AMINO-SUGARS. 213 



BERG, in close relationship to many ring systems, such as imidazole, 

 piperazine, pyrazine, pyridine and others, and also to the alkaloids. 



The amino-sugars, like the amino-aldehydes, can also unite, form- 

 ing ring compounds, and this seems to be the case on the decomposi- 

 tion of free glucosamine in aqueous solution, which occurs with access 

 of air (LOBRY DE BRUYN). As found by STOLTE 1 2,5-ditetraoxybutyl 

 pyrazine (= fructosazine) is hereby produced according to the following 

 aquation : 



NH 2 N 



.C CH 



Q 4 H 9 C 4 .CH + CHO O 4 H 9 C 4 . 



I | +0= | || +3H 2 



CHO CH.C 4 H 9 4 HC C,C 4 H 9 4 



/ V 



NH 2 N 



Fructosazine 



The 2,5-ditetraoxybutyl pyrazine, which STOLTE obtained by LOBRY 

 DE BRUYN' s 2 method from levulose in methyl alcohol solution and 

 ammonia, and which he calls /rwctosazine, can be oxidized outside of the 

 body into 2,5-pyrazine dicarboxylic acid. 



The same acid can be formed in the animal body (rabbits), although not 

 constantly, after introducing fructosazine. It also passes into the urine of 

 rabbits after intravenous injection of d-levulose and glycocoll (SPIRO), a behavior 

 which SPIRO claims indicates that carbohydrates in metabolism react with the 

 cleavage products of proteins. STOLTE'S experiments to decide the question 

 whether in the animal body the glucosamine in its decomposition passes into 

 fructosazine did not at first yield conclusive results. His more recent investiga- 

 tions 3 show on the contrary that in rabbits 2-oxymethylpyrazine-5-carboxylic 

 acid is formed as an oxidation product, and this can be oxidized outside of the 

 body into pyrazine-2,5-dicarboxylic acid. 



According to OFFER 4 , pentosamine occurs in the liver of the horse. Accord- 

 ing to OFFER, the pentose derivative, which he calls dipentosamine (C 5 H 7 03.NH 2 )2 + 

 H,O and a second, perhaps a diacetyl-pentosamine 2(CH 3 CO)Ci H 18 N 2 7 (?), also 

 occur in the liver. The first gives pentose reactions and reduces FEHLING'S 

 solution after boiling with acid. The only amino-sugar positively detected in 

 the animal organs is glucosamine. 



CH 2 OH 



, , , ., . N ^ TT A .~ (CH.OH) 3 , whose synthet- 

 d-Glucosamme 5 (chitosamme) , C 6 H 13 ^ 5 , = 



CH.NH 2 



COH 

 leal preparation has already been given on page 197, was first prepared 



1 Hofmeister's Beit rage, 11. 



2 Cited by Stolte, Hofmeister's Beitrage, 11. 



3 Spiro, Hofmeister's Beitrage, 10, p. 283; Stolte, Biochem. Zeitschr., 12. 



4 Hofmeister's Beitrage, 8. 



5 According to E. Fischer's suggestion we shall use the term glucosamine instead 

 of the term chitosamine, which has lately been generally used. 



