360 SECTIONAL TRANSACTIONS.—B. 
CH Ore GHG Ooo. cea 
| 
du,  d_cH, 
Ne 
CH 
a-Carotene III. 
Partial hydrogenation of the carotenes leads to the di-hydrocarotenes. 
The constitution of lycopene shows a similarity to that of squalen, a hydrocarbon 
derived from shark oil. The synthesis of squalen from farnesylbromide has estab- 
lished for this compound the symmeirical formula IV. 
CH, CH, CH; 
| | | 
(CH;),.0=CH.CH,CH,C=CHCH,CH,C=CH.CH,CH.CH=C.CH.CH,CH 
CH; 
| 
=C CH,CH,CH=C(CHy), 
Squalen IV. 
Vitamin A from cod-liver oil is not identical with carotene. Through saponification 
of the liver oil from Hippoglossus we prepared a residue which, after further purifica- 
tion, gives with antimony trichloride a blue colour reaction which corresponds to 
10,000 C.L.O. units, which is about 130 times as strong as that given by carotene or 
about 10,000 times stronger than natural cod-liver oil. 
Highly active vitamin A preparations give upon ozonization, just like carotene, 
geronic acid. The vitamin A of cod liver oil must therefore contain in its molecule 
the same carbon ring as carotene, and in that sense could be regarded as a derivative 
of carotene. 
Prof. H. von Euter.—Biochemical Experiments with Carotenes and 
Vitamin A. 
In close connection with Prof. Karrer’s preceding paper on the chemistry of 
carotene and carotinoids the author gives a summary of his and Mrs. v. Euler's 
recent results concerning the biological and biochemical effects of the carotenes, 
some carotene-derivates and other growth-promoting factors. 
Since it was established that two forms of carotene exist in plants and that a 
third isomeric carotene can be regenerated from carotene-triiodide, the growth response 
of these three isomers has been determined both on rats and some other animals. 
The increase of weight, produced by different additional daily doses of these carotenes, 
will be shown by curves. 
The transformation of the carotene isomers into other growth-promoting factors, 
related to the ‘ vitamin A’ of the cod-liver oil has been studied. Experiments have 
been made to determine the distribution of the growth-promoting factors in liver 
and in blood-serum of different animals, examined at different ages and under different 
physiological circumstances. 
It is the current view that only one ‘ vitamin A’ is present and acting in the 
animal body. The discovery of the heterogeneous nature of carotene seems to support 
the suggestion that there are several fat soluble factors of the vitamin A type. 
The equilibrium between the carotene isomers, the reduction products of carotene 
and ‘vitamin A’ will be mentioned and discussed in connection with the rdje of 
carotene in plant tissues. 
‘Vitamin A’ concentrates with an extremely high biological activity, giving a 
more than 100 times stronger Carr-Price reaction than carotene, have been obtained 
from animal oils. Some biological and physical properties of these concentrates have 
been measured. : 
[t is known that vitamin D has a growth-promoting effect ;- this effect is influenced 
by the presence of other vitamins and of several salts. 
a 
eee 
