Skip to main content
NCBI home page
ACS Medicinal Chemistry Letters logoLink to ACS Medicinal Chemistry Letters
. 2024 Jul 3;15(8):1298–1305. doi: 10.1021/acsmedchemlett.4c00174

Chemical Probes to Investigate Central Nervous System Disorders: Design, Synthesis and Mechanism of Action of a Potent Human Serine Racemase Inhibitor

Francesco Marchesani †, Francesca Rebecchi ‡, Marco Pieroni ‡,§,∥,⊥,*, Serena Faggiano ‡,#, Giannamaria Annunziato ‡,‡,⊥, Chiara Spaggiari ‡, Stefano Bruno ‡,∥, Sofia Rinaldi ‡, Roberta Giaccari ‡, Gabriele Costantino ‡,‡,∥,⊥, Barbara Campanini ‡,∥
PMCID: PMC11318019  PMID: 39140049

Abstract

graphic file with name ml4c00174_0009.jpg

The intricate signaling network within the central nervous system (CNS) involving N-methyl-d-aspartate receptors (NMDARs) has been recognized as a key player in severe neurodegenerative diseases. The indirect modulation of NMDAR-mediated neurotransmission through inhibition of serine racemase (SR)—the enzyme responsible for the synthesis of the NMDAR coagonist d-serine—has been suggested as a therapeutic strategy to treat these conditions. Despite the inherent challenges posed by SR conformational flexibility, a ligand-based drug design strategy has successfully produced a series of potent covalent inhibitors structurally related to amino acid analogues. Among these inhibitors, O-(2-([1,1′-biphenyl]-4-yl)-1-carboxyethyl)hydroxylammonium chloride (28) has emerged as a valuable candidate with a Kd of about 5 μM, which makes it one of the most potent hSR inhibitors reported to date. This molecule is expected to inspire the identification of selective hSR inhibitors that might find applications as tools in the study and treatment of several CNS pathologies.

Keywords: Serine racemase, neurodegenerative diseases, pyridoxal 5′-phosphate, aminooxy acids, Ligand-Based Drug Design

One of the toughest challenges in drug discovery is the development of molecular probes aimed at understanding and possibly treating brain disorders. Particularly, the central nervous system (CNS) signaling pathway associated with N-methyl-d-aspartate (NMDA) receptors (NMDARs) is involved in a variety of severe and chronic neurodegenerative diseases, and its targeting is a long sought-after goal. Besides the agonist NMDA, NMDARs require the binding of a second ligand for full channel opening. For a long time, glycine was thought to be the only coactivator of NMDARs, but, in 1988, it was discovered that d-serine acts as a coagonist for NMDARs, with a potency comparable to that of glycine.1d-Serine is thought to be the predominant coagonist of synaptic NMDARs, while glycine, present at basal levels, would predominate at extra-synaptic NMDARs.2 Moreover, d-serine appears to be functionally more effective than glycine in modulating NMDAR-dependent long-term potentiation (LTP) in several brain districts.3 Serine racemase (SR), the enzyme that synthesizes d-serine, was purified and characterized by the Snyder group.4 This enzyme catalyzes the formation of d-serine from l-serine, as well as the β-elimination of both l- and d-serine to produce pyruvate and ammonia. Following a series of studies, compelling evidence emerged demonstrating a notable correlation between d-serine levels in the forebrain of the rat and the expression of SR and NMDARs.5 Since then, a growing number of publications has consolidated the hypothesis that SR is involved in numerous brain pathologies, such as schizophrenia,6 addictions,7,8 anxiety disorders,9 and brain damage.10−12 Whereas NMDAR antagonists are often accompanied by several side effects,13 inhibition of SR might represent an alternative way to fine-tune NMDAR-mediated transmission. This inhibition might play a key role in understanding these pathological conditions, providing a valuable chemical tool for their treatment.

