Nitrocefin,头孢硝噻吩,

3-(2,4-Dinitrostyryl)-(6R, 7R)-7-(2-thienylacetamido)-ceph-3-em-4-carboxylic acid

Chromogenic cephalosporin β-lactamase substrate. Indicates β-lactamase activity via a red color intensely proportional to the original concentration of Nitrocefin. Undergoes rapid distinctive color change from yellow (max at pH 7.0 = 390 nm) to red (max at pH 7.0 = 486 nm) as the amide bond in the beta-lactam ring is hydrolyzed.

The generation of β-lactamases by bacteria affords resistance to several classes of β-lactam antibiotics, including penicillins and cephalosporins. Nitrocefin is a chromogenic cephalosporin substrate commonly used to detect β-lactamases in bacteria. The presence of β-lactamase activity is indicated by the appearance of a red color that is proportional in intensity to the original concentration of nitrocefin.

Nitrocefin is a beta-lactam antibiotic, with diagnostic properties. Nitrocefin is sensitive to hydrolysis by all lactamases produced by gram-positive and gram-negative bacteria. This agent undergoes a color change as its amide bond is hydrolyzed by beta-lactamase, making it useful as a reagent in beta-lactamase activity studies.

Nitrocefin is a chromogenic cephalosporin substrate used to detect the presence of beta-lactamase enzymes, an important mediator of bacterial antibiotic resistance. While other detection methods exist, such as PCR, nitrocefin allows for rapid detection using few materials and inexpensive equipment.

Title: Nitrocefin

CAS Registry Number: 41906-86-9

CAS Name: (6R,7R)-3-[(1E)-2-(2,4-Dinitrophenyl)ethenyl]-8-oxo-7-[(2-thienylacetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

Additional Names: 3-(2,4-dinitrostyryl)-(6R,7R)-7-(2-thienylacetamido)-ceph-3-em-4-carboxylic acid, E-isomer; 87/312

Molecular Formula: C21H16N4O8S2

Molecular Weight: 516.50

Percent Composition: C 48.83%, H 3.12%, N 10.85%, O 24.78%, S 12.42%

Literature References: Chromogenic cephalosporin. Prepd (not claimed): C. H. O'Callaghan et al., US 3830700 (1974 to Glaxo). Characterization and use in detection of b-lactamases: idem et al., Antimicrob. Agents Chemother. 1, 283 (1972). Synthesis: N. C. M. Barendse et al., Synthesis 1998, 145. Improved synthesis: M. Lee et al., J. Org. Chem. 70, 367 (2005). Review of commercially available nitrocefin-based b-lactamase tests: A. T. Meszaros et al., Am. Clin. Lab. 14, 20-22 (1995).

Properties: Orange solid, mp 103-113° (dec) (O'Callaghan, 1974); also reported as crystals from methanol, mp 167-169° (dec) (Lee). [a]D20 -224° (c = 1.0 in dioxane). Absorption max (ethanol): 231, 289, 386 nm (e 24300, 10300, 18000). Absorption max (0.1M pH 6 phosphate buffer): 233, 290, 391 nm (e 22200, 12200, 17400). Undergoes a color change from yellow to pink or red upon exposure to b-lactamases.

Melting point: mp 103-113° (dec); mp 167-169° (dec) (Lee)

Optical Rotation: [a]D20 -224° (c = 1.0 in dioxane)

Absorption maximum: Absorption max (ethanol): 231, 289, 386 nm (e 24300, 10300, 18000); Absorption max (0.1M pH 6 phosphate buffer): 233, 290, 391 nm (e 22200, 12200, 17400)

Use: In determn of b-lactamase activity in biological samples.