Nakinadines B-F: new pyridine alkaloids with a β-amino acid moiety from sponge Amphimedon sp.

Article abstract of DOI:10.1016/j.tet.2008.01.111

Five new 3-alkylpyridine alkaloids with a β-amino acid moiety, nakinadines B-F (1-5), have been isolated from an Okinawan marine sponge Amphimedon sp. (SS-1059), and the structures and stereochemistry were elucidated by spectroscopic data. Nakinadines B (1) and C (2) showed modest cytotoxicity.

Full text of DOI:10.1016/j.tet.2008.01.111

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 3127e3132
www.elsevier.com/locate/tet
Nakinadines BeF: new pyridine alkaloids with a b-amino acid
moiety from sponge Amphimedon sp.
Takami Nishi a, Takaaki Kubota a, Jane Fromont b, Takuma Sasaki c, Jun’ichi Kobayashi a,
*
a Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
b Western Australian Museum, Locked Bag 49, Welshpool DC, WA 6986, Australia
c School of Pharmacy, Aichi Gakuin University, 2-11 Semori-dori, Chikusa-ku, Nagoya 464-865, Japan
Received 17 November 2007; received in revised form 28 January 2008; accepted 29 January 2008
Available online 2 February 2008
Abstract
Five new 3-alkylpyridine alkaloids with a b-amino acid moiety, nakinadines BeF (1e5), have been isolated from an Okinawan marine
sponge Amphimedon sp. (SS-1059), and the structures and stereochemistry were elucidated by spectroscopic data. Nakinadines B (1) and C
(2) showed modest cytotoxicity.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Sponge; Alkaloid; Pyridine; b-Amino acid; Nakinadines BeF
1. Introduction
2. Results and discussion
Marine sponges are a rich source of bioactive secondary
metabolites with unprecedented skeletons. A number of 3-al-
kylpyridine alkaloids have been isolated from marine sponges
of several genera.1 Most of them possess a long aliphatic chain
with a various nitrogen-containing terminus,2 some of which
have dimeric or polymeric structures of 3-alkylpyridine.3 Dur-
ing our continuing search for bioactive substances from ma-
rine sponges,4 we previously isolated cytotoxic pyridine
alkaloids from sponges of the genera Theonella,5 Nyphates,6
Amphimedon,7 and Cribrochalina.8 More recently, new 3-al-
kylpyridine alkaloids with a b-amino acid moiety, nakinadines
BeF (1e5), have been isolated together with nakinadine A4
(6) from an Okinawan marine sponge Amphimedon sp. (SS-
1059). Here we describe the isolation and structural elucida-
tion of nakinadines BeF (1e5).
The sponge Amphimedon sp. (SS-1059) collected off Naki-
jin, Okinawa was extracted with MeOH. EtOAc-soluble mate-
rials of the MeOH extract were subjected to a silica gel
column (CHCl3/MeOH), in which a fraction eluted with
CHCl3/MeOH (7:3) was purified by C18 HPLC (MeOH/
H2O) to afford nakinadines B (1, 0.004%, wet weight) and
C (2, 0.005%). The fraction eluted with CHCl3/MeOH (9:1)
in the silica gel column was further purified by an amino silica
gel column (CHCl3/MeOH) followed by C18 HPLC (MeOH/
H2O) to afford nakinadines D (3, 0.001%, wet weight), E (4,
0.002%), and F (5, 0.001%) together with nakinadine A4 (6,
0.001%).
Nakinadine B (1) was revealed to have the molecular for-
mula, C27H40N2O2, by HRESIMS [m/z 423.2998 (MꢀH)ꢀ, D
ꢀ0.3 mmu]. Aromatic proton signals [H-2 and H-6, dH 8.43;
H-4, dH 7.48; H-5, dH 7.18; H-25 and H-29, dH 7.33 (2H); H-
26 and H-28, dH 7.26 (2H); H-27, dH 7.20] in the 1H NMR spec-
trum and five sp2 carbon signals (C-2, dC 149.8; C-3, dC 138.4;
C-4, dC 135.8; C-5, dC 123.2; C-6, dC 147.1) and four sp2 carbon
signals (C-24, dC 135.9; C-25 and C-29, dC 128.7 (2C); C-26 and
C-28, dC 128.2 (2C); C-27, dC 127.3) in the 13C NMR spectrum
* Corresponding author. Tel.: þ81 11 706 3239; fax: þ81 11 706 4989.
