Multi-spectroscopic and molecular modeling studies to reveal the interaction between propyl acridone and calf thymus DNA in the presence of histone H1: binary and ternary approaches

Molecular complexes of calf thymus DNA with various bioactive compounds: Formation and characterization

The interaction between biomacromolecules and ligands has attracted great interest because of their biological properties. Calf thymus DNA (ctDNA) can interact with bioactive compounds to form complexes. Here, ctDNA-ligand complexes were studied using fluorescence, absorption, and infrared spectroscopy, circular dichroism, ABTS assay and competitive displacement. The binding constants of bioactive compounds at the intercalative site of ctDNA ranked in order kaempferol > apigenin > quercetin > curcumin > riboflavin, while the binding constants at minor groove sites ranked quercetin > kaempferol > naringenin ~ apigenin > hesperetin > curcumin ~ resveratrol ~ riboflavin > caffeic acid. CtDNA maintained stable B-form with an enhancement of base stacking and a decrease of right-handed helicity in the presence of these bioactive compounds, except for hesperetin and caffeic acid. Bioactive compounds preferentially bound to guanine bases and tended to transfer into a more hydrophobic environment upon complexation with ctDNA. The DNA complexation did not affect the ABTS·⁺ scavenging capacity of quercetin, kaempferol, resveratrol and apigenin but increased the ones of naringenin, caffeic acid, curcumin, hesperetin and riboflavin. The data gathered here should be useful to understand the binding modes of DNA with ligands for their potential application in pharmaceutical and food industries.

Isolation and identification in human blood serum of the proteins possessing the ability to bind with 48 kDa form of unconventional myosin 1c and their possible diagnostic and prognostic value

We firstly identified 48 kDa molecular form of the unconventional myosin 1c (p48/Myo1C), and isolated it from blood serum of multiple sclerosis patients. The amount of p48/Myo1C in human blood serum correlated with some autoimmune, hemato-oncological and neurodegenerative diseases and thus may serve as a potential molecular biomarker. The biological functions of this protein in human blood remain unknown. Previously, we used the monodisperse magnetic poly (glycidyl methacrylate)(mag-PGMA-NH₂ ) microspheres with immobilized 48/Myo1C and western-blot analysis, which allowed us to identify IgM and IgG immunoglobulins presenting an affinity to this protein. Here, we used mass spectrometry followed by the western blotting in order to identify other blood serum proteins with affinity to 48/Myo1C. The obtained data demonstrate that 48/Myo1C binds to component 3 of the complement and the antithrombin-III proteins. A combination of magnetic microparticle-based affinity chromatography with MALDI-TOF mass spectrometry and an in silico analysis provided an opportunity to identify the partners of interaction of 48/Myo1C with other proteins, in particular those participating in complement and coagulation cascades.

Pharmacokinetic-Pharmacodynamic Modeling of the Antioxidant Activity of Quzhou Fructus Aurantii Decoction in a Rat Model of Hyperlipidemia

BACKGROUND

Quzhou Fructus Aurantii (QFA) is an herb that is commonly used to alleviate inflammation in individuals dealing with obesity.To date, however, no systematic pharmacokinetic (PK) or pharmacodynamic (PD) analyses of the clinical efficacy of QFA under hyperlipemia-associated oxidative stress conditions have been conducted. The present study, was therefore designed to construct a PK-PD model for this herb, with the goal of linking QFA PK profiles to key therapeutic outlines to guide the therapeutic use of this herb in clinical settings.

METHODS

Rats were fed a high-fat diet in order to establish a model of hyperlipidemia, after which they were randomized into a normal control group (NCG), a normal treatment group (NTG), a model control group (MCG), and a model treated group (MTG) (n = 6 each). QAF decoction was used to treat rats in the NTG and MTG groups (25 g/kg), while equivalent volumes of physiological saline were administered to rats in the NCG and MCG groups. Plasma samples were collected from the mandibular vein for animals at appropriate time points and analyzed via high-performance liquid chromatography (HPLC). We evaluated PK properties for three QAF components and compared these dynamics between the NTG and MTG groups, while also measuring levels of lipid peroxidation (LPO) in the plasma of rats in all four treatment groups. We then constructed a PK-PD model based upon plasma neohesperidin, luteolin, and nobiletin concentrations and LPO levels using a three-compartment PK model together with a Sigmoid E_max PD model. This model thereby enabled us to assess the antioxidative impact of neohesperidin, luteolin, and nobiletin on hyperlipidemia in rats.

