From the pollen of sunflower (Helianthus annuus L.), the biologically active substances in the rice lamina inclination test were extracted and partially purified. They were converted to bis-9-phenanthreneboronates and bismethaneboronates, and analyzed by fluorescence HPLC and GC/MS analytical methods, respectively. The active principles were identified as brassinolide, castasterone and norcastasterone (brassinone).
