Probing the binding of lomefloxacin to a calf thymus DNA-histone H1 complex by multi-spectroscopic and molecular modeling techniques

Multispectroscopic and computational techniques to study the interaction of anthraquinone appended sensor with calf thymus DNA

An anthraquinone based derivative (AQ) has been designed and synthesized to find its applications for the interactions with calf thymus DNA (ctDNA) involving various spectroscopic techniques, thermodynamic and computational approaches. The UV-vis studies pointed to interaction of AQ with ctDNA via groove binding mode, which has been further supported well by the ionic strength studies, viscosity measurement, circular dichroism and melting temperature (Tm) curves. These findings have been further validated by dye-displacement assay and molecular docking studies. The analysis of thermodynamic parameters supports that the AQ-ctDNA binding is entropy favoured and enthalpy disfavoured and main acting binding interaction is hydrophobic interaction. The outcomes of the molecular modelling suggested that AQ might have entered the A-T abundant area of the ctDNA.Communicated by Ramaswamy H. Sarma.

Quantification of mirtazapine in tablets via DNA binding mechanism; development of a new HPLC method

Atypical antidepressant mirtazapine (MIR) is mostly prescribed for the management of major depressive disorder. The identification of MIR in pharmaceutical dosage forms was made possible by developing a novel, quick, sensitive high-performance liquid chromatography (HPLC) approach that was verified in accordance with ICH recommendations. In the first part of this study, HPLC investigations were optimized with regard to variables including pH, working column, mobile phase, temperature, and flow rate. The limit of detection (LOD) was 0.013 ppm, the limit of quantification (LOQ) was 0.044 ppm, and the linear range was computed as 0.5-15 ppm (R2 = 0.9998). The recovery investigation assessed the method's accuracy, which was shown to range between 98.82 and 100.97 %. In the second part, by using UV-vis spectroscopy, HPLC, thermal denaturation, and viscosity measurements, the mechanism of binding interaction of MIR with double-stranded fish sperm deoxyribonucleic acid (dsDNA) has been thoroughly studied. The DNA binding constants (Kb) were determined using UV-Vis absorption and HPLC methods. To investigate the interactions of MIR with dsDNA, molecular docking calculations and additionally, molecular dynamics simulations were performed. Results showed that MIR is located in the minor groove of dsDNA, and in addition to hydrogen bonding, electrostatic interaction is also formed between the aromatic ring of MIR and phosphate oxygen of dsDNA. Finally, a binding characterization study using MIR tablets was also conducted in order to assess the interaction mechanism of the DNA with the drug using the validated analytical procedure developed for the MIR molecule.

Structure and energetics of serum protein complex of tea adulterant dye Bismarck brown Y using experimental and computational methods

Tea, a widely consumed aromatic beverage, is often adulterated with dyes such as Bismarck brown Y (C.I. 21000) (BBY), Prussian blue, and Plumbago, which pose potential health risks. The objective of this study is to analyze how the food dye BBY interacts with serum protein, bovine serum albumin (BSA). This study investigated the BBY-BSA interaction at the molecular level. Fluorescence spectroscopy results showed that the quenching of BSA by BBY is carried out by dynamic quenching mechanism. The displacement assay and molecular docking studies revealed that BBY binds at the flavanone binding site of BSA with hydrophobic interactions. Circular Dichroism results indicate the structural stability of the protein upon BBY binding. Molecular dynamics simulations demonstrated the stability of the complex in a dynamic solvent system, and quantum mechanics calculations showed slight conformational changes of the diaminophenyl ring due to increased hydrophobic interaction. The energetics of gas phase optimized and stable MD structures of BBY indicated similar values which further confirmed that the conformational changes were minor, and it also exhibited a moderate binding with BSA as shown by the MM/PBSA results. This study enhances our understanding of the molecular-level interactions between BBY and BSA, emphasizing the critical role of hydrophobic interactions.

The role of Colchicine on actin polymerization dynamics: as a potent anti-angiogenic factor

Over the years, cancer research has focused on different strategies to discover drugs and therapies to treat the metastatic stage of cancer. This stage depends upon the type, and the cause of cancer. One of the central facts about any cancer invasion is the formation of new blood vessels that provide nutrients to these uncontrollably dividing cells. This phenomenon is called angiogenesis and is responsible for tumor progression and metastasis. Tumor angiogenesis is a sequential process wherein various angiogenic factors produced by tumor cells bind to receptors of endothelial cells. This stimulates the cytoskeletal protein, especially actin to reorganize themselves and undergo the process of canalization. The driving force for such membrane transformation is spatially and temporally-regulated by polymerization of submembrane actin filaments. So far, Colchicine has been studied for its effectiveness in controlling microtubule reorganization during cell division, but its role is far from understood on actin polymerization. In our current study, we report the effect of Colchicine on actin polymerization dynamics using biophysical analysis like Right light scattering (RLS), Dynamic light scattering (DLS), Circular dichroism (CD) analysis, Scanning electron microscopy (SEM) study. Isothermal titration calorimetry (ITC) and kinetic measurements. Isothermal titration calorimetry (ITC) indicates multiple site binding for colchicine with actin aggregates. We have checked the in vivo effect of colchicine using end3 cells of Saccharomyces cerevisiae. We also report the anti-angiogenesis activity of colchicine via ex-ovo chicken chorioallantoic membrane (CAM) assay. We predict the target site of binding for the drug by docking studies. Based on our findings, we suggest the 'drug-repurposed' function for colchicine as a potential anti-angiogenic candidate.Communicated by Ramaswamy H. Sarma.