E-mail address: jkobay@pharm.hokudai.ac.jp (J. Kobayashi).
0040-4020/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.01.111

3128
T. Nishi et al. / Tetrahedron 64 (2008) 3127e3132
27
23
S
HOOC
19
24
25
22
21
7
N
3
H
6
N
1
1
2
3
4
5
28
26
24
S
HOOC
23
20
9
22
7
N
3
6
H
1
N
22
H
HOOC
23
21
6
1
18 20
N
3
7
N
7'
7'
18'
3'
3'
H
H
6'
1'
N
27
23
H
HOOC
24
22
21
19
7
N
3
18'
H H
6'
6
1
1'
N
N
28
27
24
H
HOOC
25
23
22
9
20
9'
9'
7'
7
N
3
19'
3'
H
6'
1'
H
6
1
N
N
23
H
HOOC
24
22
21
19
7
7'
N
3
3'
19'
6'
1'
H
H
6
N
1
N
6
Stereochemistries for 3-6 denote relative one.
suggested that 1 possessed a 3-alkylpyridine ring and a phenyl
group. The 13C NMR data disclosed the presence of a carbonyl
carbon (dC 176.6). IR absorptions at 3400e2600 and 1733 cmꢀ1
indicated the presence of carboxylic acid functionality. The 1H
and 13C NMR data suggested that CH2-19 (dH 2.89 (2H); dC
47.9) and CH2-21 (dH 3.47 and 2.89; dC 51.1) were adjacent to
a nitrogen atom.
peaks for H-22 to C-23 and C-25, and H-29 to C-24
indicated that a carboxyl and a phenyl group were both attached
to C-22.
The connection of C-8 to C-18 via a long alkyl chain was elu-
cidated on the basis of fragmentation patterns of the ESIMS/MS
spectrum of 1 (Fig. 2). Thus, the gross structure of nakinadine B
was elucidated to be 1.
The gross structure of 1 was elucidated by analyses of 2D
NMR data in CDCl3 (Fig. 1). The 1He1H COSY and TOCSY
spectra revealed connectivities of five structural fragments,
a (C-2 to C-6), b (C-7 to C-8), c (C-18 to C-19), d (C-21 to C-
22), and e (C-25 to C-29). HMBC correlations from H-7 to C-
2, C-3, and C-4 suggested the connectivity of C-7 to C-3. The
connectivity of C-19 to C-21 through a nitrogen atom was im-
plied by HMBC cross-peaks for H2-19 to C-21. HMBC cross-
To assign the absolute configuration at C-22, the carboxy
group at C-22 in 1 was convertedintothe (S)- and (R)-phenylgly-
cine methyl ester (PGME) amides. The Dd [d (S-PGME
amide)ꢀd (R-PGME amide)] values obtained from the 1H
NMR spectra of the PGME amides suggested that the absolute
configuration at C-22 in 1 was S (Fig. 3).9
22
HOOC
29
24
27
120 148 176 204 232 260
m/z 93(+H)
23
e
HOOC
c
22
18
8
25
7
b
N
H
d
19
21
N
H
289
3
18
a
8
6
N
N
1
m/z 106 134 162 190 218
246 275
1
1H-1H COSY & TOCSY
HMBC
1
Figure 2. Fragmentation patterns of nakinadine B (1) in ESIMS/MS [parent
ion; at m/z 425 (MþH)þ].
Figure 1. Selected 2D NMR correlations for nakinadine B (1).

T. Nishi et al. / Tetrahedron 64 (2008) 3127e3132
3129
-0.004
-0.004
COOH
-0.005
-0.004
O
3
3
HN
21
CH2
18'
JH-20/H-21 = 2 Hz
S
PGME
22
21
20
-0.004
+0.023
JH-21/C-18' = 8 Hz
H
H
Ph
N
H
+0.015
H
NOESY
H
Figure 3. Dd values [Dd (in ppm) dSꢀdR] obtained for (S)- and (R)-PGME
amides of nakinadine B (1).
Figure 7. Rotation model for C-20 to C-21 of nakinadine D (3).
