Structures and Biological Activities of Some Toxic Natural Products

Concerning the relation of chemical structures and physiological activities, there are cases in which similar physiological actions are observed among compounds of similar structures, whilst, in contrast, some cases are known in which slight changes of the structure of compounds result in the remarkable alteration or complete loss of their physiological activities. A typical example of the latter case is toxicity, as illus— trated with many compounds, for example, neurotoins such as tetrodotoxin, saxitoxin and batrachotoxin, and convulsants, such as anisatin, dendrobine, picrotoxinine. With these toxic compounds it will be almost impossible to find a general and clear relationship between chemical structures and toxicity.