Multispectroscopic and Theoretical Investigation on the Binding Interaction of a Neurodegenerative Drug, Lobeline with Human Serum Albumin: Perturbation in Protein Conformation and Hydrophobic-Hydrophilic Surface.

Lobeline (LOB), a naturally occurring alkaloid, has a broad spectrum of pharmacological activities and therapeutic potential, including applications in central nervous system disorders, drug misuse, multidrug resistance, smoking cessation, depression, and epilepsy. LOB represents a promising compound for developing treatments in various medical fields. However, despite extensive pharmacological profiling, the biophysical interaction between the LOB and proteins remains largely unexplored. In the current article, a range of complementary photophysical and cheminformatics methodologies were applied to study the interaction mechanism between LOB and the carrier protein HSA. Steady-state fluorescence and fluorescence lifetime experiments confirmed the static-quenching mechanisms in the HSA-LOB system. "K" (binding constant) of the HSA-LOB system was determined to be 105 M-1, with a single preferable binding site in HSA. The forces governing the HSA-LOB stable complex were analyzed by thermodynamic parameters and electrostatic contribution. The research also investigated how various metal ions affect complex binding. Site-specific binding studies depict Site I as probable binding in HSA by LOB. We conducted synchronous fluorescence, 3D fluorescence, and circular dichroism studies to explore the structural alteration occurring in the microenvironment of amino acids. To understand the robustness of the HSA-LOB complex, we used theoretical approaches, including molecular docking and MD simulations, and analyzed the principal component analysis and free energy landscape. These comprehensive studies of the structural features of biomolecules in ligand binding are of paramount importance for designing targeted drugs and delivery systems.

Binding Interaction of Coumarin Derivative Daphnetin with Ovalbumin: Molecular Insights into the Complexation Process and Effects of Metal Ions and pH in the Binding and Antifibrillation Studies.

This study investigates the interaction between daphnetin and ovalbumin (OVA) as well as its potential to inhibit OVA fibrillation using both spectroscopic and computational analysis. A moderate binding affinity of 1 × 104 M-1 was observed between OVA and daphnetin, with a static quenched mechanism identified during the fluorescence quenching processes. Metal ions' (Cu2+ and Zn2+) presence led to an increase in the binding affinities of daphnetin toward OVA, mirroring a similar trend observed with the pH variation. Synchronous and 3D fluorescence studies indicated an increase in the polarity of the microenvironment surrounding the Trp residues during binding. Interestingly, circular dichroism and Fourier transform infrared studies showed a significant change in the secondary structure of OVA upon binding with daphnetin. The efficacy of daphnetin in inhibiting protein fibrillation was confirmed through thioflavin T and Congo Red binding assays along with fluorescence microscopic imaging analysis. The thermodynamic assessment showed positive ΔH° [+(29.34 ± 1.526) kJ mol-1] and ΔS° [+(181.726 ± 5.465) J mol-1] values, indicating the presence of the hydrophobic forces, while negative ΔG° signifies spontaneous binding interactions. These experimental findings were further correlated with computational analysis, revealing daphnetin dynamics within the binding site of OVA.

Interactions of Turmeric- and Curcumin-Functionalized Gold Nanoparticles with Human Serum Albumin: Exploration of Protein Corona Formation, Binding, Thermodynamics, and Antifibrillation Studies.

