Synthesis and biological evaluation of several new heterocyclic carvacrol esters

In this work, five novel esters (E4, E5, E6, E7, and E8) were synthesized through the condensation of carvacrol with heterocyclic carboxylic acids. The structures of the newly synthesized compounds were identified by FT-IR and 1H NMR analysis. The new carvacrol-based compounds and their original natural product (carvacrol) were screened for their in vitro biological activities against various types of bacteria and cancer cells. Results showed a strong inhibitory effect of ester E4 against all studied types of bacteria, and ester E4 with a MIC of 62.5 μg/mL was more effective than carvacrol with a MIC of 125 μg/mL against the gram-negative bacteria K. pneumoniae.