The involvement of neuroinflammation in the pathogenesis of neurodegenerative disorders (NDs) is very significant. Currently, only symptomatic treatments exist, and there are no drugs that modify the progression of Alzheimer's disease (AD) or other NDs. Consequently, there is increasing attention on addressing AD-related neuroinflammation using anti-inflammatory compounds and antioxidants. Currently, there is a growing exploration of dietary phytochemicals as potential therapeutic agents for treating inflammation. Citral, a monoterpene, is under increasing investigation due to its neuroprotective effects. The dysregulation of iron homeostasis is a crucial factor in supporting neuroinflammation, underscoring the significance of proper iron balance. Human transferrin (htf) is a major factor in iron homeostasis. In this study, we examined binding and dynamics of htf–citral complex through diverse experimental methods. Molecular docking studies revealed that citral binds to crucial residues of htf, forming a stable complex. UV-visible spectroscopy demonstrated binding of citral with htf with good affinity, evident from binding constant of 1.48 X105 M-1. Further, fluorescence spectroscopy entrenched a stable htf-citral complex formation; citral demonstrates an excellent binding affinity to htf with a binding constant of 106 M-1. Moreover, fluorescence binding assay at various temperatures deciphered htf-citral complex to be driven by both static and dynamic quenching. The analysis of enthalpy change (ΔH) and entropy change (ΔS) demonstrated that htf-citral complex formation was driven mainly by hydrophobic interactions..The current work gives a platform to develop innovative therapeutic strategies targeting neuroinflammation through citral, particularly iron homeostasis.
Aflatoxin B1 (AFB1), a potent mutagen, is synthesized by Aspergillus parasiticus and Aspergillus flavus. Human serum albumin (HSA) is a globular protein with diverse roles. As AFB1 is ingested with food and is transported in the body via blood, it becomes pertinent to comprehend the effect of the binding of this toxin on the structure and conformation of HSA, which may help to get insight into the toxic effect of the exposure of the mycotoxin. In this study, multi-spectroscopic approaches have been used to evaluate the binding efficiency of AFB1 with both the native HSA (nHSA) and the glycated HSA (gHSA). Steady-state fluorescence spectroscopy reveals the static type of fluorescence quenching in the fluorescence emission spectra of nHSA and gHSA in the presence of AFB1. The binding constant (Kb) is calculated to be 6.88 × 104 M-1 for nHSA, while a reduced Kb value of 2.95 × 104 M-1 has been obtained for gHSA. The circular dichroism study confirms the change in the secondary structure of nHSA and gHSA in the presence of AFB1, followed by alterations in the melting temperature (Tm) of nHSA and gHSA. In silico computational findings envisaged the amino acid residues and bonds involved in the binding of nHSA and gHSA with AFB1. The comprehensive study analyzes the binding effectiveness of AFB1 with nHSA and gHSA and shows reduced binding of AFB1 to gHSA.Communicated by Ramaswamy H. Sarma.As revealed by UV-absorption spectroscopy, the hyperchromic effect was more prominent in nHSA than gHSA in the presence of AFB1.The binding constant (Kb) obtained for the nHSA-AFB1 complex was 6.88 × 104 M−1, and the gHSA-AFB1 complex yielded Kb value of 2.95 × 104 M−1.Negative enthalpy change (ΔH) and entropy change (ΔS) suggested hydrogen bonding and van der Waals interaction as stabilizing forces of nHSA-AFB1 and gHSA-AFB1 complex.Site markers displacement assay suggested Sudlow’s site I as the binding site for AFB1 in nHSA and gHSA.Circular dichroism study showed that AFB1 induced secondary structural changes in nHSA and gHSA.Melting temperature (Tm) increased in nHSA and decreased in gHSA in the presence of AFB1.Molecular docking results confirmed Lys-195, Arg-222 and Arg-257 as hydrogen bonding residues in the nHSA-AFB1 complex and Arg-222 and Lys-199 residues were involved in hydrogen bonding in the gHSA-AFB1 complex.
Diabetes mellitus (DM), which influences individuals of more or less all age groups, is a crucial health concern globally characterized mainly by hyperglycemia. Advanced glycation end products are generated when non-enzymatic protein glycation occurs under hyperglycaemic circumstances. AGEs circulate in the body that increase ROS formation which activates a number of harmful pathways. Plant-derived remedies (herbal products) have been in use for centuries for treatment of many disorders. Phenolic acids are active constituents of phytochemicals. In this comparative study we have used three isomers of coumaric acid namely ortho coumaric acid (oCA), meta coumaric acid (mCA) and para coumaric acid (pCA) to deduce which one could be better problem-solving entity. HSA was used as model protein. It was glycated with glucose, with and without isomers for 28 days. We did some spectroscopic studies like UV- visible, fluorescence and CD spectroscopy. Along with spectroscopic studies some biochemicals studies like fructosamine analysis, free lysine estimation free thiol group estimation and free carbonyl group estimation were also done. To investigate the ROS production, we did fluorescence microscopy of isolated lymphocytes using DAPI and DCFH-DA. It was found that in glycated protein samples the level of absorbance and fluorescence increased along with loss of secondary structure which recovered when increasing concentration of isomers were present in glycation reaction. Amount of fructosamine and carbonyl group were also elevated in glycated sample but normalised upon treatment. Free lysine group and thiol group were also found diminished in glycated samples while they gradually recovered in treated samples. ROS production was visualized using DCFH-DA in lymphocyte treated with glycated sample, which was huge as compared to lymphocytes treated with native sample. ROS production was reduced in lymphocyte when exposed to coumaric acid treated protein samples. DAPI was used to visualise the apoptotic condition in treated lymphocytes. pCA was found consistently a better antioxidant and antiglycating agent. Our next step is to evaluate this study in animal model.
Alzheimer’s disease (AD) is the most common form of age-related neurodegeneration occurs because of deposition of proteins in the form of extracellular plaques containing aggregated amyloid beta (Aβ) peptide and intracellular neurofibrillary tangles composed of aggregated microtubule-binding protein tau. Amyloid aggregation process can be enhanced by several familial AD-associated mutations in Aβ peptide. In this study, we have unravelled the interactions of 40 small molecule inhibitors with the Osaka-mutant of Aβ1–40 peptide at atomic level and characterized modes of their binding to mutant Aβ by docking approaches. We have also compared docking energies of these inhibitors with Osaka-mutant with those previously determined for the wild-type and Iowa-mutant peptides and discussed in light of the peptide conformations and non-covalent interactions. We have also discussed inhibition mechanisms of these three peptides. Our analyses revealed that these small molecules can efficiently inhibit Osaka-mutant. The binding modes of drugs with these three peptides are markedly different and so are the mechanisms of inhibition of these three peptides. Overall analysis of the data reveals that binding energy of Iowa-mutant drug complex is lowest and most stable which is followed wild-type peptide-drug complex followed by Osaka-mutant drug complex.Communicated by Ramaswamy H. Sarma
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