New Materials, Compounds and Applications

A series of 3-hydroxy-2-oxindoles and their corresponding α,β-unsaturated analogues, were synthesized via aldol condensation of isatin with selected carbonyl compounds. The target compounds were obtained in good to excellent yields and characterized by spectroscopic and physicochemical methods. Their antibacterial activity was evaluated against Staphylococcus aureus using complementary screening assays. In the primary high-throughput screening assay, several compounds exhibited pronounced antibacterial activity, inhibiting bacterial growth by 73.9-100% at 10 µM. The highest activities were observed for compounds 10 and 12. Evaluation against a drug-resistant S. aureus strain revealed moderate activity only for the dichloro-substituted derivatives 13 and 14. Structure-activity relationship analysis indicated that antibacterial efficacy was strongly influenced by structural modifications. N-Substituted derivatives generally displayed higher activity than their unsubstituted analogues, while chlorine substitution enhanced activity in the dilution assay. Among all synthesized compounds, compound 14 demonstrated the strongest antibacterial effect. These findings identify the 2-oxindole scaffold as a promising platform for the development of new antibacterial agents and provide valuable insights into the structural factors governing antibacterial activity.