Cigdem Cicek

Gamma Knife radiosurgery (GKRS) is a widely used treatment for intracranial meningiomas; however, its effects on endoplasmic reticulum (ER) stress–related molecular pathways remain unclear. This study aimed to evaluate changes in circulating ER stress–associated chaperone proteins before and three months after GKRS and to explore their relationship with radiological and dosimetric findings. A total of 27 patients with meningioma treated with GKRS and 20 healthy controls were included. Peripheral blood samples were collected prior to treatment and three months post-treatment. Serum levels of glucose-regulated protein 78 (GRP78), calreticulin (CALR), calnexin (CNX), mesencephalic astrocyte-derived neurotrophic factor (MANF), protein disulfide isomerase (PDI), and protein disulfide isomerase A3 (PDIA3) were measured using enzyme-linked immunosorbent assay (ELISA). Magnetic resonance imaging was used to evaluate tumor volume and peritumoral edema. Dosimetric parameters were obtained from the treatment planning system. Pre-treatment levels of PDIA3, CALR, CNX, MANF, and PDI were higher in patients with meningioma than in healthy controls, with statistically significant differences observed for PDIA3, CALR, CNX, MANF, and PDI. Following GKRS, all six investigated proteins showed numerical decreases. Nominally significant pre- to post-treatment reductions were observed for PDIA3, CALR, MANF, and PDI; however, after Holm correction for multiple comparisons, only the reduction in CALR remained statistically significant. MRI assessment demonstrated tumor volume reduction in 5 of 27 patients (18.5%), while tumor volume remained stable in 22 patients (81.5%). GKRS was associated with measurable changes in circulating ER stress–related proteins. These findings indicate a temporal association rather than a causal effect and should be interpreted with caution. Although these markers are not suitable as standalone biomarkers, they may provide complementary information when evaluated together with radiological findings. Further longitudinal and mechanistic studies are needed to determine their biological significance and potential clinical relevance.

Objective: Alzheimer’s disease (AD) is characterised by the gradual decline of cognitive function and impaired cholinergic neurotransmission due to reduced brain acetylcholine levels. AChE and BChE regulate acetylcholine degradation and are important targets in AD. This research investigated the inhibitory effects of indole-3-propionic acid (IPA) and indole-3-butyric acid (IBA) on human cholinesterases, using enzyme kinetics and molecular docking. Methods: We assessed the inhibitory effects of purified human BChE and commercially sourced erythrocyte-derived AChE using a modified Ellman spectrophotometric assay in a 96-well microplate. Kinetic parameters (Km, Vmax, and Ki) were determined by nonlinear regression and the Michaelis–Menten model, with Lineweaver–Burk plots used to analyse inhibition patterns. IC50 values were calculated by nonlinear regression analysis. Molecular docking simulations were performed to predict the binding positions of the indole derivatives and the reference Alzheimer’s drugs donepezil and tacrine analogue in the active sites of AChE and BChE. Results: According to docking simulations, both indole derivatives bind to the catalytic gorge of cholinesterases, but with lower predicted affinity than reference inhibitors. Enzyme inhibition assays showed that IBA exhibited weak inhibitory activity against both enzymes, with IC50 values of 15.61 mM for BChE and 54.28 mM for AChE. IPA exhibited stronger inhibition, particularly against BChE, with an IC50 of 2056 µM. Kinetic analysis indicated that IPA displays mixed-type inhibition of BChE (Km = 170.1 µM, Ki = 1774 µM), while its inhibition of AChE is competitive (IC50 = 3773 µM, Km = 268.5 µM, Ki = 6727 µM). Conclusion: These findings suggest that short-chain indole metabolites can interact with cholinesterases, but are not potent inhibitors. Compared to IBA, IPA showed higher activity and distinct inhibition profiles for BChE and AChE. The development of new indole-based cholinesterase inhibitors may prove to be potent modulators of cholinergic enzymes.

