Acetylenic strongylodiols from a Petrosia (Strongylophora) Okinawan marine sponge

Article abstract of DOI:10.1021/np040233u

Seven new long-chain acetylenic alcohols, strongylodiols D-J, were isolated from an Okinawan marine sponge of the genus Petrosia (Strongylophora). The structures of these compounds were elucidated on the basis of the results of spectroscopic analysis and

Full text of DOI:10.1021/np040233u

J. Nat. Prod. 2005, 68, 1001-1005
1001
Acetylenic Strongylodiols from a Petrosia (Strongylophora) Okinawan Marine
Sponge
Kinzo Watanabe,*,§ Yuichiro Tsuda,§ Maki Hamada,§ Miki Omori,§ Go Mori,§ Kazuo Iguchi,*,§ Hideo Naoki,#
Tsuyoshi Fujita,# and Rob W. M. Van Soest†
School of Life Science, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo 192-0392, Japan, Suntory
Institute for Bioorganic Research, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618-8503, Japan, and Institute for
Systematics and Population Biology (Zoologisch Museum), University of Amsterdam, PO Box 94766,
1090 GT Amsterdam, The Netherlands
Received December 15, 2004
Seven new long-chain acetylenic alcohols, strongylodiols D-J, were isolated from an Okinawan marine
sponge of the genus Petrosia (Strongylophora). The structures of these compounds were elucidated on
the basis of the results of spectroscopic analysis and chemical reaction. Analysis of the MNA esters of
the acetylenic alcohols disclosed that these compounds were each an enantiomeric mixture in a different
ratio.
A variety of long-chain acetylenic alcohols possessing
significant biological activities have been found in marine
sponges.1,2 Previously, we reported the isolation and struc-
tural determination of three new cytotoxic acetylenic
alcohols from an Okinawan marine sponge of the genus
Petrosia (Strongylophora).3 Interestingly, these acetylenic
alcohols, strongylodiols A, B, and C, were each found to be
an enantiomeric mixture in a different ratio. Further
investigation on acetylenic alcohols from the sponge re-
sulted in the isolation of seven new congeners, strongylo-
diols D-J. Their structures were elucidated on the basis
of spectroscopic analysis and chemical reaction. These
compounds also were each found to be an enantiomeric
mixture in a different ratio. This paper descibes the
structural elucidation of these compounds.
pseudomolecular ion at [M - H]- of m/z 385, a series of
charge remote fragmentation ions was observed as shown
in Figure 2 and was consistent with the location of the
triple bond between C-16 and C-17.
The absolute configuration of the chiral center at C-6
bearing a secondary hydroxyl group in 1 was examined by
applying the modified Mosher’s method.4,5 After protection
of the primary hydroxyl group at C-1 by a tert-butyldim-
ethylsilyl (TBS) group to give 8, the secondary hydroxyl
group at C-6 was esterified with (R)- and (S)-methoxy(2-
naphthyl)acetic acid (MNA)5,6 to give (R)-MNA ester 9 and
(S)-MNA ester 10, respectively. The 1H NMR spectrum of
(R)-MNA ester 9 revealed that 9 was accompanied by its
diastereomer in a ratio of 95:5. The (S)-MNA ester was also
found to be a diastereomeric mixture in a similar ratio.
These findings indicated that strongylodiol D existed as
an enantiomeric mixture in a different ratio. The ∆δ values
(δR-ester - δS-ester) of the corresponding protons at C-1,
C-7, and C-8 between the major diastereomers were
calculated from the 1H NMR spectra of each diastereomeric
mixture, indicating the R configuration at C-6 for the major
enantiomer (see Experimental Section).
Results and Discussion
The isolation and purification were carried out as
described in the Experimental Section.
The molecular formula of strongylodiol D (1) was found
to be C26H42O2 by HREIMS and 13C NMR data (Table 1).
