Ketolytic action of various sugars in vitro.

Abstract

The results here summarized represent a continuation of the study of the in vitro reactions between sugars and acetoacetic acid discovered in 1921 by Shaffer 1 and are believed to afford an explanation of antiketogenesis. 2

The reactions of aldehydes and sugars were studied under two conditions: (1) “non-oxidative” and (2) “oxidative”.

“non-oxidative reaction.”

Simple aldehydes such as formaldehyde, 3 acetaldehyde, glyoxylic acid, glyoxal, 4 and glyoxal carbonic acid reacted readily with potassium acetoacetate at pH 8.0 (in the absence of any oxidizing agent). Under the same conditions only simple aldoses reacted. Thus glycol aldehyde and glyceric aldehyde reacted with acetoacetate. Dihydroxy acetone did not react and in this respect it acted like other ketones such as pyruvic acid and acetone. However, when the solution of dihydroxy acetone was made strongly alkaline it reacted as readily as glyceric aldehyde, showing that rearrangement of the inert ketone form are necessary before reaction may occur. The more complex sugars, the pentoses and hexoses, did not react in non-oxidative neutral media, but they became reactive in strongly alkaline solutions, 5 the alkali perhaps opening the ring and producing the free aldehyde form of sugar which latter form is active in a manner similar to glycol- and glycer-aldehydes.