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

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, H-1 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 5g/mL) and cultured L929 cells (1g/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.