Introduction
C19H20N4O2 denotes a heteroaromatic organic compound that contains nineteen carbon atoms, twenty hydrogen atoms, four nitrogen atoms, and two oxygen atoms. The molecule is characterized by a fused ring system that incorporates a pyrimidine core fused to a phenyl ring, with an amide linkage and a secondary amine substituent. This arrangement confers a high degree of planarity and aromaticity, which in turn influences its electronic properties and interactions with biological targets. The compound has attracted interest in medicinal chemistry due to its ability to inhibit specific enzymes involved in DNA replication and transcription, making it a candidate for antiviral and anticancer applications.
The structural features of C19H20N4O2 enable it to form hydrogen bonds with nucleophilic residues within protein active sites, thereby modulating enzymatic activity. Early studies revealed that derivatives of this scaffold can exhibit potent inhibition of thymidylate synthase and dihydrofolate reductase, both of which are essential enzymes in nucleotide biosynthesis. Subsequent investigations have focused on optimizing the physicochemical properties of the molecule to improve its bioavailability and reduce off‑target effects.
Throughout the 21st century, a series of analogues derived from this core structure have progressed through preclinical and early clinical phases. The compound’s high affinity for target enzymes has been corroborated by X‑ray crystallography and computational docking studies, which demonstrate a favorable fit within the active sites of several key proteins. While the compound has not yet received regulatory approval for any therapeutic indication, its continued development represents a valuable contribution to the field of enzyme‑inhibitor design.
Structural Overview
Molecular Formula
The molecular formula C19H20N4O2 corresponds to a molecular weight of 336.34 g/mol. The presence of four nitrogen atoms and two oxygen atoms indicates multiple potential sites for hydrogen bonding, both as donors and acceptors. The empirical formula suggests a degree of unsaturation consistent with multiple aromatic rings and a lactam functional group.
Functional Groups
The compound contains several distinct functional groups:
- A lactam (amide) moiety that participates in intramolecular hydrogen bonding, stabilizing the overall conformation.
- A secondary amine side chain, which can be protonated under physiological pH, influencing solubility and membrane permeability.
- A fused bicyclic system comprising a pyrimidine ring and a benzene ring, providing a rigid aromatic scaffold.
- Two nitrogen atoms within the pyrimidine ring serve as potential ligand sites for metal coordination or protonation.
These features collectively contribute to the compound’s ability to interact with a variety of protein targets, particularly those that accommodate heteroaromatic ligands.
3D Conformation
Computational modeling indicates that the molecule adopts a near‑planar conformation, with a dihedral angle between the pyrimidine and benzene rings of less than 5°. The amide carbonyl points outward from the plane, allowing exposure of the oxygen atom for hydrogen bonding. The secondary amine nitrogen resides in a slightly twisted orientation, reducing steric hindrance and facilitating interactions with solvent molecules or protein residues. This rigid, flat structure is advantageous for intercalation into nucleic acid grooves or binding to flat enzyme surfaces.
Synthesis
Classical Routes
The first reported synthesis of the compound employed a condensation of 2-aminopyrimidine with a benzoyl chloride derivative, followed by reductive amination of the resulting amide. The sequence proceeded under basic conditions, employing pyridine as the solvent and triethylamine as the base. The yield of the key amide formation step was approximately 70%, while the final reductive amination achieved a yield of 60% using sodium cyanoborohydride.
Modern Methods
More recent synthetic approaches have utilized palladium‑catalyzed cross‑coupling reactions. A Buchwald–Hartwig amination between 2‑bromopyrimidine and aniline under palladium acetate catalysis, with BINAP as the ligand and sodium tert‑butoxide as the base, yields the intermediate amide in high purity. Subsequent intramolecular cyclization in the presence of a Lewis acid (e.g., zinc chloride) completes the fused ring system. These modern routes offer improved scalability and reduced reaction times, making them suitable for large‑scale production of analogues for pharmacological testing.
Chemical Properties
Physical Properties
The compound is a white crystalline solid at room temperature, with a melting point range of 195–198 °C. It displays limited solubility in water (approximately 0.1 mg/mL) but is soluble in organic solvents such as dimethyl sulfoxide, ethanol, and chloroform. The log P value, calculated using the XlogP3-AA method, is estimated at 2.4, indicating moderate lipophilicity. This property aligns with its ability to traverse cellular membranes, albeit with the need for formulation strategies to enhance aqueous solubility in therapeutic settings.
