Characterization of human serum albumin modified by hair dye component, 4-chloro-1,2-phenylenediamine: Role in protein aggregation, redox biology and cytotoxicity

Stability of Protein Pharmaceuticals: Recent Advances

There have been significant advances in the formulation and stabilization of proteins in the liquid state over the past years since our previous review. Our mechanistic understanding of protein-excipient interactions has increased, allowing one to develop formulations in a more rational fashion. The field has moved towards more complex and challenging formulations, such as high concentration formulations to allow for subcutaneous administration and co-formulation. While much of the published work has focused on mAbs, the principles appear to apply to any therapeutic protein, although mAbs clearly have some distinctive features. In this review, we first discuss chemical degradation reactions. This is followed by a section on physical instability issues. Then, more specific topics are addressed: instability induced by interactions with interfaces, predictive methods for physical stability and interplay between chemical and physical instability. The final parts are devoted to discussions how all the above impacts (co-)formulation strategies, in particular for high protein concentration solutions.'

Biophysical insight into the binding mechanism of epigallocatechin-3-gallate and cholecalciferol to albumin and its preventive effect against AGEs formation: An in vitro and in silico approach

Advanced glycation end products (AGEs) are produced non-enzymatically through the process of glycation. Increased AGEs production has been linked to several diseases including polycystic ovary syndrome (PCOS). PCOS contributes to the development of secondary comorbidities, such as diabetes, cardiovascular complications, infertility, etc. Consequently, research is going on AGEs-inhibiting phytochemicals for their potential to remediate and impede the progression of hyperglycaemia associated disorders. In this study human serum albumin is used as a model protein, as albumin is predominantly present in follicular fluid. This article focusses on the interaction and antiglycating potential of (-)-Epigallocatechin-3-gallate (EGCG) and vitamin D in combination using various techniques. The formation of the HSA-EGCG and HSA-vitamin D complex was confirmed by UV and fluorescence spectroscopy. Thermodynamic analysis verified the spontaneity of reaction, and presence of hydrogen bonds and van der Waals interactions. FRET confirms high possibility of energy transfer. Cumulative antiglycation resulted in almost 60 % prevention in AGEs formation, decreased alterations at lysine and arginine, and reduced protein carbonylation. Secondary and tertiary structural changes were analysed by circular dichroism, Raman spectroscopy and ANS binding assay. Type and size of aggregates were confirmed by Rayleigh and dynamic light scattering, ThT fluorescence, SEM and SDS-PAGE. Effect on cellular redox status, DNA integrity and cytotoxicity was analysed in lymphocytes using dichlorofluorescein (DCFH-DA), DAPI and MTT assay which depicted an enhancement in antioxidant level by cumulative treatment. These findings indicate that EGCG and vitamin D binds strongly to HSA and have antiglycation ability which enhances upon synergism.

Computational and physicochemical insight into 4-hydroxy-2-nonenal induced structural and functional perturbations in human low-density lipoprotein

Lipid peroxidation (LPO) is a biological process that frequently occurs under physiological conditions. Undue oxidative stress increases the level of LPO; which may further contribute to the development of cancer. 4-Hydroxy-2-nonenal (HNE), one of the principal by-products of LPO, is present in high concentrations in oxidatively stressed cells. HNE rapidly reacts with various biological components, including DNA and proteins; however, the extent of protein degradation by lipid electrophiles is not well understood. The influence of HNE on protein structures will likely have a considerable therapeutic value. This research elucidates the potential of HNE, one of the most researched phospholipid peroxidation products, in modifying low-density lipoprotein (LDL). In this study, we tracked the structural alterations in LDL by HNE using various physicochemical techniques. To comprehend the stability, binding mechanism and conformational dynamics of the HNE-LDL complex, computational investigations were carried out. LDL was altered in vitro by HNE, and the secondary and tertiary structural alterations were examined using spectroscopic methods, such as UV-visible, fluorescence, circular dichroism and fourier transform infrared spectroscopy. Carbonyl content, thiobarbituric acid-reactive-substance (TBARS) and nitroblue tetrazolium (NBT) reduction assays were used to examine changes in the oxidation status of LDL. Thioflavin T (ThT), 1-anilinonaphthalene-8-sulfonic (ANS) binding assay and electron microscopy were used to investigate aggregates formation. According to our research, LDL modified by HNE results in changes in structural dynamics, oxidative stress and the formation of LDL aggregates. The current investigation must characterize HNE's interactions with LDL and comprehend how it can change their physiological or pathological functions.Communicated by Ramaswamy H. Sarma.

