Cephalexin

Cephalexin is a beta-lactam antibiotic that works against bacteria by inhibiting cell wall synthesis. Beta-lactam antibiotics are classified as first-generation cephalosporins and include a beta-lactam ring in their chemical structure. Peptidoglycan found inside the bacterial cell contributes to mechanical support of the cell wall. Beta-lactam antibiotics inhibit peptidoglycan synthesis using the antibiotic's beta-lactam ring. More specifically, cephalexin uses its beta-lactam ring to bind penicillin-binding proteins (PBPs). The binding of PBPs inhibits synthesis of peptidoglycan by blocking the last step in synthesis known as the transpeptidation reaction. The transpeptidation reaction leads to cross-linking of bacterial peptidoglycan. By inhibiting this step, cephalexin inactivates cell viability causing bacterial cell autolysis.

Antibiotics may be losing their effectiveness in fighting bacteria due to increased antibiotic resistance. For this reason, new methods to increase antibiotic potency were investigated. Scientists aimed to increase the effectiveness of the antibiotic cephalexin against pneumonia, which kills millions of children worldwide each year. Copper oxide nanoparticles were prepared by green synthesis through wild thyme extract. UV-vis spectroscopy, X-ray diffraction, and magnetic resonance were used to characterize the nanoparticles. Cephalexin was loaded onto CuO nanoparticles as a nanocomposite. The antibiotic-nanocomposite was found to exhibit superior antibacterial activity against clinical isolates of Klebsiella pneumoniae when compared to cephalexin alone. MIC values ranged from 1.8–2.2 mg ml⁻¹. Complete inhibition was seen at 30 mg ml⁻¹. The most effective suppression of pulmonary biofilm formation was exhibited at 20 mg ml⁻¹. The result showed that cephalexin-CuO nanocomposite is a potent dual-functional candidate for advanced antibacterial and antioxidant therapeutic solutions.

Fig. 2 Ultraviolet-visible spectra of prepared copper oxide nanoparticles and cephalexin loaded on copper oxide nanoparticles. (Dali L, et al. 2026)