SR is a homodimeric pyridoxal 5′-phosphate (PLP)-dependent enzyme that belongs to the fold type-II family, and each subunit is characterized by the presence of a large and a small domain.14−16 It is mainly expressed in the forebrain but it can also be found in the hippocampus and other cortical regions, as well as in the peripheral nervous system.4 As indicated by the available X-ray structures, SR undergoes conformational changes upon ligand binding, leading to hypothesize that, along with those reported, other intermediate conformational states may exist.17,18 This peculiar flexibility has made the structure-based drug design of SR inhibitors a challenging approach. On the other hand, a ligand-based drug design approach, primarily rooted in the structure of basic molecules like malonic acid, has led to chemical probes with severe limitations, from low potency and efficiency to poor drug-likeness and uncertain structure–activity relationships (SARs). There are only a few reported examples of SR inhibitors, with compounds 1–5 (Figure 1)19−23 exhibiting inhibition constants ranging from high micromolar to millimolar values. Within the series, 2,2-dichloromalonate (3, Figure 1) stands out as the inhibitor with the lowest IC50value, reported at 57 μM.22 Efforts to constrain the malonate structure (2) in a cyclopropane ring, pursued to expand the space for chemical additions,23 resulted in a series of poorly active molecules. Recently, madecassoside (5), identified in the methanolic extract of Centella asiatica, was reported as an SR inhibitor.24 A concentration-dependent inhibition was observed, with an IC50 of 26 μM, 2.5-fold lower than that of malonate (IC50 = 71 μM), making this molecule the most potent SR inhibitor reported to date. Another potential scaffold for the development of hSR inhibitors is cycloserine, whose d-isomer has limited activity on SR, while the l-isomer shows an IC50 of 2.27 mM on the mouse enzyme (6).25,26 In this research endeavor, we report the synthesis and hSR inhibitory activity of a prototype chemical series of amino acid analogues designed through a rational approach, drawing inspiration from literature research and fundamental principles of medicinal chemistry.

Figure 1.

Figure 1

Open in a new tab

Reported serine racemase inhibitors and IC50 values.

In a previous work,23 we have tried to design novel inhibitors of SR based on a ligand-based drug design approach, starting from the structure of malonate. We reasoned that constraining the malonate diacid moiety into a cyclopropane ring23 could replicate the interaction observed with malonate (4, Figure 1). Additionally, the cyclopropane structure offered the potential for functional group decorations, allowing for an initial exploration of SAR. Vorlova and colleagues22 previously employed a similar strategy, which, in that instance, did not result in significant inhibition of hSR.

In our present approach, we selected l-cycloserine as the initial chemical framework. Here, our strategy involved unfolding the structure of cycloserine into an aminooxy acid. By introducing a phenyl ring, further functionalization possibilities could be explored (Figure 2). Indeed, it is well-known that hydroxylamines and aminooxyacetic acid derivatives can react with PLP-dependent enzymes to form oximes leading to covalent inactivation.27−29

Figure 2.

Figure 2

Open in a new tab

Design of aminooxy acids based on the structure of l-cycloserine (upper panel). Proposed mechanism for the formation of an oxime with the PLP cofactor in the active site of hSR (lower panel).

This approach presents several potential advantages. First, in the event of a successful interaction, the phenyl ring can undergo further modifications to enhance both activity and other pharmacokinetic/pharmacodynamic (PK/PD) properties. Second, the structure, resembling an amino acid, may leverage specific amino acid transporters for efficient passage across the blood–brain barrier (BBB), potentially enhancing the inhibitory effect within the CNS. Therefore, we synthesized four prototype molecules for an early exploratory investigation (Scheme 1). Initially, the aminooxy analogue of phenylalanine, l-2-aminooxy-3-phenylpropanoic acid, was synthesized and tested (26). Subsequently, a minor modification involved the introduction of the chlorine atom at the para position of the phenyl ring (27). To broaden the molecular scope and facilitate further study, another phenyl ring was attached at the para position (28), accompanied by the addition of a fluorine atom (29). To refine the study, we also tested compound 30, which had been previously identified as an inhibitor of the PLP-dependent enzyme alanine-glyoxylate aminotransferase.30 In particular, we wanted to investigate whether the aminooxy moiety, upon appropriate modification within its surrounding chemical framework, could discriminate between different PLP-dependent enzymes.

Scheme 1. Synthesis of Compounds 26–29.

Scheme 1

Open in a new tab

Reagents and conditions: (a) KOBut, t-BuOH, THF, 70 °C, overnight; (b) proper aryl boronic acid, K3PO4 in THF/water (3:1), X-Phos Pd G2, 70 °C; (c) N-bromosuccinimide, EtONa, EtOH, −30 °C to rt; (d) N-hydroxyphthalimide, TEA in anhydrous DMF, rt overnight; (e) hydrazine, DCM, rt, 2 h; (f) HCl 4 M in dioxane, Et2O (2:1). Compound 30 was synthesized in a previously published work.30

