Synthesis and Investigation of Flavanone Derivatives as Potential New Anti-Inflammatory Agents.

Flavonoids are polyphenols with broad known pharmacological properties. A series of 2,3-dihydroflavanone derivatives were thus synthesized and investigated for their anti-inflammatory activities. The target flavanones were prepared through cyclization of 2'-hydroxychalcone derivatives, the later obtained by Claisen-Schmidt condensation. Since nitric oxide (NO) represents an important inflammatory mediator, the effects of various flavanones on the NO production in the LPS-induced RAW 264.7 macrophage were assessed in vitro using the Griess test. The most active compounds were flavanone ( 4G ), 2'-carboxy-5,7-dimethoxy-flavanone ( 4F ), 4'-bromo-5,7-dimethoxy-flavanone ( 4D ), and 2'-carboxyflavanone ( 4J ), with IC50 values of 0.603, 0.906, 1.030, and 1.830 µg/mL, respectively. In comparison, pinocembrin achieved an IC 50 value of 203.60 µg/mL. Thus, the derivatives synthesized in this work had a higher NO inhibition capacity compared to pinocembrin, demonstrating the importance of pharmacomodulation to improve the biological potential of natural molecules. SARs suggested that the use of a carboxyl-group in the meta -position of the B-ring increases biological activity, whereas compounds carrying halogen substituents in the para -position were less active. The addition of methoxy-groups in the meta -position of the A-ring somewhat decreased the activity. This study successfully identified new bioactive flavanones as promising candidates for the development of new anti-inflammatory agents.