Therapeutic Agents on Amylolytic and Proteolytic Action. 63 



Caffein and Thein. 



These two closely related alkaloids were found to have only a 

 slight action on the amylolytic ferment, producing when present in 

 considerable amount a slight diminution in the amount of starch con- 

 verted. With two per cent, of the alkaloids, the following results 

 were obtained : 



Per cent, of Total amount of 



alkaloid. reducing substances. 



0-3620 gram. 



20 CafEein. 0-3342 



0-3664 



0-2 Thein. 03440 



Influence on proteolytic action. 



The influence of the above therapeutic agents on the proteolytic 

 action of pepsin-hydrochloric acid was determined, as in preceding 

 work of this kind,* by ascertaining the amount of fibrin digested or 

 dissolved in a given time, by a definite volume of standard, artificial 

 gastric juice, in the presence of varying amounts of the substances to 

 be tested. The gastric juice was made by dissolving 10 c. c. of a 

 glycerin extract of pepsin in one litre of 0*2 per cent, hydrochloric 

 acid. The volume of each digestive mixture was 50 c. c, composed 

 of 25 c. c. of the above mentioned artificial gastric juice, and 25 c. c. 

 of 0-2 per cent, hydrochloric acid containing the desired amounts of 

 the substances to be tested. The proteid material consisted of puri- 

 fied fibrin, coarsely powdered and dried at 110° C. One gram of 

 fibrin was used in each experiment. The digestive mixtures were 

 warmed at 40° C. for a certain length of time, usually two hours, 



* Studies from the Laboratory of Physiological Chemistry of Yale University, vol?, 

 i and ii. 



