻¹ for 1S3 and 2S3, respectively. Based on molecular modeling and docking studies, the binding affinities were found to be −7.9 and −9.1 kcal mol⁻¹, for 1S3 and 2S3, respectively. The compound–DNA docked model correlated with our experimental results, and they are groove binders. Furthermore, mutagenicity potential was examined. 1S3 and its metabolites showed no mutagenic activity for both TA98 and TA100 strains. 2S3 did not show any mutagenic activity for the strain TA 98, while its metabolites were only active at high doses. Both 2S3 and its metabolites showed mutagenic activity in the TA100 strain.

The interaction of new molecules obtained by the design and synthesis of flavonoid derivatives by molecular docking with DNA.     

Effect of alkyl distribution in pyrazine on pyrazine flavor release in bovine serum albumin solution

The flavor release mechanism related to the interaction of aroma compounds with proteins is still unclear. In this study, the interaction of protein with pyrazine homologues, such as 2-methylpyrazine (MP), 2,5-dimethylpyrazine (DP), 2,3,5-trimethylpyrazine (TRP) and 2,3,5,6-tetramethylpyrazine (TEP), was investigated to elucidate the effect of alkyl distribution in a pyrazine ring on its flavor release in bovine serum albumin (BSA) solution (pH 7.4). The results of SPME-GC-MS indicated that methyl distribution in a pyrazine ring significantly affected its release from BSA solution. The pyrazines released from BSA solution with an increasing order of MP, DP, TRP and TEP. The inhibition mechanism of alkyl-pyrazine release was further elucidated by the interaction between alkyl-pyrazines and BSA using multiple spectroscopic methods. The non-covalent interaction between alkyl-pyrazines and BSA was confirmed as the main interaction force by the value of the bimolecular quenching constant (K_q > 2 × 10¹⁰ L mol⁻¹ s⁻¹). A decrease in the hydrophobicity of the microenvironment between the alkyl-pyrazine and BSA was detected by synchronous fluorescence spectra, which revealed that alkyl-pyrazines were mainly bound on the sites of tyrosine and tryptophan in BSA. The UV-vis absorption spectra and circular dichromatic (CD) spectrum revealed that alkyl-pyrazines could induce polarity and conformation change of BSA. The above results indicated that the structure of the flavor homologues can affect their release in food matrices.

The methyl groups on the pyrazine ring affect the interaction of pyrazines with BSA. The non-covalent interaction between alkyl-pyrazines and BSA was confirmed. Alkyl-pyrazines could induce the polarity and conformation change of BSA.     

Versisterol,a new endophytic steroid with 3CL protease inhibitory activity from Avicennia marina (Forssk.) Vierh.

A new epoxy ergostane sterol, named versisterol, was isolated from Aspergillus versicolor, an endophytic fungus from Avicennia marina. The structure of the isolated compound was deduced by means of one- and two-dimensional NMR and high-resolution mass spectrometry. The absolute stereochemistry was elucidated by NOESY analysis, and experimental and calculated time-dependent density functional theory (TD-DFT) circular dichroism spectroscopy. Versisterol inhibited 3CL protease (3CL^pro) with an IC₅₀ value of 2.168 ± 0.09 μM. Binding affinities and molecular interactions of versisterol towards 3CL^pro were scrutinized and compared to lopinavir with the help of the combination of docking computations and molecular dynamics (MD) simulation. In silico calculations demonstrated a comparable binding affinity of versisterol with a docking score of −9.4 kcal mol⁻¹, and MM-GBSA binding energy over 200 ns MD simulation of −29.1 kcal mol⁻¹, with respect to lopinavir (−9.8 and −32.2 kcal mol⁻¹, respectively). These findings suggested that versisterol can be an auspicious prototype for developing new 3CL^pro drug candidates against COVID-19.

A new epoxy ergostane sterol, named versisterol, was isolated from Aspergillus versicolor, an endophytic fungus from Avicennia marina.     

The synthesis,characterization, DNA/BSA/HSA interactions,molecular modeling,antibacterial properties,and in vitro cytotoxic activities of novel parent and niosome nano-encapsulated Ho(iii) complexes

