Synthetic Probe Compounds for Bioorganic Studies of Nyctinasty, Based on the Leaf-opening Substance of Lespedeza cuneata G. Don

In a previous paper, the syntheses of potassium galactolespedezate (1) and potassium galactoisolespedezate (2), artificial leaf-opening substances useful for bioorganic studies of nyctinasty were reported. The fluorescent probe compounds, fluorescence-labeled galactoisolespedezate (3) and iodo-one (4), designed on the basis of 1 and 2 were prepared. Especially, compound 3 was bioactive at 5×10−5 M, one-fiftieth as strong as the natural leaf-opening substance. This fluorescent probe would be useful for bioorganic studies of nyctinasty.