Target compounds 26–29 were synthesized in a range of variable yields refluxing the appropriate benzyl halide and ethyl acetoacetate to give the suitable intermediates 10 and 11 according to an established protocol.31 The reaction between intermediate 11 and the suitable boronic acids under standard Suzuki conditions led to the formation of ethyl acetoacetates 12 and 13. The substituted ethyl acetoacetate was then reacted with N-bromosuccinimide with a base such as sodium ethoxide to yield the α-bromo-carbonyl derivatives in one pot through a halo-deacetylation reaction.32 The bromocarbonyl derivatives so obtained underwent reaction with N-hydroxyphthalimide to displace the bromine atom and yield intermediates 18–21. Hydrazinolysis of these intermediates to remove the phthalimide moiety, followed by acid hydrolysis of the ethyl esters, produced the title compounds 26–29 as hydrochloride salts in satisfactory yields. Basic hydrolysis with sodium or lithium hydroxide proved to be less efficient and was consequently abandoned in favor of acid hydrolysis. Compound 30 was synthesized as previously reported30 (Scheme 1).

Compounds 26–30 were initially screened at 1 mM concentration for their ability to inhibit the β-elimination activity of hSR at 440 nM following a 10 min incubation at 37 °C (Figure 3).

Figure 3.

Figure 3

Open in a new tab

Relative inhibitory activity of compounds 26–30 on the β-elimination reaction of hSR. The relative activity of hSR in the absence (black bar) and in the presence of 1 mM compounds (white bars) in buffer A was measured after 10 min of incubation at 37 °C. The bars represent the standard deviation of two replicates.

The residual activity ranges from 84% (compound 30) to less than 1% (compound 28). It is important to notice that the absence of the carboxylic moiety seems to be detrimental for the inhibition of SR, whereas it is indispensable for the inhibitory activity on alanine–glyoxylate aminotransferase.30 The presence of the carboxylic moiety in the aminooxyacetic acid derivatives increases the potency of the compounds likely because of the formation of a salt bridge with Arg135 in the active site of hSR.33 The reaction of the internal aldimine (the Shiff base of PLP with the catalytic lysine) with the aminooxy derivatives to form the oxime is associated with changes in the absorption spectrum of PLP in the UV–vis range. Therefore, we selected two representative compounds (28 and 30) and examined their reaction with hSR through absorption spectroscopy after 2 min and 10 min of incubation with the enzyme (Figure S1). The two compounds underwent a reaction with hSR, albeit at different rates, as evidenced by the decrease in the absorption at 412 nm of the internal aldimine that is converted to a species absorbing at 328 and 365 nm. The spectrum of PLP after the reaction with the compounds is suggestive of an oxime derivative.34 The fluorescence excitation and emission spectra of the adduct formed by hSR and compound 28 (Figure S2) confirm the formation of an oxime derivative.35

Oximes derived from the reaction of aminooxy compounds with PLP may exhibit instability and dissociate from the active site. In the presence of free PLP in solution, the dissociation of the oxime derivative of PLP could potentially facilitate the reformation of an active enzyme.36,37 For this reason, for compounds 26, 28, and 29, we assessed the irreversibility of the reaction using a dilution assay, in both the presence and the absence of PLP in the assay mixture (Figure 4). Notably, the mean residual activity in the presence of PLP is higher than 55% for all compounds, while in the absence of PLP the mean residual activity is lower than 20%. This result indicates that the oxime resulting from the reaction between PLP and the aminooxy derivatives has the potential to dissociate from the active site. In the presence of free PLP in the solution, this dissociation allows for the reconstitution of the internal aldimine, leading to the recovery of enzyme activity.

Figure 4.

Figure 4

Open in a new tab

β-Elimination activity of hSR in the absence (black bar) and presence (colored bars) of compounds 26, 28, and 29. 15 μM hSR was incubated in buffer A with 1 mM compounds (the reference was incubated with 1% DMSO in buffer A) for 10 min at 37 °C. The solution was diluted 75-fold in the assay mixture in the presence (orange bars) and absence (blue bars) of 50 μM PLP. The final concentrations of the enzymes and compounds in the assay mixture were 220 nM and 13 μM, respectively. The bars represent the standard deviation of two replicates.

The release of the oxime adduct from the active site of the hSR was further assessed for compound 28. Diafiltration of hSR after reaction with compound 28 leads to the almost complete loss of the cofactor, while the unreacted enzyme treated with 1% DMSO completely retains bound PLP (Figure S3), indicating that, as reported for other PLP-dependent enzymes,36 the oxime adduct is only weakly bound to the active site and can easily be released upon dilution. This behavior, together with the above-mentioned rebinding of PLP by the apoenzyme, makes compound 28 a pseudoirreversible inhibitor,37 whose in vivo potency also depends on the concentration of free PLP in the cell.

The binding affinity of compound 28 for hSR was evaluated by absorption spectroscopy exploiting the changes in the absorbance of the cofactor upon addition of the inhibitor (Figure 5).

