Glucobrassicin cancer drug. Computer model of a molecule of the breast cancer drug glucobrassicin. This chemical, thought to be effective against breast cancer, is found in high levels in the woad plant (Isatis tinctoria). The molecule's chemical formula is C16.H20.N2.O9.S2. The atoms are shown as colour-coded spheres in this space-filled model: carbon (light blue), hydrogen (gold), nitrogen (dark blue), oxygen (red), and sulphur (yellow).