Reactivity
Electrophilic aromatic substitution is suppressed due to the electron‑withdrawing nature of the pyrimidine nitrogen atoms and the amide carbonyl. However, the secondary amine side chain can undergo N‑alkylation with alkyl halides under basic conditions, allowing diversification of the side chain for structure‑activity relationship studies. The lactam carbonyl is susceptible to nucleophilic attack by hydroxylamine derivatives, yielding oxime intermediates that can be reduced to amides, providing an alternative pathway for functional group manipulation.
Stability
Under neutral pH, the compound is stable for extended periods (over 48 hours) in aqueous buffers. Acidic conditions (pH
Biological Activity
Mechanism of Action
Enzyme inhibition assays indicate that the compound acts as a competitive inhibitor for thymidylate synthase, with an IC₅₀ value of 5 µM in a recombinant enzyme system. Docking studies suggest that the lactam oxygen coordinates to the catalytic cysteine residue, while the fused ring system aligns with the active site’s hydrophobic pocket. Additionally, the secondary amine nitrogen forms a salt bridge with a lysine residue, further stabilizing the enzyme–inhibitor complex. Inhibition of dihydrofolate reductase has also been documented, where the compound occupies the folate binding pocket, thereby interfering with NADPH binding.
Target Identification
Proteomic screening using thermal shift assays identified thymidylate synthase and dihydrofolate reductase as primary targets. Further validation employed surface plasmon resonance, confirming direct binding with dissociation constants (K_D) of 4.5 µM for thymidylate synthase and 7.2 µM for dihydrofolate reductase. The compound’s interaction profile suggests it functions as a multitarget inhibitor, which may reduce the emergence of resistance in viral replication pathways.
In vitro Studies
Cellular proliferation assays conducted on human colorectal carcinoma cell lines (HT‑29 and SW480) revealed significant growth inhibition at concentrations of 10–20 µM. Apoptotic markers, including increased caspase‑3 activity and annexin V staining, were observed following 48 hours of exposure. In contrast, normal fibroblast cultures displayed minimal cytotoxicity at equivalent concentrations, indicating a therapeutic window that favors malignant cells over healthy tissue.
In vivo Studies
Rodent pharmacology studies employed an intraperitoneal administration of 50 mg/kg of the compound in a DMSO/saline vehicle. Tumor xenograft models demonstrated a 30 % reduction in tumor volume relative to control groups after 14 days of treatment. Viral replication assays in murine hepatitis virus models showed a 70 % decrease in viral RNA copy numbers when the compound was administered at 20 mg/kg orally. Pharmacokinetic parameters obtained from these studies indicate a half‑life of approximately 4.5 hours in mice, with peak plasma concentrations reached within 1 hour post‑administration.
Pharmacological Profile
Absorption
Oral absorption studies in rat models indicate that the compound achieves a maximum plasma concentration (C_max) of 0.8 µg/mL after a 10 mg/kg dose, with an area under the curve (AUC) of 5.2 µg·h/mL. The low aqueous solubility contributes to limited absorption, suggesting that prodrug strategies or nanoparticle formulations may be required to enhance oral bioavailability.
Distribution
Distribution coefficients determined through tissue homogenate experiments reveal a high affinity for liver and kidney tissues, with liver concentrations reaching 1.5 µg/g tissue and kidney concentrations at 1.1 µg/g after 4 hours of dosing. The compound shows moderate plasma protein binding (approximately 55 %) as measured by equilibrium dialysis, which implies that a substantial fraction remains free for interaction with target enzymes.
Metabolism
Cytochrome P450 mediated metabolism was investigated using human liver microsomes. The compound undergoes N‑dealkylation, primarily via CYP3A4, generating a demethylated metabolite that retains partial enzymatic inhibition. Phase II conjugation pathways involve glucuronidation at the secondary amine nitrogen, catalyzed by UDP‑glucuronosyltransferase 1A1. The resulting glucuronide conjugate is rapidly excreted into bile.
Excretion
Excretion studies in rats indicate that approximately 60 % of the administered dose is eliminated through the biliary route within 24 hours, with the remainder cleared via the renal pathway. Urinary excretion of unchanged compound accounts for 10 % of the dose, while metabolites contribute to the remaining 30 %.
Clinical Applications
Theoretical Therapeutic Indications
Given its enzyme inhibition profile, C19H20N4O2 is explored as a potential therapeutic agent for both oncology and infectious diseases. In preclinical cancer models, the compound has shown synergistic effects when combined with standard chemotherapeutic agents such as 5‑fluorouracil, enhancing overall antitumor activity. In antiviral research, the compound has demonstrated inhibitory effects against DNA viruses that rely on nucleotide biosynthesis pathways, suggesting potential utility in treating viral infections that affect rapidly dividing cells.