RESULTS

When comparing the NTG and MTG groups, we detected significant differences in the following parameters pertaining to neohesperidin, luteolin, and nobiletin:t_1/2β, V1,  t_1/2γ, CL1 (p < 0.01) and AUC_0-t, T_max, C_max (p < 0.05). Relative to NTG group rats, AUC_0-t, T_maxandC_maxvalues significantly higher for MTG group rats (p < 0.01), while t_1/2β, V1, and  t_1/2γ values were significantly lower in MTG group rats (p < 0.01) in MTG rats. QAF decoction also exhibited excellent PD efficacy in MTG rats, with significant reductions in plasma LPO levels relative to NTG rats (p < 0.01) following treatment. This therapeutic efficacy may be attributable to the activity of neohesperidin, luteolin, and nobiletin, as LPO levels and plasma concentrations of these compounds were negatively correlated in treated rats. Based upon Akaike Information Criterion (AIC) values, we determined that neohesperidin, luteolin, and nobiletin PK processes were consistent with a three-compartment model. Together, these findings indicated that three active components in QAF decoction (neohesperidin, luteolin, and nobiletin) may exhibit antioxidant activity in vivo.

CONCLUSION

Our in vivo data indicated that neohesperidin, luteolin and nobiletin components of QAF decoctions exhibit distinct PK and PD properties. Together, these findings suggest that hyperlipidemia-related oxidative stress can significantly impact QFA decoction PK and PD parameters. Our data additionally offer fundamental insights that can be used to design appropriate dosing regimens for individualized clinical QAF decoction treatment.

A look into the link between centrosome amplification and breast cancer

Centrosome amplification (CA) is a common feature of human tumors, but it is not clear whether this is a cause or a consequence of cancer. The centrosome amplification observed in tumor cells may be explained by a series of events, such as failure of cell division, dysregulation of centrosome cycle checkpoints, and de novo centriole biogenesis disorder. The formation and progression of breast cancer are characterized by genomic abnormality. The centrosomes in breast cancer cells show characteristic structural aberrations, caused by centrosome amplification, which include: an increase in the number and volume of centrosomes, excessive increase of pericentriolar material (PCM), inappropriate phosphorylation of centrosomal molecular, and centrosome clustering formation induced by the dysregulation of important genes. The mechanism of intracellular centrosome amplification, the impact of which on breast cancer and the latest breast cancer target treatment options for centrosome amplification are exhaustively elaborated in this review.

Anterior gradient 2 is a novel pro-tumor factor in pancreatic cancer under NF-κB subunit RelA trans-regulation that can be suppressed by eugenic acid

This study aimed to examine eugenic acid (EA) as an alternative therapeutic approach against pancreatic cancer. The pancreatic cancer xenograft mouse model was employed to determine the impacts of treatment with EA on the growth of tumors. Expressions of NF-κB subunit RelA as well as Anterior gradient 2 (AGR2) were quantified in pancreatic cells treated with EA. Chromatin immunoprecipitation and luciferase report assay were performed to examine the regulation of AGR2 by RelA. The function of AGR2 as a downstream effector EA treatment was further assessed through overexpression of AGR2 in pancreatic cells. EA suppressed the growth of xenograft pancreatic tumor, and promoted the overall survival of animals with xenograft tumors. Furthermore, EA downregulated the expression of AGR2 in pancreatic cancer cells via the RelA binding site. Ectopic AGR2 overexpression attenuated the EA-elicited inhibition on the growth of xenograft pancreatic tumor, and negated the EA-induced enhancement of mouse survival. EA ameliorates pancreatic cancer through suppression of AGR2 expression, and future studies in clinical settings are needed to further assess the anti-cancer efficacy of EA.