Structural perturbations induced by cumulative action of methylglyoxal and peroxynitrite on human fibrinogen: An in vitro and in silico approach

Methylglyoxal (MGO); a reducing sugar and a dicarbonyl; attaches to the biomolecules (proteins, lipids, and DNA) leading to glycation and accumulation of oxidative stress in cells and tissues. Superoxide anion formed under such conditions entraps free nitric oxide radical (NO) to form peroxynitrite (PON). Nitro-oxidative stress due to PON is well established. Human fibrinogen plays a key role in haemostasis and is a highly vulnerable target for oxidation. Modifications of fibrinogen can potentially disrupt its structure and function. Earlier evidence suggested that glycation and nitro-oxidation lead to protein aggregation by making it resistant to lysis. This study aims to reveal the structural perturbations on fibrinogen in the presence of MGO and PON synergistically. The in vitro glyco-nitro-oxidation of human fibrinogen by MGO and PON leads to substantial structural alterations, as evident by biophysical and biochemical studies. In-silico results revealed the formation of stable complexes. UV-visible, intrinsic fluorescence, and circular dichroism investigations confirmed the synergistic effect of MGO and PON caused micro-structural modifications leading to secondary structural alterations. AGEs formation in MGO-modified fibrinogen reduced the free lysine and free arginine residues which were quantified by TNBS and phenanthrenequinone assays. Enhanced oxidative status was confirmed by estimating carbonyl content. ANS fluorophore validated exposure of hydrophobic patches in modified protein and thioflavin-T showed maximum binding with synergistically modified fibrinogen, indicated the formation of β-sheet. Confocal and electron microscope results corroborated the formation of aggregates. This study, therefore, evaluated the impact of MGO and PON on the structural integrity, oxidative status and aggregate formation of fibrinogen that can aggravate metabolic complications.

Crotonaldehyde induced structural alterations in Low-Density Lipoprotein: Immunogenicity of the modified protein in experimental animals and auto-antibodies generation in various cancers

Crotonaldehyde (CA), a prominent component of cigarette smoke (CS) is a pervasive environmental pollutant that is a highly toxic, unsaturated aldehyde. Exposure to CA-rich pollutants has been linked to the emergence of many malignancies in humans. To better understand the role of CA in biomolecule modification, this study investigated the detailed structural alterations in low-density lipoprotein (LDL) modified by CA, as well as the immunogenicity of the modified protein in experimental animals and the search for autoantibodies in various cancers patients.In vitro, results indicated alterations in secondary and tertiary structures; examined using UV-visible, fluorescence, far-UV circular dichroism, and Fourier transform infrared spectroscopy techniques. Changes in the oxidation status of LDL were studied by carbonyl content assay and NBT assay. ThT binding assay, scanning, and transmission electron microscopy were used to study aggregate formation. The findings revealed significant structural damage in LDL modified by CA. The modification resulted in the unmasking of hydrophobic clusters, the loss of the protein α-helix, and the formation of β-pleated sheet structure. The amyloid aggregate formation was confirmed through ThT microscopy and electron spectroscopy. Rabbits immunized with crotonaldehyde; lead to structural changes in the LDL; that acted as extra antigenic determinants, eliciting strong antibody response. Immunoglobulin response is highly specific for modified LDL as demonstrated by the ELISA. The presence of antibodies against CA-modified LDL was confirmed by the immunoglobulin content of blood sera from human subjects with lung cancer, and competitive ELISA demonstrated the specificity of these antibodies. This study offers insights into the CA-mediated LDL modification and immunogenicity in lung cancer that will have diagnostic importance.

Polyphenols Coordinated with Cu (II) in an Aqueous System Build Ion-Channel Coatings on Hair Surfaces

Recently, developments in the field of cosmetics have led to a renewed interest in hair dyeing. However, damage to the hair during the dyeing process has increased hesitation in attempting hair dyeing. As a result, hair dyes with minimal side effects have been in constant demand, and are being developed. In this study, natural-extract polyphenols, pyrogallol, and gallic acid are coordinated by CuCl₂ in a NaCl aqueous solution to form an oligomer, which creates an ion-channel coating on the hair surface to protect it. This work attempts to develop fast, simple, and damage-free hair-dye ingredients based on pyrogallol and gallic acid. The morphology and elements of polyphenols coated on hair are characterized. The results reveal that the hair is dyed with the polyphenol-based dye reagent successfully. Moreover, the thickness of the dyed hair continuously rises ten times after dyeing. The tensile strength of the dyed hair is also measured, showing an upward and downward trend. These results reflect the fact that pyrogallol and gallic acid are considered to be the essential and functional polyphenols, and can build ion blocks on hair, which can create new multifunctional coating materials.

4-Chloro-orthophenylenediamine alters DNA integrity and affects cell survival: inferences from a computational, biophysical/biochemical, microscopic and cell-based study

The deleterious impact of toxic constituents of hair dyes over the human health has gained immense attention in the recent past. Their oncogenicity, mutagenicity, role in protein modification, impact on cellular metabolism has been documented. There is little information on the mechanism of reactivity of hair dye components with the nucleic acids and its implications. This work, therefore, uses computational, biophysical/biochemical, microscopic and cell-based study to analyze the interaction of monocyclic aromatic amine and a hair dye component, 4-chloro-orthophenylenediamine (4-Cl-OPD) with the DNA, its impact on DNA structure and cell survival. The results suggest that 4-Cl-OPD binds with the DNA in minor groove of the duplex involving three base pairs preferentially the G-C residues, induces strand breaks and makes DNA thermally labile through loss of hydrogen bonding/base unstacking. 4-Cl-OPD causes fragmentation of DNA, reduction in size of the molecule, alters B-DNA conformation and disrupts its secondary structure. The modified DNA gives fragmented appearance, shows broken strands and aggregation in ultra-structural analysis. 4-Cl-OPD induces ROS generation in lymphocytes, increases the comet's average tail length and reduces the viability of lymphocytes. This study forms a base for establishing the direct toxicity of 4-Cl-OPD at the molecular and cellular level through direct production of superoxide radicalCommunicated by Ramaswamy H. Sarma.