The IR spectra showed absorptions at 3287 (OH) and 2148
(CtC) cm-1. The UV absorptions at 231 (log ꢀ 2.59), 244
(2.59), and 257 (2.35) nm indicated the presence of conju-
gated triple bonds. The 1H and 13C NMR spectra (Table 1)
showed signals due to a primary hydroxyl [δH 4.35 (2H, s),
δC 51.5 (CH2)], a secondary hydroxyl [δH 4.43 (1H, t), δC
62.9 (CH)], six sp carbons [δC 69.84 (C), 69.85 (C), 77.5 (C),
80.2 (C), 80.3 (C), 80.6 (C)], and an isopropyl moiety [δH
0.86 (6H, d)]. The spectral data of 1 were very similar to
those of strongylodiol C,3 except for the lack of the NMR
signals due to the double bond at C-16 and the appearance
of a new triple bond [δC 80.2 (C), 80.3 (C)], indicating that
compound 1 was a corresponding acetylenic congener of
strongylodiol C at C-16. The position of the new triple bond
between C-16 and C-17 was confirmed by collisional
activation decomposition in tandem mass spectrometry
(MS/MS). In the negative FABMS/MS spectrum of the
The molecular formula of strongylodiol E (2) was found
to be C31H48O2 by HREIMS and 13C NMR data (Table 1).
The IR spectrum showed absorptions at 3310 (OH), 2254
(CtC), and 2160 (CtC) cm-1. The UV absorptions at 223
(log ꢀ 3.95) and 257 (2.63) nm indicated the presence of
1
conjugated multiple bonds. The H and 13C NMR spectral
data of 2 (Table 1) were similar to those of strongylodiol
A.3 However, NMR data of 2 indicated the presence of a
pent-3-ene-1-yne system at the terminal position. The
presence of the pent-3-en-1-yne system was confirmed by
HMBC analysis. The HMBC correlations from the acety-
lenic proton [δH 3.07 (1H, d, J ) 2.1 Hz, H-31)] to C-30 [δC
80.6 (C)] and C-29 [δC 107.9 (CH)], from the olefinic proton
[δH 5.44 (1H, dd, J ) 1.9, 10.8 Hz, H-29)] to C-28, C-30,
and C-31, and from another olefinic proton [δH 6.00 (1H,
dt, J ) 7.4, 10.9 Hz, H-28)] to C-27 [δC 30.3 (CH2)] and
C-29 were observed. The position of the nonconjugated
double bond between C-16 and -17 was determined by the
negative FABMS/MS of the pseudomolecular ion [M - H]-
of m/z 452. The Z configuration of the double bond at C-28
was indicated by the coupling constant (J ) 10.9 Hz)
between olefinic protons H-28 [δH 6.00 (1H, dt, J ) 7.4,
* To whom correspondence should be addressed. Tel: +81-426-76-7293.
Fax: +81-426-76-7282. E-mail: kinzo@ls.toyaku.ac.jp (for K.W.). Tel: +81-
426-76-7273. Fax: +81-426-76-7282. E-mail: onocerin@ls.toyaku.ac.jp (for
K.I.).
§ Tokyo University of Pharmacy and Life Science.
# Suntory Institute for Bioorganic Research.
† University of Amsterdam.
10.1021/np040233u CCC: $30.25
© 2005 American Chemical Society and American Society of Pharmacognosy
Published on Web 06/24/2005

1002 Journal of Natural Products, 2005, Vol. 68, No. 7
Watanabe et al.
Table 1. 13C and 1H NMR Data of for Strongylodiols D (1) and E (2)a
1
2
atom no.
δC (mult.)
δH (mult., J ) Hz)
atom no.
δC (mult.)
