Reversible Competitive Inhibitor Research Articles

Mechanism-Based Allylic Carbasugar Chlorides That Form Covalent Intermediates with α- and β-Galactosidases.

Glycoside hydrolases have been implicated in a wide range of human conditions including lysosomal storage diseases. Consequently, many researchers have directed their efforts towards identifying new classes of glycoside hydrolase inhibitors, both synthetic and from natural sources. A large percentage of such inhibitors are reversible competitive inhibitors that bind in the active site often due to them possessing structural features, often a protonatable basic nitrogen atom, that mimic the enzymatic transition state. We report that mechanism-based small molecule galacto-like configured cyclohexenyl carbasugars form reversible covalent complexes with both α-galactosidase and β-galactosidase. In addition, we show that the β-galactosidase from Aspergillus oryzae reacts with three different carbasugar inhibitors, with three different second-order rate constants (kinact/Ki), to give the same enzyme-carbasugar covalent intermediate. The surprising observation that the α-galacto-configured inhibitor covalently labels the A. oryzae β-galactosidase highlights the catalytic versatility of glycoside hydrolases. We expect that cyclohexenyl covalent inhibitors will become an important class of compounds in the chemical biologist's tool box.

Visnagin alleviates rheumatoid arthritis via its potential inhibitory impact on malate dehydrogenase enzyme: in silico, in vitro, and in vivo studies

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder. The present study aimed to evaluate the in silico, in vitro, and in vivo inhibitory effect of visnagin on malate dehydrogenase activity and elucidate its inflammatory efficacy when combined with methotrexate in the RA rat model. The molecular docking, ADMET simulations, MDH activity, expression, and X-ray imaging were detected. Moreover, CRP, RF, (anti-CCP) antibody, (TNF-α), (IL-6), (IL-17), and (IL-10) were evaluated. The expression levels of MMP3 and FOXP3 genes and CD4, CD25, and CD127 protein levels were assessed. Histological assessment of ankle joints was evaluated. The results revealed that visnagin showed reversible competitive inhibition on MDH with inhibitory constant (Ki) equal to 141 mM with theoretical IC50 equal to 1202.7 mM, LD50 equal to 155.39 mg/kg, and LD25 equal to 77.69 mg/kg. In vivo studies indicated that visnagin exhibited anti-inflammatory effects through decreasing MDH1 activity and expression and induced proliferation of anti-inflammatory CD4+CD25+FOXP3 regulatory T cells with increasing the anti-inflammatory cytokine IL-10 levels. Moreover, visnagin reduced the levels of inflammatory cytokines and the immuno-markers. Our findings elucidate that visnagin exhibits an anti-inflammatory impact against RA through its ability to inhibit the MDH1 enzyme, improve methotrexate efficacy, and reduce oxidative stress.Graphical

Selenium polysaccharide form sweet corn cob mediated hypoglycemic effects in vitro and untargeted metabolomics study on type 2 diabetes

Type 2 diabetes mellitus (T2D) causes complications due to metabolic disorders besides increasing blood glucose. Sweet corn cob selenium polysaccharide (SeSCP) is a complex of Se with Sweet corn cob polysaccharide that has good hypoglycemic efficacy, but its effect on T2D metabolism has not been determined. In this study, the hypoglycemic effect of SeSCP was investigated by in vitro and in vivo experiments, and the levels of metabolites in feces were analyzed in a high-fat diet and STZ-induced T2D mouse model by Liquid chromatography-mass spectrometry (LC-MS). The results indicated that SeSCP regulates α-amylase and α-glucosidase through competitive reversible inhibition, and the reaction is spontaneous, driven by van der Waals forces and hydrogen bonding. In vivo, SeSCP modulates glucose transport decreasing glucose entry into the bloodstream. The metabolites mainly affected by SeSCP-MC were adenine, LysoPA (0:0/18:2(9Z, 12Z)), cysteine-S-sulfate, and demeclocycline (hydrochloride) metabolites. SeSCP interfered with β-alanine metabolism, starch and sucrose metabolism, ether lipid metabolism, glycerophospholipid metabolism, glyoxylate and dicarboxylate metabolism, pantothenate and CoA biosynthesis, etc. Additionally, SeSCP exhibited more effective metabolic interventions than metformin and SCP. Therefore, SeSCP can reduce complications while improving T2D blood glucose.