Elucidation of binding mechanism of stigmasterol with human serum albumin: a biophysical and molecular dynamics simulation approach

In the present study, we have analyzed the interaction of a phytochemical, stigmasterol (Stig), with human serum albumin (HSA) under physiological conditions using fluorescence quenching, circular dichroism and molecular modeling methods. Cytotoxic studies with Stig in mouse macrophages (RAW 246.7) and HeLa cell lines showed anti-inflammatory and anti-cancer properties. Further, the intrinsic fluorescence of HSA was quenched by Stig, which was considered a static quenching mechanism. The site-specific marker experiments revealed that Stig binds to the IIIA subdomain of HSA with a binding constant of K_Stig=1.8 ± 0.03 × 10⁵ M^-1 and free energy of -7.26 ± 0.031 Kcal/mol. The secondary structure of HSA was partially unfolded after binding of Stig, which indicates an alteration in the microenvironment of the protein binding site. Molecular docking experiments found that Stig binds strongly with HSA at the IIIA domain of the hydrophobic pocket with one hydrogen bond. The rigidity of the protein-Stig complex and free energies were analyzed by molecular dynamic simulation (MDS) for 100 ns, where the HSA-Stig was stabilized after 40 ns. MDS studies revealed that HSA does not significantly change the secondary structure when it binds with Stig, which is in agreement with the circular dichroism data. Overall, the results obtained gave qualitative and quantitative insight into the binding interaction between HSA and Stig, which is essential in understanding the latter as a therapeutic molecule.Communicated by Ramaswamy H. Sarma.

Biological activity of bis-(morpholineacetato)palladium(II) complex: Preparation, structural elucidation, cytotoxicity, DNA-/serum albumin-interaction, density functional theory, in-silico prediction and molecular modeling

In an effort to discover a novel potential bioactive compound, a mono-nuclear Pd(II) complex with an amino acid derivative as ligand was synthesized and characterized through experimental and computational methodologies. A square-planar configuration was suggested for palladium(II) complex utilizing density functional theory. MEP map and Mulliken atomic charge were detected electrophilic and nucleophilic regions of the compound for reactions. The lipophilicity and cytotoxic activity of the complex was more effective than cisplatin. Also, OSIRIS DataWarrior revealed proper oral bioavailability and good drug-likeness for the compound. In-vitro binding behavior of the Pd(II) complex with DNA and serum albumin (BSA) were fully determined via variety of procedures including fluorescence, UV-Vis, CD, viscosity, gel electrophoresis experiments and molecular simulation. The negative signs of ΔH° and ΔS° for Pd(II) complex-CT-DNA/-BSA systems indicated the existence of hydrogen bonding/van der Waals interactions for both binding systems. Additionally, docking simulation illustrated the interaction of Pd(II) complex with the minor groove of DNA and the hydrophobic cavity of the BSA (drug binding site I).

Multi-spectroscopic, thermodynamic, and molecular docking/dynamic approaches for characterization of the binding interaction between calf thymus DNA and palbociclib

Studying the binding interaction between biological macromolecules and small molecules has formed the core of different research aspects. The interaction of palbociclib with calf thymus DNA at simulated physiological conditions (pH 7.4) was studied using different approaches, including spectrophotometry, spectrofluorimetry, FT-IR spectroscopy, viscosity measurements, ionic strength measurements, thermodynamic, molecular dynamic simulation, and docking studies. The obtained findings showed an apparent binding interaction between palbociclib and calf thymus DNA. Groove binding mode was confirmed from the findings of competitive binding studies with ethidium bromide or rhodamine B, UV–Vis spectrophotometry, and viscosity assessment. The binding constant (K_b) at 298 K calculated from the Benesi–Hildebrand equation was found to be 6.42 × 10³ M⁻¹. The enthalpy and entropy changes (∆H⁰ and ∆S⁰) were − 33.09 kJ mol⁻¹ and 61.78 J mol⁻¹ K⁻¹, respectively, showing that hydrophobic and hydrogen bonds constitute the primary binding forces. As indicated by the molecular docking results, palbociclib fits into the AT-rich region of the B-DNA minor groove with four base pairs long binding site. The dynamic performance and stability of the formed complex were also evaluated using molecular dynamic simulation studies. The in vitro study of the intermolecular binding interaction of palbociclib with calf thymus DNA could guide future clinical and pharmacological studies for the rational drug scheming with enhanced or more selective activity and greater efficacy.

Imperative persistent interaction analysis of anticancer noscapine-ionic liquid with calf thymus DNA

In this study, we have shown the interaction between opium poppy alkaloid noscapine-based ionic liquid [Pip-Nos]OTf and ct-DNA using UV-visible absorption spectroscopy, fluorescence spectroscopy, CD, and computational studies. The absorption spectra showed a hypochromic shift with no shift in the absorption maxima suggesting groove or electrostatic binding. Fluorescence spectra showed an enhancement in fluorescence emission suggesting that the probable mode of binding should be groove binding. Ethidium bromide (EB) competitive and Ionic strength study showed the absence of intercalative and electrostatic modes of interaction. Further, CD analysis of ct-DNA suggested a groove binding mode of interaction of [Pip-Nos]OTf with ct-DNA. [Pip-Nos]OTf displayed a strong binding with the target ct-DNA with a molecular docking score of -41.47 kJ/mol with all 3D coordinates and full conformation. Also, molecular binding contact analyses depicted the stable binding of drug and ct-DNA with potential hydrogen bonds and hydrophobic interactions. The structural superimposition dynamics analysis showed the stable binding of [Pip-Nos]OTf with the ct-DNA model through RMSD statistics. Moreover, the ligand interaction calculations revealed the involvement of large binding energy along with a high static number of molecular forces including the hydrogen bonds and hydrophobic interactions in their complexation. These significant results report the potency of [Pip-Nos]OTf and its important futuristic role in cancer therapeutics.

DLPF Targeted Repetitive Transcranial Magnetic Stimulation Improves Brain Glucose Metabolism Along with the Clinical and Electrophysiological Parameters in CBD Patients

BACKGROUND

Corticobasal Degeneration (CBD) is a rare neurological disease caused by the pathological accumulation of tau protein. The primary pathological features of CBD include progressive neurodegenerative processes resulting in remarkable frontoparietal and basal ganglia atrophy.