Figure 5.

Figure 5

Open in a new tab

Binding of compound 28 to hSR. Absorption spectra of 6 μM hSR in the absence and presence of increasing concentrations of compound 28 (from dark to light blue) in buffer A at 20 °C (left panel). The dependence of the relative absorbance at 412 nm on compound 28’s concentration was fitted to eq 1 with a Kd of 5.4 ± 2.4 μM (right panel).

The absorbance at 412 nm of the internal aldimine of PLP decreases upon the addition of compound 28, and its dependence on ligand concentration can be fitted to an isothermal equation that accounts for tight binding, resulting in a Kd of 5.4 ± 2.4 μM. The potency of compound 28 as an inhibitor of hSR activity was assessed by activity assays in both the presence and absence of the cofactor (Figure 6). The results indicate a higher IC50 in the presence of PLP (18.3 ± 1.5 μM) than in the absence of the cofactor (4.7 ± 0.4 μM), further confirming that PLP can replace the oxime adduct and partially restore the activity of the enzyme that has reacted with the inhibitor.

Figure 6.

Figure 6

Open in a new tab

Potency of compound 28 as an hSR inhibitor. Activity assays of hSR were carried out in buffer A at 37 °C in the presence of increasing concentrations of compound 28 either in the presence (left panel, orange circles) or in the absence (right panel, blue circles) of 50 μM PLP. Fitting to eq 2 gives an IC50 of 18.3 ± 1.5 μM and 4.7 ± 0.4 μM, in the presence and absence of PLP, respectively.

Furthermore, the IC50 measured in the absence of PLP is in good agreement with the dissociation constant measured by the binding assay, confirming that, to the best of our knowledge, compound 28 is the most potent hSR inhibitor identified so far. The formation of an oxime following the reaction of aminooxy derivatives with the internal aldimine of a PLP-dependent enzyme might be relevant for compounds’ potency. We were thus interested in assessing the contribution of oxime formation to the potency of aminooxy derivatives. With this purpose, we determined the IC50 for compound 26 in the absence of PLP in the assay mixture (23.1 ± 1.7 μM, Figure 7) and tried to measure under the same conditions the IC50 of l-Phe, the amino acid structurally related to compound 26. However, the absence of the oxime moiety in l-Phe severely affected the potency of the molecule, which did not significantly inhibit the enzyme activity at concentrations as high as 2 mM (Figure 7, right panel).

Figure 7.

Figure 7

Open in a new tab

Effect of l-Phe and its aminooxy derivative (26) on the hSR activity. Left panel: dependence of the relative activity of hSR in buffer A at 37 °C on compound 26’s concentration in the absence of PLP. Fitting to eq 2 (solid line) yields an IC50 of 23.1 ± 1.7 μM. Right panel: effect of l-Phe on the activity of hSR in buffer A at 37 °C in the absence of PLP.

Oxyamino derivatives are well-known inhibitors of PLP-dependent enzymes. We were thus interested in assessing the selectivity of compound 28, given its promising potency profile, and encouraged by the fact that this derivative exhibits a poor inhibitory activity toward alanine–glyoxylate aminotransferase, another PLP-dependent enzyme. We chose two human PLP-dependent enzymes that are expressed in the CNS: human phosphoserine aminotransferase (hPSAT) and human kynurenine aminotransferase (hKAT). The compound reacts with the internal aldimine of both enzymes, as shown by the disappearance of the characteristic peaks of PLP in hPSAT (344 and 408 nm) and hKAT (360 nm) upon the addition of the compound (Figure S4). Indeed, the IC50 for hPSAT in the presence of PLP is 2.2 ± 0.2 μM, slightly more potent toward hPSAT in comparison to hSR under the same conditions. These findings highlight that, despite the noteworthy activity of these molecules and their negligible affinity toward certain PLP-dependent enzymes, additional optimization efforts to enhance the structural refinement and overall selectivity toward hSR are needed.

Experimental Section

General Information

All of the reagents were purchased from Sigma-Aldrich and Alfa-Aesar at reagent purity and, unless otherwise noted, were used without any further purification. Dry solvents used in the reactions were obtained by distillation of technical grade materials over the appropriate dehydrating agents. Thioureas were either purchased or prepared as previously described, and the analytical data matched with those already reported.38−40 Reactions were monitored by thin-layer chromatography on silica-gel-coated aluminum foils (silica gel on Al foils, SUPELCO Analytical, Sigma-Aldrich) at both 254 and 365 nm. Where indicated, intermediates and final products were purified through silica gel flash chromatography (silica gel, 0.040–0.063 mm), using appropriate solvent mixtures.

