Effects of selected flavonoids on deformability, osmotic fragility and aggregation of human erythrocytes.

The effects of 8 selected flavonoids of deformability, osmotic fragility and dextran-induced aggregation of human erythrocytes were studied. The following flavonoids were found to protect against loss of filterability (deformability) through 5 microns diameter pores of erythrocytes dehydrated with calcium ionophore A23187 (1.9 mumol/l): apigenin > quercetin > cirsimaritin > rutin > luteolin > chrysoeriol-4'-O-glucoside > 3,5,7-trihydroxy 4'-methoxy flavone 7-rutinoside, whereas beta-naphtho flavone enhanced the loss of filterability. When the potassium ionophore valinomycin (18 mumol/l) was used to induce cell dehydration, the order of potency of the flavonoids in protecting against loss of filterability was apigenin > cirsimaritin = chrysoeriol-4'-O-glucoside > 3,5,7-trihydroxy 4'-methoxy flavone 7-rutinoside > luteolin = rutin > quercetin, whereas beta-naphtho flavone again enhanced the loss of filterability. All flavonoids reduced ESR measured over 1 h except for 3,5,7-trihydroxy 4'-methoxy flavone 7-rutinoside which showed no effect, and for quercetin which significantly enhanced ESR. All flavonoids also improved erythrocyte osmotic fragility except for apigenin which significantly increased osmotic fragility. These effects were explained in terms of the number and location of hydroxyl groups on the basic skeleton of flavone. The results suggest that the presence of an OH and C5 is essential for the described rheological effects of these flavonoids.