Synthesis and pharmacological properties of naturally occurring prenylated and pyranochalcones as potent anti-inflammatory agents

An efficient approach has been developed for the synthesis of naturally occurring prenylated chalcones viz. kanzonol C (1), stipulin (2), crotaorixin (3), medicagenin (4), licoagrochalcone A (5) and abyssinone D (6) along with the pyranochalcones paratocarpin C (7), anthyllisone (8) and 3-O-methylabyssinone A (9). The key step of the synthesis is a Claisen–Schmidt condensation. Subsequently, their anti-inflammatory effects were investigated in lipopolysaccharides (LPSs)-induced RAW-264.7 macrophages. Of the synthesized chalcones, compounds 5 (IC50 = 10.41 μmol/L), 6 (IC50 = 9.65 μmol/L) and 8 (IC50 = 15.34 μmol/L) show remarkable activity with no cytotoxicity. Compound 9 (IC50 = 4.5 μmol/L) exhibits maximum (83.6%) nitric oxide (NO) inhibition, but shows slight cytotoxicity. The results reveal that the chalcones bearing the prenyl group at 3- and/or 5-position on ring A (acetophenone moiety), i.e., 1–4 and 7 show weak, or no inhibition activity, whereas chalcones having the prenyl group only on ring B (aldehyde part), i.e., 5, 6 and 8 show significant activity on the production of inflammatory mediated NO with no cytotoxicity.

Graphical abstractA facile approach for the synthesis of naturally occurring prenylated and pyranochalcones is achieved using Claisen–Schmidt condensation as a key step. Subsequently, their anti-inflammatory study revealed that the chalcones bearing the prenyl group at 3- and/or 5-position on ring A (acetophenone moiety), i.e., 1–4 and 7 show weak, or no inhibition activity, whereas chalcones having the prenyl group only on ring B (aldehyde part), i.e., 5, 6 and 8 show significant activity on the production of inflammatory mediated NO with no cytotoxicity.Figure optionsDownload full-size imageDownload as PowerPoint slide