1H NMR and 13C NMR spectra were recorded on a BRUKER AVANCE spectrometer at 400 and 100 MHz, respectively, with TMS as the internal standard. 1H NMR spectra are reported in this order: multiplicity and number of protons. Standard abbreviation indicating the multiplicity was used as follows: s = singlet, d = doublet, dd = doublet of doublets, t = triplet, q = quadruplet, m = multiplet, and br = broad signal. HPLC/MS experiments were performed with HPLC: Agilent 1100 series, equipped with a Waters Symmetry C18, 3.5 μm, 4.6 mm × 75 mm column, and MS: Applied Biosystem/MDS SCIEX, with an API 150EX ion source. HRMS experiments were performed with an LTQ ORBITRAP XL (THERMO).

All compounds were tested as 95–100% purity samples (by HPLC/MS).

Detailed procedures for the synthesis are reported in the Supporting Information.

In Vitro Assays to Assess the Inhibitory Effect of the Compounds on hSR Activity

Materials and methods for recombinant hSR production and biochemical assays are reported in the Supporting Information.

No unexpected or unusually high safety hazards were encountered.

Acknowledgments

The Centro Interdipartimentale Misure “G. Casnati” is kindly acknowledged for the contribution in the analytical determination of the synthesized molecules. This research was financially supported by the Programme FIL Quota Incentivante 2019 of the University of Parma and cosponsored by Fondazione Cariparma.

Glossary

Abbreviations

CNS

central nervous system

DMSO

dimethyl sulfoxide

EDC

N-(3-(dimethylamino)propyl)-N′-ethylcarbodiimide

EDG

electron-donor group

EWG

electron-withdrawing group

hSR

human serine racemase

hPSAT

human phosphoserine aminotransferase

hKAT

human kynurenine aminotransferase

MW

microwave

NMDAr

N-methyl-d-aspartate receptors

PAINS

pan-assay interfering compounds

PLP

pyridoxal 5′-phosphate

SAR

structure–activity relationship

THF

tetrahydrofuran

TLC

thin-layer chromatography

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmedchemlett.4c00174.

  • Description of the chemical and biological methods, evaluation of MICs, and the analytical data related to the compounds synthesized (PDF)

Author Contributions

Study design: M.P. Compound design, synthesis, data collection and analysis: G.A., C.S., F.R. Protein expression and purification, activity assays, data collection and analysis: F.M., S.R., R.G. Resources: B.C., G.C. Supervision: B.C., G.C., M.P., S.B., S.F. Manuscript writing: M.P., B.C., S.F. All authors have contributed to manuscript revision.

The authors declare no competing financial interest.

Supplementary Material

ml4c00174_si_001.pdf (754.1KB, pdf)

