Synthesis, Antioxidant Activity and Theoretical Investigation of Isoxazolines Derivatives of Monoterpenoids

Abstract

The 3+2 cycloaddition reactions are important to generate five-membered heterocyclic compounds as well as altering biological activity effects based on structure. In the study, we synthesized new isoxazoline derivatives of different monoterpenoids and examined the structure analysis using spectroscopical analysis methods, reveal changes in the theoretical analysis related to the biological activity. These new compounds exhibit antioxidant activities; DPPH radical scavenging, ferric reducing, metal chelating activities which are significantly higher than the related commercial monoterpenoids. Theoretical approaches on the compounds containing isoxazole moiety have been performed by the DFT/B3LYP/method, 6-31G(d,p) basis set in the ground state. The global and local chemical reactivity properties of the compounds were investigated by considering the values of electronegativity, global hardness-softness, electronic chemical potential, electrophilicity index and condensed Fukui functions, local softness and local electrophilicity index. Furthermore, total energy, FMOs energy values and the dipole moment (mu), mean polarizability (alpha), and first order hyperpolarizability (beta) values were analysed at the theoretical level to examine the polarizability characteristics of the compounds. The antioxidant activity values of the newly synthesized compounds were compared with a finding of the computational study. The results obtained exhibited good correlation on some parameters.