4. SPECIES DIFFERENCES IN BILE SALTS
223
information about microbial artifacts is now available, and this has
done much to clarify the position of some biliary constituents. It is
considered below.
B. EVOLUTION OF BILE SALTS
It seems abundantly clear that evolution of bile salts has taken
place. The subject has been briefly reviewed (11), and it will suffice
here to point out that the stages seem to be similar to some of those
occurring in a modern vertebrate in the route cholesterol —» bile salts
(48,48a). Cholesterol is probably converted to (A/B eis) primary alcohols with molecules containing additional «-orientated hydroxyl groups in
the "bile salt" positions; such alcohols are found, conjugated with sulfate
and functioning as bile salts, in Selachii, Teleostei, and Amphibia. Next,
the C-27 terminal primary alcoholic group (e.g., structure II) is oxidized to produce hydroxylated coprostanic acids (e.g., Ill) and such
are found (conjugated with taurine) in Amphibia and more "primitive"
reptiles. Side-chain ^-oxidation
. . . CH 2 · CH, ' CH(CH 3 )COOH
or (e.g.)
. . . CH 2 · CHOH · CH(CH 2 OH) 2
24
!
24
!
gives the C 24 bile acids commonly found in all "modern" vertebrates.
Glycine conjugates of the C 24 acids are perhaps still more modern, being
found only in mammals and possibly only in the Eutheria,
No information, for example about the relative physiological efficiency of the different types of bile salts, is available at present to
provide material for speculation as to the selection pressures or other
forces which may have caused this type of evolution. It appears to have
gone part passu with "modernization" in most orders, and might be
expected to lead to the presence in all surviving vertebrates of the C 24
acids or their evolutionary successors.
a Names of Japanese fishes will be found in catalogues from Tokyo (119).
6 Ohta's acid (allo(5a)cholic acid); see text (Section I,B,3).
c May be an artifact, derived from A
4 -7a-hydrox3^-3-oxocholenic acid.
d Not confirmed, as an individual substance, by later work.
e The seals, sea lions, and walruses are grouped in the suborder Pinnipedia.
Πη a review (1) this animal, described originally (109) as Eumetopia tubata was
incorrectly listed as a fish.
0 The bile was reported to yield also "α-phocaecholic acid" (what is here called
"phocaecholic acid" being designated "ß-phocaecholic acid"). Recent work on the "a"
acid of Hammarsten (110) has shown that it contains 3a,7«,12a,23-tetrahydroxycholanic
acid and also allocholic acid (82, 33).
h Probably not bile acids in the sense used here.
223
information about microbial artifacts is now available, and this has
done much to clarify the position of some biliary constituents. It is
considered below.
B. EVOLUTION OF BILE SALTS
It seems abundantly clear that evolution of bile salts has taken
place. The subject has been briefly reviewed (11), and it will suffice
here to point out that the stages seem to be similar to some of those
occurring in a modern vertebrate in the route cholesterol —» bile salts
(48,48a). Cholesterol is probably converted to (A/B eis) primary alcohols with molecules containing additional «-orientated hydroxyl groups in
the "bile salt" positions; such alcohols are found, conjugated with sulfate
and functioning as bile salts, in Selachii, Teleostei, and Amphibia. Next,
the C-27 terminal primary alcoholic group (e.g., structure II) is oxidized to produce hydroxylated coprostanic acids (e.g., Ill) and such
are found (conjugated with taurine) in Amphibia and more "primitive"
reptiles. Side-chain ^-oxidation
. . . CH 2 · CH, ' CH(CH 3 )COOH
or (e.g.)
. . . CH 2 · CHOH · CH(CH 2 OH) 2
24
!
24
!
gives the C 24 bile acids commonly found in all "modern" vertebrates.
Glycine conjugates of the C 24 acids are perhaps still more modern, being
found only in mammals and possibly only in the Eutheria,
No information, for example about the relative physiological efficiency of the different types of bile salts, is available at present to
provide material for speculation as to the selection pressures or other
forces which may have caused this type of evolution. It appears to have
gone part passu with "modernization" in most orders, and might be
expected to lead to the presence in all surviving vertebrates of the C 24
acids or their evolutionary successors.
a Names of Japanese fishes will be found in catalogues from Tokyo (119).
6 Ohta's acid (allo(5a)cholic acid); see text (Section I,B,3).
c May be an artifact, derived from A
4 -7a-hydrox3^-3-oxocholenic acid.
d Not confirmed, as an individual substance, by later work.
e The seals, sea lions, and walruses are grouped in the suborder Pinnipedia.
Πη a review (1) this animal, described originally (109) as Eumetopia tubata was
incorrectly listed as a fish.
0 The bile was reported to yield also "α-phocaecholic acid" (what is here called
"phocaecholic acid" being designated "ß-phocaecholic acid"). Recent work on the "a"
acid of Hammarsten (110) has shown that it contains 3a,7«,12a,23-tetrahydroxycholanic
acid and also allocholic acid (82, 33).
h Probably not bile acids in the sense used here.