Based on the importance of metal-centered complexes that can interact with DNA, this research focused on the synthesis of a new Ho(iii) complex. This complex was isolated and characterized via elemental analysis, and FT-IR, fluorescence, and UV-vis spectroscopy. Additional confirmation of the Ho(iii) complex structure was obtained via single-crystal X-ray diffraction. DNA interaction studies were carried out via circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy, viscosity measurements and emission spectroscopy; it was proposed that the metal complex acts as an effective DNA binder based on studies in the presence of fish DNA (FS-DNA), showing high binding affinity to DNA in the presence of hydrophobic and electron donating substituents. Also, the interactions of this complex with human (HSA) and bovine serum albumin (BSA) proteins were studied via fluorescence spectroscopy techniques and the obtained results reveal an excellent propensity for binding in both cases. Furthermore, the interactions of the Ho(iii) complex with DNA, BSA and HSA were confirmed via molecular docking analysis. The antimicrobial activities of the Ho(iii) complex were tested against Gram-negative bacteria and Gram-positive bacteria. In addition, a niosome nano-encapsulated Ho(iii) complex was synthesized, and the parent and encapsulated complexes were evaluated as potential antitumor candidates. The main structure of the Ho(iii) complex is maintained after encapsulation using niosome nanoparticles. The MTT method was used to assess the anticancer properties of the Ho(iii) complex and its encapsulated form toward human lung carcinoma and breast cancer cell lines. The anticancer activity in the encapsulated form was more than that of the parent Ho(iii) complex. In conclusion, these compounds could be considered as new antitumor candidates.

A new complex of holmium, [Ho(bpy)(H₂O)₆]Cl₃ has been synthesized, their DNA/BSA/HSA binding, molecular docking, antibacterial activity and MTT assay of niosome nano-encapsulated are investigated.     

Differences between the binding modes of enantiomers S/R-nicotine to acetylcholinesterase

Nicotine causes neurotoxic effects because it quickly penetrates the blood–brain barrier after entering the human body. Acetylcholinesterase (AChE) is a key enzyme in the central and peripheral nervous system associated with neurotoxicity. In this study, a spectroscopic method and computer simulation were applied to explore the mode of interaction between AChE and enantiomers of nicotine (S/R-nicotine). Fluorescence spectroscopy showed that the quenching mechanism of endogenous fluorescence of AChE by S/R-nicotine was static, as confirmed by the time-resolved steady-state fluorescence. The binding strength of both nicotine to AChE was weak (S-AChE: K_a = 80.06 L mol⁻¹, R-AChE: K_a = 173.75 L mol⁻¹). The main driving forces of S-AChE system interaction process were van der Waals force and hydrogen bonding, whereas that of R-AChE system was electrostatic force. Computer simulations showed that there were other important forces involved. S/R-Nicotine had a major binding site on AChE, and molecular docking showed that they bound mainly to the cavities enclosed by the active sites (ES, PAS, OH, AACS, and AP) in the protein. UV-vis spectroscopy and 3D spectroscopy indicated that nicotine significantly affected the microenvironment of Trp amino acids in AChE. The CD spectra indicated that S-nicotine increased the α-helical structure of AChE, but the overall conformation did not change significantly. By contrast, R-nicotine significantly changed the secondary structure of AChE. 5,5′-Dithiobis-2-nitrobenzoic acid (DTNB) method indicated that S and R nicotine produced different degrees of inhibition on the catalytic activity of AChE. Both experimental methods and computer simulations showed that R-nicotine had a significantly higher effect on AChE than S-nicotine. This research comprehensively and systematically analyzed the mode of interaction between nicotine and AChE for neurotoxicity assessment.

Study on the binding modes of AChE to S/R-nicotine.     

In silico prediction and interaction of resveratrol on methyl-CpG binding proteins by molecular docking and MD simulations study

Resveratrol enhances the BRCA1 gene expression and the MBD family of proteins bind to the promoter region of the BRCA1 gene. However, the molecular interaction is not yet reported. Here we have analyzed the binding affinity of resveratrol with MBD proteins. Our results suggest that resveratrol binds to the MBD proteins with higher binding affinity toward MeCP2 protein (ΔG = −6.5) by sharing four hydrogen bonds as predicted by molecular docking studies. Further, the molecular dynamics simulations outcomes showed that the backbones of all three protein–ligand complexes are stabilized after the period of 75 ns, constantly fluctuating around the deviations of 0.4 Å, 0.5 Å and 0.7 Å for MBD1, MBD2 and MeCP2, respectively. The inter-molecular hydrogen bonding trajectory analysis for protein–ligand complexes also support the strong binding between MeCP2–resveratrol complex. Further, binding free energy calculations showed binding energy of −94.764 kJ mol⁻¹, −53.826 kJ mol⁻¹ and −36.735 kJ mol⁻¹ for MeCP2–resveratrol, MBD2–resveratrol and MBD1–resveratrol complexes, respectively, which also supported our docking results. Our study also highlighted that the MBD family of proteins forms a binding interaction with other signaling proteins that are involved in various cancer initiation pathways.

Resveratrol enhances the BRCA1 gene expression and the MBD family of proteins bind to the promoter region of the BRCA1 gene.     