δH (mult., J ) Hz)
1
51.5 (CH2)
77.5 (C)
4.35 (s)
1
51.5 (CH2)
77.5 (C)
4.34 (s)
2
2
3
69.84 (C)b
69.85 (C)b
80.6 (C)
3
69.8 (C)
4
4
68.8 (C)
5
5
80.58 (C)e
62.9 (CH)
37.5 (CH2)
25.0 (CH2)
6
62.9 (CH)
37.5 (CH2)
25.0 (CH2)
4.43 (t, 6.6)
1.72 (m)
1.43 (m)
6
4.43 (t, 6.6)
1.72 (m)
1.44 (m)
7
7
8
8
9-12c
13
14
15
16
17
18
19
20
21c
22
23
24
25
26
1.25-1.29 (m)
1.36 (m)
9-13f
14
15
16
17
18
19
20-25f
26
27
28
29
30
31
1.27-1.33 (m)
1.27-1.33 (m)
2.01 (m)
5.33 (t, 4.7)
5.33 (t, 4.7)
2.01 (m)
1.27-1.33 (m)
1.27-1.33 (m)
1.39 (m)
2.32 (q, 7.4)
6.00 (td, 7.4, 10.9)
5.44 (dd, 2.1, 10.9)
28.91 (CH2)d
29.2 (CH2)
18.8 (CH2)
80.3 (C)
29.8 (CH2)
27.2 (CH2)
129.92 (CH)g
129.87 (CH)g
27.2 (CH2)
29.8 (CH2)
1.46 (m)
2.14 (t, 6.7)
80.2 (C)
18.8 (CH2)
29.2 (CH2)
28.85 (CH2)d
2.14 (t, 6.7)
1.46 (m)
1.36 (m)
1.25-1.29 (m)
1.25-1.29 (m)
1.16 (m)
1.49 (m)
0.86 (d, 6.7)
0.86 (d, 6.7)
28.7 (CH2)
30.3 (CH2)
146.3 (CH)
107.9 (CH)
80.59 (C)e
81.1 (CH)
27.3 (CH2)
39.0 (CH2)
28.0 (CH)
22.7 (CH3)
22.7 (CH3)
3.07 (d, 2.1)
a 13C NMR: 125 MHz, 1H NMR: 500 MHz. Assignments of the 13C and 1H signals were made on the basis of HMQC. b,d,e,g Values with
the same superscript are interchangeable. c The unassignable 13C signals [δC 29.1 (CH2), 29.2 (CH2), 29.4 (CH2 × 3)] were observed for
these carbons. f The unassignable 13C signals [δC 29.17 (CH2), 29.19 (CH2), 29.28 (CH2), 29.30 (CH2), 29.43 (CH2), 29.47 (CH2), 29.50 (CH2
× 2), 29.53 (CH2), 29.56 (CH2), 29.60 (CH2)] were observed for these carbons.
Figure 2. MS/MS data for the [M - H]- ion (m/z 385) of strongylodiol
D (1) (the numerals in parentheses show relative intensities).
natural strongylodiol E (2) existed as an enantiomeric
mixture in a different ratio. The R configuration of the
chiral center at C-6 for the major enantiomer was deter-
mined by the ∆δ values.
The IR, UV, and NMR data of strongylodiol F (3)
(C31H46O2) were very similar to those of 2, except for the
lack of the NMR signals due to one of the disubstituted
double bonds and the appearance of those due to an
additional triple bond [δC 80.2 (C), 80.3 (C)], indicating that
compound 3 was a corresponding acetylenic congener of
strongylodiol E (2) at C-16. The location of the new triple
bond at C-16, the enantiomeric ratio (80:20), and the
absolute configuration (R) at C-6 of the major enantiomer
were determined by the same methods used for 1 and 2.The
IR, UV, and NMR data of strongylodiol G (4) (C24H42O2)
were very similar to those of strongylodiols A and B, except
for the lack of the NMR signals due to the multiple bond
at C-16 present in strongylodiols A and B and the appear-
ance of those due to a secondary methyl group [δH 0.83 (3H,
d, J ) 6.5 Hz, H-24)], indicating that compound 4 was a
Figure 1. Structures of new acetylenic alcohols and derivatives (the
branched acetylenic alcohol. The location of the secondary
R configuration at C-6 for the major enantiomer is depicted in the
methyl at C-15 was determined by a similar method used
for 1, 2, and 3. The relative configuration at C-15 bearing
the secondary methyl was not determined. Interestingly,
compound 4 was found to be almost optically pure on the
basis of the analysis of the NMR spectra of its (R)- and
(S)-MNA esters. The absolute configuration (R) at C-6 was
determined by ∆δ values.
structures).
10.9 Hz)] and H-29 [δH 5.44 (1H, dd, J ) 1.9, 10.9 Hz)].
The Z configuration of the double bond at C-16 was
elucidated by comparison of the 13C chemical shift (δC 27.2)
for allylic carbons with those in (Z)-2-heptene (δC 27.0) and
(E)-2-heptene (δC 32.8).7
The (R)- and (S)-MNA esters were each found to be a
diastereomeric mixture in a ratio of 61:39, indicating that
The IR and NMR data of strongylodiol H (5) (C25H40O2)
were very similar to those of strongylodiol A, except for

Acetylenic Strongylodiols from a Petrosia Sponge
Journal of Natural Products, 2005, Vol. 68, No. 7 1003
Table 2. 13C and 1H NMR Data for Strongylodiols F (3) and G (4)a
3
4
atom no.
