The Influence of Halogens at Meta-positions of Aromatic Rings In Chalcones on Their In Vitro Anti-inflammatory Activity

Abstract

The discovery of new therapeutic agents for inflammatory disorders has attracted more attention in recent years. Chalcone term is given to the flavonoid compounds bearing the 1,3-diphenyl-2-propen-1-one framework. Generally, chalcones are precursors of flavonoids with two aromatic rings joined together through three carbons, α, β-unsaturated carbonyl system. In plants, chalcones are converted to the respective (2S)-flavanones by enzymatic reaction of chalcone isomerase. Based on the close chemical and biogenetic relationship between flavanones and chalcones, they are considered as natural products. For anti-inflammatory activity of chalcones, activated macrophages play an important role and compounds with that inhibit nitro oxide production by macrophages have been found potential for the prevention and treatment of inflammatory disorders. Some functional groups such as dimethylamine, methoxy and butoxy groups increase the electron density of the B-ring resulting in significant loss of anti-inflammatory activity. Therefore, in this project we synthesised five compounds for chalcones containing halogens (-Cl, -F) at meta-positions on aromatic rings in chalcones and tested for their anti-inflammatory activity. The synthesized compounds were purified by column chromatography and characterised by 1H-NMR, 13C-NMR, FTIR, Mass and UV spectra. Further evaluation of their in vitro anti-inflammatory activity were carried out using RAW 264.7 mouse macrophages. The test dose of chalcones were determined was cytotoxicity (MTT) assay on RAW264.7 mouse macrophages. The results showed that the halogen substitution at meta-positions on aromatic rings improved the anti-inflammatory activity for the compound (E)-1,3-bis(3-chlorophenyl) prop-2-en-1-one (III) shows the best activity. The table below showed the compounds activity with IC50 values. Keywords: Chalcones, m-chlorobenzaldehyde, m-chloroacetophenone, Ethyl alcohol, Anti-inflammatory activity, RAW 264.7 cells