Synthesis, characterization, and antitumour studies of some curcuminoid analogues and their aluminum complexes

Abstract

Aluminum(III) complexes of three curcuminoid analogues [1,7-diphenyl-1,6-heptadiene-3,5-dione, HL¹; 1,7-bis(2-hydroxyphenyl)-1,6-heptadiene-3,5-dione, HL²; and 1,7-bis(4-ethoxyphenyl)-1,6-heptadiene-3,5-dione, HL³] of [AlL₃] stoichiometry were synthesized and characterized by UV, IR, ¹H NMR, and mass spectral data. The compounds were investigated for cytotoxic and antitumor activities. The aluminum chelates are remarkably active compared to free curcuminoid analogues. The aluminum complex of HL² with hydroxyl in the phenyl ring was most active towards Ehrlich ascites carcinoma cells (concentration needed for 50% inhibition of 5 μg/mL) and cultured L929 cells (1 μg/mL produced 60 + 3% cell death). Increase in lifespan and reduction of solid tumor volume in mice were also largest for the aluminum complex of HL². The study reveals that the antitumor activities of curcuminoids are more enhanced by complexation with aluminum than with transition metal ions.

Keywords:

• Curcuminoids
• Aluminum complexes
• Cytotoxic and antitumor activities
• Spectral studies

Acknowledgments

The authors are grateful to Dr Girija Kuttan and the Director of the Amala Cancer Research Centre, Thrissur, Kerala, India, for their help in the antitumor studies.