The Mode of Inhibitory Action of α-Mangostin, a Novel Inhibitor, on the Sarcoplasmic Reticulum Ca²⁺-Pumping ATPase from Rabbit Skeletal Muscle

Abstract

α-Mangostin, the principal ingredient of the fruit hull of Garcinia mangostana, caused a concentration-dependent decrease in the activities of both Ca²⁺-ATPase and Ca²⁺-transport of the sarcoplasmic reticulum from rabbit skeletal muscle with an IC₅₀ value of 5 μM. Neither Ca²⁺ release nor other enzyme activities were affected by α-mangostin. Kinetic analysis of the inhibitory effects of α-mangostin on Ca²⁺-ATPase suggests that the inhibition of the ATPase is a noncompetitive-type with respect to ATP or Ca²⁺. α-Mangostin may become a useful pharmacological tool for clarifying the physiological functions of Ca²⁺-pumping ATPase and sarcoplasmic reticulum.