Nakinadine C (2) was revealed to have the molecular for-
mula, C28H40N2O2, by HRESIMS [m/z 437.3163 (MþH)þ, D
Nakinadine D (3) was revealed to have the molecular for-
mula, C43H65N3O2, by HRESIMS [m/z 656.5179 (MþH)þ,
1
ꢀ0.6 mmu]. H and 13C NMR data of 2 were similar to those
1
D þ2.4 mmu]. H and 13C NMR data of 3 were similar to
of nakinadine B (1), except for the presence of signals due to
a double bond in 2. Z-Geometry of an olefin at C-9 was assigned
from chemical shifts of allylic carbons [C-8, dC 28.7; C-11, dC
26.7].10 The 1He1H COSY, TOCSY, and HMBC spectra
revealed connectivities from a b-substituted pyridine ring to
C-12 and C-19 to C-30 (Fig. 4). The fragmentation patterns ob-
tained from ESIMS/MS spectrum of 2 disclosed connectivities
from C-12 to C-19 (Fig. 5). The Dd values obtained from the
1H NMR spectra of the PGME amides of 2 showed the same pat-
tern as those of 1, suggesting that the absolute configuration at
C-23 of 2 was S. Thus, the stereostructure of nakinadine C
was elucidated to be 2.
those of nakinadine A (6), except for lack of signals due to
a double bond in 6. Analysis of the ESIMS/MS spectrum of
3 revealed connectivities from two pyridine rings to b-amino
acid moiety (Fig. 6). Thus, the gross structure of nakinadine
D was assigned as 3.
The relative stereochemistry of 3 was deduced from NO-
ESY correlations and J-values11 as shown in Figure 7. A
gauche relation for H-20 and H-21 was deduced from the NO-
3
ESY cross-peak for H-20/H-21 and JH-20/H-21 (2 Hz). The
NOESY cross-peaks for H-20/H-24 and H-20/H-25 suggested
a gauche relation for H-20 and a phenyl group. A large cou-
pling constant (3JH-21/C-18 ¼8 Hz), which was obtained from
0
the HETLOC spectrum of 3, indicated an anti relation for
H-21 and C-180 (Fig. 7).
30
25
28
24
HOOC
23
26
The spectral data of nakinadine E (4) were almost identical
with those of nakinadine D (3), except for the molecular weight
derived from ESIMS [m/z 670 (MþH)þ]. The molecular for-
mula of 4, C44H67N3O2, revealed by HRESIMS [m/z 670.5315
(MþH)þ, D þ0.3 mmu] suggested that the carbon chain of 4
was longer by one methylene unit as compared with that of 3.
The fragmentation patterns obtained from ESIMS/MS data of
4 (Fig. 8) also supported the proposed structure of nakinadine
E (4). The relative stereochemistry at C-21 and C-22 of 4 was
elucidated to be the same as those of 3 on the basis of NOESY
correlations (H-21 to H-22, H-25, and H-26) and J-values
9
7
12
20
22
N
H
3
19
6
1
N
1H-1H COSY & TOCSY
HMBC
2
Figure 4. Selected 2D NMR correlations for nakinadine C (2).
25
HOOC
272
m/z 93(+H)
132 160 188 216 244
(3JH-21/H-22¼2 Hz and 3JH-22/C-18 ¼8 Hz) of 4. Thus, the struc-
19
0
12
N
H
301
ture of nakinadine E was elucidated to be 4.
The spectral data of nakinadine F (5) were similar to those
of nakinadine A (6). The molecular formula, C46H67N3O2,
N
m/z 106
146 174 202 230
258 287
2
revealed from HRESIMS [m/z 694.5313 (MþH)þ,
D
Figure 5. Fragmentation patterns of nakinadine C (2) in ESIMS/MS [parent
ion; at m/z 437 (MþH)þ].
1
þ0.2 mmu] and the H and 13C NMR spectra indicated that
A
26
28
22
21
HOOC
23
6
24
1
3
7
18'
N
N
18
N
20
7'
m/z 520
3'
6'
H
1'
N
m/z 273 246
134 162 190 218 246 273 301 329 357 385 413
B
m/z 106
N
N
120 148 176 204 232
287 315 343 371 399 427
m/z 93(+H)
m/z 261(+H) 260(+H)
3
Figure 6. Fragmentation patterns of nakinadine D (3) in ESIMS/MS [parent ion; (A) at m/z 656 (MþH)þ, (B) at m/z 520 (MꢀC8H9O2þH)þ].

