A<unk>  is a harmful substance produced within living cells or organisms; synthetic<unk> ants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919) and is derived from the word<unk> .<unk> s can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors.<unk> s vary greatly in their<unk> ity, ranging from usually minor (such as a bee sting) to potentially fatal even at extremely low doses (such as botulinum<unk> .<unk> s are largely secondary metabolites, which are organic compounds that are not directly involved in an organism's growth, development, or reproduction, instead often aiding it in matters of defense.
Toxin
Eoxin
Chlorotoxin
Neurotoxin
Toxicophore
Dinotoxin
Agitoxin
Insect toxin