Effects of Derivatives of Hydroxypyruvaldehyde Phenylosazone on the Ca2+-Adenosine Triphosphatase Activity of Porcine Erythrocyte Membrane

Thirteen derivatives of hydroxypyruvaldehyde phenylosazone were tested for their effects on the Ca2+-adenosine triphosphatase (ATPase) activity of porcine erythrocyte membranes. Seven drugs including hydroxypyruvaldehyde phenylosazone itself and the m-CH3, p-CH3, o-Cl, p-Cl, 3, 4-di-Cl and p-Br derivatives, inhibited Ca2+-ATPase activity, while other derivatives such as o-CH3, 2, 4-di-Cl, 2, 5-di-Cl, o-NO2, m-NO2 and p-NO2 derivatives were essentially without effect. Hydroxypyruvaldehyde p-chlorophenylosazone was the most potent inhibitor, inhibiting the enzyme activity completely at 1 mM, whereas carbonylcyanide m-chlorophenylhydrazone, a typical inhibitor of Ca2+-ATPase, inhibited the activity by 85% at the same concentration.