sentences:  The compounds are biosynthesized partly through the phenylpropanoid pathway and the mevalonate pathway, which is biosynthesized by a coupling of dimethylallyl pyrophosphate (DMAPP) and 7-hydroxycoumarin (umbelliferone).Many furanocoumarin compounds are toxic.The phytochemicals enter the nucleus of epithelial cells and form a bond with the DNA, which causes the cells to die.