Many constituents of plants elicit pharmacological or toxicological effects in man and animals and may be classified as plant toxins. These are commonly secondary metabolites, i.e. they are produced within the plant besides primary biosynthetic metabolites such as carbohydrates and lipids.
Plant toxins fulfill important functions in living plants, for example function flavanoids as free radical scavengers, terpenoids may attract pollinators and some alkaloids can ward off herbivore animals or insect attacks. One possible way of classifying plant toxins is based on their common chemistry and biochemistry:
- Glycosides (cardiac glycosides, cyanogenic glycosides, glucosinolates and saponins)
- Flavanoids and proanthocyanidins
- Terpenes (mono-, di- and sesquiterpenoids)
- Alkaloids (tropane alkaloids, pyrrolizidine alkaloids, isoquinoline alkaloids and methylxanthine alkaloids)
- Furocoumarines and naphtodianthrones
- Proteins and peptides (e.g. ricin)