4-Amino-3-alkylbutanoic acids as substrates for gamma-aminobutyric acid aminotransferase

Epinephrine, Pregabalin, and Crizotinib as Three Medicines with Polish Implications over Three Last Centuries and in View of Three Different Drug Discovery Approaches

The discovery of epinephrine (adrenaline) and its subsequent implications in medicine owes significant contributions to Cybulski across different centuries, who, in 1894, was pivotal in identifying the adrenal medulla's role in blood pressure regulation and naming the active substance "nadnerczyna", known today as adrenaline. His work demonstrated the adrenal glands' critical function in the body's regulatory mechanisms beyond the nervous system. Cybulski's groundbreaking research laid foundational knowledge for future endocrinological studies and pharmaceutical advancements. In the late 20th century, Andruszkiewicz collaborated with Silverman at Northwestern University to develop pregabalin, the active ingredient in Lyrica. Their innovative synthesis of gamma-aminobutyric acid derivatives led to a significant advancement in treating epilepsy, neuropathic pain, and fibromyalgia. Andruszkiewicz's expertise in organic chemistry and enzymology was crucial in this collaborative effort, resulting in the successful development and commercialization of Lyrica. Additionally, Mroczkowski's leadership at Pfizer contributed to the development of crizotinib, a notable anaplastic lymphoma kinase and proto-oncogene 1 tyrosine-protein kinase inhibitor used to treat specific types of non-small cell lung cancer. Her work exemplifies the continuing influence of Polish researchers in pioneering drug discovery and advancing therapeutic treatments over the past three centuries. These contributions highlight Poland's significant role in global pharmaceutical innovations and medical research.

History and Prospects of Drug Discovery and Development Collaboration between Industry and Academia

Research collaborations and licensing deals are critical for the discovery and development of life-saving drugs. This practice has been ongoing since the inception of the pharmaceutical industry. The current process of drug discovery and development is complex, regulated, and highly regimented, having evolved over time. Academia excels in the discovery of fundamental scientific concepts and biological processes, while industry excels in translational science and product development. Potential for collaboration exists at every step of the drug discovery and development continuum. This perspective walks through such collaborative activities, provides examples, and offers tips for potential collaborations.

Effect of Differential Geminal Substitution of γ Amino Acid Residues at the (i + 2) Position of αγ Turn Segments on the Conformation of Template β-Hairpin Peptides

The effect of insertion of three geminally dimethyl substituted γ amino acid residues [γ^2,2 (4-amino-2,2-dimethylbutanoic acid), γ^3,3 (4-amino-3,3-dimethylbutanoic acid), and γ^4,4 (4-amino-4,4-dimethylbutanoic acid)] at the (i + 2) position of a two-residue αγ C₁₂ turn segment in a model octapeptide sequence Leu-Phe-Val-Aib-Xxx-Leu-Phe-Val (where Xxx = γ amino acid residues) has been investigated in this study. Solution conformational studies (NMR, CD, and IR) and ab initio calculations indicated that γ^3,3 and γ^4,4 residues were well accommodated in the β-hairpin nucleating αγ C₁₂ turns, which gave rise to well-registered hairpins, in contrast to γ^2,2, which was unable to form a tight C₁₂ β-hairpin nucleating turn and promote a well-registered β-hairpin. Geminal disubstitution at the C^α carbon in γ^2,2 led to unfavorable steric contacts, disabling its accommodation in the αγ C₁₂ hairpin nucleating turn unlike the γ^3,3 and γ^4,4 residues. Geminal substitutions at different carbons along the backbone constrained backbone torsion angles for the three γ amino acid residues differently, generating diverse conformational preferences in them. Folded hairpins were energetically more stable (∼8 to 9 kcal/mol) than the unfolded peptides. Conformational preference of the peptides was independent of the N-terminal protecting group. Such fundamental understanding will instrumentalize the future directed design of foldamers.