In order to better understand the bioavailability and biocompatibility of polyphenol-assisted surface-modified bioengineered nanoparticles in nanomedicine applications, here, we address a series of photophysical experiments to quantify the binding affinity of serum albumin toward polyphenol-capped gold nanoparticles. For this, two different gold nanoparticles (AuNPs) were synthesized via the green synthesis approach, where curcumin and turmeric extract act as reducing as well as capping agents. The size, surface charge, and surface plasmon bands of the AuNPs were highly affected by the adsorption of human serum albumin (HSA) during protein corona formation, which was investigated using dynamic light scattering (DLS), ξ-potential, ultraviolet-visible (UV-vis) spectroscopy, and transmission electron microscopy (TEM) measurements. Fluorescence-based methods, absorbance, and SERS experiments were carried out to evaluate the binding aspects of AuNPs with HSA. We found that the AuNPs show moderate binding affinity toward HSA (Kb ∼ 104 M-1), irrespective of the capping agents on the surface. Hydrophobic association, along with some contribution of electrostatic interaction, played a key role in the binding process. The binding interaction was more toward the subdomain IIA region of HSA, as indicated by the competitive displacement studies using site-specific binders (warfarin and flufenamic acid). Because of the large surface curvature of small-sized AuNPs, the secondary structural conformations of HSA were slightly altered, as revealed by circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, and surface-enhanced Raman scattering (SERS) measurements. Additionally, the findings of the binding interactions were re-evaluated using molecular dynamics (MD) simulation studies by determining the root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), radius of gyration (Rg), and changes in the binding energy of HSA upon complexation with AuNPs. To determine the tentative evidence for pharmacokinetic administration, these biocompatible AuNPs were applied to inhibit the amyloid fibril formation of HSA and monitored by using the thioflavin T (ThT) assay, ANS fluorescence assay, fluorescence microscopic imaging, and FESEM. AuNPs were found to show better resistance toward fibrillation of the adsorbed protein.

Formation of CdTe core and CdTe@ZnTe core-shell quantum dots via hydrothermal approach using dual capping agents: deciphering the food dye sensing and protein binding applications.

Excessive use of food coloring agents in the food industry to make the food more attractive or improve the taste has caused various health and ecological problems. Therefore, it is necessary to develop a reliable, sensitive, and selective sensing probe to detect food dyes in different food products for future industrial processing and biosafety. In recent decades, surface-functionalized quantum dots (QDs), owing to their unique optical properties, have gained tremendous interest for a wide range of applications, including biomedical, bioimaging and sensing applications. Herein, we have reported the synthesis of excellent colloidal stable and highly luminescent CdTe core and CdTe@ZnTe core-shell QDs using dual functionalizing agents, polyvinyl pyrrolidone and vitamin C. The synthesized QDs were explored as excellent sensing probes for the food dyes carmoisine, Ponceau 4R and tartrazine with limit of detection (LOD) values of 0.097 ± 0.006, 0.147 ± 0.001 and 0.044 ± 0.001 µM for CdTe-PVP QDs and 0.079 ± 0.001, 0.114 ± 0.002 and 0.042 ± 0.001 µM for CdTe@ZnTe-PVP QDs, respectively. The sensitivity of the synthesized QDs for the food dyes was also investigated in real samples (soft drinks and medications). Moreover, considering the potential effects of QDs as therapeutics or nano-drug carriers, the interactions between the synthesized QDs and carrier protein human serum albumin (HSA) were investigated. The binding affinity was observed to be in the order of 104 M-1. QDs were found to quench the intrinsic fluorescence of HSA, and both types of quenching (static and dynamic) occur via electrostatic interactions in association with hydrophobic forces without any significant alteration in the protein structure.

Evaluation of prescriptions from tertiary care hospitals across India for deviations from treatment guidelines & their potential consequences.

