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

Azoospermia is a condition in which sperm cells are completely absent in a male's ejaculate. Typically, sperm production occurs in the testes and is regulated by a complex series of cellular and molecular interactions. Endoplasmic reticulum (ER) stress arises when there is a deviation from or damage to the normal functions of the ER within cells. In response to this stress, a cascade of response mechanisms is activated to regulate ER stress within cells. This study aims to investigate the role of ER stress-regulated chaperones as potential biomarkers in male infertility. ER stress associated with azoospermia can manifest in cells such as spermatogonia in the testes and can impact sperm production. As a result of ER stress, the expression and activity of a variety of proteins within cells can be altered. Among these proteins are chaperone proteins that regulate the ER stress response. The sample size was calculated to be a minimum of 36 patients in each group. In this preliminary study, we measured and compared serum levels of protein disulfide-isomerase A1, protein disulfide-isomerase A3 (PDIA3), mesencephalic astrocyte-derived neurotrophic factor (MANF), glucose regulatory protein 78 (GRP78), clusterin (CLU), calreticulin (CRT), and calnexin (CNX) between male subjects with idiopathic nonobstructive azoospermia and a control group of noninfertile males. Serum PDIA1 (P = 0.0004), MANF (P = 0.018), PDIA3 (P < 0.0001), GRP78 (P = 0.0027), and CRT (P = 0.0009) levels were higher in the infertile group compared to the control. In summary, this study presents novel findings in a cohort of male infertile patients, emphasizing the significance of incorporating diverse biomarkers. It underscores the promising role of ER stress-regulated proteins as potential serum indicators for male infertility. By elucidating the impact of ER stress on spermatogenic cells, the research illuminates the maintenance or disruption of cellular health. A deeper understanding of these results could open the door to novel treatment approaches for reproductive conditions, including azoospermia.

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: Nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are known as gaseous autocoids. It is not clear how the application of exogenous NO, H2S and CO alters the thiol/disulfide balance and advanced oxidation protein products (AOPPs) in the hippocampus and serum. Materials and Methods: In the study, rats were exogenously injected with L-arginine (100 mg/kg) as a NO donor, NaHS (10 mg/ kg) as a H2S donor, and CORM-2 (10 mg/kg) as a CO donor (II) (a tricarbonyldichlororuthenium dimer). Thiol/disulfide balance and advanced protein oxidation products were analyzed in hippocampus and serum samples. Results: The native thiol level in the hippocampus of the L-arginine group was statistically decreased compared to the native thiol level of the control group (p≤0.0001). The disulfide level in the hippocampus of the L-arginine group was statistically increased compared to the control group (p=0.009). Hippocampal total thiol level of NaHS group and CORM-2 group increased statistically (p=0.008,p=0.0157, respectively), while serum disulfide level of CORM-2 group decreased (p=0.0005). Serum and hippocampus AOPPs levels of the NaHS group were statistically increased compared to the control group (***p=0.0006, **p=0.0047, respectively). Similarly, the hippocampal AOPP level in the CORM-2 group was found to be statistically increased compared to the AOPP level in the control group (p=0.0437). Conclusion: As NaHS can improve thiol/disulfide balance, new studies are needed for CORM-2 and L-Arginine. This study is the first to report the effects of NO, H2S and CO on thiol/disulfide balance and AOPPs in the hippocampus and serum. Keywords: NO, H2S, CO, AOPPs, Thiol/disulfide