3130
T. Nishi et al. / Tetrahedron 64 (2008) 3127e3132
27
29
23
22
HOOC
24
25
18'
7
19
N
21
7'
m/z 534
3
3'
6'
H
6
N
1'
1
N
m/z 287 246
m/z 93(+H)
273
315 343 371 399 427
120 148 176 204 232 260
N
N
N
m/z 106 134 162 190 218
246
301 329 357 385 413 441
260(+H)
m/z 275(+H)
4
Figure 8. Fragmentation patterns of nakinadine E (4) in ESIMS/MS [parent ion; (A) at m/z 670 (MþH)þ, (B) at m/z 534 (MꢀC8H9O2þH)þ].
28
30
24
23
HOOC
25
26
19'
7
22
7'
20
N
H
m/z 558
3
3'
6'
N
6
1'
1
N
m/z 299 258
132 160 188 216 244
m/z 93(+H)
272285
327 355 383 411
449
N
N
N
m/z 106
146 174 202 230
258
313 341 369 397 423
463
m/z 287(+H) 272(+H)
5
Figure 9. Fragmentation patterns of nakinadine F (5) in ESIMS/MS [parent ion; (A) at m/z 694 (MþH)þ, (B) at m/z 558 (MꢀC8H9O2þH)þ].
the carbon chain of 5 was shorter by one methylene unit as
compared with that of 6, and 5 had two Z double bonds. Anal-
ysis of the ESIMS/MS spectrum of 5 revealed connectivities
from two pyridine rings to b-amino acid moiety including po-
sition of two double bonds (Fig. 9). The relative stereochem-
istry of a b-amino acid moiety in 5 was elucidated to be the
same as those of 3 on the basis of NOESY correlations (H-
references for 1H and 13C NMR spectra, respectively. ESI
mass spectra were obtained on
spectrometer.
a JEOL JMS-700TZ
3.2. Sponge description
The sponge Amphimedon sp. (SS-1059; order Haplosclerida;
family Niphatidae) was collected off Nakijin, Okinawa and kept
frozen until used. The sponge is thick walled tube with a dense
internal skeleton. Specimen has a central oscule and canal.
Sponge has a reticulate fiber skeleton, close meshed, centrally
cored with spicules. Primary meshes are slightly elongate. Pri-
mary fibers are multispicular, approximately 60 mm wide cored
by approximately 5 spicules. Secondary fibers are occasionally
unispicular, 40 mm wide cored by 1e2 spicules. Spicules are
oxeas, 105ꢁ5 mm. Exterior surface is smooth, shiny.
22 to H-23, H-26, and H-27) and J-values (3JH-22/H-23¼2 Hz
3
0
and JH-23/C-19 ¼8 Hz) of 5. Thus, the structure of nakinadine
F was assigned as 5.
Nakinadines B (1) and C (2) showed cytotoxicity against
L1210 murine leukemia (IC50, 3.0 and 5.0 mg/mL, respectively)
and KB human epidermoid carcinoma cells (IC50, 7.0 and
>10 mg/mL, respectively) in vitro, while nakinadines D (3), E
(4), and F (5) did not show such activity (IC50>10 mg/mL).
3. Experimental
3.3. Extraction and isolation
3.1. General
The sponge (SS-1059, 0.2 kg, wet weight) was extracted with
MeOH (1.0 Lꢁ3), and the extract was partitioned between
EtOAc and H2O. The EtOAc-soluble materials were subjected
to a silica gel column (CHCl3/MeOH, 10:0 to 0:10) to give alka-
loidal fractions. The fraction eluted with CHCl3/MeOH (7:1)
was purified by reversed-phase HPLC (Luna 5u phenylehexyl,
IR and UV spectra were recorded on a JASCO FT/IR-230 and
a Shimadzu UV-1600PC spectropolarimeters. 1H and 13C NMR
spectra were recorded on a Bruker AMX-600 spectrometer
using 2.5 mm micro cells (Shigemi Co., Ltd). The 7.26 and
77.0 ppm resonances of residual CDCl3 were used as internal

T. Nishi et al. / Tetrahedron 64 (2008) 3127e3132
3131
250ꢁ10 mm; eluent, MeOH/H2O, 85:15; flow rate, 1.5 mL/min;
UV detection at 263 nm) to afford nakinadines B (1, 0.0037%
wet weight, tR 19 min) and C (2, 0.0045%, tR 21 min). The frac-
tion eluted with CHCl3/MeOH (9:1) was separated by an amino
silica gel column chromatography (CHCl3/MeOH, 10:0 to 0:10)
followed by reversed-phase HPLC (Luna 5u phenylehexyl,
250ꢁ10 mm; eluent, MeOH/H2O, 89:11; flow rate, 1.0 mL/
min; UV detection at 263 nm) to afford nakinadines D (3,
0.0011%, tR 12 min), E (4, 0.0022%, tR 15 min), F (5,
0.0022%, tR 18 min), and A (6, 0.0011%, tR 12 min).