OBJECTIVE

Like in many other neurodegenerative disorders, there is still no effective disease-modifying drug therapy in CBD. Therefore, the development of new treatment methods is of great importance. In this study, we aimed to assess the stimulating effects of high-frequency DLPFC rTMS on the motor, cognitive and behavioral disturbances in four CBD patients.

METHODS

Four (three females, one male) CBD patients who had been diagnosed as CBD were enrolled in this study. Patients were evaluated before and after the rTMS procedure regarding the motor, neuropsychometric and behavioral tests. The results of statistical analysis of behavioral and neuropsychometric evaluation were assessed via SPSS 18.0 package program. Data are expressed as mean, standard deviation. Before and after values of the groups were compared with the Wilcoxon sign rank test, and p<0.05 was considered significant.

RESULTS

We have provided strong preliminary evidence that the improvement in clinical parameters was associated with the normalizations of the theta activity and glucose metabolism.

CONCLUSION

Our current results are consistent with some previous trials showing a strong association between DLPFC targeted rTMS and electrophysiological normalizations in the left DLPFC.

Fabrication and characterization of octenyl succinic anhydride modified pullulan micelles for encapsulating curcumin

BACKGROUND

Curcumin has become increasingly popular in functional foods and beverages field as a result of its high biological activity. Nevertheless, the application of curcumin is usually limited by its poor water solubility, low absorption, rapid metabolism and instability. Accordingly, the development of an appropriate wall material is crucial for its effective use. In the present study, curcumin-octenyl succinic anhydride modified pullulan (Cur-OSAP) micelles were successfully prepared by an anti-solvent co-precipitation method.

RESULTS

Octenyl succinic anhydride modified pullulan (OSAP) micelles exhibited the highest encapsulation efficiency (57.31%) and loading capacity (5.73%) of curcumin when the mass ratio of OSAP to curcumin was 10:1 and the degree of substitution of OSAP was 0.0469, at which point Cur-OSAP micelles formed via hydrogen binding and hydrophobic interactions, as confirmed by Fourier transform infrared and fluorescence techniques. The transmission electron microscopy results showed that the Cur-OSAP micelles were roughly spherical in shape with diameters in the approximate range 30-60 nm.

CONCLUSION

The encapsulation of OSAP greatly improved photostability and sustained release properties of curcumin in Cur-OSAP micelles. These findings suggest that OSAP can be used as a carrier to encapsulate and protect hydrophobic food ingredients. © 2021 Society of Chemical Industry.

Interaction of Synthetic Pyrethroid Insecticide Deltamethrin with Human Alpha-2-Macroglobulin: Spectroscopic and Molecular Docking Studies

Background:

Deltamethrin (DLM) is a commercial insecticide of the synthetic pyrethroid family that is used to control disease-causing insects and vectors. When humans are exposed to the fumes or aerosols of DLM, it enters the body via cuticular absorption and reacts with proteins and other biomolecules.

Objective:

Alpha-2-macroglobulin (α2M) is a serum proteinase inhibitor that also carries out receptor- mediated endocytosis of extracellular substances. This study was done to decipher the structural and functional alterations of α2M by DLM.

Method:

Various spectroscopic techniques, including UV absorption and fluorescence spectroscopy, binding studies, and molecular docking, were used to characterize the interaction of DLM with α2M. The affinity constant was calculated from the Stern-Volmer equation using fluorescence data.

Results:

The UV-Vis and fluorescence spectral studies indicated the formation of a complex between α2M and DLM. Thermodynamically, the interaction was found to be spontaneous with ΔG = -4.23 kcal/mol. CD spectra suggested a change in the secondary structure of the protein from β to α helical content with increasing concentration of DLM. The molecular docking study by Autodock Vina established the interaction of DLM with Glu-926, Ala-1103, Ala-1108, Val-1116, Asn-1159, Glu-1220, Leu-1261, Thr-1272, Ile-1390, Pro-1391, Lys-1393, Val-1396, Lys-1397, Thr-1408, Glu-1409, Val-1410, Ser-1411, Ser-1412, and Asn-1413 with an improved docking score of -6.191 kcal/mol. The binding was carried out in the vicinity of the receptor-binding domain at the C-terminal of α2M.

Conclusion:

The decrease in the functional activity and structural changes of protein after binding with DLM has a significant effect on human α2M. The information may be useful for exploring the role of DLM in a clinical chemistry laboratory.

Investigation of binding characteristics of ritonavir with calf thymus DNA with the help of spectroscopic techniques and molecular simulation

The binding behavior of ritonavir (RTV), a HIV/AIDS protease inhibitor, with ct-DNA was characterized through multiple testing technologies and theoretical calculation. The findings revealed that the RTV-DNA complex was formed through the noncovalent interaction mainly including conventional hydrogen bonds and carbon hydrogen bonds as well as hydrophobic interactions (pi-alkyl interactions). The stoichiometry and binding constant of the RTV-DNA complex were 1:1 and 1.87 × 10³ M^-1 at 298 K, respectively, indicating that RTV has moderate affinity with ct-DNA. The findings confirmed that RTV binds to the minor groove of DNA. The outcomes of CD experiments showed that the binding with RTV changed the conformation of DNA slightly. However, the conformation of RTV had obvious changes after binding to DNA, meaning that the flexibility of RTV molecule played an important role in stabilizing the RTV-DNA complex. Meanwhile, the results of DFT calculation revealed that the RTV and DNA interaction caused the changes in the frontier molecular orbitals, dipole moment and atomic charge distribution of RTV, altering the chemical properties of RTV when it bound to DNA. Communicated by Ramaswamy H. Sarma.

