446 YOUNGKEN, JR. 



ward Strasburger. The chemotherapeutic age in medicine was given great 

 exploitation in 1935, when the Nobel Prize winner Domagk discovered the 

 chemotherapy of prontosil, the forerunner of the synthetic sulfa drugs. Mod- 

 ern therapeutics such as the sulfa drugs, barbiturates, synthetic quartenary 

 ammonium salts, local anesthetics, and several antihistaminics all originated 

 as the result of the development in chemical structure-activity relationships. 



This does not mean, of course, that specific chemical configuration can 

 be entirely reliable in predicting drug action. Indeed, much evidence to the 

 contrary is available. For example, there are many instances among com- 

 pounds which affect the central nervous system (nitrous oxide and ethyl 

 ether) and others (the antibiotics) where such relationships do not hold 

 true. But certainly investigations of plant, animal, and synthetic medicinals 

 and their structural-pharmacological relationships have led the modern ad- 

 vance in new pharmacotherapeutics, and most likely this approach will con- 

 tinue to lead the way. 



Reinvestigation of plants for medicine. With a modern advance in 

 synthetic medicinal organic chemistry there has developed recently a very 

 keen interest in the re-investigation of the constituents biosynthesized by 

 plants and animals. Again botany has become a tool of medicine through the 

 .';"■, need to properly select plants for new drugs. Research in this phase has in- 

 creased more during the last decade, because of success with the antibiotics 

 and plant drugs such as rauwolfia, than at any time during the previous period 

 of the 20th century. It has also brought medical scientists into closer con- 

 tact with botanical experts in taxonomy, anatomy, and plant biochemistry. 

 Such investigations have been prompted by three general interests: (1) the 

 search for plant constituents responsible for a biological activity, the latter 

 implied by the use of a crude drug in folklore, foreign or domestic empirical 

 medicine; (2) the search for newer therapeutically active chemical derivatives 

 of natural compounds, especially those compounds which have already been 

 well established; and (3) the investigation of the biochemical and physiologi- 

 cal role played by plant and animal constituents in the organisms producing 

 them. Indeed, investigations in each of these interests are sometimes inter- 

 related, and a discovery in one pursuit might very well open the way for 

 fruitful discoveries in other closely related interests. Modern research ob- 

 serves no boundaries either in its pure or applied aspects. The discussion that 

 follows will deal largely with the first two of these interests. 



1. The search for plant constituents. Antibiotics. It has been stated 

 that the most recent stimulus leading to the investigation of plants for bio- 

 logically active compounds began about two decades ago in the early 1930s. 

 It may be recalled that this was the period when Fleming, Florey, and 

 Chain described the antibiotic properties of extracts from the blue-green mold 

 Penicillium. From these observations came the antibiotic crystalline penicillin. 

 But lest we become too smug in our beliefs that the use of antibiotics from 



