66 P-AMINOBENZOIC ACID 



on T. equiperdum. No such effect could be demonstrated with the corres- 

 ponding free acids. 



The observations reported by Sandground on the protective action of 

 PABA against the toxicity of arsenicals have been supplemented by anal- 

 ogous findings with respect to the detoxication of other organo-metallic 

 substances. Sandground'^ extended his studies to the antimonial, "stibosan" 



CH3CONH— <. ^— SbOsHNa 



"Stibosan" 



and found PABA to afford a high order of protection against the toxic 

 action in rats of this drug, without a reduction of its trypanocidal potency. 

 Hardcastle and Foster''^ found that PABA appears to have promise as a 

 detoxicant for borax. Voss and Tatum'^ have reported that PABA exerts a 

 protective action in rats against lethal doses of sodium bismuthyl citrate, 

 mannonate, or tartrate. Similar findings have been published by Sala and 

 Borasi^^ concerning the detoxication by PABA of both organic and in- 

 organic mercury compounds. 



XIII. Sulfonamide Reversal 



LEMUEL D. WRIGHT AND PETER A. TAVORMINA 



The advent of the sulfonamides (1935-1940) stimulated considerable 

 research into the mechanism of action of these highly useful chemothera- 

 peutic agents. Lockwood in 1938 showed' that sulfonamide activity in 

 vitro can be reversed by peptone. Heat-killed bacterial cells or their extracts 

 were shown by Stamp^ to reverse sulfonamide action. He showed also 

 that the sulfonamide-neutralizing activity of such bacterial extracts is 

 stable to heat, acid, and alkali. MacLeod^ confirmed the antisulfonamide 

 activity of peptone and tissue extracts. He further demonstrated that the 

 production of sulfonamide-neutralizing material by the pneumococcus is 

 markedly increased as the organism becomes resistant to sulfonamides. 



16 J. H. Sandground, Proc. Soc. Expll. Biol. Med. 52, 188 (1943). 

 " A. B. Hardcastle and A. O. Foster, Proc. Helminthol. Soc. Wash., D. C. 11, 60 

 (1944). 



18 E. Voss and A. L. Tatum, J. Pharmacol. Exptl. Therap. 90, 101 (1947). 



19 G. Sala and M. Borasi, Atti soc. lomharda sci. med. e biol. 3, 70 (1948) [C. A. 45, 

 3946 (1951)]. 



1 J. S. Lockwood, J. Immunol. 35, 155 (1938). 



2 T. C. Stamp, Lancet II, 10 (1939). 



3 C. M. MacLeod, J. Exptl. Med. 72, 217 (1940). 



