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What is a toxin?
Toxlcon, 1970, Vol . 8, p. 251 . PerQamon Prea+. Printed in Great 9ritain
LETTER TO THE EDITOR WHAT IS A TOXIN? RECENTLY (at the Second International Symposium on Animal and Plant Toxins), the suggestion has been made to restrict the term `toxin' to proteinaceous and antigenic substances. In my opinion this classification would have serious disadvantages. For instance, substances like muscarin-a classical toxin-and tetrodotoxín would not be toxins any more . On the other hand, the difference between eledoisin-a toxin-and bradykinin (a substance endogenous to mammalians) which both are similarly acting peptides would be obscured. To my view the term `toxin' has never been used as a chemical characteristic, with possibly one exception, namely that `true' toxins were meant not to be enzymes. The term has always been used to characterize adverse biological actions. It is certainly not possible to give a perfect and strict definition of a toxin. Besides its nature and actions, its relation to the victim and the aspect of its study are of relevance. I would therefore suggest that substances can be called toxins when the following premises are fulfilled
1 . It should be a substance of natural occurrence (plant, animal, bacteria etc.). 2. It should be foreign to the victim, i.e. human beings . A substance which is endogenous to the victim can be visualized as a toxin if it is applied in toxic doses under nonphysiological conditions (e.g. histamine as contained in wasp venom and applied by a sting) .
3. The compound should be predominantly toxic and adverse to the well-being or life of the victim, or the aspects under which it is investigated or described should deal with its adverse and undesired effects. Thus, when used as a remedy and viewed under therapeutic aspects bee venom should not be called a toxin. Vice versa, when poisoning by digitalis is dealt with digitoxin is the main `toxin' responsible for the poisoning. The significance ofthe aspect under which the substance is viewed results also from (2) above . Max-Planck Institutfür Experimentelle Medizin GSttingen, Cermany
251
W . VOGT
LETTER TO THE EDITOR WHAT IS A TOXIN? RECENTLY (at the Second International Symposium on Animal and Plant Toxins), the suggestion has been made to restrict the term `toxin' to proteinaceous and antigenic substances. In my opinion this classification would have serious disadvantages. For instance, substances like muscarin-a classical toxin-and tetrodotoxín would not be toxins any more . On the other hand, the difference between eledoisin-a toxin-and bradykinin (a substance endogenous to mammalians) which both are similarly acting peptides would be obscured. To my view the term `toxin' has never been used as a chemical characteristic, with possibly one exception, namely that `true' toxins were meant not to be enzymes. The term has always been used to characterize adverse biological actions. It is certainly not possible to give a perfect and strict definition of a toxin. Besides its nature and actions, its relation to the victim and the aspect of its study are of relevance. I would therefore suggest that substances can be called toxins when the following premises are fulfilled
1 . It should be a substance of natural occurrence (plant, animal, bacteria etc.). 2. It should be foreign to the victim, i.e. human beings . A substance which is endogenous to the victim can be visualized as a toxin if it is applied in toxic doses under nonphysiological conditions (e.g. histamine as contained in wasp venom and applied by a sting) .
3. The compound should be predominantly toxic and adverse to the well-being or life of the victim, or the aspects under which it is investigated or described should deal with its adverse and undesired effects. Thus, when used as a remedy and viewed under therapeutic aspects bee venom should not be called a toxin. Vice versa, when poisoning by digitalis is dealt with digitoxin is the main `toxin' responsible for the poisoning. The significance ofthe aspect under which the substance is viewed results also from (2) above . Max-Planck Institutfür Experimentelle Medizin GSttingen, Cermany
251
W . VOGT