Action of Opium Alkaloids on Trypanosoma brucei. 27 



Experiments in vitro revealed as in the case of paramecia that 

 the papaverin group of opium alkaloids was very toxic for try- 

 panosomes. Papaverin itself in dilutions of 1 to 10,000 markedly 

 inhibited the movements of the organisms in a few minutes and 

 killed them completely within thirty minutes. Similarly the al- 

 kaloids narcotin and narcein were also found to be very toxic for 

 trypanosomes in vitro. 



Contrary to expectations however the morphin group of alka- 

 loids while not as toxic as papaverin was also found to be dele- 

 terious to the trypanosomes, but in a much lesser degree. Dilu- 

 tions of morphin sulphate 1 to 2,000 did not kill the organisms 

 within an hour but were found to inhibit slightly their movements 

 after the lapse of some ten minutes. Stronger solutions of mor- 

 phin, for example 1 to 2,000, inhibited the movements and killed 

 the parasites in less than half an hour. A similar action was 

 noted in cases of codein and thebain. Heroin was found to be 

 more toxic than morphin and killed the organisms in about fifteen 

 minutes. 



A comparative study of various alkaloids in addition to those 

 already mentioned, namely, benzyl morphin or peronin, cotarnin, 

 hydrastin, hydrastinin, and others seemed to point as in the case 

 of paramecia to the benzyl grouping as the toxophoric portion of 

 the papaverin molecule. 



Having studied the effect of papaverin on trypanosomes in 

 vitro some experiments were made on infected rats to ascertain 

 whether that alkaloid could be employed in curing the infection 

 with trypanosomes in vivo. It was found that small doses of 

 papaverin had no effect in shortening the course of the disease 

 when injected into rats. Neither were small doses of benzyl ben- 

 zoate or benzyl alcohol efficient in this respect. These findings 

 were not at all surprising as it is well known that experimental 

 results with anti-syphilitic drugs in vitro can not at all be taken 

 as an index to the clinical use of the same. 



