Full resolution (JPEG) - On this page / på denna sida - XI. Brain and Nerves
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
608 BRAIN AND NERVES.
ordinary temperature, and that as shown by Rosenheim and Tebb,
on dissolving in pyridine at 30° C. and heating or cooling the solution
deposits a precipitate of a substance rich in phosphorus. Although we
generally consider the phosphorized component of protagon as lecithin,
still, according to Rosenheim and Tebb, it is probably a diamido-
phosphatide, called sphingomyelin by Thudichum. On boiling protagon
with dilute mineral acids it yields galactose, due to the decomposition
of the cerebrosides.
Protagon appears, when dry, as a loose white powder. It dissolves
in alcohol of 85 vols, per cent at 45° C, but separates on cooling as a
snow-white, flaky precipitate, consisting of globules or groups of fine
crystalline needles. On heating to 150° it becomes yellowish, softens
at 180° and melts sharply at 200° forming a brown, oily liquid (Cramer).
It is difficultly soluble in cold alcohol or ether, but dissolves, at least
when freshly precipitated, in ether on warming. It dissolves in methyl
alcohol containing chloroform and, as above stated, separates cerebron.
Protagon is soluble in pyridine at 30° C, yielding a clear solution, and
this solution has a specific rotation (a) D = +6.9 to 7.7° according to
the concentration of the solution (Wilson and Cramer). On warm-
ing or cooling according to Rosenheim and Tebb, the rotation changes
with the separation of sphingomyelin so that it first diminishes in rota-
tion, then is zero, and then becomes strongly levorotatory until it reaches
— 242°, and finally, when nearly all the sphingomyelin has separated
out it becomes constant at about -13.3°. The strong levorotation
depends upon the accumulations of doubly refracting spheroid crystals
of sphingomyelin. With little water protagon swells up and is partly
decomposed. With more water it forms a jelly or pasty-like mass which,
with the addition of considerable water, forms an opalescent liquid.
Protagon can be prepared in the following way: The finely ground
brain-mass, as free as possible from blood and membrane, is dehydrated,
which is best done by cold acetone or by grinding with burned plaster-of-
paris or anhydrous sodium sulphate, and then extracted with ether.
The mass is then extracted at 45° C. with 85 vol. per cent alcohol until
the filtrate when cooled to 0° C. gives no more precipitate. All the
precipitates obtained on cooling to 0° C. are extracted with ether and
recrystallized from alcohol. Further details can be found in the cited
works of Cramer, Wilson, Gies, Rosenheim and Tebb.
Among the phosphatides occurring in the brain we must mention besides the
lecithin and ccphalin, the following substances.
Myelin, C.,oII 7 :,XPOio, according to Thudichum, is not well known but is char-
acterized by the fact that itfl alcoholic solution is not precipitated by CdCl2 or
PtCl4 . On" the contrary an alcoholic solution of lead acetate gives a precipitate.
The existence of a second monaminomonophosphatide, paramyelin, C38H26NPO9,
according to Thudichum, is very improbable.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