Investigation of the adsorption behavior of BSA with tethered lipid layer-modified solid-state nanopores in a wide pH range

Nanopore technology was introduced for the study of the dynamic interactions between bovine serum albumin (BSA) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) phospholipids based on a modified nanopore. The results reveal that the interaction mechanism between DOPE and BSA is affected by the pH of the subphase. Far above the BSA isoelectric point (pH > 7), a weaker hydrophobic interaction and stronger electrostatic repulsion exist between the DOPE and BSA molecules. At pH = 7, the BSA structure nearly does not change, and the interaction is weak. At pH 5 and pH 6, BSA is marginally affected by the adsorption interaction, and below pH 5, the DOPE film becomes disordered, so there is a strong repulsive force interaction between the BSA and DOPE.

Nanopore technology was introduced for the study of the interaction between bovine serum albumin (BSA) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) phospholipids.     

Interaction mechanism of aloe-emodin with trypsin: molecular structure–affinity relationship and effect on biological activities

The molecular mechanism of interaction between aloe-emodin (AE) and trypsin was investigated, exhibiting remarkable outcomes. To detect the interaction mechanism, the binding of AE with trypsin was examined by a multi-spectroscopy and molecular docking method. Results showed that the binding of AE and trypsin would lead to static quenching and their binding forces were van der Waals forces and hydrogen bonding. The results of simultaneous and three-dimensional fluorescence spectroscopy showed that the combination of AE and trypsin caused changes in the microenvironment around the trypsin fluorophore, which might change the spatial structure of trypsin. FT-IR spectroscopy showed that the contents of α-helix and β-turn in trypsin were decreased and the contents of β-sheet, random coil and antiparallel β-sheet were increased. Moreover, all these experimental results were verified and reasonably explained by molecular docking results. We also investigated the enzyme activity of trypsin and the antioxidant activity of AE. The results showed that both the enzyme activity of trypsin and the antioxidant activity of AE were decreased after interaction between AE and trypsin. The findings outlined in this study should elucidate the molecular mechanisms of interaction between AE and trypsin and contribute to making full use of AE in the food industry.

The mechanism of interaction between AE and trypsin was studied firstly. The biological activity of both decreased after the interaction. These results provide a basis for the development and utilization of AE.     

Novel huperzine A based NMDA antagonists: insights from molecular docking,ADME/T and molecular dynamics simulation studies

Huperzine A (HupA) is an alkaloidal natural product and drug isolated from Chinese herb Huperzia serrata, which is a potent selective anticholinesterase inhibitor. HupA has symptomatic, cognitive-enhancing and protective effect on neurons against amyloid beta-induced oxidative injury and antagonizing N-methyl-d-aspartate receptors by blocking the ion channels. The present study aimed to identify the docking, ADME/T and molecular dynamics simulation parameters of a library of 40 analogues which can correlate the binding affinity, conformational stability and selectivity of the ligands towards NMDA receptor through in silico approach. Glide molecular docking analysis was performed for the designed analogues to understand the binding mode and interactions. MD simulations were performed to explain the conformational stability and natural dynamics of the interaction in physiological environmental condition of protein–ligand complex affording a better understanding of chemical-scale interactions between HupA and its analogues with NMDA channel that could potentially benefit the development of new drugs for neurodegenerative diseases involving NMDA receptors.

The in silico study explores the structural behavior and binding affinities of 40 novel analogues of huperzine A. Novel NMDA receptor antagonists have been virtually identified by molecular docking, ADME/T and molecular dynamics simulation studies.     

An investigation on 3-acetyl-7-methoxy-coumarin Schiff bases and their Ru(ii) metallates with potent antiproliferative activity and enhanced LDH and NO release

New cyclometallated ruthenium(ii) complexes of 3-acetyl-7-methoxycoumarin-4N-substituted thiosemicarbazones were synthesized and characterized by analytical and spectral techniques. The crystal structures of the ligands H₂L^1–3 and complexes (1, 2 and 4) were confirmed by X-ray crystallography. The analysis showed that the ligands have undergone C–H activation at the C(4) carbon of the pyrone ring and acted in a tridentate fashion by binding through C, N and S atoms. CT-DNA and protein (BSA/HSA) binding studies were carried out to analyze their interaction with biomolecules. Good binding affinity with DNA was observed with intercalative binding mode, which was further confirmed by EB displacement and viscosity measurement studies. The quenching mechanism with BSA/HSA was found to be static. Three dimensional (3D) fluorescence measurements were carried out to validate the micro environmental changes in the serum albumins. Their antioxidant propensity and antimicrobial study insisted that the compounds displayed good spectrum of activity. Evaluation of their anticancer potential against MCF-7 (human breast cancer) and A549 (human lung carcinoma) cell lines revealed that the complexes exhibited better activity than the ligands and cisplatin. Further, the results of LDH and NO release assays supported the cytotoxic nature of the compounds. The non-toxic nature of the compounds was established by testing against the non-cancerous cell line HaCaT (human normal keratinocyte).

