glycoalkaloid

Glycoalkaloids are a class of naturally occurring organ nitrogen compounds that consist of a steroidal alkaloid aglycone bound to one or more sugar molecules. They occur mainly in the nightshade family (Solanaceae), including potato, tomato, eggplant, and related species, where they serve as chemical defenses against herbivores and pathogens. In humans, consuming high amounts can cause toxicity, ranging from gastrointestinal upset to more severe neurologic symptoms.

Chemically, the glycoalkaloid structure features a hydrophobic steroidal base linked to sugar residues. The aglycone portion is typically a solanidine- or tomatine-type skeleton, while the sugar chains commonly include glucose, galactose, and/or rhamnose. The most familiar examples are alpha-solanine and alpha-chaconine in potatoes, and alpha-tomatine and dehydrotomatine in tomatoes; eggplants contain solasonine and solamargine. Levels vary among plant parts and developmental stages, with higher concentrations often found in skins, sprouts, and green or damaged tissues.

Biosynthesis derives from cholesterol through a series of enzymatic steps that generate the steroidal alkaloid core, followed by glycosylation to form the glycoalkaloid. Environmental factors such as light exposure, wounding, stress, and storage conditions can influence accumulation in edible tissues.

Safety and regulation: glycoalkaloids disrupt cell membranes by associating with cholesterol, which can lead to fluid imbalance and cell damage. Symptoms of poisoning include nausea, vomiting, abdominal pain, dizziness, and, in severe cases, neurological effects. Regulatory guidance typically sets limits for total glycoalkaloids in susceptible foods (for example, potatoes) to minimize risk, and processing methods such as peeling and thorough cooking can reduce levels, though not always eliminate them. Detection and quantification are commonly performed by chromatographic methods such as HPLC or LC-MS.