Sulfisoxazole

Synthetic Routes and Reaction Conditions: The preparation of sulfisoxazole involves a condensation reaction where 3-aminoisoxazole is reacted with p-acetamido-benzenesulfonyl chloride in the presence of toluene and pyridine. This reaction is typically carried out over 20-24 hours. The resulting product undergoes hydrolysis with liquid caustic soda, followed by a salt-forming reaction to obtain this compound sodium .

Industrial Production Methods: Industrial production of this compound follows similar synthetic routes but on a larger scale. The process involves careful control of reaction conditions to ensure high yield and purity. The final product is often crystallized and purified to meet pharmaceutical standards .

Types of Reactions: Sulfisoxazole undergoes various chemical reactions, including:

Oxidation: this compound can be oxidized under specific conditions to form different derivatives.

Reduction: It can also undergo reduction reactions, although these are less common.

Substitution: this compound can participate in substitution reactions, particularly involving the sulfonamide group.

Common Reagents and Conditions:

Oxidation: Common oxidizing agents include hydrogen peroxide and potassium permanganate.

Reduction: Reducing agents such as sodium borohydride can be used.

Substitution: Reagents like alkyl halides and acyl chlorides are often used in substitution reactions.

Major Products: The major products formed from these reactions depend on the specific conditions and reagents used. For example, oxidation can lead to the formation of sulfone derivatives .

Antitumor Activity

Inhibition of Small Extracellular Vesicles (sEV) Secretion

Recent studies have identified sulfisoxazole as a potent inhibitor of small extracellular vesicle secretion from breast cancer cells. This mechanism is significant because sEVs are known to facilitate cancer progression and metastasis. This compound interferes with the endothelin receptor A (ETA), which is crucial for the biogenesis and secretion of sEVs. In mouse models, this compound demonstrated substantial anti-tumor and anti-metastatic effects, reducing tumor burden without significant toxicity .

• Mechanism of Action :
  • This compound targets ETA, leading to reduced expression of proteins involved in sEV biogenesis.
  • The compound promotes the degradation of multivesicular endosomes by triggering their co-localization with lysosomes .

Immunomodulatory Effects

Reinvigoration of Exhausted T Cells

This compound has shown promise in enhancing the effectiveness of immune checkpoint inhibitors in cancer therapy. It significantly decreases the levels of PD-L1 in exosomes derived from tumors, which is crucial for overcoming immunosuppression in the tumor microenvironment. When combined with anti-PD-1 antibodies, this compound reinvigorates exhausted CD8+ T cells, thereby eliciting robust antitumor responses .

• Clinical Implications :
  • The combination therapy could improve response rates in patients receiving immune checkpoint inhibitors, addressing a major limitation in current cancer therapies.

Safety Profile and Adverse Reactions

While this compound is generally well-tolerated, it is essential to consider its safety profile in clinical settings. A study monitoring hospitalized patients revealed that adverse reactions occurred in approximately 3.1% of cases treated with this compound. Common reactions included skin rashes and eosinophilia; however, serious reactions were rare (0.14%) and often associated with prolonged therapy .

Environmental Applications

Biodegradation Research

This compound has also been studied for its biodegradation properties in environmental contexts. Research indicates that this compound can be relevant in assessing the impact of pharmaceutical contaminants on ecosystems, particularly regarding microbial degradation processes .

Data Table: Summary of Applications

Sulfisoxazole exerts its effects by inhibiting the enzyme dihydropteroate synthetase. This enzyme is crucial for the bacterial synthesis of dihydrofolic acid, a precursor for nucleic acid synthesis. By preventing the condensation of pteridine with para-aminobenzoic acid, this compound effectively halts bacterial growth and replication .

Sulfamethoxazole: Another sulfonamide antibiotic with a similar mechanism of action but different pharmacokinetics.

Sulfadiazine: Used primarily in the treatment of toxoplasmosis.

Sulfapyridine: Used in the treatment of dermatitis herpetiformis.

Uniqueness: Sulfisoxazole is unique in its short-acting nature and its effectiveness against a broad spectrum of bacterial species. It is particularly useful in combination therapies to enhance antibacterial efficacy .

Sulfisoxazole (SFX) is a sulfonamide antibiotic that has garnered attention not only for its antibacterial properties but also for its potential biological activities in cancer therapy and immunomodulation. This article explores the biological activity of this compound, focusing on its mechanisms of action, effects on cancer cells, and associated research findings.

This compound primarily functions as an antibacterial agent by inhibiting bacterial dihydropteroate synthase, an enzyme critical for folate synthesis. However, recent studies have revealed additional mechanisms through which this compound exerts biological effects:

• Inhibition of Small Extracellular Vesicles (sEV) Secretion : SFX has been identified as an inhibitor of sEV secretion from breast cancer cells. It interferes with the endothelin receptor A (ETA), leading to reduced tumor growth and metastasis in mouse models of breast cancer. This inhibition is linked to decreased expression of proteins involved in sEV biogenesis and enhanced lysosomal degradation of multivesicular endosomes .
• Modulation of Immune Responses : SFX has shown promise in enhancing antitumor immune responses. It decreases the levels of exosomal PD-L1 in blood, which is associated with immune evasion in tumors. By reinvigorating exhausted CD8+ T cells, this compound may improve the efficacy of immune checkpoint inhibitors like anti-PD-1 antibodies .