J¼7.1 and 6.7 Hz), 1.61 (2H, br s), 1.0e1.4 (14H, m); 13C
NMR (CDCl3) d 176.7 (s), 149.9 (d), 147.2 (d), 137.3 (s),
135.8 (s), 135.8 (d), 131.4 (d), 128.7 (2C, d), 128.2 (2C, d),
127.7 (d), 127.3 (d), 123.2 (d), 51.1 (t), 50.8 (d), 47.9 (t), 33.0
(t), 29e30 (7C, t), 28.7 (t), 27.2 (t), 26.7 (t); ESIMS (neg.) m/z
437 (MþH)þ; HRESIMS (pos.) m/z 437.3163 (MþH)þ,
D ꢀ0.6 mmu.
3.3.5. (S)-PGME amide of nakinadine C (2)
The (S)-PGME amide of 2 (0.4 mg) was obtained from 2
(1.0 mg) according to the same procedure as described for the
preparation of (S)-PGME amide of 1. (S)-PGME amide of naki-
3.3.1. Nakinadine B (1)
Colorless oil; UV (MeOH) lmax 257 (3 3100), 263 (3300),
and 270 (2900) nm; IR (film) nmax 3360, 3190, 2910, and
1
nadine C (2); colorless amorphous solid; H NMR (CDCl3)
d 8.42 (2H, m), 7.85 (NH, d), 7.47 (m), 7.36 (5H, m), 7.31
(2H, m), 7.29 (2H, m), 7.24 (m), 7.18 (m), 5.53 (m), 5.34 (2H,
m), 3.79 (m), 3.69 (3H, s), 3.24 (m), 2.95 (3H, m), 2.61 (2H,
m), 2.31 (2H, m), 1.95 (2H, m), 1.0e1.8 (16H, m); ESIMS
(pos.) m/z 584 (MþH)þ.
1
1733 cmꢀ1; H NMR (CDCl3) d 8.43 (2H, m), 7.48 (m), 7.33
(2H, m), 7.26 (2H, m), 7.20 (m), 7.18 (m), 4.10 (br s), 3.47 (br
s), 2.89 (3H, br s), 2.59 (2H, m), 1.60 (2H, m), 1.0e1.4 (20H,
m); 13C NMR (CDCl3) d 176.6 (s), 149.8 (d), 147.1 (d), 138.4
(s), 135.9 (s), 135.8 (d), 128.7 (2C, d), 128.2 (2C, d), 127.3
(d), 123.2 (d), 51.1 (t), 50.8 (d), 47.9 (t), 33.0 (d), 29e30
(11C, t), 26.8 (t); ESIMS (neg.) m/z 423 (MꢀH)ꢀ; HRESIMS
(neg.) m/z 423.2998 (MꢀH)ꢀ, D ꢀ0.3 mmu.
