D. Complex Poly cyclic Compounds
157
H
Ο
CONMe
MeNH
V
I
CO OH
> K
RO
^ F ° 6
c
MsO kV
A C
F ^ 0
4 a A c
kJ>>>>i>»/*
0 /k/V
N
0 >kpi^
N
v°
v° v°
129
130
131
a: R = Ac
b: R = Ms
4. Cypridina LUCIFERIN
The complexity of the structure of Cypridina luciferin lies primarily in the
accumulation of diverse heterocyclic systems and in its instability rather than
in a high ratio of hetero to carbon atoms as is the case with tetrodotoxin
(111) or saxitoxin (107). The molecule is extended rather than fused and thus
presented fewer difficulties in structural elucidation than might have been
expected of a molecule having a composition of C22H27N7O · 2 HX (Kishi
et al, 1966a).
The intriguing phenomenon of bioluminescence has been observed and
described by naturalists and biologists in a wide variety of organisms ranging
from bacteria to fish for many years. Even now, chemical structures and
detailed mechanisms are known for only very few organisms, one of them
the bioluminescence of the ostracod crustacean Cypridina hilgendorfii, a tiny,
so-called seed shrimp, about 3 mm long, that occurs abundantly along the
coasts of Japan. Although the compound that is responsible for the bioluminescence is referred to as Cypridina luciferin, it is structurally unrelated
to the much better known firefly luciferin (Goto and Kishi, 1968).
Structural studies date from the time when crystalline Cypridina luciferin
was first obtained by Shimomura et al. (1957) as orange-red needles. This was
followed by recognition of a few of the structural parts as e.g., indole and
guanidine that make up the molecule (Hirata et al., 1959). Its bioluminescence
mechanism is considered to be relatively simple since the reaction which
accompanies light emission requires only the enzyme luciferase and oxygen.
The resulting products Cypridina oxyluciferin and C. etioluciferin can also be
produced by reaction with ammonia alone, however without luminescence. It
appears that oxyluciferin is the initial product, which with acid may be
transformed to etioluciferin and 2-keto-3-methylpentanoic acid (132). The
end product etioluciferin is far less sensitive to light and moisture than is C.
luciferin and it was therefore chosen for structural work (Kishi et al., 1966a).
The simplest of the three compounds, C. etioluciferin, has a composition
of Ci 6 H 1 9 N 7 -2 HX. On the basis of spectral data and chemical degradations
157
H
Ο
CONMe
MeNH
V
I
CO OH
> K
RO
^ F ° 6
c
MsO kV
A C
F ^ 0
4 a A c
kJ>>>>i>»/*
0 /k/V
N
0 >kpi^
N
v°
v° v°
129
130
131
a: R = Ac
b: R = Ms
4. Cypridina LUCIFERIN
The complexity of the structure of Cypridina luciferin lies primarily in the
accumulation of diverse heterocyclic systems and in its instability rather than
in a high ratio of hetero to carbon atoms as is the case with tetrodotoxin
(111) or saxitoxin (107). The molecule is extended rather than fused and thus
presented fewer difficulties in structural elucidation than might have been
expected of a molecule having a composition of C22H27N7O · 2 HX (Kishi
et al, 1966a).
The intriguing phenomenon of bioluminescence has been observed and
described by naturalists and biologists in a wide variety of organisms ranging
from bacteria to fish for many years. Even now, chemical structures and
detailed mechanisms are known for only very few organisms, one of them
the bioluminescence of the ostracod crustacean Cypridina hilgendorfii, a tiny,
so-called seed shrimp, about 3 mm long, that occurs abundantly along the
coasts of Japan. Although the compound that is responsible for the bioluminescence is referred to as Cypridina luciferin, it is structurally unrelated
to the much better known firefly luciferin (Goto and Kishi, 1968).
Structural studies date from the time when crystalline Cypridina luciferin
was first obtained by Shimomura et al. (1957) as orange-red needles. This was
followed by recognition of a few of the structural parts as e.g., indole and
guanidine that make up the molecule (Hirata et al., 1959). Its bioluminescence
mechanism is considered to be relatively simple since the reaction which
accompanies light emission requires only the enzyme luciferase and oxygen.
The resulting products Cypridina oxyluciferin and C. etioluciferin can also be
produced by reaction with ammonia alone, however without luminescence. It
appears that oxyluciferin is the initial product, which with acid may be
transformed to etioluciferin and 2-keto-3-methylpentanoic acid (132). The
end product etioluciferin is far less sensitive to light and moisture than is C.
luciferin and it was therefore chosen for structural work (Kishi et al., 1966a).
The simplest of the three compounds, C. etioluciferin, has a composition
of Ci 6 H 1 9 N 7 -2 HX. On the basis of spectral data and chemical degradations