δC (mult.)
δH (mult., J ) Hz)
atom no.
δC (mult.)
δH (mult., J ) Hz)
1
51.5 (CH2)
77.5 (C)
4.35 (d, 6.1)e
1
51.5 (CH2)
77.5 (C)
4.34 (s)
2
2
3
69.84 (C)
69.83 (C)
80.56 (C)
62.9 (CH)
37.5 (CH2)
25.0 (CH2)
3
69.8 (C)
4
4
68.8 (C)
80.6 (C)
62.9 (CH)
37.5 (CH2)
25.0 (CH2)
5
5
6
4.43 (dt, 6.0, 6.3)e
1.72 (m)
1.45 (m)
1.25-1.29 (m)
1.35 (m)
6
4.43 (t, 6.6)
1.72 (m)
1.44 (m)
7
7
8
8
9-12b
13
14
15
16
17
18
19
20
21-25b
26
27
28
29
30
31
9-13f
14
1.26-1.32 (m)
1.26-1.32 (m)
1.26-1.32 (m)
1.26-1.32 (m)
1.26-1.32 (m)
1.26-1.32 (m)
1.26-1.32 (m)
0.88 (t, 6.9)
0.83 (d, 6.5)
28.86 (CH2)c
29.16 (CH2)
18.8 (CH2)
80.3 (C)d
37.1 (CH2)
32.8 (CH)
37.1 (CH)
1.48 (m)
2.13 (t, 7.1)
15
16
17-20f
21
80.2 (C)d
31.9 (CH2)
22.7 (CH2)
14.1 (CH3)
19.7 (CH3)
18.8 (CH2)
29.16 (CH2)
28.84 (CH2)c
2.13 (t, 7.1)
22
1.48 (m)
23
1.35 (m)
24
1.25-1.29 (m)
1.39 (m)
28.7 (CH2)
30.3 (CH2)
146.3 (CH)
107.9 (CH)
80.60 (C)
2.32 (brq, 7.4)
6.00 (td, 7.4, 10.9)
5.44 (brdd, 2.1, 10.9)
81.1 (CH)
3.07 (d, 2.1)
a
13C NMR: 125 MHz, 1H NMR: 500 MHz. Assignments of the 13C and 1H signals were made on the basis of HMQC. b The unassignable
13C signals [δC 29.10 (CH2), 29.16 (CH2 × 3), 29.41 (CH2 × 3), 29.52 (CH2 × 2)] were observed for these carbons. c,d Values with the same
superscript are interchangeable. e Each proton couples with the hydroxylic proton. f The unassignable 13C signals [δC 27.06 (CH2), 27.08
(CH2), 29.21 (CH2), 29.35 (CH2), 29.49 (CH2), 29.59 (CH2), 29.68 (CH2), 29.97 (CH2), 30.03 (CH2)] were observed for these carbons.
the appearance of the signals due to an additional disub-
stituted double bond. The position of the new double bond
at C-7 was deduced from the correlations exhibited by the
HMBC from the olefinic proton [δH 5.57 (1H, dd, J ) 6.2,
15.3 Hz, H-7)] to C-5 [δC 78.7 (C)], C-6 [δC 63.3 (CH)], and
C-9 [δC 31.9 (CH2)] and from another olefinic proton [δH
5.89 (1H, td, J ) 6.7, 15.3 Hz, H-8)] to C-6 and C-9. The E
configuration of the double bond at C-7 was determined
by the coupling constant (15.3 Hz) between H-7 and H-8.
The position of the remaining disubstituted double bond
was determined by oxidative cleavage of the double bond.
