In his publication Grete Herball, he considered tomatoes poisonous due to their levels of what would later be called tomatine, plus high acid content.

[7][better source needed] In 1837, the first medicinal tomato pills were advertised in the United States because of their positive effects upon the biliary organs.

[13] At first it was thought that the synthesis of steroidal alkaloids only involved multiple steps of hydroxylation, oxidation and amination of cholesterol with arginine as the source of the incorporated nitrogen.

[12] These genes produce the glycoalkaloid metabolism enzymes, which are responsible for the synthesis of steroidal alkaloid aglycones in potato and tomato plants.

Tomatine may play a major role in resistance of the tomato plant against fungal, microbial, insect, and herbivoral attack.

[citation needed] The effects of the glycoalkaloids (to which tomatine belongs), can be divided in two main parts: the disruption of cellular membranes and the inhibition of the enzyme acetylcholinesterase.

[15][16] The membrane disruptive properties of tomatine are caused by the ability to form 1:1 complexes with cholesterol.

[14][15] The majority of synthetic pesticides used in agriculture work by inhibition of acetylcholinesterase to kill insects.

Other fungal species hydrolyze tomatine to the less toxic aglycon tomatidine by removing all the sugar residues.

These symptoms include vomiting, diarrhea, abdominal pain, drowsiness, confusion, weakness, and depression.

[23] Generally, tomatine is regarded to cause less toxic effects to mammals than other alkaloids such as solanine.

[24] The human consumption of moderate amounts of tomatine seems to occur without notable toxic effects.

cerasiforme, better known as the "cherry tomato", indigenous to Peru) with very high tomatine content (in the range of 500–5000 μg/kg of dry weight).

[25] New York Times food science writer Harold McGee found scant evidence for tomato toxicity in the medical and veterinary literature, and observed that dried tomato leaves (which contain higher concentrations of alkaloids than the fruits) are occasionally used as a food flavoring or garnish, without problems.

He also reported that an adult human would probably have to eat over half a kilogram of tomato leaves to ingest a toxic (not necessarily lethal) dose.