Objective: This study investigated the dual-target binding potential of seven natural compounds celastrol, pachypodol, hinokitiol, withanone, isobavachalcone, magnolol, and xanthorrhizol against AChE and BChE, using donepezil and rivastigmine as references.Material and Method: Molecular structures were obtained from PubChem and energy-minimised with the MMFF94 force field. Docking was performed using AutoDock Vina with human AChE (PDB ID: 4M0E) and BChE (PDB ID: 6QAA). Binding affinities and interaction profiles were assessed with Discovery Studio Visualizer.Results: Isobavachalcone (–9.2 kcal/mol) and magnolol (–8.4 kcal/mol) showed high affinity for AChE, while withanone (–9.7 kcal/mol) and celastrol (–9.6 kcal/mol) strongly bound BChE, comparable to donepezil. These compounds established stabilising interactions, including hydrogen bonds, π–π stacking, and hydrophobic contacts, with minimal steric conflicts, supporting structural compatibility with target enzymes.Conclusion:Isobavachalcone, magnolol, celastrol, and withanone are identified as promising multifunctional candidates. Their dual cholinesterase inhibition and reported antioxidant properties suggest potential to address both cholinergic dysfunction and ferroptosis-associated neurodegeneration, warranting further experimental validation.

Butyrylcholinesterase is an abundant detoxification enzyme in human serum that is mainly synthesized in the liver. It plays a crucial role in the hydrolysis of a variety of choline esters and xenobiotics, and there is emerging evidence that it is also involved in lipid metabolism. In this study, the inhibitory effects of the major unsaturated fatty acids — arachidonic acid (AA), linoleic acid (LA), oleic acid (OA), and alpha-linolenic acid (α-LA) — on human BChE are investigated using enzyme kinetics experiments and molecular modeling analyses. These fatty acids, integral components of membrane phospholipids, differ in chain length and degree of unsaturation, which influence their inhibitory effect on BChE. Our results showed that AA had the highest IC₅₀ value of 611 µM against BChE, followed by OA, α-LA, and LA. All fatty acids showed noncompetitive inhibition, in contrast to AA, which displayed uncompetitive inhibition. Inhibitory constants (Ki) showed that OA had the strongest binding affinity due to its lowest Ki value of 321.4 µM, followed by AA, α-LA, and LA. Molecular modeling supported the in vitro results. The fatty acids were predicted to bind to a newly proposed allosteric site on BChE. Our results demonstrate that the number and position of double bonds in the alkenyl chains of fatty acids significantly influence their interactions with BChE, providing new insights into how dietary lipids regulate the enzyme. This study offers a foundation for further exploration of BChE’s role in lipid metabolism and its implications for neurodegenerative and metabolic diseases. Graphical abstract

Phenylketonuria (PKU) stems from a rare genetic metabolic imbalance attributed to an insufficiency in the enzyme phenylalanine hydroxylase. Within the context of PKU, brain‑derived neurotrophic factor (BDNF) plays a pivotal role in brain function. 7,8‑dihydroxyflavone (7,8‑DHF) operates as a tropomyosin receptor kinase B (TrkB) agonist, mimicking the effects of BDNF. This study aimed to examine the effects of administering 7,8‑DHF in chemically‑induced rat models specifically induced to simulate PKU chemically. The rats were subcutaneously injected with phenylalanine and p‑chlorophenylalanine, a phenylalanine hydroxylase inhibitor, along with 7,8‑DHF. The injections began on the 2nd day after birth and continued until the 10th day. Levels of interleukin‑1β (IL‑1β), interleukin‑6 (IL‑6), interleukin‑33 (IL‑33), BDNF, malondialdehyde (MDA), monoamine oxidase (MAO), and superoxide dismutase (SOD) in the brain tissues were quantified using the enzyme‑linked immunosorbent assay (ELISA). Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to assess the gene expressions of inducible nitric oxide synthase (iNOS), nuclear factor kappa beta (NF‑κB), caspase‑3, nuclear factor erythroid 2‑related factor 2 (Nrf2), heme oxygenase‑1 (HO‑1), and BDNF. The results showed a decrease in mRNA levels of iNOS, IL‑1β, IL‑6, and lipid peroxidation in the group that received 7,8‑DHF. These results indicate that administering 7,8‑DHF has the potential to reduce brain damage in PKU by lowering proinflammatory cytokine levels and lipid peroxidation in PKU models. Thus, 7,8‑DHF, as a small molecule, might offer a promising adjunct therapeutic approach for PKU.