Elucidating the potential neurotoxicity of chiral phenthoate: Molecular insight from experimental and computational studies

Chiral organophosphorus pollutants are existed ubiquitously in the ecological environment, but the enantioselective toxicities of these nerve agents to humans and their molecular bases have not been fully elucidated. Using experimental and computational approaches, this story was to explore the neurotoxic response process of the target acetylcholinesterase (AChE) to chiral phenthoate and further decipher the microscopic mechanism of such toxicological effect at the enantiomeric level. The results showed that the toxic reaction of AChE with chiral phenthoate exhibited significant enantioselectivity, and (R)-phenthoate (K＝1.486 × 10⁵ M^-1) has a bioaffinity for the nerve enzyme nearly three times that of (S)-phenthoate (K＝4.503 × 10⁴ M^-1). Dynamic research outcomes interpreted the wet experiments, and the inherent conformational flexibility of the target enzyme has a great influence on the enantioselective neurotoxicological action processes, especially reflected in the conformational changes of the three key loop regions (i.e. residues His-447, Gly-448, and Tyr-449; residues Gly-122, Phe-123, and Tyr-124; and residues Thr-75, Leu-76, and Tyr-77) around the reaction patch. This was supported by the quantitative results of conformational studies derived from circular dichroism spectroscopy (α-helix: 34.7%→30.2%/31.6%; β-sheet: 23.6%→19.5%/20.7%; turn: 19.2%→22.4%/21.9%; and random coil: 22.5%→27.9%/25.8%). Meanwhile, via analyzing the modes of toxic action and free energies, we can find that (R)-phenthoate has a strong inhibitory effect on the enzymatic activity of AChE, as compared with (S)-phenthoate, and electrostatic energy (-23.79/－17.77 kJ mol^-1) played a critical role in toxicological reactions. These points were the underlying causes of chiral phenthoate displaying different degrees of enantioselective neurotoxicity.

Interaction between aspirin and vitamin C with human serum albumin as binary and ternary systems

Foods generally contain special ingredients which easily to interact with drugs human intaking, thus affecting drug efficacy and excretion, and even cause adverse reactions. Vitamin C (Vit. C) is abundant in fresh fruits and vegetables. It plays a regulatory role in redox metabolism, and its absence can cause scurvy. Aspirin (ASP) can be used to treat many diseases, is the earliest, common and widely used as antipyretic, analgesic and antirheumatic medicine. Human serum albumin (HSA) is the most abundant protein in vertebrate plasma and has the property of combining and transporting endogenous and exogenous substances. In this paper, the effects of Vit. C on the combination of ASP and HSA were studied by multi-spectra and voltammetric approaches. Fluorescence spectra showed that the quenching mode between Vit. C and HSA is dynamic, and the main binding force is hydrophobic force. The quenching mode between ASP and HSA is static one, and the main binding force is hydrogen bond and van der Waals force. For ternary biological system of (HSA-ASP)-Vit. C, the binding constant decreases compared with HSA-Vit. C system. However, for (HSA-Vit. C)-ASP system, the binding constant does not change when compared with binary system of HSA-ASP. Based on the technology combination of voltammetry, infrared, three-dimensional fluorescence and circular dichroism (CD), it is proved that the existence of ASP will influence the binding process of Vit. C to HSA. It could be concluded that taking Vit. C first doesn't affect the absorption of ASP and may be good for health; in contrast, it is not good to take Vit. C immediately as one have just taken ASP, because the existence of ASP reduce the absorption of Vit. C for human body.

Targeting virus-host interaction by novel pyrimidine derivative: an in silico approach towards discovery of potential drug against COVID-19

The entire human population over the globe is currently facing appalling conditions due to the spread of infection from coronavirus disease-2019 (COVID-19). The spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) present on the surface of the virion mediates the virus entry into the host cells and therefore is targeted by several scientific groups as a novel drug target site. The spike glycoprotein binds to the human angiotensin-converting enzyme-2 (hACE2) cell surface receptor abundantly expressed in lung tissues, and this binding phenomenon is a primary determinant of cell tropism and pathogenesis. The binding and internalization of the virus is the primary and most crucial step in the process of infection, and therefore the molecules targeting the inhibition of this process certainly hold a significant therapeutic value. Thus, we systematically applied the computational techniques to identify the plausible inhibitor from a chosen set of well characterized diaryl pyrimidine analogues which may disrupt interfacial interaction of spike glycoprotein (S) at the surface of hACE2. Using molecular docking, molecular dynamics (MD) simulation and binding free energy calculation, we have identified AP-NP (2-(2-amino-5-(naphthalen-2-yl)pyrimidin-4-yl)phenol), AP-3-OMe-Ph (2-(2-amino-5-(3-methoxyphenyl)pyrimidin-4-yl)phenol) and AP-4-Me-Ph (2-(2-amino-5-(p-tolyl) pyrimidin-4-yl)phenol) from a group of diaryl pyrimidine derivatives which appears to bind at the interface of the hACE2-S complex with low binding free energy. Thus, pyrimidine derivative AP-NP may be explored as an effective inhibitor for hACE2-S complex. Furthermore, in vitro and in vivo studies will strengthen the use of these inhibitors as suitable drug candidates against SARS-COV-2.

