DIHYDROKAEMPFEROL GLUCOSIDE FROM COTYLEDONS PROMOTES FLOWERING IN PHARBITIS-NIL

An extract of cotyledons of Pharbitis nil, which had been exposed to s hort-day conditions, was tested for flower-promoting activity in a sho ot-tip assay system in vitro. The crude extract had no flower-promotin g activity, however, after partitioning of the crude extract with dich loromethane, the resulting aqueous fraction had flower-promoting activ ity. This activity was separated into two fractions by column chromato graphy on Toyopearl HW-40. One active fraction was identified as dihyd rokaempferol-7-O-beta-D-glucoside (DHK-glc). This compound exhibited f lower-promoting activity at the extremely low concentration of 4.4 x 1 0(-9) M.