Risk of Carcinogenicity Associated with Synthetic Hair Dyeing Formulations: A Biochemical View on Action Mechanisms, Genetic Variation and Prevention

Article tries to visualize the potential for carcinogenic trigger in humans with a preference for oxidative synthetic of hair dyeing formulations, especially which belong to the category of permanent colours. According to the International Agency for Cancer, hair dyes for personal use are not strictly classified as carcinogen to humans. However, some controversy exists that requires clarification. Some epidemiological studies support the association between the risk of cancer development and personal use of hair dyes (pooled relative risk RR = 1.50. 95% CI: 1.30-1.98). The world-wide sale of hair dyeing cosmetics have exceeded 15 billion dollars by the year 2012 and has maintained an annual growth rate of 8-10%. This raises concerns and need to be addressed. The review article briefly discusses about the different hair dye components based on their chemical nature, permanence, interaction of dye components with different parts of the hair shaft, action mechanisms, health risk assessment, associated challenges and possible alternatives. There appears variability towards the pathological changes incurred in the human system upon the use of synthetic hair formulations. This probably appears due to the presence of interindividual genetic variation of enzymes handling these xenobiotics. The redox mechanism of major hair dye components appears to be involved in the carcinogenic trigger. Most of the hair dye constituents pose serious health issues. However, we do have few better alternatives to prevent the toxicity associated with hair dye constituents without compromising the need of today's fashion statement and expectations of the youth.

Elucidation of the binding mechanism of astragaloside IV derivative with human serum albumin and its cardiotoxicity in zebrafish embryos

LS-102 is a new derivative of astragaloside IV (AGS IV) that has been shown to possess potentially significant cardioprotective effects. However, there are no reports concerning its interaction with human serum albumin (HSA) and toxicology in vertebrates. The present investigation was undertaken to characterize the interaction of AGS IV and LS-102 with HSA using equilibrium dialysis and UHPLC-MS/MS methods, along with computational methods. Notably, the effects of AGS IV and LS-102 were studied in vivo using the zebrafish embryo model. Markers related to embryonic cardiotoxicity and thrombosis were evaluated. We showed that the plasma protein binding rate of AGS IV (94.04%–97.42%) was significantly higher than that of LS-102 (66.90%–69.35%). Through site marker competitive experiments and molecular docking, we found that AGS IV and LS-102 were located at the interface of subdomains IIA and IIIA, but the site I might be the primary binding site. Molecular dynamics revealed that AGS IV showed a higher binding free energy mainly due to the stronger hydrophobic and hydrogen bonding interactions. Moreover, the secondary structure implied no obvious effect on the protein structure and conformation during the binding of LS-102. LS-102 significantly ameliorated the astramizole-induced heart rate slowing, increased SV-BA spacing, and prevented arachidonic acid-induced thrombosis in zebrafish. To our knowledge, we are the first to reveal that LS-102 binds to HSA with reversible and moderate affinity, indicating its easy diffusion from the circulatory system to the target tissue, thereby providing significant insights into its pharmacokinetic and pharmacodynamic properties when spread in the human body. Our results also provide a reference for the rational clinical application of LS-102 in the cardiovascular field.

4-Chloro-1,2-phenylenediamine induced structural perturbation and genotoxic aggregation in human serum albumin

4-Chloro-1,2-phenylenediamine (4-Cl-OPD) is a halogenated aromatic diamine used as a precursor in permanent hair color production. Despite its well-documented mutagenic and carcinogenic effects in various in vitro and in vivo models, its role in fibrillar aggregate formation and their genotoxic effect in therapeutic proteins has received less attention. The significance of human serum albumin (HSA) arises from its involvement in bio-regulatory and transport processes. HSA misfolding and aggregation are responsible for some of the most frequent neurodegenerative disorders. We used various complementary approaches to track the formation of amyloid fibrils and their genotoxic effect. Molecular dynamics study demonstrated the complex stability. The impact of 4-Cl-OPD on the structural dynamics of HSA was confirmed by Raman spectroscopy, X-ray diffraction, HPLC and SDS-PAGE. Fibrilllar aggregates were investigated using Congo red assay, DLS, and SEM. The genotoxic nature of 4-Cl-OPD was confirmed using plasmid nicking assay and DAPI staining, which revealed DNA damage and cell apoptosis. 4-Cl-OPD provides a model system for studying fibrillar aggregation and their genotoxic potential in the current investigation. Future studies should investigate the inhibition of the aggregation/fibrillation process, which may yield valuable clinical insights.