Elucidating the binding mechanism of an antimigraine agent with a model protein: insights from molecular spectroscopic, calorimetric and computational approaches

Sumatriptan (SUM), a serotonin activator used to treat migraines and cluster headaches. Molecular spectroscopic methods including fluorescence quenching, time dependent fluorescence, FRET, absorption, circular dichroism, differential scanning calorimetric and computational approaches were employed to unravel the interaction between sumatriptan and bovine serum albumin (BSA). The fluorescence quenching studies suggested the interaction between SUM and BSA with a moderate binding with the binding constant (K_b) in the order of 10⁴. The findings of temperature and time dependent fluorescence quenching studies confirmed the role of static quenching mechanism. Thermodynamic parameters suggested the key role of electrostatic force in the interaction of SUM with BSA. Absorption and CD spectral studies revealed the bioenvironmental changes around the Trp in BSA upon binding of SUM. Calorimetric based thermal denaturation results confirmed that the thermal stability of BSA was improved in the presence of SUM. resulted in the this decreased flexibility of protein chain. Site competitive studies indicated SUM was located in the hydrophobic cavity of site I which was further confirmed by the docking and dynamic simulation studies. Additionally, molecular dynamics simulations inferred the microenvironmental condition around the SUM and the amino acids and forces involved in the binding of SUM with BSA.Communicated by Ramaswamy H. Sarma.

Benzothiazole Pyrazoline: Acid-Switchable Absorption and Fluorescence of Photoinduced Electron Transfer (PET)

Acid-responsive fluorescent compounds were prepared by introducing an ortho-hydroxyphenyl to pyrazoline with a benzothiazole backbone. These compounds demonstrated normal fluorescence photoinduced electron transfer (PET) under neutral conditions but the addition of trifluoroacetic acid showed an arctic blue fluorescence, we verified that a protonation process of nitrogen in the thiazole ring which weakened the ability of thiazole to donate electrons to the pyrazoline and changed the photoinduced electron transfer led to photoinduced electron transfer (PET), which was the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. The photophysical properties of Benzothiazole pyrazoline exhibited blue emission at 421 nm in aqueous DMSO. The blue shift in the emission was switched by acid in DMSO, showing the compound's distinct fluorescence peak at 554 nm. To investigate solvatochromism, eight different solvents were used. The red-shift emission observed in enhancing the polarity of solvents and emission in DMSO suggested the conformation of the molecule which led to the intramolecular charge transfer by color and emission changes. Furthermore, the probe was also applied using the High-performance liquid chromatography (HPLC) with a UV detector to determine the trifluoroacetic acid in water samples. Interestingly, the method was found to be linear over the range of 10.0 µg L^-1 to 250.0 µg L^-1 (0.999). Under the optimum condition, the separation of trifluoroacetic acid was achieved in 20 min with the LOD of 1.3 µg L^-1 and LOQ of 5.1 µg L^-1. This proposed method also showed satisfactory results when applied for the analysis of trifluoroacetic acid in a water sample.

Synthesis, crystal structures, DNA interactions, and antitumor activity of two new dinuclear copper(ii) complexes with thiazole ligand

Two new dinuclear copper(ii) complexes, [Cu(ambt)2(cnba)4] (1) and [Cu(ambt)2(clba)4] (2) were synthesized with 2-amino-6-methoxybenzothiazole (ambt) as the main ligand. The structures of the two complexes were characterized by single-crystal XRD. The binding between CT-DNA (calf thymus DNA) and the complexes was evaluated by viscometry, electronic absorption, and fluorescence spectroscopy, and the binding constants were calculated using the Stern-Volmer equation. The complexes were intercalatively bound to CT-DNA, and [Cu(ambt)2(clba)4] having a greater binding constant than [Cu(ambt)2(cnba)4]. The two complexes had better antitumor properties against HepG2 (human hepatocellular carcinoma), A549 (human lung carcinoma), and HeLa (human cervical carcinoma) tumor cell lines than their respective ligands and cisplatin. Furthermore, [Cu(ambt)2(clba)4] had a stronger inhibitory ability on the three types of tumor cells than [Cu(ambt)2(cnba)4], which is congruent with the binding power of the complexes with DNA. Flow cytometry revealed that [Cu(ambt)2(cnba)4] and [Cu(ambt)2(clba)4] could trigger apoptosis or necrosis, arrest the HepG2 cell cycles, and cause G0/G1-phase cells to accumulate.

Evaluation of the binding effect and cytotoxicity assay of 2-Ethyl-5-(4-methylphenyl) pyramido pyrazole ophthalazine trione on calf thymus DNA: spectroscopic, calorimetric, and molecular dynamics approaches

With advances in new drug therapies, it is essential to understand the interactions between drugs and target molecules. In this study, we applied multiple spectroscopic techniques including absorbance, fluorescence, circular dichroism spectroscopy, viscosity, thermal melting, calorimetric, and molecular dynamics (MD) simulation to study the interaction between 2-Ethyl-5-(4-methylphenyl) pyramido pyrazole ophthalazine trione (PPF) and calf thymus DNA (ct DNA) in the absence or presence of histone H1. PPF exhibits a high binding affinity towards ct DNA in binary and ternary systems. In addition, the result for the binding constant was observed within the range 10⁴  M^-1 achieved through fluorescence quenching data, while the values for enthalpy and entropy changes for ct DNA-PPF and (ct DNA-H1) PPF complexes were measured to be -72.54 kJ.mol^-1 , -161.14 J.mol^-1  K^-1 , -85.34 kJ.mol^-1 , and -19.023 J.mol^-1  K^-1 , respectively. Furthermore, in accordance with circular dichroism spectra, the inducement of ct DNA structural changes was observed during binding of PPF and H1 in binary and ternary system forms. The essential roles of hydrogen bonding and van der Waals forces throughout the interaction were suggested using thermodynamic parameters. According to the obtained data, the interaction mode of ct DNA-PPF and (ct DNA-H1) PPF complexes was intercalation binding. Suggested by the MD simulation study, the ct DNA-H1 complex caused a reduction in the stability of the DNA structure in the presence or absence of ligand, which demonstrated that PPF as an intercalating agent can further distort the structure. The information achieved from this study will be very helpful in understanding the effects of PPF on the conformational state of ct DNA in the absence or presence of the H1 molecule, which seems to be quite significant for clarifying the mechanisms of action and its pharmacokinetics.

