Curcumin, an active biphenolic molecule present in turmeric (Curcuma longa), has been reported to elicit plethora of health protective effects. The present study was carried out in vitro, in vivo and in silico to investigate the modulatory effects of curcumin on erythrocyte membrane Na(+)/K(+)-ATPase activity. In vitro curcumin (10(-) (5) M to 10(-) (8) M) was incubated with human erythrocytes membrane. In vivo curcumin (340 mg/kg b.w. and 170 mg/kg b.w.) was supplemented to wistar rats for 21 days. In silico, catalytic unit α of Na(+)/K(+)-ATPase (3b8e.pdb) protein was used as a receptor for the natural ligand ATP to study curcumin-mediated docking simulation using AutoDock4. The in vitro effect of curcumin on the Na(+)/K(+)-ATPase activity in human erythrocytes was biphasic. An inhibitory response was observed at 10(-) (5) M (p < 0.001). An activation of the Na(+)/K(+)-ATPase activity was observed at 10(-) (7) and 10(-) (8) M (p < 0.001 and p < 0.01). In vivo, curcumin supplementation to rats increased the Na(+)/K(+)-ATPase activity at doses 340 mg/kg b.w. (p < 0.001) as well as at 170 mg/kg b.w., (p < 0.01). AutoDock4 docking simulation study showed that both ligands curcumin and ATP actively interacted with amino acids Glu214, Ser215, Glu216, Thr371, Asn377, Arg378, Met379, Arg438, Val440, Ala444, Lys451 and Asp586 at the catalytic cavity of Na+/K+-ATPase. ATP had more H bonding and hydrophobic interaction with active site amino acid residues compared to curcumin. These finding may explain some of the health beneficial properties of curcumin associated with deregulated Na(+)/K(+)-ATPase activity or ions homeostasis.
Keywords: ATP, Adenosine Tri-Phosphate; CUR, curcumin; Curcumin; Erythrocytes; In silico; Na+/K+ ATPase; RBCs, Red Blood Cells; RMS, root mean square.