3.3.6. (R)-PGME amide of nakinadine C (2)
The (R)-PGME amide of 1 (0.5 mg) was obtained from 2
(1.0 mg) according to the same procedure as described for the
preparation of (S)-PGME amide of 1. (R)-PGME amide of naki-
3.3.2. (S)-PGME amide of nakinadine B (1)
1
To an ice cooled DMF solution (1 mL) of 1 (1.0 mg) and
(S)-PGME (1.0 mg) were added PyBOPÒ (benzotriazole-1-yl-
oxytrispyrrolidinephosphoniumhexafluorophosfate) (2.0 mg),
HOBt (1-hydroxybenzotriazole) (1.0 mg), and N-methylmor-
pholine (50 mL), and stirring was continued at rt for 18 h. After
addition of 5% HCl, the mixture was extracted with EtOAc
(2.5 mL). The extract was washed with satd NaHCO3 aq and
brine, and then concentrated invacuo. The residuewas subjected
to a silica gel column (CHCl3/MeOH, 10:0 to 0:10) to give the
(S)-PGME amide of 1 (0.6 mg). (S)-PGME amide of nakinadine
B (1); colorless amorphous solid; 1H NMR (CDCl3) d 8.42 (2H,
m), 7.85 (NH, d), 7.47 (m), 7.36 (5H, m), 7.31 (2H, m), 7.29 (2H,
m), 7.24 (m), 7.18 (m), 5.50 (m), 3.79 (m), 3.66 (3H, s), 3.24 (m),
2.95 (3H, m), 2.58 (2H, m), 1.0e1.8 (22H, m); ESIMS (pos.) m/z
572 (MþH)þ.
nadine C (2); colorless amorphous solid; H NMR (CDCl3)
d 8.42 (2H, m), 7.85 (NH, d), 7.47 (m), 7.34 (5H, m), 7.32
(2H, m), 7.29 (2H, m), 7.24 (m), 7.18 (m), 5.54 (m), 5.34 (2H,
m), 3.76 (m), 3.66 (3H, s), 3.21 (m), 2.94 (3H, m), 2.61 (2H,
m), 2.31 (2H, m), 1.95 (2H, m), 1.0e1.8 (16H, m); ESIMS
(pos.) m/z 584 (MþH)þ.
3.3.7. Nakinadine D (3)
Colorless oil; UV (MeOH) lmax 258 (3 4700), 263 (5000),
and 270 (4400) nm; IR (film) nmax 3200, 2853, and
1
1725 cmꢀ1; H NMR (CDCl3) d 8.44 (4H, m), 7.49 (2H, m),
7.32 (4H, m), 7.20 (2H, m), 7.19 (m), 3.84 (br s), 2.98 (br s),
2.82 (m), 2.72 (m), 2.60 (4H, t, J¼7.8 and 7.5 Hz), 1.1e1.7
(42H, m); 13C NMR (CDCl3) d 176.0 (s), 149.6 (2C, d), 146.8
(2C, d), 136.9 (2C, s), 135.8 (s), 135.5 (2C, d), 129.4 (2C, d),
128.2 (2C, d), 127.0 (d), 122.9 (2C, d), 59.5 (d), 51.9 (d), 44.9
(t), 32.7 (2C, t), 30.8 (2C, t), 28e30 (17C, t), 26.9 (t), 26.6 (t);
ESIMS (pos.) m/z 656 (MþH)þ; HRESIMS (pos.) m/z
656.5179 (MþH)þ, D þ2.4 mmu.
3.3.3. (R)-PGME amide of nakinadine B (1)
The (R)-PGME amide of 1 (0.5 mg) was obtained from 1
(1.0 mg) according to the same procedure as described for the
preparation of (S)-PGME amide of 1. (R)-PGME amide of naki-
1
nadine B (1); colorless amorphous solid; H NMR (CDCl3)
d 8.42 (2H, m), 7.85 (NH, d), 7.47 (m), 7.34 (5H, m), 7.32
(2H, m), 7.29 (2H, m), 7.24 (m), 7.18 (m), 5.51 (m), 3.76 (m),
3.66 (3H, s), 3.21 (m), 2.94 (3H, m), 2.58 (2H, m), 1.0e1.8
(22H, m); ESIMS (pos.) m/z 572 (MþH)þ.
3.3.8. Nakinadine E (4)
Colorless oil; UV (MeOH) lmax 259 (3 4900), 263 (5100),
and 269 (4500) nm; IR (film) nmax 3200, 2853, and
1
1725 cmꢀ1; H NMR (CDCl3) d 8.41 (4H, m), 7.50 (2H, m),
7.33 (4H, m), 7.21 (2H, m), 7.20 (m), 3.87 (br s), 3.05 (br s),
2.85 (m), 2.72 (m), 2.61 (4H, m), 1.0e1.8 (44H, m); 13C
NMR (CDCl3) d 176.0 (s), 149.6 (2C, d), 146.8 (2C, d), 136.9
(2C, s), 135.8 (s), 135.5 (2C, d), 129.4 (2C, d), 128.2 (2C, d),
127.0 (d), 122.9 (2C, d), 59.5 (d), 51.9 (d), 44.9 (t), 32.7 (2C,
t), 30.8 (2C, t), 28e30 (18C, t), 26.9 (t), 26.6 (t); ESIMS
(pos.) m/z 670 (MþH)þ; HRESIMS (pos.) m/z 670.5315
(MþH)þ, D þ0.3 mmu.
