ALKALOIDS 



251 



The alkaloids have been known for many years and have been of interest mostly 

 because of their physiological effects on man and their use in pharmacy. Some of the 

 pharmacological effects of alkaloids are tabulated below: 



PHYSIOLOGICAL 

 ACTION 



emetic 



local anesthetic 



antihemorrhagic 



antispasmodic 



narcotic 



vermifuge 



aphrodisiac 



tranquilizer 



cardiac depressant 



diaphoretic 



muscle paralysant 



nervous stimulant 



ALKALOID 

 emetine 

 cocaine 

 hydrastine 



hyoscyamine, atropine 

 morphine 

 pelletierine 

 yohimbine 

 reserpine 

 quinine 

 pilocarpine 

 tubocurarine 

 strychnine 



PLANT SOURCE 

 ipecacuanha 

 coca 



hydrastis 

 belladonna 

 opium poppy 

 pomegranate 

 Pausinystalia yohimba 

 Rauwolfia serpentina 

 Cinchona spp. 

 Pilocarpus pennatifolius 

 Chundudendron spp. 

 Strychnos niix-vomica 



This listing provides only a sketchy illustration of some alkaloid effects. Many alkaloids 

 have more than one type of action, depending for instance on the dose level. 



The function of alkaloids in plants is almost completely obscure although many sug- 

 gestions have been made. Some of these follow: 



1. One of the earliest suggestions was that alkaloids function as nitrogen waste 

 products like urea and uric acid in animals. 



2. Some alkaloids may serve as nitrogen storage reservoirs although many seem 

 to accumulate and are not farther metabolized even in severe nitrogen starva- 

 tion. 



3. In some cases alkaloids may protect the plant against attack by parasites or 

 herbivores. Although evidence favoring this function has been brought forward 

 in some instances, it is probably an overworked and anthropocentric concept. 

 Many alkaloids poisonous to man have no effect on other (and more significant) 

 enemies of the plants. 



4. Alkaloids may serve as growth regulators since structures of some of them 

 resemble structures of known growth regulators. More specifically, certain 

 plant hormones may act by virtue of their chelating ability, and some alkaloids 

 may also possess chelating ability. Maisuryan (1) has shown that lupine alka- 

 loids may act as germination inhibitors and Jacquiot (2) has shown that alkaloids 

 may remove the inhibitory effect of tannins on growth of plant tissue cultures. 



5. It was originally suggested by Liebig that the alkaloids being mostly basic might 

 serve in the plant to replace mineral bases in maintaining ionic balance. In 