Factorial design-assisted spectroscopic determination of oxybutynin hydrochloride

In this study, we have developed two facile spectroscopic methods for quantifying oxybutynin (OBT) hydrochloride in its pure form and tablets using design of experiments (DOEs). The spectroscopic methods depended on the ion-pair complex formation between the tertiary amino group in the drug and eosin in 0.2 M acetate buffer of pH 4. Method I involves spectrophotometric measurement of the absorbance of the developed complex at 550 nm and showed linearity through 1.0-10.0 µg ml-1. Method II involves spectrofluorometric measurement of the quenching influence of OBT on the native fluorescence of eosin (λ excitation/λ emission of 304/548 nm) and showed linearity through 1.0-6.0 µg ml-1. Critical parameters were identified through preliminary trials and optimized using the DOE. Additionally, the quenching mechanism was investigated and the pathway of the reaction was postulated. The fluorescence quenching constant and thermodynamic parameters were explored using the Stern-Volmer plot and Van't Hoff graph, respectively. Assessments conducted via analytical ecoscale revealed the 'excellent-greenness' of the methodology. The two methods have the potentials of being green and fast compared with other reported methods.

Surgical wounds in reduction mammoplasty: a comparison of Monocryl and Prolene sutures on scars

OBJECTIVE

The type of suture material affects the quality of scars. The aim of this study was to find the superior suture material for reduction mammoplasty between Prolene and Monocryl based on the comparison of scars.

METHOD

A prospective observational study was conducted at a university-based hospital in Mashhad, Iran between October 2015 and September 2017. Monocryl and Prolene suture materials, used for closing the outermost layer in mammoplasty, were compared. Patients' incision scars were assessed objectively according to the Patient and Observer Scar Assessment (POSAS) criteria. The relevant CONSORT guideline was used for reporting this study.

RESULTS

Seventy-eight women with a mean age of 36.8±9.5 years were entered into the study. The frequency of wound healing in both groups was 97.4% 1 month after surgery and by the third visit, 3 months after surgery, only one patient had a stretched scar. Moreover, wound inflammation in the first two visits was less frequent in the Prolene group that healed completely 3 months after surgery (after excluding the one patient with wide scar inflammation). The frequency of itching of the wound in the Monocryl group was 24.4%, 11.5% and 12.8% in the three follow-up visits, respectively, and the values for the Prolene group were 24.4%, 9.0% and 6.4%, respectively. No significant difference was seen between the two groups in terms of wound healing, inflammation and itching (p>0.05). Overall, 94.8% of patients were satisfied with the surgery.

CONCLUSIONS

Our study revealed that there was no significant difference between Monocryl and Prolene. Hence, either of the two suture materials can be used for wound closure in reduction mammoplasty.

Surfactant efficiency on pentachlorophenol-contaminated wastewater enhanced by Pseudomonas putida AJ 785569

This study aims to evaluate the effect of three surfactants on the removal of PCP (800 mg L^-1) from Secondary Treated Wastewater (STWW) by Pseudomonas putida AJ 785569. The effect of surfactants [sodium lauryl sulfate (SDS) as anionic, Tween 80 (TW80) as non-anionic and cetyltrimethylammonium bromide (CTAB) as cationic] is tested about the three following aspects: (1) bacterial growth, (2) bacterial biofilm formation or development and (3) PCP rate removal. The results showed that strain P. putida AJ 785569 could adsorb around 30 mg L^-1 and remove 600 mg L^-1 of PCP within 168 h of incubation. The SDS developed the growth of bacteria and the removal of PCP. This PCP removal in mineral salt medium (MSM) is around 760 mg L^-1 (95% degradation) higher than the ones registered with CTAB and TW80 with a value 506.75 (63% degradation) and 364.1 mg L^-1 (45% degradation), respectively. The obtained results of chloride concentration showed an important relation with PCP removal during incubation with an important value. Monitoring the development of bacterial biofilm, in MSM medium added with PCP (100 mg L^-1) by strain P. putida AJ 785569, showed a significant increase in the optical density value from 0.9 to 4 at λ = 595 nm, a modification of strain P. putida AJ 785569's morphotype, density and color colonies.

Early-stage culprit in protein misfolding diseases investigated using electrochemical parameters: New insights over peptide-membrane interactions

The dysfunctioning of β-cells caused by the unspecific misfolding of the human islet amyloid polypeptide (hIAPP) at the membrane results in type 2 diabetes mellitus. Here, we report for the first time, the early-stage interaction of hIAPP oligomers on the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) lipid membrane using electrochemical parameters. Electrochemical techniques are better than other techniques to detect hIAPP at significantly lower concentrations. The surface level interactions between the peptide (hIAPP) and lipid membrane (DMPC) were investigated using atomic force microscopy (AFM), confocal microscopy (CM) and electrochemical techniques such as Tafel polarization, cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Inserting IAPP into the fluid domains results in breaking the lipid-to-lipid interaction, leading to restriction of membrane mobility. The S_Lateral values of the liposome and IAPP co-solubilized liposome indicates the cooperative insertion of IAPP. Further, a new method of immobilizing a membrane to the gold surface has been employed, resulting in an electrical contact with the buffer, preventing the direct utilization of a steady-state voltage across the bilayer. The electrochemical studies revealed that the charge transfer resistance decreased for 3-mercaptopropanoic acid modified gold (MPA-Au) electrode coated with the liposome and after the addition of IAPP, followed by an increase in the capacitance. The present study has opened up new dimensions to the understanding of peptide-membrane interactions and shows different experimental approaches for the future researchers in this domain.

