Leaf-movement factors of nyctinastic plant, Phyllanthus urinaria L.; The universal mechanism for the regulation of nyctinastic leaf-movement

Phyllanthurinolactone (1) and phyllurine (2) were isolated from Phyllanthus urinaria L. as bioactive substances for nyctinasty. Compound 1 was quite e ffective for leaf-closing of the plant at 1 x 10(-7) M in the daytime and 2 was quite effective for the leaf-opening at 2.5 x 10(-5) M, whereas both 1 and 2 were not effective for other nyctinastic plants even at 1 x 10(-4) M . The concentration of 1 increased before leaf-closure in the plant body, w hereas that of 2 was constant through a day. Thus, the leaf-movement of P. urinaria L, is proposed to be controlled by the change in the balance of co ncentration between 1 and 2, which is regulated by a beta-glucosidase, simi lar to the case of Lespedeza cuneata G. Don. (C) 1999 Elsevier Science Ltd. All rights reserved.