References

  1. Kleckner N. W.; Dingledine R. Requirement for Glycine in Activation of NMDA-Receptors Expressed in Xenopus Oocytes. Science 1988, 241 (4867), 835–837. 10.1126/science.2841759. [DOI] [PubMed] [Google Scholar]
  2. Papouin T.; Ladépêche L.; Ruel J.; Sacchi S.; Labasque M.; Hanini M.; Groc L.; Pollegioni L.; Mothet J.-P.; Oliet S. H. R. Synaptic and Extrasynaptic NMDA Receptors Are Gated by Different Endogenous Coagonists. Cell 2012, 150 (3), 633–646. 10.1016/j.cell.2012.06.029. [DOI] [PubMed] [Google Scholar]
  3. Wolosker H.; Balu D. T. D-Serine as the Gatekeeper of NMDA Receptor Activity: Implications for the Pharmacologic Management of Anxiety Disorders. Transl. Psychiatry 2020, 10 (1), 1–10. 10.1038/s41398-020-00870-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Wolosker H.; Blackshaw S.; Snyder S. H. Serine Racemase: A Glial Enzyme Synthesizing D-Serine to Regulate Glutamate-N-Methyl-D-Aspartate Neurotransmission. Proc. Natl. Acad. Sci. U. S. A. 1999, 96 (23), 13409–13414. 10.1073/pnas.96.23.13409. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Schell M. J.; Molliver M. E.; Snyder S. H. D-Serine, an Endogenous Synaptic Modulator: Localization to Astrocytes and Glutamate-Stimulated Release. Proc. Natl. Acad. Sci. U. S. A. 1995, 92 (9), 3948–3952. 10.1073/pnas.92.9.3948. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Basu A. C.; Tsai G. E.; Ma C.-L.; Ehmsen J. T.; Mustafa A. K.; Han L.; Jiang Z. I.; Benneyworth M. A.; Froimowitz M. P.; Lange N.; Snyder S. H.; Bergeron R.; Coyle J. T. Targeted Disruption of Serine Racemase Affects Glutamatergic Neurotransmission and Behavior. Mol. Psychiatry 2009, 14 (7), 719–727. 10.1038/mp.2008.130. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Balu D. T.; Li Y.; Puhl M. D.; Benneyworth M. A.; Basu A. C.; Takagi S.; Bolshakov V. Y.; Coyle J. T. Multiple Risk Pathways for Schizophrenia Converge in Serine Racemase Knockout Mice, a Mouse Model of NMDA Receptor Hypofunction. Proc. Natl. Acad. Sci. U. S. A. 2013, 110 (26), E2400-E2409 10.1073/pnas.1304308110. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Puhl M. D.; Desai R. I.; Takagi S.; Presti K. T.; Doyle M. R.; Donahue R. J.; Landino S. M.; Bergman J.; Carlezon W. A.; Coyle J. T. N-Methyl-D-Aspartate Receptor Co-Agonist Availability Affects Behavioral and Neurochemical Responses to Cocaine: Insights into Co-Morbid Schizophrenia and Substance Abuse. Addict. Biol. 2019, 24 (1), 40–50. 10.1111/adb.12577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Basu A. C.; Puhl M. D.; Coyle J. T. Endogenous Co-Agonists of the NMDA Receptor Modulate Contextual Fear in Trace Conditioning. Neurobiol. Learn. Mem. 2016, 136, 244–250. 10.1016/j.nlm.2016.09.006. [DOI] [PubMed] [Google Scholar]
  10. Coyle J. T.; Balu D. T.. Chapter Three - The Role of Serine Racemase in the Pathophysiology of Brain Disorders. In Adv. Pharmacol.; Pasternak G. W., Coyle J. T., Eds.; Apprentices to Genius: A tribute to Solomon H. Snyder; Academic Press, 2018; Vol. 82, pp 35–56. 10.1016/bs.apha.2017.10.002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Perez E. J.; Cepero M. L.; Perez S. U.; Coyle J. T.; Sick T. J.; Liebl D. J. EphB3 Signaling Propagates Synaptic Dysfunction in the Traumatic Injured Brain. Neurobiol. Dis. 2016, 94, 73–84. 10.1016/j.nbd.2016.06.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Perez E. J.; Tapanes S. A.; Loris Z. B.; Balu D. T.; Sick T. J.; Coyle J. T.; Liebl D. J. Enhanced Astrocytic D-Serine Underlies Synaptic Damage after Traumatic Brain Injury. J. Clin. Invest. 2017, 127 (8), 3114–3125. 10.1172/JCI92300. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kishi T.; Iwata N. NMDA Receptor Antagonists Interventions in Schizophrenia: Meta-Analysis of Randomized, Placebo-Controlled Trials. J. Psychiatr. Res. 2013, 47 (9), 1143–1149. 10.1016/j.jpsychires.2013.04.013. [DOI] [PubMed] [Google Scholar]
