Semisynthetic derivatives of pyrrolizidine alkaloids of pharmacodynamic importance: a review.

Pyrrolizidine alkaloids occur in more than 40 genera. Among these are two important genera, Senecio and Crotalaria, which have been responsible for heavy losses of livestock and poisoning in man due to their hepatotoxicity. Pyrrolizidine alkaloids are also reported to possess a number of other biological activities. Attempts have been made to convert the pyrrolizidine alkaloids to new structures by synthetic modifications. One hundred and twenty semisynthetic compounds were developed and investigated pharmacologically. The range of activity exhibited was hypotensive, local anesthetic, ganglion blocking, neuromuscular blocking and antispasmodic. The five most promising compounds of these series were subjected to detailed pharmacological investigations.