Insights on the interaction mechanism of exemestane to three digestive enzymes by multi-spectroscopy and molecular docking

Exemestane is an irreversible steroidal aromatase inhibitor, typically used to treat breast cancer. As an anti-tumor drug, exemestane has more obvious side effects on the gastrointestinal tract. The purpose of this work is to investigate the combination of exemestane with three important digestive enzymes including pepsin (Pep), trypsin (Try) and α-Chymotrypsin (α-ChT) so as to analyze the mechanism of the gastrointestinal adverse effects causing by exemestane binding. Enzyme activity experiment showed that the enzyme activity of Pep was decreased in the presence of exemestane. Fluorescence spectra revealed that exemestane formed stable complexes with digestive enzymes, and the quenching mechanism of drug-digestive enzymes interaction were all static quenching. The binding constants of Pep, Try and α-ChT at 298 K were 2.34 × 10⁵, 1.45 × 10⁵, and 2.05 × 10⁵ M^-1, respectively. Synchronous fluorescence and 3D fluorescence spectroscopy showed that the conformation of exemestane was slightly changed after combining with digestive enzymes, and non-radiative energy transfer occurred. Circular dichroism results indicated that exemestane could change the secondary structure of digestive enzymes via increase the α-helix content and decrease in the β-sheet content. Thermodynamic parameters (ΔH⁰, ΔS⁰, and ΔG⁰) revealed that exemestane interacted with α-ChT through electrostatic force, and the binding force with Pep and Try was van der Waals interactions and hydrogen, which was basically consistent with the molecular docking results.

Binding and drug displacement study of colchicine and bovine serum albumin in presence of azithromycin using multispectroscopic techniques and molecular dynamic simulation

The binding and displacement interaction of colchicine and azithromycin to the model transport protein bovine serum albumin (BSA) was evaluated in this study. Azithromycin, a macrolide antibiotic, has antiviral properties and hence, has been used concomitantly with hydroxychloroquine against SARS-CoV-2. Colchicine, a natural plant product is used to treat and prevent acute gout flares. Some macrolide antibiotics are reported to have fatal drug-drug interactions with colchicine. The displacement interaction between colchicine and azithromycin on binding to BSA was evaluated using spectroscopic techniques, molecular docking and molecular dynamic simulation studies. The binding constant recorded for the binary system BSA-colchicine was 7.44 × 104 whereas, the binding constant for the ternary system BSA-colchicine in presence of azithromycin was 7.38 × 104 and were similar. Azithromycin didn't bind to BSA neither did it interfere in binding of colchicine. The results from molecular docking studies also led to a similar conclusion that azithromycin didn't interfere in the binding of colchicine to BSA. These findings are important since there is possibility of serious adverse event with co-administration of colchicine and azithromycin in patients with underlying gouty arthritis and these patients need to be continuously monitored for colchicine toxicity.

Immunoadjunctive Therapy against Bacterial Infections Using Herbal Medicines Based on Th17 Cell-mediated Protective Immunity

One of the major health concerns in the world is the global increase in intractable bacterial infectious diseases due to the emergence of multi- and extensively drug-resistant bacterial pathogens as well as an increase in compromised hosts around the world. Particularly, in the case of mycobacteriosis, the high incidence of tuberculosis in developing countries, resurgence of tuberculosis in industrialized countries, and increase in the prevalence of Mycobacterium avium complex infections are important worldwide health concerns. However, the development of novel antimycobacterial drugs is currently making slow progress. Therefore, it is considered that devising improved administration protocols for clinical treatment against refractory mycobacteriosis using existing chemotherapeutics is more practical than awaiting the development of new antimycobacterial drugs. The regulation of host immune responses using immunoadjunctive agents may increase the efficacy of antimicrobial treatment against mycobacteriosis. The same situations also exist in cases of intractable infectious diseases due to common bacteria other than mycobacteria. The mild and long-term up-regulation of host immune reactions in hosts with intractable chronic bacterial infections, using herbal medicines and medicinal plants, may be beneficial for such immunoadjunctive therapy. This review describes the current status regarding basic and clinical studies on therapeutic regimens using herbal medicines, useful for the clinical treatment of patients with intractable bacterial infections. In particular, we focus on immunoadjunctive effects of herbal medicines on the establishment and manifestation of host antibacterial immunity related to the immunological roles of Th17 cell lineages.

Spectroscopic studies of simultaneous binding of cyclophosphamide and imatinib mesylate to human holo-transferrin

The interactions of proteins with drugs are very important from a pharmacological point of view. Holo-transferrin is a blood-plasma glycoprotein whose main function is iron-binding and the transport of other ligands. Additionally, the protein is only transferrin-form recognized by TfR1 and TfR2 receptors at the surface of rapidly proliferating malignant cells. Imatinib mesylate is a tyrosine-kinase inhibitor mainly used in the treatment of blood cancers, frequently in multidrug therapy with cyclophosphamide. In this study the effect of cyclophosphamide on the interaction of imatinib mesylate with human holo-transferrin has been investigated. Using spectroscopic techniques such as fluorescence, circular dichroism, ultraviolet-visible and electrophoretic light scattering additive parameters, system stability and the effect of the ligands on the protein conformation at varying pH values have been defined. Calculated quenching constants are in the order of 2 × 10⁴ M^-1 and the type of interaction depends on the reaction medium. Under physiological conditions binding constant is 1.329 × 10⁶ M^-1 whereas in an environment similar to that of cancer cells the constant is significantly lower, K_a = 6.060 × 10⁴ M^-1. N values are approximate to 1 in all cases. Moreover, some changes are observed in the α-helical structure of the protein after interaction with the drugs and the presence of cyclophosphamide slightly stabilizes the protein secondary structure. All collected data proves the effect of cyclophosphamide on the interaction between imatinib mesylate and human holo-transferrin. It is of great clinical interest due to anticancer, multidrug therapies including both imatinib mesylate and cyclophosphamide.

Inhibitory effect of lignin from Canna edulis Ker residues on trypsin: kinetics and molecular docking studies

BACKGROUND

Lignin extracted from Canna edulis Ker residues shows a strong inhibitory effect on α-glucosidase and a promoting effect on α-amylase. Protease activity inhibition may play a key role in disease processes, such as metastasis, tumor invasion and bacterial colonization. Hence, in the present study, the inhibitory mechanism of lignin on trypsin was examined, including the interaction type, thermodynamic parameters, structure, reaction site and molecular docking.