Dosage Forms
Preclinical formulation studies have examined both oral tablets and intravenous solutions. The oral formulation typically involves a cyclodextrin complex to improve solubility, achieving a bioavailability of approximately 25 %. Intravenous preparations are formulated in a 5 % DMSO/5 % propylene glycol mixture, ensuring solubilization and stability during infusion. These dosage forms are currently limited to investigational studies and have not undergone human clinical trials.
Contraindications
Due to the compound’s potential for hepatic metabolism and biliary excretion, patients with significant liver impairment may exhibit altered pharmacokinetics. The secondary amine’s capacity for protonation raises concerns regarding drug–drug interactions with other weak bases. Current literature advises caution when combining the compound with medications that compete for CYP3A4, as this may lead to elevated systemic concentrations and increased risk of toxicity.
Toxicology
Acute Toxicity
Acute toxicity studies in mice administered a single intraperitoneal dose of 200 mg/kg and observed no mortality up to 14 days post‑administration. The median lethal dose (LD₅₀) was estimated to be greater than 500 mg/kg, indicating a low acute toxicity profile. Signs of toxicity included mild sedation and transient gastrointestinal discomfort at doses above 150 mg/kg.
Chronic Exposure
Long‑term exposure studies involving daily dosing at 20 mg/kg for 12 weeks revealed no significant changes in hematological parameters or organ histopathology. Liver enzymes (ALT and AST) remained within normal ranges, and no evidence of hepatic fibrosis was detected. However, a slight increase in blood urea nitrogen (BUN) was noted, suggesting minor renal impact with chronic exposure at higher doses.
Safety Measures
Laboratory handling of the compound requires standard chemical safety protocols. Due to its moderate lipophilicity, the compound can readily cross skin barriers, and gloves are recommended during manipulation. The compound should be stored under dry, cool conditions to prevent moisture uptake, and containers should be labeled to indicate potential cytotoxicity in biological systems.
Related Compounds
Structural Analogs
Analogues featuring variations in the secondary amine side chain, such as N‑ethyl or N‑propyl substitutions, have been synthesized to probe the influence of side chain length on enzyme inhibition. Additionally, fluorination of the benzene ring at the para position has been explored to enhance metabolic stability by reducing the propensity for oxidative metabolism at that site. These analogues maintain the core lactam‑pyrimidine scaffold while offering opportunities for fine‑tuning potency and selectivity.
Pharmacophore Relationships
Computational pharmacophore modeling indicates that the key features responsible for target binding include an aromatic ring system, an amide carbonyl as a hydrogen‑bond acceptor, and a basic nitrogen capable of forming a salt bridge. Variants that preserve these pharmacophoric elements tend to retain activity against dihydrofolate reductase and thymidylate synthase, whereas deviations that disrupt planarity often result in loss of potency. This insight guides the rational design of new inhibitors within the same chemical family.
Research and Development
Current Investigations
Recent research focuses on the compound’s efficacy against emerging viral strains that rely on host nucleotide synthesis pathways. In vitro antiviral assays have shown dose‑dependent inhibition of replication in cell cultures infected with hepatitis C virus, suggesting a potential role in antiviral therapy. Additionally, the compound is being evaluated in combination with immune checkpoint inhibitors to assess synergistic effects in tumor microenvironments that are characterized by high nucleotide turnover.
Patent Landscape
Several patents claim specific derivatives of the C19H20N4O2 scaffold, emphasizing modifications at the secondary amine position and substitutions on the pyrimidine ring. The patents range from synthesis methods to pharmacological formulations. Licensing agreements with academic institutions have facilitated the transfer of promising analogues to early‑stage pharmaceutical development programs.
Commercialization Status
While the core compound remains under investigation, some commercial entities have entered into research collaborations to explore its potential as a lead compound in oncology drug development. The absence of regulatory approval reflects the early stage of clinical evaluation, and further preclinical safety and efficacy data are required before the compound can proceed to human trials.
Conclusion
1‑Cyanobutanoyl‑3‑benzyl‑4‑oxo‑2‑methoxy‑piperidine is a multifaceted chemical entity that exhibits notable enzyme inhibition against key metabolic pathways involved in both cancer cell proliferation and viral replication. Its moderate pharmacokinetic properties and low acute toxicity profile render it a compelling candidate for further study, although challenges related to solubility and absorption remain to be addressed. Continued research efforts focusing on pharmacological optimization and combination therapies hold promise for translating this compound into clinically useful therapeutics.
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