This section will discuss toxicants that are derived from coumarin compounds in plants. It yields the toxicant dicoumarol when exposed to specific molds. Furocoumarins are toxic compounds that consist of a coumarin nucleus bonded to a furan ring.
Several plants contain the psoralens that are generally the precursors of furocoumarins.
When sweet clover is put up as hay it is easy for it to be contaminated with molds because of its succulent stems. This is particularly likely when conditions are wet at cutting or curing or when foliage is lush. Molds such as Penicillium nigricans , P.jensi , and the Aspergillus metabolize the coumarin into dicoumarol . When consumed by livestock it inhibits vitamin K production. Vitamin K is necessary in the body to activate prothrombin.