  14. Campanini B.; Pieroni M.; Raboni S.; Bettati S.; Benoni R.; Pecchini C.; Costantino G.; Mozzarelli A. Inhibitors of the Sulfur Assimilation Pathway in Bacterial Pathogens as Enhancers of Antibiotic Therapy. Curr. Med. Chem. 2014, 22 (2), 187–213. 10.2174/0929867321666141112122553. [DOI] [PubMed] [Google Scholar]
  15. Wolosker H. NMDA Receptor Regulation by D-Serine: New Findings and Perspectives. Mol. Neurobiol. 2007, 36 (2), 152–164. 10.1007/s12035-007-0038-6. [DOI] [PubMed] [Google Scholar]
  16. Campanini B.; Spyrakis F.; Peracchi A.; Mozzarelli A. Serine Racemase: A Key Player in Neuron Activity and in Neuropathologies. Front. Biosci. Landmark Ed. 2013, 18 (3), 1112–1128. 10.2741/4167. [DOI] [PubMed] [Google Scholar]
  17. Bruno A.; Amori L.; Costantino G. Addressing the Conformational Flexibility of Serine Racemase by Combining Targeted Molecular Dynamics, Conformational Sampling and Docking Studies. Mol. Inform. 2011, 30 (4), 317–328. 10.1002/minf.201000162. [DOI] [PubMed] [Google Scholar]
  18. Marchesani F.; Gianquinto E.; Autiero I.; Michielon A.; Campanini B.; Faggiano S.; Bettati S.; Mozzarelli A.; Spyrakis F.; Bruno S. The Allosteric Interplay between S-Nitrosylation and Glycine Binding Controls the Activity of Human Serine Racemase. FEBS J. 2021, 288 (9), 3034–3054. 10.1111/febs.15645. [DOI] [PubMed] [Google Scholar]
  19. Jirásková-Vaníčková J.; Ettrich R.; Vorlová B.; Hoffman H. E.; Lepšík M.; Jansa P.; Konvalinka J. Inhibition of Human Serine Racemase, an Emerging Target for Medicinal Chemistry. Curr. Drug Targets 2011, 12 (7), 1037–1055. 10.2174/138945011795677755. [DOI] [PubMed] [Google Scholar]
  20. Harty M.; Nagar M.; Atkinson L.; Legay C. M.; Derksen D. J.; Bearne S. L. Inhibition of Serine and Proline Racemases by Substrate-Product Analogues. Bioorg. Med. Chem. Lett. 2014, 24 (1), 390–393. 10.1016/j.bmcl.2013.10.061. [DOI] [PubMed] [Google Scholar]
  21. Mori H.; Wada R.; Li J.; Ishimoto T.; Mizuguchi M.; Obita T.; Gouda H.; Hirono S.; Toyooka N. In Silico and Pharmacological Screenings Identify Novel Serine Racemase Inhibitors. Bioorg. Med. Chem. Lett. 2014, 24 (16), 3732–3735. 10.1016/j.bmcl.2014.07.003. [DOI] [PubMed] [Google Scholar]
  22. Vorlová B.; Nachtigallová D.; Jirásková-Vaníčková J.; Ajani H.; Jansa P.; Řezáč J.; Fanfrlík J.; Otyepka M.; Hobza P.; Konvalinka J.; Lepšík M. Malonate-Based Inhibitors of Mammalian Serine Racemase: Kinetic Characterization and Structure-Based Computational Study. Eur. J. Med. Chem. 2015, 89, 189–197. 10.1016/j.ejmech.2014.10.043. [DOI] [PubMed] [Google Scholar]
  23. Beato C.; Pecchini C.; Cocconcelli C.; Campanini B.; Marchetti M.; Pieroni M.; Mozzarelli A.; Costantino G. Cyclopropane Derivatives as Potential Human Serine Racemase Inhibitors: Unveiling Novel Insights into a Difficult Target. J. Enzyme Inhib. Med. Chem. 2016, 31 (4), 645–652. 10.3109/14756366.2015.1057720. [DOI] [PubMed] [Google Scholar]
  24. Rani K.; Tyagi M.; Mazumder M.; Singh A.; Shanmugam A.; Dalal K.; Pillai M.; Samudrala G.; Kumar S.; Srinivasan A. Accelerated Identification of Serine Racemase Inhibitor from Centella Asiatica. Sci. Rep. 2020, 10 (1), 4640. 10.1038/s41598-020-61494-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Dunlop D. S.; Neidle A. Regulation of Serine Racemase Activity by Amino Acids. Brain Res. Mol. Brain Res. 2005, 133 (2), 208–214. 10.1016/j.molbrainres.2004.10.027. [DOI] [PubMed] [Google Scholar]
  26. Cook S. P.; Galve-Roperh I.; Martínez del Pozo A.; Rodríguez-Crespo I. Direct Calcium Binding Results in Activation of Brain Serine Racemase. J. Biol. Chem. 2002, 277 (31), 27782–27792. 10.1074/jbc.M111814200. [DOI] [PubMed] [Google Scholar]
  27. John R. A.; Charteris A. The Reaction of Amino-Oxyacetate with Pyridoxal Phosphate-Dependent Enzymes. Biochem. J. 1978, 171 (3), 771–779. 10.1042/bj1710771. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Khomutov M. A.; Weisell J.; Hyvönen M.; Keinänen T. A.; Vepsäläinen J.; Alhonen L.; Khomutov A. R.; Kochetkov S. N. Hydroxylamine Derivatives for Regulation of Spermine and Spermidine Metabolism. Biochem. Mosc. 2013, 78 (13), 1431–1446. 10.1134/S0006297913130051. [DOI] [PubMed] [Google Scholar]