In Vitro In Silico Screening Strategy and Mechanism of Novel Tyrosinase Inhibitory Peptides from Nacre of Hyriopsis cumingii.

For thousands of years, pearl and nacre powders have been important traditional Chinese medicines known for their skin whitening effects. To prepare the enzymatic hydrolysates of Hyriopsis cumingii nacre powder (NP-HCH), complex enzymatic hydrolysis by pineapple protease and of neutral protease was carried out after the powder was pre-treated with a high-temperature and high-pressure method. The peptides were identified using LC-MS/MS and picked out through molecular docking and molecular dynamics simulations. Subsequently, the tyrosinase inhibitory and antioxidant properties of novel tyrosinase inhibitory peptides were investigated in vitro. In addition, the enzymatic activity of tyrosinase in B16F10 cells as well as melanin content and antioxidant enzyme levels were also examined. The results showed that a tyosinase inhibitory peptide (Tyr-Pro-Asn-Pro-Tyr, YPNPY) with an efficient IC50 value of 0.545 ± 0.028 mM was identified. The in vitro interaction results showed that YPNPY is a reversible competitive inhibitor of tyrosinase, suggesting that it binds to the free enzyme. The B16F10 cell whitening test revealed that YPNPY can reduce the melanin content of B16F10 cells by directly inhibiting the activity of intracellular tyrosinase. Additionally, it indirectly affects melanin production by acting as an antioxidant. These results suggest that YPNPY could be widely used as a tyrosinase inhibitor in whitening foods and drugs.

Inhibition of monoamine oxidases and neuroprotective effects: chalcones vs. chromones.

Eighteen compounds derived from two sub-series, (HC1-HC9) and (HF1-HF9), were synthesized and evaluated for their inhibitory activities against monoamine oxidase (MAO). HC (chalcone) series showed higher inhibitory activity against MAO-B than against MAO-A, whereas the HF (chromone) series showed reversed inhibitory activity. Compound HC4 most potently inhibited MAO-B with an IC50 value of 0.040μM, followed by HC3 (IC50 = 0.049μM), while compound HF4 most potently inhibited MAO-A (IC50 = 0.046μM), followed by HF2 (IC50 = 0.075μM). The selectivity index (SI) values of HC4 and HF4 were 50.40 and 0.59, respectively. Structurally, HC4 (4-OC2H5 in B-ring) showed higher MAO-B inhibition than other derivatives, suggesting that the -OC2H5 substitution of the 4-position in the B-ring contributes to the increase of MAO-B inhibition, especially -OC2H5 (HC4) > -OCH3 (HC3) > -F (HC7) > -CH3 (HC2) > -Br (HC8) > -H (HC1) in order. In MAO-A inhibition, the substituent 4-OC2H5 in the B-ring of HF4 contributed to an increase in inhibitory activity, followed by -CH3 (HF2), -F (HF7), -Br (HF8), -OCH3 (HF3), and-H (HF1). In the enzyme kinetics and reversibility study, the Ki value of HC4 for MAO-B was 0.035 ± 0.005μM, and that of HF4 for MAO-A was 0.035 ± 0.005μM, and both were reversible competitive inhibitors. We confirmed that HC4 and HF4 significantly ameliorated rotenone-induced neurotoxicity, as evidenced by the reactive oxygen species and superoxide dismutase assays. This study also supports the significant effect of HC4 and HF4 on mitochondrial membrane potential in rotenone-induced toxicity. A lead molecule was used for molecular docking and dynamic simulation studies. These results show that HC4 is a potent selective MAO-B inhibitor and HF4 is a potent MAO-A inhibitor, suggesting that both compounds can be used as treatment agents for neurological disorders.

Identification and functional characterization of a novel cystatin in amphioxus, ancient origin of vertebrate type-2 cystatin homologues