BACKGROUND OBJECTIVES: Irrational prescribing practices have major consequences on patient safety and also increase the economic burden. Real-life examples of impact of irrational prescription have potential to improve prescribing practices. In this context, the present study aimed to capture and evaluate the prevalence of deviations from treatment guidelines in the prescriptions, potential consequence/s of the deviations and corrective actions recommended by clinicians. METHODS: It was a cross-sectional observational study conducted in the outpatient departments of tertiary care hospitals in India wherein the 13 Indian Council of Medical Research Rational Use of Medicines Centres are located. Prescriptions not compliant with the standard treatment guidelines and incomplete prescriptions with respect to formulation, dose, duration and frequency were labelled as 'prescriptions having deviations'. A deviation that could result in a drug interaction, lack of response, increased cost, preventable adverse drug reaction (ADR) and/or antimicrobial resistance was labelled as an 'unacceptable deviation'. RESULTS: Against all the prescriptions assessed, about one tenth of them (475/4838; 9.8%) had unacceptable deviations. However, in 2667/4838 (55.1%) prescriptions, the clinicians had adhered to the treatment guidelines. Two thousand one hundred and seventy-one prescriptions had deviations, of which 475 (21.9%) had unacceptable deviations with pantoprazole (n=54), rabeprazole+domperidone (n=35) and oral enzyme preparations (n=24) as the most frequently prescribed drugs and upper respiratory tract infection (URTI) and hypertension as most common diseases with unacceptable deviations. The potential consequences of deviations were increase in cost (n=301), ADRs (n=254), drug interactions (n=81), lack of therapeutic response (n=77) and antimicrobial resistance (n=72). Major corrective actions proposed for consideration were issuance of an administrative order (n=196) and conducting online training programme (n=108). INTERPRETATION CONCLUSIONS: The overall prevalence of deviations found was 45 per cent of which unacceptable deviations was estimated to be 9.8 per cent. To minimize the deviations, clinicians recommended online training on rational prescribing and administrative directives as potential interventions.

Usage Pattern of Fixed-dose Combinations at ICMR Network of Rational Use of Medicine Centres across India: Recommendations for Policymakers and Prescribers.

AIM: Irrational use of medicines is a global problem. In India, one contributing factor is the availability of a large number of fixed-dose combinations (FDCs). To improve rational use and to strengthen policies, it is important to assess the usage patterns and rationality of FDCs. METHODS: This study was conducted as part of a 1-year prospective cross-sectional analysis of prescriptions in the outpatient clinics of broad specialities from 13 tertiary care hospitals across India. Five most commonly prescribed FDCs in each center were analyzed. In addition, all the prescribed FDCs were classified as per the Kokate Committee classification and it was noted whether any of the FDCs were irrational or banned as per the reference lists released by regulatory authorities. RESULTS: A total of 4,838 prescriptions were analyzed. Of these, 2,093 (43.3%) prescriptions had at least one FDC. These 2,093 prescriptions had 366 different FDCs. Of the 366 FDCs, 241 were rational; 10 were irrational; 14 required further data generation; and the remaining 96 FDCs could not be categorized into any of the above. Vitamins and minerals/supplements, antibacterial for systemic use, and drugs for gastroesophageal reflux disease (GERD) and peptic ulcer were the most used FDCs. CONCLUSION: Based on the finding that some prescriptions contained irrational FDCs, it is recommended that a rigorous, regular, and uniform method of evaluation be implemented to approve/ban FDCs and that prescribers be periodically notified about the status of the bans.

The effect of Bacillus coagulans Unique IS-2 supplementation on plasma amino acid levels and muscle strength in resistance trained males consuming whey protein: a double-blind, placebo-controlled study.

