Abstract
In the course of the investigation of the effects of various snake venoms on lipolytic action controls were run to determine whether any of the observed effects might be due to the decreased surface tension caused by the venoms. Two of the agents so employed were “purified” saponin, Merck, and Hoffman-LaRoche digitonin. The following communication is a report on the rather interesting observation that the former markedly inhibits the activity of pancreatic lipase but inhibits the lipase activity of blood only slightly, while digitonin in very low concentrations increases the lipolytic action of pancreatic lipase and has little or no effect on blood lipase action. That the activity in each case seems to be due to some factor apart from the effect on surface tension is indicated by the fact that both of these reagents are very powerful surface tension depressants. The inability of both to show the same marked effects on blood lipase seems to indicate that they are inactivated or removed by some constituent in blood serum. It is likely that the serum cholesterol combines with the saponin or the digitonin to form a very slightly soluble digitonide, thus removing the inhibiting or stimulating factor.
Lipolytic activity was determined by the method of Sure, et al., 1 with olive oil as the substrate and gum arabic, U.S.P., as the protective colloid. The enzymes employed were serum from fresh defibrinated horse blood, Eimer & Amend Lipase “pure”, and Difco steapsin. The saponin solution contained 5 mg./cc.; lipase, 2.5 mg./cc.; steapsin, 2.5 mg./cc.; digitonin solution prepared according to the method of Schoenheimer and Sperry, 2 1.4 mg./cc. The amount of lipolytic action was determined after 24 hours at 37° by titration with N/100 NaOH in alcoholic solution, using phenol-phthalein as an indicator.
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