Divergent Synthesis of γ-Amino Acid and γ-Lactam Derivatives from meso-Glutaric Anhydrides

The first divergent synthesis of both γ-amino acid and γ-lactam derivatives from meso-glutaric anhydrides is described. The organocatalytic desymmetrisation with TMSN₃ relies on controlled generation of a nucleophilic ammonium azide species mediated by a polystyrene-bound base to promote efficient silylazidation. After Curtius rearrangement of the acyl azide intermediate to access the corresponding isocyanate, hydrolysis/alcoholysis provided uniformly high yields of γ-amino acids and their N-protected counterparts. The same intermediates were shown to undergo an unprecedented decarboxylation-cyclisation cascade in situ to provide synthetically useful yields of γ-lactam derivatives without using any further activating agents. Mechanistic insights invoke the intermediacy of an unconventional γ-N-carboxyanhydride (γ-NCA) in the latter process. Among the examples prepared using this transformation are 8 APIs/molecules of considerable medicinal interest.

Pregabalin in the Management of Painful Diabetic Neuropathy: A Narrative Review

Pregabalin is a first-line treatment in all major international guidelines on the management of painful diabetic neuropathy (pDPN). Treatment with pregabalin leads to a clinically meaningful improvement in pain scores, offers consistent relief of pain and has an acceptable tolerance level. Despite its efficacy in relieving neuropathic pain, more robust methods and comprehensive studies are required to evaluate its effects in relation to co-morbid anxiety and sleep interference in pDPN. The sustained benefits of modulating pain have prompted further exploration of other potential target sites and the development of alternative GABAergic agents such as mirogabalin. This review evaluates the role of pregabalin in the management of pDPN as well as its potential adverse effects, such as somnolence and dizziness, which can lead to withdrawal in ~ 30% of long-term use. Recent concern about misuse and an increase in deaths linked to its use has led to demands for reclassification of pregabalin as a class C controlled substance in the UK. We believe these demands need to be tempered in relation to the difficulties it would create for repeat prescriptions for the many millions of patients with pDPN for whom pregabalin provides benefit.Plain Language Summary: Plain language summary available for this article.

An historical perspective on GABAergic drugs

In 1950, γ-aminobutyric acid (GABA) was discovered in the brain and in 1967 it was recognized as an inhibitory neurotransmitter. The discovery of the benzodiazepines Librium® (launched in 1960) and Valium® by Sternbach initiated huge research activities resulting in 50 marketed drugs. In 1975, Haefely found that GABA is involved in the actions of benzodiazepines. The baclofen-sensitive, bicuculline-insensitive GABAB receptor was discovered by Bowery in 1980, and the baclofen-insensitive, bicuculline-insensitive GABAC receptor by Johnston in 1984. Barnard & Seeburg reported the cloning of the GABAA receptor in 1987, Cutting the GABAC receptor in 1991 and Bettler the GABAB1a and GABAB1b receptors in 1997. Six groups cloned the GABAB2 receptor in 1998/1999 showing that the GABAB receptor functions as a heterodimer with GABAB1b/GABAB2 mediating postsynaptic inhibition and GABAB1a/GABAB2 mediating presynaptic inhibition. Möhler and McKernan dissected the pharmacology of the benzodiazepine-receptor subtypes. Antagonists and positive allosteric modulators of GABAB receptors were discovered in 1987 and 2001, respectively. GABA transporter inhibitor, tiagabine, was launched in 1996, a GABA aminotransferase inhibitor, vigabatrin, in 1998 and a glutamic acid decarboxylase activator, pregabalin, in 2004. Most recently, brain-penetrating GABAC-receptor antagonists were reported in 2009.

Cephalosporin prodrugs of paclitaxel for immunologically specific activation by L-49-sFv-beta-lactamase fusion protein

Paclitaxel conjugates of 7-phenylacetamidocephalosporanic acid were prepared as prodrugs for site specific activation by targeted beta-lactamase. Immunologically specific activation of the prodrug 5 containing 3,3-dimethyl-4-amino-butyric acid as linker in combination with the fusion protein L-49-sFv-beta-lactamase was demonstrated in vitro on 3677 melanoma cells.