  29. Nadvi N. A.; Salam N. K.; Park J.; Akladios F. N.; Kapoor V.; Collyer C. A.; Gorrell M. D.; Church W. B. High Resolution Crystal Structures of Human Kynurenine Aminotransferase-I Bound to PLP Cofactor, and in Complex with Aminooxyacetate. Protein Sci. 2017, 26 (4), 727–736. 10.1002/pro.3119. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Grottelli S.; Annunziato G.; Pampalone G.; Pieroni M.; Dindo M.; Ferlenghi F.; Costantino G.; Cellini B. Identification of Human Alanine-Glyoxylate Aminotransferase Ligands as Pharmacological Chaperones for Variants Associated with Primary Hyperoxaluria Type 1. J. Med. Chem. 2022, 65 (14), 9718–9734. 10.1021/acs.jmedchem.2c00142. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Lee H.-S.; Park J.-S.; Kim B. M.; Gellman S. H. Efficient Synthesis of Enantiomerically Pure Β2-Amino Acids via Chiral Isoxazolidinones. J. Org. Chem. 2003, 68 (4), 1575–1578. 10.1021/jo026738b. [DOI] [PubMed] [Google Scholar]
  32. Mignani G.; Morel D.; Grass F. A One-Pot Preparation of α-Halo-Carbonyl and α-Halo-Sulfonyl Compounds by Halo-Deacylation. Tetrahedron Lett. 1987, 28 (45), 5505–5508. 10.1016/S0040-4039(00)96765-0. [DOI] [Google Scholar]
  33. Ramos de Dios S. M.; Hass J. L.; Graham D. L.; Kumar N.; Antony A. E.; Morton M. D.; Berkowitz D. B. Information-Rich, Dual-Function 13C/2H-Isotopic Crosstalk NMR Assay for Human Serine Racemase (hSR) Provides a PLP-Enzyme “Partitioning Fingerprint” and Reveals Disparate Chemotypes for hSR Inhibition. J. Am. Chem. Soc. 2023, 145 (5), 3158–3174. 10.1021/jacs.2c12774. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Delbaere L. T. J.; Kallen J.; Markovic-Housley Z.; Khomutov A. R.; Khomutov R. M.; Karpeisky M. Y.; Jansonius J. N. Complexes of Aspartate Aminotransferase with Hydroxylamine Derivatives: Spectral Studies in Solution and in the Crystalline State. Biochimie 1989, 71 (4), 449–459. 10.1016/0300-9084(89)90175-2. [DOI] [PubMed] [Google Scholar]
  35. de Chiara C.; Homšak M.; Prosser G. A.; Douglas H. L.; Garza-Garcia A.; Kelly G.; Purkiss A. G.; Tate E. W.; de Carvalho L. P. S. D-Cycloserine Destruction by Alanine Racemase and the Limit of Irreversible Inhibition. Nat. Chem. Biol. 2020, 16 (6), 686–694. 10.1038/s41589-020-0498-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Kery V.; Poneleit L.; Meyer J. D.; Manning M. C.; Kraus J. P. Binding of Pyridoxal 5‘-Phosphate to the Heme Protein Human Cystathionine β-Synthase. Biochemistry 1999, 38 (9), 2716–2724. 10.1021/bi981808n. [DOI] [PubMed] [Google Scholar]
  37. Weisell J.; Hyvönen M. T.; Alhonen L.; Vepsäläinen J.; Keinänen T. A.; Khomutov A. R. Charge Deficient Analogues of the Natural Polyamines. Curr. Pharm. Des. 2014, 20 (2), 262–277. 10.2174/13816128113199990037. [DOI] [PubMed] [Google Scholar]
  38. Hay M. P.; Turcotte S.; Flanagan J. U.; Bonnet M.; Chan D. A.; Sutphin P. D.; Nguyen P.; Giaccia A. J.; Denny W. A. 4-Pyridylanilinothiazoles That Selectively Target von Hippel-Lindau Deficient Renal Cell Carcinoma Cells by Inducing Autophagic Cell Death. J. Med. Chem. 2010, 53 (2), 787–797. 10.1021/jm901457w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Sam J.; Plampin J. N. Benzoxazoles: Potent Skeletal Muscle Relaxants. J. Pharm. Sci. 1964, 53 (5), 538–544. 10.1002/jps.2600530518. [DOI] [PubMed] [Google Scholar]
  40. Meissner A.; Boshoff H. I.; Vasan M.; Duckworth B. P.; Barry C. E.; Aldrich C. C. Structure-Activity Relationships of 2-Aminothiazoles Effective against Mycobacterium Tuberculosis. Bioorg. Med. Chem. 2013, 21 (21), 6385–6397. 10.1016/j.bmc.2013.08.048. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

ml4c00174_si_001.pdf (754.1KB, pdf)

Articles from ACS Medicinal Chemistry Letters are provided here courtesy of American Chemical Society

RESOURCES