Leaf-opening substance of Mimosa pudica L.; Chemical studies on the other leaf movement of mimosa

We have isolated mimopudine (1) as a leaf-opening substance of mimosa that keeps the leaves open even at night. 1 was quite effective for leaf- opening of Mimosa pudica L. at 2 x 10^-5 M at night, but not effective for other nyctinastic plants even at 1 x 10^-2 M. Interestingly, the leaves kept open at night with 1 were sensitive to stimulus by touch. This result suggests that 1 is effective only for the obstruction of slow nyctinastic leaf-closing movement, but not effective for the rapid thigmonastic movement. Therefore, the slow nyctinastic movement of mimosa is controlled by a different mechanism from that of the rapid thigmonastic movement.