Abstract
Attempts to obtain toxic preparations of endotoxin from Pseudomonas aeruginosa (C~2~) were initiated by employing five different extraction procedures which were subsequently assayed for mouse lethality using a variety of routes. The standard methods of extraction were the aqueous phenol, trichloracetic acid, ethylenediaminetetraacetateβlysozyme, ethyl ether, and hot water procedures. The aqueous phenol preparation was found to be the most toxic and exhibited an LD~50~ value of 450 ΞΌg dry weight when administered intravenously and 840 ΞΌg intraperitoneally. No lethality was observed when endotoxin was administered intranasally. The second most lethal preparation was obtained by the trichloroacetic acid extraction and yielded LD~50~ values of 589 ΞΌg intravenously and 947 ΞΌg intraperitoneally. The other three preparations were considerably less lethal. The aqueous phenol and trichloroacetic acid preparation tended to have a higher content of those carbohydrates associated with the core region of the lipopolyssacharide molecule than did the lesser toxic preparations. Some correlation between lethality and lipid content as determined by the alkaline hydroxylamine procedure was also observed.