Cystatins are well known as a vast superfamily of functional proteins participated in the reversible competitive inhibition of cysteine proteases. Currently, increasing evidences point to the extensive phylogenetic diversity and crucial immune roles of type-2 cystatins in the vertebrate species. However, no information is available regarding the homologue in cephalochordate amphioxus, the representative of most basal living chordates, whose immune regulation are still ambiguous. Here, we clearly identified the presence of type-2 cystatin gene in amphioxus Branchiostoma japonicum, termed Bjcystatin-2, which was structurally characterized by typical wedge-shaped cystatin feature. Evolutionary analyses revealed that Bjcystatin-2 is the putative ancestral type-2 cystatin for chordates, with gene diversity emerging through duplication events. The expression of Bjcystatin-2 showed tissue-specific profile and was inducible upon invasive pathogens. Significantly, the recombinant Bjcystatin-2 exhibited not merely cathepsin L inhibitory activity, but also the ability to bind with bacteria and their characteristic molecules. Furthermore, Bjcystatin-2 also showed the capacity to enhance the macrophage-driven bacterial phagocytosis and to attenuate the generation of pro-inflammatory cytokines within macrophages. In summary, these findings demonstrate that Bjcystatin-2 exhibits dual role acting as both a protease inhibitor and an immunoactive molecule, greatly enriching our understanding of immune defense mechanisms of type-2 cystatin within the amphioxus.

Structural characterization and hypoglycemic effect of polysaccharides of Polygonatum sibiricum.

Polygonatum sibiricum polysaccharide (PSP) was extracted and purified from raw material obtained from P. sibiricum. The structural features of PSP were investigated by Congo red, circular dichroism spectrum, high-performance gel permeation chromatography, scanning electron microscope, atomic force microscope, ultraviolet spectroscopy, and Fourier transform infrared spectroscopy analysis. In vitro simulations were conducted to investigate the kinetics of PSP enzyme inhibition. Moreover, a type II diabetes mouse model (T2DM) with streptozotocin-induced insulin resistance was established, and the indexes of lipid quadruple, insulin resistance index, oral glucose tolerance (OGTT), organ index, and pancreatic morphology of model mice were measured. The results showed that PSP mainly consists of monosaccharides, such as mannose, glucose, galactose, xylose, and arabinose. It also has a β-glycosidic bond of a pyranose ring and an irregular reticulated aggregated structure with a triple helix. In vitro enzyme inhibition assays revealed that PSP acts as a reversible competitive inhibitor of α-glucosidase and α-amylase. Furthermore, PSP was found to reduce insulin resistance index, increase OGTT and serum insulin levels, decrease free fatty acid content to improve lipid metabolism, and lower glycated serum protein content to enhance glucose metabolism in T2DM mice, thereby leading to a reduction in blood glucose concentration. Additionally, PSP exhibited reparative effects on the damaged liver tissue cells and pancreatic tissue in T2DM mice. The experiment results provide a preliminary basis for the therapeutic mechanism of PSP about type II diabetes and a theoretical reference for application in food and pharmaceutical development.

A novel tyrosinase inhibitory peptide obtained from Sipunculus nudus gelatin hydrolysate: Preparation, identification, and action mechanism

Tyrosinase inhibitory peptides (TIPs) derived from food resources have attracted immense attention in the food, cosmetic, and pharmaceutical industries owing to their excellent biological safety and ease of absorption. In this study, single-factor experiment and response surface optimization were used to prepare the Sipunculus nudus gelatin enzymatic hydrolysis (SNGH) product. Subsequently, a novel tyrosinase inhibitory peptide was screened out through ultrafiltration classification, biological activity prediction, molecular docking, and molecular dynamics simulation, and its inhibitory mechanism was analyzed. The results revealed that the optimal enzymatic hydrolysis process was: the enzyme addition was 4768.87 U/g, the enzymatic hydrolysis time was 4.72 h, and the enzymatic hydrolysis temperature was 42.76 °C. A total of 287 peptides were detected in the ultrafiltration component Ⅰ (SNGH-Ⅰ) with a high tyrosinase inhibitory activity, and 161 peptides with binding energies < −7.0 kcal/mol were screened out through molecular docking. Subsequently, 91 peptides with a biological activity score >0.3 were obtained after biological activity screening. Finally, 5 possible TIPs were screened out according to their hydrophobicity, peptide score, and molecular weight. Among them, IIAPPERKY, VWDESFKVF, and FAGDDAPRAVFPS exhibited a superior tyrosinase inhibitory activity. Molecular dynamics simulations revealed that IIAPPERKY had better conformational stability and belonged to the group of reversible competitive inhibitors.

Structural Insights into the Marine Alkaloid Discorhabdin G as a Scaffold towards New Acetylcholinesterase Inhibitors.

