The stimulant effect of the plant was originally attributed to "katin", cathine, a phenethylamine-type substance isolated from the plant. However, the attribution was disputed by reports showing the plant extracts from fresh leaves contained another substance more behaviourally active than cathine. In 1975, the related alkaloid cathinone was isolated, and its absolute configuration was established in 1978. Cathinone is not very stable and breaks down to produce cathine and norephedrine. These chemicals belong to the PPA (phenylpropanolamine) family, a subset of the phenethylamines related to amphetamines and the catecholamines epinephrine and norepinephrine. In fact, cathinone and cathine have a very similar molecular structure to amphetamine. Khat is sometimes confused with methcathinone (also known as "cat"), a Schedule I substance that possesses a similar chemical structure to the khat plant's cathinone active component. However, both the side effects and the addictive properties of methcathinone are much stronger than those associated with khat use.