[Problem] The present invention addresses the problem of providing a novel compound. The present invention also addresses the problem of providing an OCT3 detection agent or an OCT3 activity inhibitor, which comprises the novel compound. [Solution] A compound represented by formula (A), a pharmaceutically acceptable salt thereof, or a pharmaceutically acceptable solvate thereof. €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒR 1 -R 2 -R 3 -R 4 €ƒ€ƒ€ƒ€ƒ€ƒ(A)