Case Studies and Experimental Data

• Anti-Tumor Effects : In a study involving mouse models of breast cancer xenografts, this compound demonstrated significant anti-tumor and anti-metastatic effects. The results indicated that SFX could serve as a potential therapeutic agent targeting cancer progression through its action on ETA and sEV secretion pathways .
• Electrochemical Analysis : Recent electrochemical studies have developed sensitive methods for detecting this compound in biological samples. Using modified glassy carbon electrodes, researchers achieved detection limits as low as 0.4 μM, showcasing the compound's presence in various biological matrices .
• Adverse Reactions : While this compound is generally well-tolerated, adverse reactions have been reported. A study monitoring hospitalized patients revealed that 3.1% experienced severe reactions necessitating discontinuation of therapy, with skin rashes and eosinophilia being the most common manifestations .

Data Table: Summary of Biological Activities

Basic Research Questions

Q. What is the mechanism of action of sulfisoxazole, and how can researchers validate it experimentally?

this compound inhibits bacterial dihydropteroate synthase (DHPS), a key enzyme in folate biosynthesis. To validate this, researchers can perform in vitro enzyme inhibition assays using purified DHPS, monitor substrate (p-aminobenzoic acid) utilization via spectrophotometry, and compare inhibition kinetics with control compounds. Competitive binding studies using radiolabeled this compound analogs can further confirm target specificity .

Q. What synthetic methodologies are commonly used to produce this compound, and how can purity be ensured?

this compound is synthesized via condensation of 4-aminobenzenesulfonamide with 3,4-dimethyl-5-isoxazolylamine. Post-synthesis, purity is assessed using high-performance liquid chromatography (HPLC) with UV detection (λ = 265 nm) and nuclear magnetic resonance (NMR) spectroscopy to confirm structural integrity. Recrystallization in ethanol-water mixtures (70:30 v/v) is recommended to achieve ≥98% purity .

Q. Which analytical techniques are most reliable for quantifying this compound in biological matrices?

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is optimal for quantifying this compound in plasma or tissue homogenates, offering sensitivity down to 0.1 ng/mL. For non-biological samples, UV-Vis spectrophotometry (at 257 nm) or reverse-phase HPLC with C18 columns provides reproducible results. Calibration curves should be validated using spiked samples to account for matrix effects .

Advanced Research Questions

Q. How can researchers investigate this compound resistance mechanisms in Gram-negative bacteria?

Resistance often arises from mutations in the folP gene (encoding DHPS) or overexpression of efflux pumps. To study this:

• Perform whole-genome sequencing of resistant strains to identify folP mutations.
• Use quantitative PCR (qPCR) to measure efflux pump gene expression (e.g., acrAB-tolC in E. coli).
• Conduct competitive growth assays with and without efflux inhibitors (e.g., phenylalanine-arginine β-naphthylamide) .

Q. What experimental strategies optimize this compound’s pharmacokinetics while minimizing toxicity?

• Structural modification : Introduce hydrophilic groups (e.g., hydroxyl or carboxyl) to enhance solubility and reduce renal crystallinity risk.
• Nanoparticle encapsulation : Use poly(lactic-co-glycolic acid) (PLGA) nanoparticles to improve bioavailability and target tissue delivery.
• Toxicity screening : Employ in vitro hepatocyte models (e.g., HepG2 cells) to assess metabolic stability and cytotoxicity .

Q. How can researchers resolve contradictions in reported this compound efficacy across different bacterial strains?

Contradictions may stem from variations in bacterial folate biosynthesis pathways or assay conditions. Mitigate this by:

• Standardizing MIC (minimum inhibitory concentration) assays using CLSI guidelines (e.g., Mueller-Hinton broth, pH 7.2–7.4).
• Including positive controls (e.g., trimethoprim) and strain-specific folate pathway annotations .

Q. What methodologies are effective for studying this compound’s synergism with other antibiotics?

Use checkerboard assays to calculate fractional inhibitory concentration indices (FICIs). For example, combining this compound with trimethoprim (targeting DHFR) often shows synergy (FICI ≤0.5). Time-kill curves over 24 hours can further validate synergistic bactericidal activity .

Q. How should researchers design in vivo studies to evaluate this compound’s tissue penetration?

• Animal models : Use neutropenic murine thigh infections for pharmacokinetic/pharmacodynamic (PK/PD) modeling.
• Tissue sampling : Measure drug concentrations in target tissues (e.g., kidneys, lungs) via microdialysis or homogenization followed by LC-MS/MS.
• Data analysis : Apply non-compartmental analysis (NCA) to calculate AUC/MIC ratios .

Q. What experimental approaches assess this compound’s stability under varying physiological conditions?

Conduct forced degradation studies :

• Acidic/alkaline hydrolysis (0.1M HCl/NaOH, 70°C for 24 hours).
• Oxidative stress (3% H₂O₂, 25°C for 6 hours).
• Photostability (ICH Q1B guidelines, 1.2 million lux hours). Analyze degradation products using LC-MS and compare to stability-indicating HPLC methods .

Q. How can predictive modeling improve this compound derivative screening?

Quantitative structure-activity relationship (QSAR) models trained on existing sulfonamide datasets can predict bioactivity and ADMET (absorption, distribution, metabolism, excretion, toxicity) profiles. Use molecular docking (e.g., AutoDock Vina) to simulate binding to DHPS active sites, prioritizing derivatives with lower binding energies (ΔG ≤ -8 kcal/mol) .