glycoalkaloid

450px|thumb|right|Chemical structure of α-solanine distinguishing the sugar (solatriose moiety) and the alkaloid ([[solanidine moiety) portions]] Glycoalkaloids are a family of chemical compounds derived from alkaloids to which sugar groups are appended. Most have a bitter taste and confer some protection against plant pathogens and herbivores. Several are potentially toxic to humans, most notably the poisons commonly found in the plant species Solanum dulcamara (bittersweet nightshade) and other plants in the genus Solanum, including potato. Some are antinutritional factors. They are an example of chemical defense in plants.

A prototypical glycoalkaloid is solanine (composed of the sugar solanose and the alkaloid solanidine), which is found in the potato. The alkaloidal portion of the glycoalkaloid is also generically referred to as an aglycone. The intact glycoalkaloid is poorly absorbed from the gastrointestinal tract, therefore causing gastrointestinal irritation. The aglycone is absorbed and is believed to be responsible for observed nervous system signs.