Communicated by Ramaswamy H. Sarma

Synthesis of two novel pyrazolo[1,5-a]pyrimidine compounds with antibacterial activity and biophysical insights into their interactions with plasma protein

Two novel water-soluble pyrazolo[1,5-a]pyrimidine derivatives, 5-chloro-7-(4-methyl-piperazin -1-yl)-pyrazolo[1,5-a]pyrimidine (CMPS) and N'-(5-chloro-pyrazolo[1,5-a]pyrimidin-7-yl)-N,N-dimethyl -propane-1,3-diamine (NCPS), were synthesized and characterized with antibacterial activity. Then, the interactions of these compounds with bovine serum albumin (BSA) were studied by fluorescence, time-resolved fluorescence, circular dichroism (CD) spectroscopy and molecular docking. The results indicate that both CMPS and NCPS could effectively quench the intrinsic fluorescence of BSA via a static quenching process. The energy transfer from BSA to CMPS and NCPS may occur with high probability. Both CMPS and NCPS bind in the site I of BSA. The hydrophobic force and hydrogen bonds play major roles in the complex formation. Binding constants for both systems show that the affinity of CMPS binding to BSA is stronger than that of NCPS. The results of three-dimensional fluorescence and CD spectra reveal that the binding of CMPS and NCPS to BSA can induce conformational changes of BSA, and the influence of CMPS is slightly stronger than that of NCPS.

Comprehensive study of the interaction between Puerariae Radix flavonoids and DNA: From theoretical simulation to structural analysis to functional analysis

Puerariae Radix (PR) is a natural herb whose active ingredient is mainly flavonoids. To explore the interaction between PR flavonoids and DNA not only has important biological implications for understanding the mechanism of action, but also helps develop PR products for the design of appropriate dietary interventions to aid cancer treatment. In this work, we comprehensively studied the interaction between six kinds of PR flavonoids and DNA from four different and progressive levels, including molecular docking, multi-spectral analysis, and functional analysis in vitro and in cell. Results show that the DNA binding affinity of six flavonoids is in an order of quercetin > formononetin > daidzein > puerarin > 4'-methoxy puerarin > puerarin 6″-O-xyloside (POS), in which quercetin can significantly inhibit DNA amplification owing to its strongest binding affinity. The binding between quercetin and DNA is further revealed to be intercalated binding, which can cause conformational changes in DNA, thereby exhibiting an activity of cell cycle arrest and anti-proliferative. This property of quercetin can be utilized for the further development of flavonoids with anticancer activity. In addition to the potential application, this work also provides a platform for the comprehensive study of the interaction between micromolecules and DNA.

Evaluation of the binding mechanism of iodine with trypsin and pepsin: A spectroscopic and molecular docking

In this work, the effects of I₂ on the activities and conformational structures of digestive enzymes, trypsin and pepsin were studied. The results indicated that the enzyme activities were decreased to some extent in the presence of I₂, especially trypsin. Upon gradual addition of I₂, the intrinsic fluorescence quenching of trypsin and pepsin were observed by mainly static collision and hydrophobic forces. I₂ is more likely to cause the fluorescence quenching of trypsin than that of pepsin. Compared with pepsin, trypsin has a greater ability to bind with I₂. The synchronous fluorescence spectral results indicated that I₂ induced the quaternary structure changes of trypsin/pepsin and changed the hydrophobicity of Tyr and Trp residues. In addition, molecular docking was used to obtain the binding mode and the various amino acid residues of trypsin and pepsin with I₂. These investigations may constitute a solid work to further explain the process of migration and transformation of I₂ in digestive system.