RESULTS

The isolated lignin presented an inhibitory effect on trypsin activity with an IC₅₀ value of 1.35 μmol L^-1 . This inhibition was a mixed linear type with a constant K_i of 3.92 μmol L^-1 . The lignin could bind with the key amino acid residue Ser195 on the active site of the trypsin molecule to inhibit its activity, and the phenolic hydroxyl group and -OH on the β-O-4 structure of the lignin molecule were the major groups bound with trypsin.

CONCLUSION

These results illustrate the inhibitory effects of Canna edulis residue lignin on protease, which helps with respect to understanding the possible application of lignin in the food industry in functional foods. © 2020 Society of Chemical Industry.

Investigations of the molecular mechanism of diltiazem binding to human serum albumin in the presence of metal ions, glucose and urea

The molecular mechanism and thermodynamic properties of the interaction between diltiazem (DTZ) and human serum albumin (HSA), has been studied in vitro using spectroscopic techniques (UV-Vis, fluorescence, FTIR), and molecular docking methods. The effect of acidic and basic pH, glucose, urea, and metal ions on the DTZ-HSA binding has been investigated as well. According to the results, there is a 1:1 interaction between DTZ and HSA, while the quenching mechanism is static up to 313 K. The apparent binding constant was 2.09 × 10⁶ M^-1 that indicates a strong binding between DTZ and HSA. DTZ binding was increased in acidic pH while its binding was slowly decreased in the presence of glucose, urea, and metal ions. Thermodynamic studies showed that DTZ binds to HSA via an exothermic and spontaneous reaction via hydrogen bonding and electrostatic interactions. The conformational alteration of HSA is obvious according to the FTIR study. The site marker competitive study confirmed the binding of DTZ to the warfarin binding site. Molecular docking studies showed that DTZ binds to subdomain IB (-9.22 kcal mol^-1) and subdomain IIIA (-9.03 kcal mol^-1) with a higher tendency. Also, the results showed that the oxygen and nitrogen atoms of hydroxyl and amino functional groups of DTZ facilitate hydrogen bond formation. HighlightsStrong binding of diltiazem to HSA was studied and confirmed by fluorescence quenching titrations.Diltiazem binding to HSA reduces in the presence of metal ions, glucose, urea and alkaline pH.Diltiazem binding to HSA is exothermic and spontaneous.

Interaction of organophosphate pesticide chlorpyrifos with alpha-2-macroglobulin: Biophysical and molecular docking approach

Organophosphate class of pesticides causes neurotoxicity and carcinogenicity in humans. Once inside the human body, these pesticides often interact with plasma proteins, such as alpha-2-macroglobulin (α₂M) which is the key anti-proteinase. Our work focuses on the structural and functional alteration of α₂M by chlorpyrifos (CPF), a member of organophosphates. We explored the binding interaction between alpha-2-macroglobulin and CPF by using UV absorption and fluorescence spectroscopy (steady state and synchronous), circular dichroism and molecular docking approach. The functional activity of α₂M was analyzed by anti-proteinase trypsin inhibitory assay which showed dose-dependent decrease in alpha-2-macroglobulin antiproteolytic potential. UV absorption studies and fluorescence quenching experiments suggested the formation of a complex between α₂M and CPF. The CD spectra suggested a reduction in the beta helical (β helix) content of α₂M. Analysis of thermodynamic parameters suggested the process is spontaneous and endothermic with the ΔG and ΔH values being -5.501 kJ/mol, 11.49 kJ/mol, respectively. CPF binds with Ile-1390, Pro-1391, Leu-1392, Lys-1393, Val-1396, Lys-1397, Arg-1407, Thr-1408, Glu-1409, Val-1410, Asp-282, Glu-281 of α₂M as suggested by molecular docking.

Preparation and characterization of iron-chelating peptides from whey protein: An alternative approach for chemical iron fortification

Iron fortification of staple food is a strategy utilized worldwide to address the concern of dietary iron deficiency. However, traditional salt-based fortification methods have limitations with gastrointestinal stability and bioavailability. Iron chelating peptides from easily available and scalable proteins such as whey protein have been proposed as promising candidates to circumvent the above mentioned limitations by enhancing iron absorption and bioavailability. In this study, we report methods to produce whey protein derived iron-chelating peptides and describe their physicochemical characteristics. Peptides derived from whey proteins prepared by ultrafiltration of whey followed by hydrolysation were iron chelated to produce peptide-iron complexes. These complexes had a size of 422.9 ± 3.41 nm, chelated iron content of 36.42 µg/ mg protein, and a low zeta potential (-10.80 mV) compared to whey peptides. Spectra analysis using ultraviolet-visible absorption and Fourier transform infrared spectroscopy showed structural transformation indicating iron chelation. Mass spectrometric analysis using LC-MS/MS confirmed the presence of both hydrophilic and hydrophobic peptides in the complexes with sizes ranging from 275 Da to 1916 Da. Furthermore, reduction in the antioxidant property of peptides following iron complexing indicates iron chelation. Our results suggest that whey protein derived peptide-iron complexes can be used as a potential alternative for chemical iron fortificants for food products and also as iron supplements.

Investigation into the site-specific binding interactions between chlorogenic acid and ovalbumin using multi-spectroscopic and in silico simulation studies

The binding interactions of bioactive compounds with proteins are of great importance in the food, biochemistry and pharmaceutical fields. Herein, the binding mechanisms between 5-O-caffeoylquinic acid (5-CQA) and ovalbumin (OVA) were investigated by multi-spectroscopic studies combined with docking and molecular dynamics (MD) simulations. The emission intensity of OVA was quenched by 5-CQA and Stern-Volmer analysis indicated the existence of a static suppression by OVA-5-CQA complex formation. Thermodynamic parameters revealed that the formation of complex was spontaneously driven by electrostatic and hydrogen-bonding interactions. Circle dichroism analyses showed that 5-CQA decreased the α-helix content of OVA structure from 58.05% to 54.32% upon increased OVA:5-CQA ratio to 1:3. Molecular docking results suggested 5-CQA forms hydrogen bond interactions with N88, T91, K92, N94, S98, F99, S100 and L101 residues of OVA. The experimental values were in good agreement with the calculated binding free energy values obtained by MD simulation (R² = 0.89).Communicated by Ramaswamy H. Sarma.