Syntheses of (Z)-and (E)-4-amino-2-(trifluoromethyl)-2-butenoic acid and their inactivation of gamma-aminobutyric acid aminotransferase

(Z)- and (E)-4-amino-2-(trifluoromethyl)-2-butenoic acid (4 and 5, respectively) were synthesized and investigated as potential mechanism-based inactivators of gamma-aminobutyric acid aminotransferase (GABA-AT) in a continuing effort to map the active site of this enzyme. The core alpha-trifluoromethyl-alpha,beta-unsaturated ester moiety was prepared via a Reformatsky/reductive elimination coupling of the key intermediates tert-butyl 2,2-dichloro-3,3,3-trifluoropropionate and N,N-bis(tert-butoxy-carbonyl)glycinal. Both 4 and 5 inhibited GABA-AT in a time-dependent manner, but displayed non-pseudo-first-order inactivation kinetics; initially, the inactivation rate increased with time. Further investigation demonstrated that the actual inactivator is generated enzymatically from 4 or 5. This inactivating species is released from the active site prior to inactivation, and as a result, 4 and 5 cannot be defined as mechanism-based inactivators. Furthermore, 4 and 5 are alternate substrates for GABA-AT, transaminated by the enzyme with Km values of 0.74 and 20.5 mM, respectively. Transamination occurs approximately 276 and 305 times per inactivation event for 4 and 5, respectively. The enzyme also catalyzes the elimination of the fluoride ion from 4 and 5. A mechanism to account for these observations is proposed.

General synthesis of 3-substituted alkenyl GABA as potential anticonvulsants

Stereospecific synthesis of cis and trans 3-substituted vinyl-gamma-aminobutyric acid analogs were obtained by either a Claisen rearrangement or a Wittig reaction from common diene precursors.

Characterisation of [3H]gabapentin binding to a novel site in rat brain: homogenate binding studies

The binding characteristics of [3H]gabapentin, the radiolabelled analogue of the novel anticonvulsant gabapentin (1-(aminomethyl)cyclohexaneacetic acid) were studied using purified synaptic plasma membranes prepared from rat cerebral cortex. In 10 mM HEPES buffer [3H]gabapentin bound to a single population of sites with high affinity (KD = 38 +/- 2.8 nM) with a maximum binding capacity of 4.6 +/- 0.4 pmol/mg protein, reaching equilibrium after 30 min at 20 degrees C. This novel site was unique to the central nervous system with little or no specific [3H]gabapentin being measurable in a range of peripheral tissues. Binding was potently inhibited by a range of gabapentin analogues and 3-alkyl substituted gamma-aminobutyric acid (GABA) derivates although GABA itself and the selective GABAB receptor ligand baclofen, were only weakly active. Gabapentin itself (IC50 = 80 nM) and 3-isobutyl GABA (IC50 = 80 nM) which also has anticonvulsant properties, showed the highest affinity for the binding site. Of a wide range of other pharmacologically active compounds only the polyamines spermine and spermidine influenced [3H]gabapentin binding, with both compounds producing a maximum of 50% inhibition of specific binding. Magnesium ions produced a similar pattern of inhibition but the effect of the polyamines and magnesium ions were not additive. The data provide evidence for the existence in brain of a novel binding site that may mediate the anticonvulsant effects of gabapentin and other potential anticonvulsant compounds.

Beta-lactams: a new class of conformationally-rigid inhibitors of gamma-aminobutyric acid aminotransferase

A structural similarity of several monobactams (2-4), 3-aminonocardicinic acid (6), 6-aminopenicillanic acid (7), 7-aminocephalosporanic acid (8), and 7-aminodesacetoxycephalosporanic acids (9, 10) to gamma-aminobutyric acid (GABA) and to known inhibitors and substrates of GABA aminotransferase is described. Because of this, the above-mentioned compounds were tested as competitive inhibitors and as inactivators of pig brain GABA aminotransferase. All of the compounds were competitive inhibitors of GABA aminotransferase. On the basis of the inhibitory potency of these conformationally-rigid GABA analogues it is hypothesized that GABA is bound at the active site with its amino and carboxylate groups in a syn orientation. None of the compounds inactivates GABA aminotransferase. These beta-lactam analogues represent the first examples of a new class of inhibitors of GABA aminotransferase.