In this study, Antarctic Latrunculia sponge-derived discorhabdin G was considered a hit for developing potential lead compounds acting as cholinesterase inhibitors. The hypothesis on the pharmacophore moiety suggested through molecular docking allowed us to simplify the structure of the metabolite. ADME prediction and drug-likeness consideration provided valuable support in selecting 5-methyl-2H-benzo[h]imidazo[1,5,4-de]quinoxalin-7(3H)-one as a candidate molecule. It was synthesized in a four-step sequence starting from 2,3-dichloronaphthalene-1,4-dione and evaluated as an inhibitor of electric eel acetylcholinesterase (eeAChE), human recombinant AChE (hAChE), and horse serum butyrylcholinesterase (BChE), together with other analogs obtained by the same synthesis. The candidate molecule showed a slightly lower inhibitory potential against eeAChE but better inhibitory activity against hAChE than discorhabdin G, with a higher selectivity for AChEs than for BChE. It acted as a reversible competitive inhibitor, as previously observed for the natural alkaloid. The findings from the in vitro assay were relatively consistent with the data available from the AutoDock Vina and Protein-Ligand ANTSystem (PLANTS) calculations.

Using Amylase Beads to Investigate Factors Affecting Enzyme Activity

Existing laboratory protocols for investigating the effects of factors affecting enzyme activity often require extensive hands-on manipulations and time. This can result in students either not getting the desired results or being distracted from thinking about the scientific ideas underlying the experimental designs and procedures of these protocols. In this paper, we present a lesson plan that includes a simple microscale laboratory protocol that allows students to study the action of amylase on starch and to investigate the effects of various factors (i.e., temperature, pH, substrate concentration, enzyme concentration, and competitive reversible inhibitors) on enzyme activity using immobilized amylase beads. We also show how to engage students in thinking about procedural knowledge, such as repeating measurements, measurement range, and interval. These concepts are critical to designing valid and reliable scientific investigations.

6'-O-Caffeoylarbutin from Quezui Tea: A Highly Effective and Safe Tyrosinase Inhibitor.

Tyrosinase is vital in fruit and vegetable browning and melanin synthesis, crucial for food preservation and pharmaceuticals. We investigated 6'-O-caffeoylarbutin's inhibition, safety, and preservation on tyrosinase. Using HPLC, we analyzed its effect on mushroom tyrosinase and confirmed reversible competitive inhibition. UV_vis and fluorescence spectroscopy revealed a stable complex formation with specific binding, causing enzyme conformational changes. Molecular docking and simulations highlighted strong binding, enabled by hydrogen bonds and hydrophobic interactions. Cellular tests showed growth reduction of A375 cells with mild HaCaT cell toxicity, indicating favorable safety. Animal experiments demonstrated slight toxicity within safe doses. Preservation trials on apple juice showcased 6'-O-caffeoylarbutin's potential in reducing browning. In essence, this study reveals intricate mechanisms and applications of 6'-O-caffeoylarbutin as an effective tyrosinase inhibitor, emphasizing its importance in food preservation and pharmaceuticals. Our research enhances understanding in this field, laying a solid foundation for future exploration.

Development of a New Class of Monoamine Oxidase-B Inhibitors by Fine-Tuning the Halogens on the Acylhydrazones.

A total of 14 acyl hydrazine derivatives (ACH1-ACH14) were developed and examined for their ability to block monoamine oxidase (MAO). Thirteen analogues showed stronger inhibition potency against MAO-B than MAO-A. With a half-maximum inhibitory concentration of 0.14 μM, ACH10 demonstrated the strongest inhibitory activity against MAO-B, followed by ACH14, ACH13, ACH8, and ACH3 (IC50 = 0.15, 0.18, 0.20, and 0.22 μM, respectively). Structure-activity relationships suggested that the inhibition effect on MAO-B resulted from the combination of halogen substituents of the A- and/or B-rings. This series concluded that when -F was substituted to the B-ring, MAO-B inhibitory activities were high, except for ACH6. In the inhibition kinetics study, the compounds ACH10 and ACH14 were identified as competitive inhibitors, with Ki values of 0.097 ± 0.0021 and 0.10 ± 0.038 μM, respectively. In a reversibility experiment using the dialysis methods, ACH10 and ACH14 showed effective recoveries of MAO-B inhibition as much as lazabemide, a reversible reference. These experiments proposed that ACH10 and ACH14 were efficient, reversible competitive MAO-B inhibitors. In addition, the lead molecules showed good blood-brain barrier permeation with the PAMPA method. The molecular docking and molecular dynamics simulation study confirmed that the hit compound ACH10 can form a stable protein-ligand complex by forming a hydrogen bond with the NH atom in the hydrazide group of the compound.