Studies to explore the UVA photosensitizing action of 9-phenylacridine in cells by interaction with DNA

Acridine and its derivatives are well known for their DNA binding properties. In this report, we present our findings on evaluating different binding parameters of the interaction of 9-phenylacridine (ACPH) with DNA. Absorption spectroscopic studies including standard and reverse titration, the effects of ionic strength and temperature on titration, and Job plot analysis were done to calculate the binding constant and determine the different thermodynamic parameters and stoichiometry of the binding. Spectrofluorimetry and circular dichroism (CD) spectral titration were also utilized to confirm these findings. The results indicated that ACPH binds to DNA reversibly through non-electrostatic interactions by hydrogen bonding and van der Waals interactions. The binding constant and the number of binding sites were of the order 10³ M^-1 and ≈2, respectively with a binding stoichiometry of 1:4. The binding of ACPH with DNA was spontaneous, exothermic and enthalpy-driven. The extent of uptake of ACPH in B16 melanoma cells was estimated. As this compound absorbs in the UVA region, the effect of treatment with ACPH prior to UVA exposure was assessed to evaluate its phototoxicity in these cells. Our results indicated that the binding to DNA enhanced damage to sensitize cells to killing through apoptosis. Our findings indicated its potential to act as a photosensitizer.

Novel pH-responsive nanohybrid for simultaneous delivery of doxorubicin and paclitaxel: an in-silico insight

BACKGROUND

The distribution of drugs could not be controlled in the conventional delivery systems. This has led to the developing of a specific nanoparticle-based delivery system, called smart drug delivery systems. In cancer therapy, innovative biocompatible nanocarriers have received much attention for various ranges of anti-cancer drugs. In this work, the effect of an interesting and novel copolymer named "dimethyl acrylamide-trimethyl chitosan" was investigated on delivery of paclitaxel and doxorubicin applying carboxylated fullerene nanohybrid. The current study was run via molecular dynamics simulation and quantum calculations based on the acidic pH differences between cancerous microenvironment and normal tissues. Furthermore, hydrogen bonds, radius of gyration, and nanoparticle interaction energies were studied here. Stimulatingly, a simultaneous pH and temperature-responsive system were proposed for paclitaxel and doxorubicin for a co-polymer. A pH-responsive and thermal responsive copolymer were utilized based on trimethyl chitosan and dimethyl acrylamide, respectively. In such a dualistic approach, co-polymer makes an excellent system to possess two simultaneous properties in one bio-polymer.

RESULTS

The simulation results proposed dramatic and indisputable effects of the copolymer in the release of drugs in cancerous tissues, as well as increased biocompatibility and drug uptake in healthy tissues. Repeated simulations of a similar article performed for the validation test. The results are very close to those of the reference paper.

CONCLUSIONS

Overall, conjugated modified fullerene and dimethyl acrylamide-trimethyl chitosan (DMAA-TMC) as nanohybrid can be an appropriate proposition for drug loading, drug delivery, and drug release on dual responsive smart drug delivery system.

Assessment on the binding characteristics of residual marbofloxacin in animal-derived food to bovine/human serum albumin by spectroscopy and molecular modelling

To assess the toxicity of residual marbofloxacin from animal-derived food, the interaction characteristics of marbofloxacin to bovine/human serum albumins (BSA/HSA) were explored using spectroscopic methods combined with molecular modelling. According to fluorescence spectra and time-resolved fluorescence spectra measurements, quenching of BSA/HSA fluorescence induced by marbofloxacin was characterized as static quenching. A 1:1 ground-state complex of marbofloxacin to BSA/HSA was formed with binding constant (K_a ) 1.66 × 10⁴ /9.74 × 10³ M^-1 at 291 K. The location of marbofloxacin binding at site I within BSA/HSA was clarified by site marker competitive experiments. Molecular modelling demonstrated that the binding region for marbofloxacin to BSA and HSA were at site I with the lowest binding free energies of -22.86 and -21.60 kJ mol^-1 , respectively. Hydrogen bonds and van der Waals forces were dominantly involved in the spontaneous binding. Nonradiation energy transferred from BSA and HSA to marbofloxacin, due to the close distance (r₀ ) between marbofloxacin and Trp residues of BSA (4.28 nm) and HSA (3.34 nm). As explained by circular dichroism (CD) spectra, an increased BSA/HSA α-helix structure was observed after binding to marbofloxacin. Ultraviolet-visible (UV-vis) and Fourier transform infrared (FT-IR) spectra suggested that conformation of the two proteins was altered by marbofloxacin.

Host assisted molecular recognition by human serum albumin: Study of molecular recognition controlled protein/drug mimic binding in a microfluidic channel

Human serum albumin (HSA) plays a pivotal role in drug release from its delivery vehicles such as cyclodextrins (CDs) by binding to the drugs. Here molecular recognition and binding of a drug mimic (CD1) to HSA have been explored in a microfluidic channel when CD1 is encapsulated in β-cyclodextrin (βCD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB), respectively, to investigate whether change of the host vehicle modulate the rate of drug binding to the serum protein. Molecular recognition of βCD encapsulated CD1 by HSA occurs by the conformational selection fit mechanism leading to rapid binding of CD1 to HSA (k₁ ~ 700 s^-11) when the βCD/CD1 complex interacts with HSA. In contrary, HSA recognizes CD1 encapsulated in TRIMEB by an induced fit mechanism leading to a significantly slower binding rate (k₁ ~ 20.8 s^-1) of the drug mimic to the protein. Thus molecular recognition controls the rate of HSA binding by CD1 which in turn modulates the rate of delivery of the drug mimic from its macrocyclic hosts. The remarkable change in the molecular recognition pathway of CD1 by HSA, upon change of the host from βCD to TRIMEB, originates from significantly different conformational flexibility of the host/drug mimic complexes.