1. Various esters of betaine have, unlike betaine itself, a marked physiological action (chiefly a muscarine action). The toxicity and physiological action of the methyl, ethyl and n-butyl esters diminish with increasing molecular weight.
The esters also have "nicotine" actions but these are not pronounced.
2. The amide of betaine is physiologically active ("muscarine" and "nicotine" actions) but this action is much less intense than that of some of the esters.
3. The substitution of a hydrogen atom in the methylene group of betaine ester by an alkyl group led to a diminution of toxicity and of the muscarine action, the diminution of the muscarine action increasing with increasing molecular weight. The introduction of a phenyl group practically abolished the intense "muscarine" action of the ester. These compounds had a weak stimulating nicotine action and a more pronounced paralyzing nicotine action.
4. Triethylphosphonium compounds analogous to betaine ethyl ester and to choline and to acetyl-choline did not have a "muscarine" action but had a marked paralyzing but no stimulating nicotine action.