In vitro xanthine oxidase inhibitory and in vivo anti-hyperuricemic properties of sodium kaempferol-3'-sulfonate.

Xanthine oxidase (XO), a key enzyme in purine catabolism, catalyzes the oxidation of xanthine to uric acid in the body, but overproduction of uric acid may lead to hyperuricemia. This study aims to investigate in vitro XO inhibitory and in vivo anti-hyperuricemic properties of sodium kaempferol-3'-sulfonate (KS). The kinetic analysis indicates that KS is a reversible competitive inhibitor and has significant inhibitory effects on XO activity with an IC50 value of 0.338μM. Fluorescence spectra suggested that KS could cause fluorescence quenching and conformational changes of XO due to the formation of a KS-XO complex. Molecular docking studies demonstrated that KS interacted with several amino acid residues of XO by the π-π stacking, hydrogen bonds, and hydrophobic interactions. The inhibitory mechanism of KS on XO activity might be the insertion of KS into the active site of XO to prevent the entrance of the substrate xanthine and induce conformational changes of XO. The results carried out in hyperuricemic mice showed that KS reduced serum XO activity, serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels, as well as alleviating renal histopathological injury. These findings suggest that KS may be a new potent XO inhibitor against hyperuricemia-related diseases.

Mechanism of active acetylcholinesterase inhibition by organic sulfanes in garlic: Non-covalent binding and covalent modifications

Numerous secondary metabolites in medicinal food homology plants such as Allium inhibit the activity of acetylcholinesterase (AChE), but the current understanding of the inhibition mechanism is limited. In this study, we employed ultrafiltration, spectroscopic, molecular docking, and matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) techniques to investigate the inhibition mechanism of AChE by garlic organic sulfanes, including diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS). The results of UV-spectrophotometry and ultrafiltration experiments showed the inhibition of AChE activity by DAS and DADS was reversible (competitive inhibition), but inhibition by DATS was irreversible. Molecular fluorescence and molecular docking indicated DAS and DADS changed the positions of key amino acids inside the catalytic cavity through hydrophobic interactions with AChE. By using MALDI-TOF-MS/MS, we found DATS irreversibly inhibited AChE activity by opening disulfide-bond switching of disulfide bond 1 (Cys-69 and Cys-96) and disulfide bond 2 (Cys-257 and Cys-272) in AChE, as well as by covalently modifying Cys-272 in disulfide bond 2 to generate AChE–SSA derivatives (strengthened switch). This study provides a basis for further exploration of natural AChE inhibitors using organic active substances in garlic and presents a hypothesis of U-shaped spring force arm effect based on the disulfide bond-switching reaction of DATS that can be used to evaluate the stability of disulfide bonds in proteins.

Bufotalin inhibits porcine kidney cortex aminopeptidase N and is cytotoxic to APN+ tumor cells

Abstract Bufadienolides are steroids that inhibit the Na+/K+ ATPase pump. Recent studies show that members of the bufadienolide family also inhibit the activity of aminopeptidase N (APN). APN is upregulated in different pathologies, including cancer and is a current target for drug development. Bufadienolides are cytotoxic in tumor cells, but there is no enough evidences that inhibition of APN activity contributes to their effect. In the present contribution we investigated the effect of another member of the bufadienolide family, bufotalin, on porcine APN (pAPN) activity. Bufotalin inhibited pAPN activity with K i values in the submicromolar range and an uncompetitive inhibition mechanism; it also inhibited porcine aminopeptidase A (pAPA) activity, but with a classical reversible competitive inhibition mechanism. In addition, we determined the effect of bufotalin on the viability/metabolism of APN+ A549, H292, MeWo and CT26 cancer cells. Bufotalin was cytotoxic in a dose dependent manner; the highest cytotoxicity was detected in A549 cells, the cells with the highest APN activity. Thus, tumor cell line sensitivity to the cytotoxic effect of bufotalin correlates with cell surface APN activity.

Topical Tranexamic Acid: Risks, Benefits and Novel Complications in Aesthetic Plastic Surgery.

