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CHOLIC ACID. 423
can be precipitated from the solution of the alkali salts by the addition
of mineral acids, like glycocholic acid (Hammarsten x
).
As repeatedly mentioned above, the two bile-acids split on boiling
with acids or alkalies into non-nitrogenous cholic acids and into glycocoll
or taurine. Of the various cholic acids the following have been best
studied.
Cholic Acid or Cholalic Acid. The ordinary cholic acid obtained as
a decomposition product of human and ox-bile, which occurs, regularly
in the contents of the intestine, and also in the urine in icterus, has, accord-
int to Strecker and nearly all recent investigators, the constitution
f
CHOH
C24H40O5, = C2oH3i j
(CH2 OH)2. According to Mylius,2
cholic acid is a
LCOOH
monobasic alcohol-acid with one secondary and two primary alcohol
groups. Curtius 3 has shown by preparing the cholamine, C23H39O3.NH2,
from the above-mentioned (p. 419) cholic-acid azide, with cholic-acid
urethane as an intermediary step, that the carboxyl group is not imme-
diately connected with the CHOH group, but is combined with the chief
nucleus without the neighboring secondary alcohol group. On oxida-
tion it first yields dehydrocholic acid, C24H34O5 (Hammersten) from
which by electric reduction, Schenck obtained the reducto-dehydro-
cholic acid, C24H36O5. On further oxidation bilianic acid, C24H34OS
(Cleve), is obtained, or, more correctly, according to Latschinoff,
Lassar-Cohn and Pregl, a mixture of bilianic and isobilianic acids
discovered by Latschinoff. On oxidation, bilianic acid yields cilianic
acid (Lassar-Cohn), whose formula, according to Pregl,4 is C20H28O8.
The products formed on a more active oxidation are of great interest.
If we discard the still somewhat problematic cholesterinic acid, we
find in these products in the first place choloidanic acid which has also
been called cholecamphoric acid and has the formula, Cis^sOs, accord-
ing to Pregl. This acid, as well as the acid obtained by Letsche s
on the oxidation of cholic acid and with the formula, C19H28O10, have
been obtained by Pregl 6
from the three most closely studied cholic acids,
1
Zeitschr. f. physiol. Chem., 61.
2
The important researches of Strecker on the bile-acids may be found in Annal. d.
Chem. u. Pharm., 65, 67, and 70; Mylius, Ber. d. deutsch. chem. Gesellsch., 19.
• Ibid., 39.
4
Hammarsten, Ber. d. deutsch. chem. Gesellsch., 14; Schenck, ibid., 63 and 69;
Clevc, Bull. Soc. chim., 35; Latschinoff, Ber. d. d. chem. Gesellsch., 15; Lassar-Cohn,
Ber. d. d. chem. Gesellsch., 32; Pregl, Wein. Sitzungsber., Ill, 1902.
5
Zeitschr. f. physiol. Chem., 61.
6
Ibid., 65.
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