PURPOSE: The aim of the present study was to assess the effect of Bacillus coagulans Unique IS-2 supplementation on absorption and utilization of protein in resistance-trained males. METHODS: In this double blind, placebo-control trial, resistance-trained males (21.08 ± 2.84 years) were randomized to consume, either 20 g of whey protein powder {80% whey protein concentrate (WPC80), amounting to 15.4 g protein} with 2 billion CFU Bacillus coagulans Unique IS-2 (supplemental group) or 20 g of whey protein powder and lactose instead of Bacillus coagulans (placebo group) once daily for 60 days with a controlled resistance exercise protocol. The whey protein concentrate (WPC-80) given to both groups had a lactose content of 6.8%. Plasma-free amino acids (PFAAs) were determined at baseline, at 30 and 60 days of supplementation. Muscle strength, hypertrophy, VO2 max, and body composition, and other biochemical parameters were assessed at baseline and end line. RESULTS: A positive effect of probiotic Bacillus coagulans Unique IS-2 supplementation was observed on protein absorption as evidenced by an increase in total PFAA by + 16.1% (p = 0.004). Branched chain amino acids (BCAA) comprising isoleucine (p = 0.016), leucine (p = 0.001), and valine (p = 0.002) were increased by + 33.1% in ITT analysis as compared to placebo after 60 days. At 30 days an increase in isoleucine by + 35% (p = 0.113), leucine by + 43% (p = 0.032), and valine by + 32% (p = 0.017) was observed in ITT analysis. Probiotic effect was shown on exercise performance as evidenced by an increase in one RM of leg press and vertical jump power by + 16.61% (p = 0.024) and + 7.86% (p = 0.007), respectively. CONCLUSION: Significantly increased absorption of BCAA with supplementation of B. coagulans Unique IS-2 along with whey protein and improvement in leg press and vertical jump power was noted indicating the positive effect of the probiotic on muscle power in the lower body. TRIAL REGISTRATION NUMBER: CTRI/2017/03/008117; Date:16.03.2017.

Interaction properties of biosynthesized cadmium sulphide quantum dots with human serum albumin: further investigation of antibacterial activities and sensing applications.

The synthesis of small-sized quantum dots (QDs) (1-10 nm) via the green route has garnered great interest regarding their prospective use in many biological applications (diagnosis, drug delivery and in vivo sensing); this is difficult to achieve using chemical synthesis methods, which produce larger size QD particles and also require hazardous reagents. Here, we synthesized biogenic cadmium sulphide (CdS) QDs using green tea extract as the reducing agent to produce particles that were homogeneous and a smaller size of 2-4 nm. We also elucidated the (a) protein binding, (b) antibacterial use and (c) sensing applications of biogenic CdS QDs in this present work. The biosynthesized CdS QDs were found to have extensive antibacterial activity against both Gram-negative Escherichia coli and Gram-positive Enterococcus faecalis bacterial strains. The introduction of QDs in biological medium can lead to the formation of protein-QD complexes; therefore we investigated the binding interaction of CdS QDs with the carrier protein human serum albumin (HSA) in vitro. The synthesized CdS QDs quenched the intrinsic fluorescence of HSA through a static quenching mechanism and the binding constant (Kb ) was in the order of 104 M-1 . It was also observed that the presence of biogenic CdS QDs affected the HSA-ligand interactions in vitro. The synthesized CdS made highly effective sensors for tetracycline, rifampicin, and bilirubin with limit of detection (LOD) values of 99, 141 and 29 ng/ml, respectively.

Multispectroscopic studies on the molecular interactions between bovine γ-globulin and borohydride-capped silver nanoparticles.

Interactions between bovine γ-globulin (BGG) and borohydride-capped silver nanoparticles (BAgNPs) were studied using dynamic light scattering (DLS) and spectroscopic techniques such as UV-vis spectroscopy, fluorescence, and circular dichroism. The results were compared with earlier reported interactions between γ-globulin and citrate-coated AgNPs (CAgNPs). BAgNPs were synthesized and characterized. Irrespective of the coating on AgNPs, nanoparticles had formed ground-state complexes with the protein. CAgNPs, as well as BAgNPs had caused static quenching of tryptophan (Trp) fluorescence of the protein. The change in the capping agent from citrate to borohydride weakened the binding of nanoparticles with the protein. But the same change in capping agent had increased the fluorescence quenching efficiency of AgNPs. Hydrogen bonding and van der Waals interactions were involved in BGG-BAgNPs complex similar to the CAgNPs complex with γ-globulin. Polarity of the Trp microenvironment in BGG was not altered using BAgNPs as opposed to CAgNPs, as supported using synchronous and three-dimensional fluorescence. Resonance light scattering experiments also suggested nano-bio conjugation. Far-UV and near-UV circular dichroism (CD) spectra respectively pointed towards changes in the secondary and tertiary structure of BGG by BAgNPs, which was not observed for CAgNPs.

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

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