Quantum Chemical Insights into Antibiotic Structure-Activity Relationships and Mechanisms of Action: A Review.

This review examines recent quantum chemical methodologies applied to investigating antibiotic structure and mechanisms of action. The discussion is organised into three sections: (1) enzymatic hydrolysis of the β-lactam ring, (2) interactions of antibiotics with ribosomal subunits and enzyme active sites, and (3) complex formation with metal ions. Each section evaluates how quantum chemical approaches, particularly density functional theory (DFT) and hybrid QM/MM techniques, model molecular processes relevant to antibiotic function, including transition states, electron density analyses, and metal coordination effects on antibacterial activity. Selected studies demonstrate the utility of these methodologies in interpreting experimental data and predicting physicochemical and biological properties of novel compounds. Distinct from previous literature, this review provides a comparative and up-to-date synthesis of quantum chemical methods related to enzymatic mechanisms and metal-based antibiotic systems, emphasising experimental validation strategies and practical guidelines for method selection in antibiotic research. It also identifies areas where quantum chemical modelling can integrate with experimental pharmacology and structural biology to support the rational design of next-generation antimicrobial agents. The review concludes by advocating an interdisciplinary framework combining quantum chemistry, biochemistry, and pharmacology to address antibiotic resistance. The review focuses primarily on antibiotics targeting bacterial cell wall and protein synthesis, particularly β-lactam antibiotics, ribosome-targeting agents, and their interactions with metal ions. Computational methods discussed are mainly limited to DFT, ab initio, and hybrid QM/MM approaches. It does not cover membrane-disrupting antibiotics, antiviral or antifungal agents, machine learning-based prediction methods, or purely molecular dynamics approaches outside a quantum mechanical context.