Oxidation of 5 with osmium tetroxide and periodic acid
followed by treatment with 2,4-dinitrophenylhydrazine
afforded compound 11. The structure of 11, 2,4-dinitrophe-
nylhydrazone of nonanal, was identified by MS and 13C
NMR data (see Experimental Section). The enantiomeric
ratio (94:6) for 5 and the absolute configuration (R) at C-6
of the major enantiomer were determined by the same
methods used for 1-4.The IR, UV, and NMR data of
strongylodiol I (6) (C26H42O2) were very similar to those of
5, except for the appearance of a 6H methyl doublet [δH
0.86 (6H, d, J ) 6.6 Hz)] coupled to a methine multiplet at
δH 1.52 (1H, m), indicating that compound 6 was an
isopropyl congener of 5. The location of the double bond at
C-16, the enantiomeric ratio (97:3), and the absolute
configuration (R) at C-6 of the major enantiomer were
determined by the same method used for 5.
The IR, UV, and NMR data of strongylodiol J (7)
(C31H46O2) were very similar to those of strongylodiol E (2),
except for the appearance of an additional disubstituted
double bond. The position of the new double bond at C-7
was deduced from HMBC correlations. The enantiomeric
ratio (96:4) and the absolute configuration (R) at C-6 of the
major enantiomer were determined by the same methods
used for 5 and 6. The location of the double bond at C-16
is inferred from NMR data comparisons to be the same as
that of compound 2.Optically active natural products
isolated as a racemic mixture have been frequently en-
countered. However, natural products isolated as an enan-
tiomeric mixture in a different ratio are fairly limited.8-10
This phenomenon is of interest and may be attributed to
an artificial change or functions of biosynthetic enzymes.
Further investigation on biosynthetic enzymes is expected.
Experimental Section
General Experimental Procedures. Optical rotations
were measured with a JASCO DIP-370 automatic polarimeter.
IR spectra were recorded with a Perkin-Elmer FT-IR 1600
spectro-photometer and UV spectra with a JASCO V-520
spectrophotometer. All NMR spectra were recorded with a
Bruker DRX-500 (1H, 500 MHz; 13C, 125 MHz) spectrometer
in CDCl3. 1H-1H COSY, NOESY, HMQC, and HMBC spectra
were measured using standard Bruker pulse sequences.
Chemical shifts are given on a δ (ppm) scale with CHCl3 (1H,
7.26 ppm) and CDCl3 (13C, 77.0 ppm) as the internal standard.
Mass spectra were taken with a Micromass Auto Spec spec-
trometer. Tandem mass spectra (MS/MS) were taken with a
JEOL HX110A spectrometer.
Animal and Material. The sponge of the genus Petrosia
(Strongylophora) (class Demospongiae, order Haplosclerida,
family Petrosidae) was collected from a coral reef off Ishigaki
Island, Okinawa Prefecture, Japan, in June 1998 and June
2002, at a depth of 13-15 m. The sponge formed a lumpy
branched cylindrical body of 2-3 cm in diameter. The oscules
were studded on the upper part of the body. The texture was
hard. The colors of the surface and inside were greenish-gray
and pale yellowish-brown, respectively. One of the authors,
R.W.M.V.S., identified the sponge as belonging to the genus
Strongylophora. Recently, he proposed that the genus Strongy-
lophora should be combined with the genus Petrosia.11 There-
fore, we expressed the present sponge as the genus Petrosia
(Strongylophora) in this paper. A voucher specimen is pres-
ently on deposit in the Zoological Museum at the University
of Amsterdam under the registration number ZMA POR.
14879.
Extraction and Isolation. Wet specimens (1.93 kg) of the
sponge collected in 1998 were extracted with MeOH. The
MeOH extract was partitioned between EtOAc and H2O to
obtain an EtOAc-soluble portion (37.2 g). A part (25.6 g) of
the EtOAc-soluble portion was chromatographed on a silica

1004 Journal of Natural Products, 2005, Vol. 68, No. 7
Watanabe et al.
Table 3. 13C and 1H NMR Data for Strongylodiols H (5) and I (6)a
5
6
atom no.
δC (mult.)
δH (mult., J ) Hz)
atom no.
δC (mult.)
