Sulfamethoxazole

- Overview
  - Sulfamethoxazole is a bacteriostatic sulfonamide antibiotic that was first synthesized in 1957 by researchers at Shionogi Inc. in Japan and launched as Sinomin. Sulfamethoxazole has broad-spectrum antimicrobial activity and is normally given in combination with Trimethoprim, a dihydrofolate reductase inhibitor, which inhibits the reduction of dihydrofolic acid to tetrahydrofolic acid. Studies have shown that bacterial resistance develops more slowly with the combination of the two drugs than with either Trimethoprim or Sulfamethoxazole alone.
    
    Sulfamethoxazole is one of the compounds that is being screened for potential utility for COVID-19.
    Sulfamethoxazole is insoluble in water and freely soluble in acetone.
    
    Please contact us at for specific academic pricing.
    
    Background
    
    Sulfonamides, like sulfamethoxazole, inhibit the enzymatic conversion of pteridine and p-aminobenzoic acid (PABA) to dihydropteroic acid by competing with PABA for binding to dihydrofolate synthetase, an intermediate of tetrahydrofolic acid (THF) synthesis. THF is required for the synthesis of purines and dTMP and inhibition of its synthesis inhibits bacterial growth.
- Properties
  - CAS Number
    
    723-46-6
    
    Molecular Formula
    
    C10H11N3O3S
    
    Molecular Weight
    
    253.28
    
    Appearance
    
    White to off-white crystalline powder
    
    Other Properties
    
    Source: Synthetic
    Assay: (on dried basis): 99.0% - 101.0%
    Residue On Ignition: Not more than 0.1%
    Loss on Drying: Not more than 0.5%
    Melting Point: 168°C – 172°C
    Identification: Positive
    
    Storage
    
    2 - 8°C
    
    * For research use only
- Applications
  - Application Description
    
    Spectrum: Sulfamethoxazole, like other sulfonamides, is a broad-spectrum antimicrobial inhibiting both Gram-positive and Gram-negative bacteria, as well as some protozoa, such as coccidia. They are considered ineffective against most obligate anaerobes and should not be used to treat serious anaerobic infections. However, they may affect aerobic organisms that contribute to the lowered oxygen tension in the microenvironment and, as such, they may be useful in certain diseases involving Fusobacteria, although the organism itself is often resistant. Sulfamethoxazole has shown activity against Chlamydia trachomatis.
    
    Microbiology Applications: Sulfamethoxazole (SMX) is commonly used in clinical in vitro microbiological antimicrobial susceptibility tests (panels, discs, and MIC strips) against Gram-positive and Gram-negative microbial isolates. Medical microbiologists use AST results to recommend antibiotic treatment options for infected patients.Sulfamethoxazole can be added to Muller Hinton II agar for antibiotic susceptibility testing protocols.
    Recently, Sulfamethoxazole was among the top 6 of 187 compounds screened in silica for potential activity against SARS-CoV-2 using machine learning models and high-fidelity ensemble docking studies as part of a global expansion in knowledge of small-molecule ligands with binding affinity for S-protein and S-protein:human ACE2 receptor interface (Batra et al, 2020).
    
    Plant Biology Applications: The sulfanilamide family comprises a clinically important group of antimicrobial compounds which also display bioactivity in plants. There is evidence that sulfanilamides, like Sulfamethoxazole, inhibit folate biosynthesis in both bacteria and plants.