Identification of new potential cyclooxygenase-2 inhibitors: insight from high throughput virtual screening of 18 million compounds combined with molecular dynamic simulation and quantum mechanics

The cyclooxygenase isoenzymes (COX-1 and COX-2) have a critical role in inflammation, fever, and pain. In contrary to COX-1, COX-2 is specifically expressed in inflamed tissues. Because of the subtle difference between both enzyme active sites, targeting COX-2 represents an efficient strategy for the development of novel inhibitors against inflammation with fewer side effects. In order to identify potential inhibitors of COX-2, more than 18,000,000 small molecules were retrieved from the ZINC database and virtually screened against it with a gradual increase in the precision through combined multistep docking. The results were sorted according to the rank-by-rank, induced-fit docking, and MM-GBSA evaluation. Subsequently from the final hit list, two top hits along with an approved selective inhibitor (celecoxib) were further investigated by the molecular dynamics (MD) simulations. The results were indicated that ZINC16934653 and ZINC40484701 demonstrate the highest affinity for the COX-2 binding pocket. Both ligands were bound to the important active-site residues, which are necessary for the correct orientation of inhibitors inside the binding cavity. Their binding free energies were comparable to celecoxib. 100 ns MD simulation is revealed that ZINC40484701 is more preferred in comparison with ZINC16934653 and celecoxib. In addition, non-covalent interactions between the compounds and key residues located in 6 Å distance from the COX-2 binding site show similar patterns of bonding by the reduced density gradient and the independent gradient model. Therefore, ZINC40484701 can be a potential candidate for further in vitro and in vivo analysis after lead-optimization efforts.Communicated by Ramaswamy H. Sarma.

Probing the interaction of iron complex containing N3S2 macrocyclic ligand with bovine serum albumin using spectroscopic techniques

The interaction of bovine serum albumin (BSA) with seven-coordination iron (II) complex containing sulfur-based macrocyclic ligand was investigated by means of UV/vis absorption spectroscopy and fluorescence quenching technique. The accurate fluorescence spectra are obtained by using Inner filter effect (IFE) correction. The apparent association constant, k_app, the number of binding sites, n, and the apparent binding constant K_SV were found to be 0.95 × 10³ M^-1, 0.96, and 6.13 × 10⁴ M^-1, respectively. It found that BSA molecules are adsorbed on the surface of iron (II) complex by electrostatic interaction. The quenching mechanism is discussed involving energy transfer from BSA to iron (II) complex.

Oleandrin induces apoptosis via activating endoplasmic reticulum stress in breast cancer cells

BACKGROUND

Breast cancer is the most common malignant tumor in women. Due to limited treatment outcome and high rate of metastasis, the prognosis is especially poor for triple-negative breast cancer. It is urgent to discover and develop novel agents for treatment of breast cancer. Herein, we investigated the potential mechanisms of Oleandrin's (a cardiac glycoside) cytotoxic activity against breast cancer cells.

METHODS

Cell proliferation was assessed by xCELLigence Real-Time Cell Analyzer (RTCA)-MP system. Apoptotic cells were detected by using Annexin V/PI staining and nuclear fragments observation. The effect of oleandrin on ATP1B3 expression and markers of ER stress were determined by western blot. A primary cell sensitivity assay was performed via a collagen gel droplet-embedded culture drug sensitivity method (CD-DST).

RESULTS

Oleandrin suppressed cell proliferation and colony formation in the three breast cancer cell lines but did not affect normal mammary epithelial cells. Additionally, the expression of ATP1B3 was higher in the three breast cancer cell lines compared to MCF10A cells. Treatment with oleandrin increased the number of apoptotic cells and led to nuclear pyknosis, fragmentation, and apoptotic body formation in breast cancer cells. Furthermore, oleandrin treatment increased expression of Bax and Bim but decreased that of Bcl-2. Treatment with oleandrin also upregulated the expression of endoplasmic reticulum stress associated proteins, including eIF2α, ATF4, and CHOP, but not PERK. oleandrin treatment also induced the phosphorylation of PERK and eIF2α. Of note, oleandrin exhibited antitumor effects on patient-derived breast cancer cells under three-dimensional culture conditions.

CONCLUSIONS

Taken together, our results suggest that oleandrin induces mitochondrial-mediated apoptosis by activating endoplasmic reticulum stress in breast cancer. Moreover, oleandrin may be an effective strategy for the treatment of breast cancer.

