Sulfisoxazole is a bioactive small molecule and broad-spectrum sulfanilamide antibacterial agent with an oxazole substituent. It is an ETA selective endothelin receptor antagonist (ETAR antagonist). It is a synthetic analog of the natural compound para-aminobenzoic acid (PABA).
| Mechanism of Action | Sulfisoxazole competes with PABA for the bacterial dihydropteroate synthase, thus preventing incorporation of PABA into dihydrofolic acid, the precursor to folic acid. Folic acid is a coenzyme in the synthesis of purines and pyrimidines, leading to reduced cell growth and cell death. Unlike bacteria (and fungi/ plants) that synthesize their own folic acid, mammals do not, and thus are unaffected by PABA inhibitors. |
| Spectrum | Broad-spectrum against a range of Gram-positive and Gram-negative bacteria including otitis media. |
| Microbiology Applications | Sulfisoxazole is commonly used in clinical in vitro microbiological antimicrobial susceptibility tests (Sensi-Disc, from BD) against Gram- positive and Gram-negative bacteria. Sulfisoxazole has IC50 of 0.6 uM for ETA receptor, and 22 uM for rETA receptor. Sulfisoxazole was used in a novel engineered E. coli 12-member reporter panel of bioluminescent reporter stains, constructed using a novel non-antibiotic selection system, to survey environmental residues. The selectivity marker was developed based on the requirement for tryptophan, and folic acid-free medium was employed (Melamed et al, 2012). |
| Molecular Formula | C11H13N3O3S |
| Solubility | soluble in DMSO. acetone. slightly soluble in alcohol |
| References | Chan MF(1994) Identification of a new class of ETA selective endothelin antagonists by pharmacophore directed screening. Biochem Biophys. Res. Commun. 201(1):228-234. PMID 8198578 Kuo C, Wang S and Grayston JT (1977) Antimicrobial activity of several antibiotics and a sulfonamide against Chlamydia trachomatis organisms in cell culture. Antimicrob. Agents. Chemother. 12(1):80-83 Antimicrobial Agents and Chemotherapy Jul 1977, 12 (1) 80-83; DOI: 10.1128/AAC.12.1.80 Melamed S et al (2012) A bacterial reporter panel for the detection and classification of antibiotic substances.Microb Biotechnol. 5(4):536-548 |