Anthocyanins as lipoxygenase inhibitors

Health benefits associated with diets rich in anthocyanins are ascribed to multilevel biological activities including antioxidative and anti-inflammatory effects. The present study addresses lipoxygenase inhibition as a mechanism by which anthocyanins may exert health promoting effects. The inhibitory potential of delphinidin (Dp), cyanidin (Cy), peonidin (Pn), and malvidin (Mv) glycosides, i.e., 3-O-glucosides, 3-O-galactosides, and 3-O-arabinosides as well as their aglycons was analyzed by using soybean lipoxygenase-1 and human neutrophil granulocyte 5-lipoxygenase. The determined IC(50) values comprised a wide range, i.e., from the sub-microM level until practically no effect of inhibition (Mv and its glycosides). With IC(50) values of 0.43 and 0.49 microM Dp 3-O-glucoside (Dp3glc) and Dp 3-O-galactoside (Dp3gal) were found to be the most effective soybean lipoxygenase-1 inhibitors; their strong inhibitory potential was also reflected by the IC(50) values determined for these anthocyanins in the 5-lipoxygenase inhibition exhibiting 2.15 and 6.9 microM, respectively. As to the mechanism of inhibition, experiments carried out with lipoxygenase-1 revealed the uncompetitive type. Considering the powerful inhibitory properties of Dp glycosides in relation to their currently known availability in human metabolism, in vivo prevention of inflammatory diseases by these anthocyanins could be envisaged.