α-Isolupanine

A quinolizidine alkaloid found in lupins, one of the bitter, toxic secondary metabolites that protect the plant from herbivores but limit the use of lupin seeds as food. Like other lupin alkaloids it causes bitterness and, at high doses, neurological symptoms, which is why lupins for human consumption must come from sweet, low-alkaloid varieties and why traditional debittering by soaking and washing remains important for bitter landraces. Breeders select for low total alkaloid content, and food regulations set maximum levels for lupin products. Its presence is the central safety consideration in the growing use of lupin flour as a high-protein, gluten-free ingredient, and processors verify alkaloid levels in every batch.