**5. Conclusions**

In order to identify new bioactive compounds, we designed and synthesized novel derivatives that incorporate in the same molecule the *N*-acyl-α-amino acid, 4*H*-1,3-oxazol-5-one, 2-acylamino ketone, or 1,3-oxazole template and, a biologically active fragment derived from diphenyl sulfone. The obtained compounds' structures were confirmed on the basis of spectral studies and elemental analysis data. Taken together, the results of the qualitative and quantitative antimicrobial activity evaluation, antioxidant effect assessment, toxicity bioassay, as well as of in silico analysis revealed a promising potential of *N*-acyl-*L*valine **5** and 2-substituted 4-isopropyl-4*H*-1,3-oxazol-5-one **6** for the development of novel antimicrobial agents to combat infections produced by Gram-positive bacterial strains, and in particular of *E. faecium* biofilm-associated infections.
