 The fungus contains a cyclopropylglutamine compound called coprine . Its active metabolite , 1 @-@ aminocyclopropanol , blocks the action of an enzyme , acetaldehyde dehydrogenase , which breaks down acetaldehyde in the body . Acetaldehyde is an intermediate metabolite of ethanol and is responsible for most symptoms of a hangover ; its effect on autonomic β receptors is responsible for the vasomotor symptoms . 