Antifibrinolytics, particularly tranexamic acid (TXA), are agents used to reduce bleeding. TXA is a synthetic reversible competitive inhibitor to the lysine receptor found on plasminogen. By reversibly binding to this site, it leads to plasminogen being unable to bind to fibrin and so prevents fibrinolysis, this stabilizes the clot and thus prevents hemorrhage. (Pekrul in Der Anaesth 70:515-521, 2021) It can be used either intravenously or topically but has never entered mainstream use in plastic surgery. (Pekrul in Der Anaesth 70:515-521, 2021) This is most likely due to understandable fears of thromboembolic events. On the other hand, the tempting benefits are reduced bleeding (perioperatively) decreased bruising and swelling, and thus increased aesthetic, important for obvious reasons. A review of the literature was done to go deeper on this issue, examining topical use in aesthetic surgery. Clear benefit was shown in the literature, it could be postulated that it would not be unwise to consider more research on topical use of TXA in certain cases, the benefits could greatly outweigh the risks. Old fears and conceptions, unsupported by the literature at the time of writing, should not hold back further research, and the benefits shown could even potentially justify the topical use of these agents in the near future. Further studies evaluating the utility of TXA in Panniculectomy and Abdominoplasty surgery should be performed especially, since only one was found which reported no significant benefit. Minor complications were present, such as minor delayed post-auricular skin healing, temporary unilateral marginal mandibular neuropraxia and increased cumulative seroma volume. These were novel findings and could warrant further investigation as well. After performing a review of the literature, it was seen that topical TXA generally adds benefit in aesthetic plastic surgery, with no particularly significant complications. We would like to bring more attention to the issue and support more studies on TXA use. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Exploration of a new class of monoamine oxidase B inhibitors by assembling benzyloxy pharmacophore on halogenated chalcones.

Eight derivatives of benzyloxy-derived halogenated chalcones (BB1-BB8) were synthesized and tested for their ability to inhibit monoamine oxidases (MAOs). MAO-A was less efficiently inhibited by all compounds than MAO-B. Additionally, the majority of the compounds displayed significant MAO-B inhibitory activities at 1 μM with residual activities of less than 50%. With an IC50 value of 0.062 μM, compound BB4 was the most effective in inhibiting MAO-B, followed by compound BB2 (IC50 = 0.093 μM). The lead molecules showed good activity than the reference MAO-B inhibitors (Lazabemide IC50 = 0.11 μM and Pargyline Pargyline IC50 = 0.14). The high selectivity index (SI) values for MAO-B were observed in compounds BB2 and BB4 (430.108 and 645.161, respectively). Kinetics and reversibility experiments revealed that BB2 and BB4 were reversible competitive MAO-B inhibitors with Ki values of 0.030 ± 0.014 and 0.011 ± 0.005 μM, respectively. Swiss target prediction confirmed the high probability in the targets of MAO-B for both compounds. Hypothetical binding mode revealed that the BB2 or BB4 is similarly oriented to the binding cavity of MAO-B. Based on the modelling results, BB4 showed a stable confirmation during the dynamic simulation. From these results, it was concluded that BB2 and BB4 were potent selective reversible MAO-B inhibitors and they can be considered drug candidates for treating related neurodegenerative diseases such as Parkinson's disease.

Identification of New N-methyl-piperazine Chalcones as Dual MAO-B/AChE Inhibitors

Monoamine oxidase-B (MAO-B), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) have been considered target enzymes of depression and neurodegenerative diseases, including Alzheimer's disease (AD). In this study, seventeen N-methyl-piperazine chalcones were synthesized, and their inhibitory activities were evaluated against the target enzymes. Compound 2k (3-trifluoromethyl-4-fluorinated derivative) showed the highest selective inhibition against MAO-B with an IC50 of 0.71 μM and selectivity index (SI) of 56.34, followed by 2n (2-fluoro-5-bromophenyl derivative) (IC50 = 1.11 μM, SI = 16.04). Compounds 2k and 2n were reversible competitive MAO-B inhibitors with Ki values of 0.21 and 0.28 μM, respectively. Moreover, 2k and 2n effectively inhibited AChE with IC50 of 8.10 and 4.32 μM, which underscored their multi-target inhibitory modes. Interestingly, compound 2o elicited remarkable inhibitions over MAO-B, AChE, and BChE with IC50 of 1.19-3.87 μM. A cell-based assay of compounds 2k and 2n against Vero normal cells pointed out their low cytotoxicity. In a docking simulation, 2k showed the lowest energy for MAO-B (-11.6 kcal/mol) with four hydrogen bonds and two π-π interactions. Furthermore, in silico studies were conducted, and disclosed that 2k and 2n are expected to possess favorable pharmacokinetic properties, such as the ability to penetrate the blood-brain barrier (BBB). In view of these findings, compounds 2k and 2n could serve as promising potential candidates for the treatment of neurodegenerative diseases.

