The Structure of Cypridina Luciferin

TetrahedronLetters, Ro. 5, pp. 4-9, 1959. Pergsmon Press Ltd. Printed in Great Britain.

TRR STRUCTURE OF CYPRIDINALUCIFEXIN YoshimasaHirata, Osamu Shimomura and Shoji Eguchi Nagoya University,Nagoya, Japan (Received22 April 1959)

CYPRIDINA luoiferinwas obtained crystalline,and preliminaryresults on the constitutionof luciferinusing the crystallinematerial have already been reported.1 Molecular WeiRht and Molecular Formula of CspridinaLuciferin The molecular weight of crystallineluciferinwas estimated to be

470 by various methods; Barer (357), (467),

oxidatlve titrationwith ferrlcyanide

the U. V, absorptionof hydroluoiferin(478),

hydrogenationof

luciferin (498), and analyses of chlorine and nitrogen. The percentageanalysis is as follows: c Found

53.2

Calcd. for C21H2802N66?EC1 53.7

A

N

0

Cl

Ash

6.38

18.86 6.7

16.2

0

6.39

17.91

15.1

o

6.8

M. W,

469

The results from hydrolysisexperimentsand pKal measurementsof luciferindihydrochloridewere also taken into considerationin deducing the molecular formula of C21H2802N6.2HC1.

1 0. Shimomura,T. Goto and Y. Hlrata, Bull. Chem. Sot. Japan z, 929 (1957). 4

The structure

of oyprldina

Deduotion of the Structure

luciferin

5

of E.ydraluoiferin luciferin

When hydrogenated with Adams’ platinum oxide catalyet, absorbed 3 moles of hydrogen and was converted

into a compound whioh

showed an U. V. absorption

the presence of a

group. A positive

&indolethylamlno a-position afforded

speotrum suggesting

of the lndole

Ehrlioh reaction

showed that the

nucleus is free and hydrolysis

of hydroluoiferin

tryptamiue.

Hydroluciferln

thus aontalns the grouping

CH2-CH2-yH The sakrrgrrohl reaction luciferin stituted

and orcyluciferins,

Is positive

for hydroluciferin

as well as for

and this shows the presenoe of a monosub-

guanidlno group whiah in turn is oonfirmed by the irolation

Y-guanidinobutyric

aold by acid hydrolysis

Y-Nanidlnobutyric

said wae produoed only when the hydrolysis

in the presenoe of oxygen(air).

under the presenos of o%ygsn. Thus the Y-guauidluobutyrlc in a peptide linkage;

not contained Isoleuoine

Y-duanfdinobutyrio

aooounts for 21 oarbon atome and 6 nitrogen Partial

hy&olysls

and Ehrlloh reaotloue.

aoid moiety is

Aouordingly hydroluoiferin

acid and leoleuoine.

This

atoms.

with Ba(OS), gave a fraction Extraction

was couduoted

It Is present in a more reduoed state.

was also obtained bf hydrolysis.

is aomposed of tryptmlne,

of

of thir fraotion

with positive and further

niuhydrin

hydrolyrlr

6

The struoture

under the au0 oondltiona

of oypridlna

gave iroleuoine

luoiferin

and trypta8i.n0,

and thum theae

two oomponentr me linked by a peptide bond. In spite

of the poritive

(but weak) ninhydrin naotion,

oontainta no primary amino group from the following (a) afford

After treatment vith 2.4-D.

D. 1. P. lsoleuoine (b)

Bydroluobferin

hydroluolferin

faotrr

H. F. B., hydroluoiferln

did not

by hydrolyrir. did not reaot vith nitrous

sold.

2

OJ /

CH2-CH2+CO-yH-y

II 'Iv H

Attaohment of the Y-guanidino afford

the oyolio

etruoture

R CH; -%Hs

butyrio

aold group to poritions

la favored b;r the following

1 and 2 to

faeta.

CH H CH;'C2H5

c!

The alternative

poeelbillty

of attaohment to position

2 only would give a

ohain structure.

CH2-CI$2-NH-CO-~H-NH-(CH2)4-NH-f-NH2 NH CH

The atruoture

whioh would be rather &able

of cypridina

luoiferin

7

oontraryto the extreme instability

of

hydroluolferln. Hydrolaoiferin

hae pKale at oa. 5.2 and 12.0 (guanidlno group) In

33 $HeOH, The lower pKa* at 5.2 18 only explloable the oyolic

oecondary amino group dth

eeoondary arainee are generally

to It

group. The pKaca of

a WKO

around 9.5.

by assIgning

The Dragendorf reaction

is

poeitiee, Deduction of the Structure It appeara that the skeletal with

of hydroluolferin

is identical

that of luciferin. The WewIts

This

structure

of Luolferin

aud Ehrlich

ahowe that the iudole

the nitrogen

nnoleus on luciferin

or at the a-porition.

detached by catalytic

!Phie property

at

group in luciferin.

curve showe that the pKa$ at 8.3 mat be attributed

derivative

taken in

with the p&%1at 0.3 In 33 $ MeOHi6 moat suitably indole

either

should br easily

since a B-indolethylamine

of luciferin.

for by the presence of a I-hydroxy titration

were negative.

is aubetituted

Thir subetituent

hydrogenation,

waa produced upon hydrogenation oonjunction

(Heubauer-Rhode) reaction

socounted The to the acldio

grcup. A few R-hydroxy indole model compounds showed that the pKa’ of these are of the order of ca, 8.3, into

Ml3 by oatalytic

is further (a)

and that the >N-OH group is converted

hydrogenation

supported by the following

with platinum oxide catalyst. facts:

Aromatio primary amine derivative8

mild hydrolysis

of luoiferin

could not be produced by

with Ba(OH)2; this excluder

the poeeibility

of the preeenoe of a-OH group. (b)

Ferricyanide

oxidation

Thle

of IT-hydroxy indole

compounds gave

The rtruoture

8 oxidation

results

at

moiety is further

for the production

luoiferin

to those obtained with luoiferin.

of luolferin

The A,

the indole

similar

of oypridlna

435pp~ emggemta thatthe

extended as follows

of glyolne

by hydrolysis

ohromophore of

and thir also acoomts

and also for the absorption

of hydrogen.

/I OJ i!iI 1

\

Oxidation of luoiferin aamoula gave oryatalline various

oonditions

lroleuoine These facto oxjluoiferin

with hydrogen peroxide

oxyluolferin

is resumed If oqluoiferin

In the prerenoe of

C, the hydrolysis

produoed no lsoleuolne.

C. The facts

of which under

However, the produotion

C is reduoed prior

suggest the presenoe of au lT(lroleuolne)-oxide

of

to hydrolysis, group In

that seoondwy amino groups are not oonverted

into N-oxide under the oondltion bond is present in lualferin of luciferin)

CH=CH-y

employed and that au additional

(from the molecular fomuls

and hydrogenation

lead to the presenoe of the group I(lroleuoine)-<

thus so the present tentative

struoture

of

CH-i+j-(CH2) O=C, /N YH

3

double

-Fir-I- -NH2 F &I

and

9

The etructure of cyprldina luciferin

The exact position of the double bond in the 4(or

5)-imidasolonering

is not established.It is provisionallyplaced ae shorn from the results of hydrolyeiawhich did not afford any acid like HOOC-CH-Cli-C2B5, and rlao I I OH CE 3 in order to amount for ite rather lpng wavelengthabsorptionmaximum, The guanidine and oxo-diasagroupe are reeponeiblefor the formation of a dihydroohloride,whereas the B-OH group in the indole moiety gives rise to the pKa' at 8.3.