Anti-inflammatory activities of selected synthetic homoisoflavanones

Abstract

Four homoisoflavanones of the 3-benzylidene-4-chromanone type, some of which were previously isolated from Caesalpinia pulcherrima, were synthesised to determine their anti-inflammatory activity and cytotoxicity. A range of four different homoisoflavanones (compounds 4a–4d) were synthesised from the corresponding substituted phenols.¹H- and ¹³C-NMR data together with high-resolution mass spectroscopy data were employed to elucidate the structures. Anti-inflammatory activity was determined in mice with acute croton oil-induced auricular dermatitis. In vitro cytotoxicity was tested against a Chinese hamster ovarian cell line using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay. Compound 4a exhibited a tendency to inhibit oedema in a dose-dependent manner after 3 and 6 h of treatment. Compounds 4b–4d also inhibited oedema, although a clear dose-response relationship was not observed. Compounds 4a–4c were found to be less cytotoxic than compound 4d. Compound 4b was the least cytotoxic. Compounds 4a–4d exhibited anti-inflammatory activity and varying levels of cytotoxicity.

Keywords:

• homoisoflavanones
• Caesalpinia pulcherrima
• synthesis
• anti-inflammatory
• cytotoxicity

Acknowledgements

The authors acknowledge the University of KwaZulu-Natal Competitive Research Fund and Rolexsi (Pty) Ltd for financial support, as well as Ms Sithabile Buthelezi and Mr Dennis Ndwandwe for experimental assistance.