Medicarpin and Homopterocarpin Isolated from Canavalia lineata as Potent and Competitive Reversible Inhibitors of Human Monoamine Oxidase-B

Thirteen compounds were isolated from the Canavalia lineata pods and their inhibitory activities against human monoamine oxidase-A (hMAO-A) and -B (hMAO-B) were evaluated. Among them, compounds 8 (medicarpin) and 13 (homopterocarpin) showed potent inhibitory activity against hMAO-B (IC50 = 0.45 and 0.72 µM, respectively) with selectivity index (SI) values of 44.2 and 2.07, respectively. Most of the compounds weakly inhibited MAO-A, except 9 (prunetin) and 13. Compounds 8 and 13 were reversible competitive inhibitors against hMAO-B (Ki = 0.27 and 0.21 µM, respectively). Structurally, the 3-OH group at A-ring of 8 showed higher hMAO-B inhibitory activity than 3-OCH3 group at the A-ring of 13. However, the 9-OCH3 group at B-ring of 13 showed higher hMAO-B inhibitory activity than 8,9-methylenedioxygroup at the B-ring of 12 (pterocarpin). In cytotoxicity study, 8 and 13 showed non-toxicity to the normal (MDCK) and cancer (HL-60) cells and moderate toxicity to neuroblastoma (SH-SY5Y) cell. Molecular docking simulation revealed that the binding affinities of 8 and 13 for hMAO-B (-8.7 and -7.7 kcal/mol, respectively) were higher than those for hMAO-A (-3.4 and -7.1 kcal/mol, respectively). These findings suggest that compounds 8 and 13 be considered potent reversible hMAO-B inhibitors to be used for the treatment of neurological disorders.

Nesidioblastosis: an uncommon complication seen post Roux-en-Y gastric bypass.

Adult-onset nesidioblastosis is a rare complication of Roux-en-Y gastric bypass surgery and may occur months to years after the initial surgical procedure. It is manifested by a hyperinsulinemic, hypoglycemic state. The annual incidence of adult-onset hyperinsulinemic hypoglycemia is believed to be less than 0.1 in 1 000 000 with a mean age of onset of 47 years (1). Here, we describe a patient who presented with worsening hypoglycemic symptoms for 1 year prior to presentation that eventually progressed to hypoglycemic seizures. The onset of this hypoglycemia was 5 years after Roux-en-Y gastric bypass surgery. A full neurological evaluation, which included an EEG, head CT, and MRI, was performed to rule out epilepsy and other seizure-related disorders. After hypoglycemia was confirmed, extensive laboratory studies were obtained to elucidate the cause of the hypoglycemia and differentiate nesidioblastosis from insulinoma. Once the diagnosis of nesidioblastosis was established, a sub-total pancreatectomy was performed, and the patient was discharged and placed on acarbose, a competitive reversible inhibitor of pancreatic α-amylase and intestinal brush border α-glucosidases which slows carbohydrate absorption. The lack of information and understanding of nesidioblastosis due to its rarity makes any knowledge of this rare but important surgical complication essential. As incidence of obesity increases, the number of gastric bypasses being performed increases with it, and understanding this disease process will be essential for the primary care provider. This is the primary reason for the writing of this publication. Nesidioblastosis is a persistent hyperinsulinemic, hypoglycemic state, mostly seen after Roux-en-Y gastric bypass surgery, with symptoms occurring postprandially. The incidence is 0.1-0.3% of all post Roux-en-Y gastric bypass patients. The key diagnostic clue to identifying nesidioblastosis is a positive selective arterial calcium stimulation test, showing a diffuse pattern of increased basal hepatic venous insulin concentration, whereas insulinomas would show focal increases. Pathological specimen of pancreas will show diffuse hypertrophy of beta cells. Management includes acarbose and total or subtotal pancreatectomy, which can be curative. With the prevalence of obesity increasing and more patients turning to Roux-en-Y gastric bypass, more patients may be at risk of this potential surgical complication.