Chloramphenicol

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Cat Number

API56757

CAS Number

56-75-7

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CAS Number

56-75-7

EINECS

200-287-4

Storage

Store at room temperature

Synonyms

Chlornitromycin; Levomycetin; Chloroamphenicol; Alficetyn; Chlorocid; Levomicetina; Halomycetin

Molecular Formula

C11H12Cl2N2O5

Molecular Weight

323.13

Smiles

C1=CC(=CC=C1[C@H]([C@@H](CO)NC(=O)C(Cl)Cl)O)[N+](=O)[O-]

Appearance

White to off-white crystalline powder

Melting Point

148-150°C (lit.)

Boiling Point

644.9±55.0°C (Predicted)

Relative Density

1.6±0.1

General Description

Chloramphenicol is a broad-spectrum antibiotic with a nitrobenzene group and a dichloroacetamide side chain, originally isolated from Streptomyces venezuelae. Its structure is a nitrophenylpropanediol with two hydroxyl groups and an amide bond.

Mechanism of Action

Chloramphenicol binds reversibly to the 50S ribosomal subunit of susceptible bacteria, inhibiting peptidyl transferase activity and blocking peptide bond formation. This prevents protein synthesis at the elongation step, exerting a bacteriostatic effect. The drug has a high affinity for bacterial ribosomes, but it can also inhibit mitochondrial protein synthesis at higher concentrations, contributing to its toxicity.

Application

Chloramphenicol is indicated for the treatment of serious infections caused by susceptible organisms, including typhoid fever, meningitis (especially due to Haemophilus influenzae and Neisseria meningitidis), and rickettsial infections. It is also used for intraocular infections and anaerobic infections.

Two α,β-unsaturated carbonyl derivatives of chloramphenicol (compounds 1 and 4) showed broader antibacterial activity (MIC 2–32 µg/mL) against Gram-positive pathogens but did not inhibit translation. Instead, they inhibited early-stage cell wall peptidoglycan biosynthesis without rapid membrane permeabilization. Both were bacteriostatic and cytotoxic to nucleated cells but not erythrocytes.

Fig. 1 Time-kill kinetics of S. aureus ATCC 29213. (Louzoun Zada S, et al., 2018)

References

Louzoun Zada S, et al. Derivatives of Ribosome-Inhibiting Antibiotic Chloramphenicol Inhibit the Biosynthesis of Bacterial Cell Wall. ACS Infect Dis. 2018;4(7):1121-1129.

A series of chloramphenicol derivatives were synthesized by tethering alpha- and beta-amino acids (glycine, lysine, histidine, ornithine, beta-alanine) to the free amine group of chloramphenicol base, with further modifications using protecting groups or dichloroacetyl groups. The bis-dichloroacetyl derivative of ornithine displayed the highest antimicrobial activity both in vivo and in vitro, representing a promising new pharmacophore for further development.

Fig. 2 Bacteria E. coli ΔTolC growth in the presence of CLB derivatives. (Tsirogianni A, et al., 2021)

References

Tsirogianni A, et al. New Chloramphenicol Derivatives with a Modified Dichloroacetyl Tail as Potential Antimicrobial Agents. Antibiotics (Basel). 2021;10(4):394.

Does Chloramphenicol require protection from light and moisture during storage?

Yes, it is sensitive to both light and moisture. Light causes photodegradation and moisture promotes hydrolysis of the amide group. Store in light-resistant, tightly sealed containers with desiccant.

What is the recommended storage temperature for Chloramphenicol?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which accelerates degradation of the nitrobenzene ring.

Is Chloramphenicol stable in ophthalmic and injectable formulations?

Aqueous solutions are stable when protected from light and stored at room temperature.

How is the impurity chloramphenicol base (a hydrolysis product) monitored?

This degradation product is specifically quantified using a stability-indicating HPLC method, ensuring it remains below pharmacopoeial limits.