A bioelectrochemical approach based on a solid supported membrane to evaluate the effect of natural products on Ca2+-ATPase: The case of 6-gingerol

The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) plays an essential role in maintaining the low cytosolic Ca2+ level that enables a variety of cellular processes. SERCA couples ATP hydrolysis to the transport of two Ca2+ ions against their electrochemical potential gradient from the cytoplasm into the lumen of the sarco/endoplasmic reticulum (SR/ER). Because of its central role in regulating cytoplasmic Ca2+ concentration, SERCA dysfunction has been associated with several pathological conditions. Stimulation of SERCA activity may represent a po-tential therapeutic strategy in various disease states connected with dysfunctional SERCA. The natural phenolic compound 6-gingerol, the most abundant and the major biologically active compound of ginger, was reported to activate the SERCA enzyme. The present study aimed at investigating the effect of 6-gingerol on SERCA transport activity using a bioelectrochemical approach based on a solid supported membrane (SSM). We first performed a voltammetric characterization of 6-gingerol to better understand its electrochemical behavior. We then studied the interaction of 6-gingerol with SR vesicles containing SERCA adsorbed on the SSM electrode. The measured current signals indicated that ATP-dependent Ca2+ translocation by SERCA was remarkably increased in the presence of 6-gingerol at low micromolar concentration. We also found that 6-gingerol has a rather high affinity for SERCA (EC50 of 1.8 +/- 0.3 mu M), and SERCA activation by 6-gingerol is reversible. The observed stimulatory effect of 6-gingerol on SERCA Ca2+-translocating activity may be beneficial in the prevention and/or treatment of pathological conditions related to SERCA dysfunction.