New cyclometallated ruthenium(ii) complexes of 3-acetyl-7-methoxycoumarin-4N-substituted thiosemicarbazones were synthesized and characterized by analytical and spectral techniques.     

Elucidation of molecular interactions of theaflavin monogallate with camel milk lactoferrin: detailed spectroscopic and dynamic simulation studies

Lactoferrin is a heme-binding multifunctional glycoprotein known for iron transportation in the blood and also contributes to innate immunity. In this study, the interaction of theaflavin monogallate, a polyphenolic component of black tea, with camel milk lactoferrin was studied using various biophysical and computational techniques. Fluorescence quenching at different temperatures suggests that theaflavin monogallate interacted with lactoferrin by forming a non-fluorescent complex, i.e., static quenching. Theaflavin monogallate shows a significant affinity towards lactoferrin with a binding constant of ∼10⁴–10⁵ M⁻¹ at different temperatures. ANS binding shows that the binding of polyphenol resulted in the burial of hydrophobic domains of lactoferrin. Moreover, thermodynamic parameters (ΔH, ΔS and ΔG) suggested that the interaction between protein and polyphenol was entropically favored and spontaneous. Circular dichroism confirmed there was no alteration in the secondary structure of lactoferrin. The energy transfer efficiency (FRET) from lactoferrin to theaflavin was found to be approximately 50%, with a distance between protein and polyphenol of 2.44 nm. Molecular docking shows that the binding energy of lactoferrin–theaflavin monogallate interaction was −9.7 kcal mol⁻¹. Theaflavin monogallate was bound at the central cavity of lactoferrin and formed hydrogen bonds with Gln89, Tyr192, Lys301, Ser303, Gln87, and Val250 of lactoferrin. Other residues, such as Tyr82, Tyr92, and Tyr192, were involved in hydrophobic interactions. The calculation of various molecular dynamics simulations parameters indicated the formation of a stable complex between protein and polyphenol. This study delineates the binding mechanism of polyphenol with milk protein and could be helpful in milk formulations and play a key role in the food industry.

Lactoferrin is a heme-binding multifunctional glycoprotein known for iron transportation in the blood and also contributes to innate immunity.     

Coumarin–carbazole based functionalized pyrazolines: synthesis,characterization, anticancer investigation and molecular docking

A series of novel pyrazoline scaffolds from coumarin–carbazole chalcones were synthesized. We explored various acetyl, amide, and phenyl substituents at the N-1 position of the pyrazoline core. The synthesized compounds were characterized by FTIR, ¹H-NMR, ¹³C-NMR, DEPT, and mass spectroscopic techniques. The in vitro cytotoxicity study of all the synthesized compounds was evaluated against HeLa, NCI-H520 and NRK-52E cell lines. Compounds 4a and 7b became the most active compounds and exhibited their potential to arrest the cell cycle progression and induce apoptosis in both the cell lines. In addition, molecular docking studies revealed a higher binding affinity of both the molecules with CDK2 protein. Based on the obtained results, a comprehensive analysis is warranted to establish the role of compounds 4a and 7b as promising cancer therapeutic agents.

Coumarin–carbazole based functionalised pyrazolines: synthesis, anticancer activity and molecular docking.     

Exploring the interaction between Salvia miltiorrhiza and α-glucosidase: insights from computational analysis and experimental studies

α-Glucosidase has emerged as an important target for type 2 diabetes mellitus. Salvia miltiorrhiza is a widely used traditional Chinese medicine. The interaction between the chemicals of S. miltiorrhiza and α-glucosidase are still not clear, and need to be deeply investigated. Herein, an integrated approach consisting of computational analysis and experimental studies was employed to illustrate the interactions between S. miltiorrhiza and α-glucosidase. Molecular docking simulations were performed to reveal the proposed binding characteristics of the chemicals identified in S. miltiorrhiza on the basis of the total docking scores and key molecular determinants for binding. The affinities of 13 representative compounds from the medicinal herb to α-glucosidase were predicted and then confirmed by enzyme inhibitory assay in vitro. The obtained results suggested that two compounds including salvianolic acid C and salvianolic acid A in S. miltiorrhiza showed potent α-glucosidase inhibitory activity with IC₅₀ values of 4.31 and 19.29 μM, respectively. The active inhibitor, salvianolic acid C, exerted a mixed-competitive inhibition mode when binding to α-glucosidase. Such findings could be helpful to efficiently discover bioactive molecules from complex natural products, which suggests the usefulness of the integrated approach for this scenario.

An integrated approach was used to explore the interaction between Salvia miltiorrhiza and α-glucosidase.