Phenylketonuria (PKU) results from congenital defects of amino acid metabolism. Accumulated phenylalanine crosses the blood-brain barrier and causes permanent brain damage, but the neuro-pathophysiology underlying phenylketonuria is not fully understood. Chemically-induced rat phenylketonuria model of both genders was generated to examine the role of inflammatory response, lipid peroxidation and oxidative stress in the prefrontal cortex. Our results showed that in phenylketonuria there was an increase in lipid peroxidation compared to controls, which was significantly different only in males (p<0.001). In male rat PKU groups, statistically significant differences were also observed in serum tryptophan (p<0.001) and interleukin-1β levels (p=0.014) as compared to male controls. In this study, gender-based changes in neuroinflammation and lipid peroxidation were reported for the first time in a PKU model.

Introduction: Phenylketonuria (PKU) is a rare inherited metabolic disorder characterized by a deficiency of the enzyme phenylalanine hydroxylase. The absence of this enzyme leads to elevated levels of phenylalanine in the blood, causing accumulation in the brain and resulting in permanent brain damage. To investigate the neurological effects of PKU, an experimental PKU model was developed, and cholinergic parameters were analyzed in brain tissue and serum from both female and male rats. Serum AChE, BChE, and total ChE activities were examined, while AChE activity was specifically analyzed in hippocampal tissue. Material and Methods: Brain tissue and serum samples were collected from female and male rats from an induced phenylketonuria model for analysis. AChE, BChE, and total ChE activities were measured in serum samples, while AChE activity was examined in hippocampal tissue. Enzyme activities were measured according to Ellman assay. The data analysis and graphical presentations were done by GraphPad prism. Results: Hippocampal AChE activity was significantly increased in both PKU groups compared to the control groups (Male ***p=0.0001; female *p=0.046). Serum analysis revealed decreased total serum cholinergic activity in both the female and male PKU groups compared with the control groups (**p≤0.002 and ***p≤0.0003, respectively). These results were consistent with findings from total serum cholinergic activity analysis. Additionally, the AChE activity in both the female and male PKU groups was decreased compared to their respective control groups (***p≤0.002 and ***p≤0.0006, respectively). It was also found that BChE activity in the serum of male rats in the PKU group was decreased compared to male rats in the control group (*p=0.038). Conclusion: These findings indicate that the cholinergic system in the phenylketonuria model may vary according to gender. The observed changes in both brain tissue and serum provide new insights into the gender-dependent neurological effects of PKU. Keywords: Phenylketonuria, cholinergic system, enzyme activity, hippocampal tissue, gender differences

Amaç: Fenilketonüri (PKU), fenilalanin hidroksilaz enzim eksikliği ile karakterize nadir görülen bir kalıtsal metabolik hastalıktır. Bu enzimin eksikliği, kan fenilalanin seviyesini yükselterek, beyinde fenilalanin birikmesine ve geri dönüşümsüz nörolojik hasar oluşmasına neden olur. . Bu çalışmada fenilketonüri modelinde beyin tiyol/disülfit dengesindeki değişimin belirlenmesi amaçlanmıştır. Yöntem: PKU modeli oluşturulmuş sıçan yavrularında (n:7) ve kontrol grubunda beyin total tiyol ve serbest tiyol seviyesi modifiye elman yöntemi ile ölçüldü. Total tiyol ve native tiyol seviyelerine göre disülfit seviyesi hesaplandı. Bulgular: PKU grubun beyin total tiyol seviyesi kontrol grubuna göre istatistiksel olarak azdır (*p=0.0369). PKU grubun beyin serbest tiyol seviyesi kontrol grubuna göre istatistiksel olarak azdır (****p<0.001). PKU grubun beyin disülfit seviyesi kontrol grubuna göre istatistiksel olarak değişiklik göstermemiştir (p=0.1107). Sonuç: PKU’de oluşan oksidatif strese tiyol/disülfit seviyelerininde değişikliklerinde etki edebileceği sonucuna varılmıştır. Literatürde ilk kez rapor edilen çalışmada PKU patofizyolojine tiyol/disülfit dengesininde değişiklik olduğu gösterilmiştir.