3.3.4. Nakinadine C (2)
Colorless oil; UV (MeOH) lmax 258 (3 3200), 263 (3300),
and 269 (3000) nm; IR (film) nmax 3350, 3200, 2920, and
1
1733 cmꢀ1; H NMR (CDCl3) d 8.44 (2H, m), 7.49 (m), 7.33
(2H, m), 7.25 (2H, m), 7.20 (m), 7.18 (m), 5.37 (2H, m), 4.11
(br s), 3.49 (br s), 2.86 (br s), 2.82 (2H, br s), 2.65 (2H, t,
J¼7.4 Hz), 2.35 (2H, dt, J¼7.4 and 6.7 Hz), 1.92 (2H, dt,

3132
T. Nishi et al. / Tetrahedron 64 (2008) 3127e3132
~ `
2. (a) Quinoa, E.; Crews, P. Tetrahedron Lett. 1987, 28, 2467e2468; (b)
3.3.9. Nakinadine F (5)
Colorless oil; UV (MeOH) lmax 258 (3 4900), 264 (5200),
and 270 (4600) nm; IR (film) nmax 3200, 2853, and
Sakemi, S.; Totton, L. E.; Sun, H. H. J. Nat. Prod. 1990, 53, 995e999;
(c) Stierle, D. B.; Faulkner, D. J. J. Nat. Prod. 1991, 54, 1134e1136;
(d) Carroll, A. R.; Scheuer, P. J. Tetrahedron 1990, 46, 6637e6644; (e)
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5953e5954; (f) Wang, G.-Y.-S.; Kuramoto, M.; Uemura, D. Tetrahedron
Lett. 1996, 37, 1813e1816.
1
1725 cmꢀ1; H NMR (CDCl3) d 8.40 (4H, m), 7.49 (2H, m),
7.31 (4H, m), 7.20 (2H, m), 7.18 (m), 5.38 (4H, m), 3.84 (br
s), 3.01 (br s), 2.80 (m), 2.70 (m), 2.65 (2H, m), 2.60 (2H, m),
2.35 (4H, m), 1.0e1.7 (36H, m); 13C NMR (CDCl3) d 176.0
(s), 149.6 (2C, d), 146.8 (2C, d), 136.9 (2C, s), 135.8 (s),
135.5 (2C, d), 131.1 (2C, d), 129.4 (2C, d), 128.2 (2C, d),
127.4 (2C, d), 127.0 (d), 122.9 (2C, d), 59.5 (d), 51.9 (d), 44.9
(t), 32.7 (2C, t), 28.4 (2C, t), 28e30 (14C, t), 26.9 (3C, t), 26.6
(t); ESIMS (pos.) m/z 694 (MþH)þ; HRESIMS (pos.) m/z
694.5313 (MþH)þ, D þ0.2 mmu.
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Acknowledgements
AuthorsthankZ. Nagahama and K. Uehara for their help with
collection of the sponge, Ms. S. Oka, Center for Instrumental
Analysis, Hokkaido University, for measurements of ESIMS.
This work was partly supported by a grant from the Uehara Me-
morial Foundation, the Yakult Bio-Science Foundation, and
a Grant-in-Aid for Scientific Research from the Ministry of Ed-
ucation, Culture, Sports, Science and Technology of Japan.
7. (a) Tsuda, M.; Hirano, K.; Kubota, T.; Kobayashi, J. Tetrahedron Lett.
1999, 40, 4819e4820; (b) Hirano, K.; Kubota, T.; Tsuda, M.; Mikami,
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H.; Tsuda, M.; Endo, T.; Kobayashi, J. Molecules 2005, 10, 312e316.
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J. Bioorg. Med. Chem. 2006, 14, 8415e8419.
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References and notes
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