Antioxidant, antimutagenic and antibacterial activities of curcumin-β-diglucoside

Curcumin, the yellow colour constituent of turmeric, has several important biological activities but its use as a food colourant is restricted due to its insolubility in water. Curcumin-β-diglucoside (III), prepared by glycosylation of curcumin (I) at the phenolic hydroxyl group, was soluble in water at 10 mg/ml concentration. Studies of the radical-scavenging, as well as antioxidant properties, of III at different concentrations showed that these activities were higher than that of I. The mutagenicity studies showed that I, as well as III, afforded high protection against the mutagenicity of sodium azide to Salmonella typhimurium TA 1531 and TA 98. Also, III exhibited higher antibacterial properties against Staphylococcus aureus and Escherichia coli but showed lower activity against Bacillus cereus and Yersinia enterocolitica than did I. The results clearly demonstrate that conjugation of the phenolic hydroxyl group of curcumin to a sugar moiety rendered it water-soluble whilst retaining/enhancing its in vitro antioxidant, antimutagenic and antibacterial properties.