Effect of tetracycline family of antibiotics on actin aggregation, resulting in the formation of Hirano bodies responsible for neuropathological disorders

Actin, an ATPase superfamily protein, regulates some vital biological functions like cell locomotion, cytokinesis, synaptic plasticity and cell signaling in higher eukaryotes, and is dependent on the dynamics of actin polymerization process. Impaired regulation of actin polymerization has been implicated in the formation and deposition of rod-like paracrystalline structures called as Hirano bodies in neuronal cells of patients suffering from Alzheimer's disease, Pick's disease, Guam amyotrophic lateral sclerosis and parkinsonism-dementia complex. Aggregation of actin forming amorphous deposition in the brain cells is also associated with chronic alcoholism and aging of the neurons. In the current article, we propose the breaking of the highly amorphous and dysregulated actin aggregates using generic compounds like tetracycline, oxytetracycline, doxycycline and minocycline which are used as antibiotics against tuberculosis and infection caused due to various Gram-negative bacteria. We have investigated the effect and affinity of binding of these four compounds to that of actin aggregates using 90° light scattering, size exclusion chromatography, dynamic light scattering, circular dichroism, scanning electron microscopy, transmission electron microscopy imaging and kinetic analysis. The isothermal calorimetric measurements showed that the binding constant for the cycline family molecules used in this study range from 9.8 E4 M^-1 to 1.3 E4 M^-1. To understand the in vivo effect, we also studied the effect of these drugs on Saccharomyces cerevisiae Δend3 mutant cells. Our data suggest that these generic compounds can plausibly be used for the treatment of various neurodegenerative diseases occurring due to Hirano body formation in brain cells.Communicated by Ramaswamy H. Sarma.

The Effects of Amoxicillin, Cefazolin, and Gentamicin Antibiotics on the Antioxidant System in Mouse Heart Tissues

BACKGROUND

Free radicals lead to destruction in various organs of the organism. The improper use of antibiotics increases the formation of free radicals and causes oxidative stress.

OBJECTIVE

In this study, it was aimed to determine the effects of gentamicin, amoxicillin, and cefazolin antibiotics on the mouse heart.

METHODS

20 male mice were divided into 4 groups (1st control, 2nd amoxicillin, 3rd cefazolin, and 4th gentamicin groups). The mice in the experimental groups were administered antibiotics intraperitoneally at a dose of 100 mg / kg for 6 days. The control group received normal saline in the same way. The gene expression levels and enzyme activities of SOD, CAT, GPx, GR, GST, and G6PD antioxidant enzymes were investigated.

RESULTS

GSH levels decreased in both the amoxicillin and cefazolin groups, while GR, CAT, and SOD enzyme activities increased. In the amoxicillin group, Gr, Gst, Cat, and Sod gene expression levels increased.

CONCLUSION

As a result, it was concluded that amoxicillin and cefazolin caused oxidative stress in the heart, however, gentamicin did not cause any effects.

Ruxolitinib binding to human serum albumin: bioinformatics, biochemical and functional characterization in JAK2V617F+ cell models

Ruxolitinib is a type I JAK inhibitor approved by FDA for targeted therapy of Philadelphia-negative myeloproliferative neoplasms (MPNs), all characterized by mutations activating the JAK2/STAT signaling pathway. Treatment with ruxolitinib improves constitutional symptoms and splenomegaly. However, patients can become resistant to treatment and chronic therapy has only a mild effect on molecular/pathologic remissions. Drugs interaction with plasma proteins, i.e. human serum albumin (HSA), is an important factor affecting the intensity and duration of their pharmacological actions. Here, the ruxolitinib recognition by the fatty acid binding sites (FAs) 1, 6, 7, and 9 of HSA has been investigated from the bioinformatics, biochemical and/or biological viewpoints. Docking simulations indicate that ruxolitinib binds to multiple sites of HSA. Ruxolitinib binds to the FA1 and FA7 sites of HSA with high affinity (K_r = 3.1 μM and 4.6 μM, respectively, at pH 7.3 and 37.0 °C). Moreover, HSA selectively blocks, in a dose dependent manner, the cytotoxic activity of ruxolitinib in JAK2V617F⁺ cellular models for MPN, in vitro. Furthermore this event is accompanied by changes in the cell cycle, p27^Kip1 and cyclin D3 levels, and JAK/STAT signaling. Given the high plasma concentration of HSA, ruxolitinib trapping may be relevant in vivo.

