Evaluation of the antimicrobial-cytotoxic activities and molecular docking study of L-cysteine ethyl ester and L-cysteine methyl ester.

Antibiotic resistance is a growing problem in the treatment of life-threatening diseases. Recently, a variety of covalent drugs have emerged. Cysteine ​​is one of the least abundant amino acids in the proteins of many organisms, and the thiol group in its structure makes it unique and has become a common covalent amino acid residue in covalent drug development. Therefore, it is important to conduct research on cysteine ​​derivatives. In this study, the in vitro antibacterial activity of L-cysteine esters were tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli using the modified microdilution broth method. In vitro cytotoxic activities of the esters were carried out against the healthy HEK293T cell line and well-differentiated liver cancer cell lines PLC/PRF/5 and HEP3B at different concentrations by using an MTS assay. In addition, molecular docking studies, ADMET properties, and drug-likeness were also reported. The results obtained are new and it is thought that these results of the study will contribute to the development of new synthesizable cysteine-based drugs. In conclusion, a thorough examination of the frontier orbital (HOMO and LUMO) and MEP studies was conducted using quantum chemistry techniques to determine the molecule's reactivity, electrophilic and nucleophilic sites.