is known about the bioavailability, pharmacokinetics and metabolism of the glycoalkaloids in humans. One important factor is the poor uptake of tomatine into general blood circulation. When tomatine is orally ingested, much tomatine may form complexes with cholesterol from the other food present in the stomach. The complexes of tomatine and cholesterol are not absorbed in the intestine, but are excreted. For the complexation with cholesterol to occur, the presence of a carbohydrate chain is essential. The aglycon tomatidine, which is tomatine without the sugars, does not form the complexes. The complexation probably occurs in the duodenum, because the acidic conditions in the stomach itself lead to protonation of the tomatine, and the protonated form of tomatine does not bind to cholesterol. Hydrolysis of tomatine likely takes place, but whether it is acid- or glycosidase-catalyzed is not known. The hydroxylation of tomatine likely leads to the formation of tomatidine, which is the aglycon of tomatine. Tomatidine is a metabolite which may not be completely nontoxic; it could have effects on the human body. Fungal tomatinase enzymes can transform tomatine to deactivate it. Detoxification can take place by removing one glucose residue. Other fungal species hydrolyze tomatine to the less toxic aglycon tomatidine by removing all the sugar residues. Tomatidine can still inhibit some fungal species, but is less toxic than tomatine. Fungi use diverse pathways for the hydrolysis of tomatine. Also, the level of toxicity depends on the type of fungus. The metabolite tomatidine can be hydrolyzed further by membrane-bound CYP-450 oxygenases. Uses Tomatine has been used as a reagent in analytical chemistry for precipitating cholesterol from solution. Also, tomatine is known to be an immune adjuvant in connection with certain protein antigens. Toxicity The possible risks of tomatine for humans have not been formally studied, so no NOAEL can be deduced. The toxicity of tomatine has only been studied on laboratory animals. The symptoms of acute tomatine poisoning in animals are similar to the symptoms of poisoning by solanine, a potato glycoalkaloid. These symptoms include vomiting, diarrhea, abdominal pain, drowsiness, confusion, weakness, and depression. Generally, tomatine is regarded to cause less toxic effects to mammals than other alkaloids such as solanine. The human consumption of moderate amounts of tomatine seems to occur without notable toxic effects. This is reinforced by the widespread consumption of “pickled green” and “fried green tomatoes” and the consumption of high-tomatine tomatoes (a variant of