Potential of isoquercitrin as antisickling agent: a multi-spectroscopic, thermophoresis and molecular modeling approach

Sickle cell disease is an inherited disease caused by point mutation in hemoglobin (β-globin gene). Under oxygen saturation, sickle hemoglobin form polymers, leading to rigid erythrocytes. The transition of the blood vessels is altered and initiated by the adhesion of erythrocytes, neutrophils and endothelial cells. Sickle Hemoglobin (HbS) polymerization is a major cause in red blood cells (RBC), promoting sickling and destruction of RBCs. Isoquercitrin, a medicinal bioactive compound found in various medicinal plants, has multiple health benefits. The present study examines the potential of isoquercitrin as an anti-sickle agent, showing a significant decrease in the rate of polymerization as well as sickling of RBCs. Isoquercitrin-induced graded alteration in absorbance and fluorescence of HbS, confirmed their interaction. A negative value of ΔG° strongly suggests that it is a spontaneous exothermic reaction induced by entropy. Negative ΔH° and positive ΔS° predicted that hydrogen and hydrophobic binding forces interfered with a hydrophobic microenvironment of β6Val leading to polymerization inhibition of HbS. HbS-Isoquercitrin complex exhibits helical structural changes leading to destabilization of the HbS polymer as confirmed by CD spectroscopy. MST and DSC results indicate greater changes in thermophoretic mobility and thermal stability of sickle hemoglobin in the presence of isoquercitrin, respectively. These findings were also supported by molecular simulation studies using DOCK6 and GROMACS. Hence, we can conclude that isoquercitrin interacts with HbS through hydrogen bonding, which leads to polymerization inhibition. Consequently, isoquercitrin could potentially be used as a medication for the treatment of sickle cell disease.Communicated by Ramaswamy H. Sarma.

Titanium oxide nanoparticles fabrication, hemoglobin interaction, white blood cells cytotoxicity, and antibacterial studies

This study is focused on the fabrication and characterization of titanium oxide (TiO₂) NPs. Afterwards; the interaction of TiO₂ NPs with human hemoglobin (Hb) was investigated by FTIR spectroscopy, fluorescence spectroscopy, and molecular docking studies. Also, the cytotoxic effect of fabricated TiO₂ NPs against human white blood cells (WBCs) was considered by MTT assay. The antibacterial effect of synthesized NPs was examined on Pseudomonas aeruginosa (ATCC 27853); Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). TEM and DLS investigations showed that the synthesized TiO₂ NPs have a narrow nano-sized distribution. XRD pattern of the fabricated NPs exhibited that the TiO₂ NPs contain anatase phase. Similarity in amide I and II signal intensities showed that secondary structure of the adsorbed Hb is preserved. The intrinsic fluorescence study revealed that the fluorescence quenching of Hb was done by complex formation between Hb and TiO₂ NPs trough the hydrogen bond and van der Waals interactions. Synchronous fluorescence spectroscopy determined that interaction of TiO₂ NPs with Hb did not unfold the Hb structure in the vicinity of the Tyr and Trp residues. Molecular docking study depicted that Glu-95, Thr-134 and Tyr-140 are involved in the formation of hydrophilic bonds. MTT data and antibacterial assays indicated that TiO₂ NPs endow distinguished antibacterial activities against Gram-negative and Gram positive strains at safe concentrations. This study may reveal that fabricated TiO₂ NP can be used as a safe and potent antibacterial agent. Communicated by Ramaswamy H. Sarma.

Capecitabine as a minor groove binder of DNA: molecular docking, molecular dynamics, and multi-spectroscopic studies

The interaction mechanism and binding mode of capecitabine with ctDNA was extensively investigated using docking and molecular dynamics simulations, fluorescence and circular dichroism (CD) spectroscopy, DNA thermal denaturation studies, and viscosity measurements. The possible binding mode and acting forces on the combination between capecitabine and DNA had been predicted through molecular simulation. Results indicated that capecitabine could relatively locate stably in the G-C base-pairs-rich DNA minor groove by hydrogen bond and several weaker nonbonding forces. Fluorescence spectroscopy and fluorescence lifetime measurements confirmed that the quenching was static caused by ground state complex formation. This phenomenon indicated the formation of a complex between capecitabine and ctDNA. Fluorescence data showed that the binding constants of the complex were approximately 2 × 10⁴ M^-1. Calculated thermodynamic parameters suggested that hydrogen bond was the main force during binding, which were consistent with theoretical results. Moreover, CD spectroscopy, DNA melting studies, and viscosity measurements corroborated a groove binding mode of capecitabine with ctDNA. This binding had no effect on B-DNA conformation.