δH (mult., J ) Hz)
1
51.5 (CH2)
77.9 (C)
4.36 (d, 6.3)
1
51.5 (CH2)
77.9 (C)
4.35 (d, 5.8)
2
2
3
69.8 (C)
3
69.80 (C)g
68.83 (C)g
78.7 (C)
4
69.8 (C)
78.7 (C)
63.3 (CH)
127.7 (CH)
135.2 (CH)
31.9 (CH2)b
28.8 (CH2)
4
5
5
6
4.89 (brt, 6.2)
5.57 (dd, 6.2, 15.3)
5.89 (td, 6.7, 15.3)
2.06 (q, 6.7)d
1.39 (m)
1.24-1.31 (m)
1.34 (m)
2.01 (q, 6.1)
5.35 (m)
5.35 (m)
2.01 (q, 6.1)
2.14 (t, 6.7)
1.24-1.31 (m)
1.24-1.31 (m)
1.24-1.31 (m)
0.88 (t, 6.7)
1.16 (m)
6
63.3 (CH)
127.7 (CH)
135.2 (CH)
32.0 (CH2)
28.8 (CH2)
4.89 (brt, 6.0)
5.51 (brdd, 6.0, 15.3)
5.90 (td, 6.8, 15.3)
2.06 (q, 6.8)
1.39 (m)
1.24-1.30 (m)
1.34 (m)
2.02 (q, 6.0)
5.34 (m)
5.34 (m)
7
7
8
8
9
9
10
11-13c
14
15
16
17
18
19
20-22c
23
24
25
23
24
25
10
11-13h
14
28.7 (CH2)d
27.18 (CH2)e
129.8 (CH)f
130.0 (CH)f
27.21 (CH2)e
29.8 (CH2)d
29.74 (CH2)i
27.19 (CH2)j
129.8 (CH)k
130.0 (CH)k
27.22 (CH2)j
29.77 (CH2)i
15
16
17
18
2.02 (q, 6.0)
1.34 (m)
19
20-21h
22
1.24-1.30 (m)
1.24-1.30 (m)
1.15 (m)
32.0 (CH2)b
22.7 (CH2)
14.1 (CH3)
39.0 (CH2)
28.0 (CH)
22.7 (CH3)
27.4 (CH2)
39.0 (CH2)
28.0 (CH)
22.7 (CH3)
22.7 (CH3)
23
24
1.52 (m)
25
0.86 (d, 6.6)
0.86 (d, 6.6)
1.60 (brt, 5.8)
1.83 (d, 6.0)
1.49 (m)
0.86 (d, 6.7)
26
CH2OH
CHOH
a
13C NMR: 125 MHz, 1H NMR: 500 MHz. Assignments of the 13C and 1H signals were made on the basis of HMQC. b,d,e,f,g,i,j,k Values
with the same superscript are interchangeable. The unassignable 13C signals [δC 29.1 (CH2), 29.2 (CH2), 29.31 (CH2 × 2), 29.33 (CH2),
29.5 (CH2)] were observed for these carbons. hThe unassignable 13C signals [δC 29.1 (CH2), 29.2 (CH2), 29.3 (CH2 × 2), 29.81 (CH2)] were
observed for these carbons.
c
Table 4. 13C and 1H NMR Data for Strongylodiol J (7)a
acetonitrile) of the third fraction (4.94 g, eluted with EtOAc)
afforded six fractions (A-F). Purification of fraction B using
HPLC (reversed-phase, acetonitrile, equipped with a recycle
loop) afforded strongylodiols B3 (229 mg) and H (5, 2.4 mg).
Similar purification of the other fractions afforded strongylo-
diols F (3, 34 mg) and I (6, 2.7 mg) from fraction C, strongy-
lodiols A3 (227 mg), D (1, 16 mg), and E (2, 50 mg) from fraction
E, and strongylodiols C3 (127 mg), G (4, 26 mg), and J (7, 3.3
mg) from fraction F.
atom no.
δC (mult.)
δH (mult., J ) Hz)
4.35 (brs)
1
51.5 (CH2)
78.0 (C)
2
3
69.8 (C)
4
69.8 (C)
5
78.7 (C)
6
63.3 (CH)
127.7 (CH)
135.2 (CH)
32.0 (CH2)
28.7 (CH2)b
4.88 (brs)
7
5.57 (tdd, 1.4, 6.2, 15.3)
5.89 (dtd, 1.0, 6.8, 15.3)
2.06 (q, 6.8)
Strongylodiol D (1): amorphous solid; [R]25D -8.0° (c 0.56,
CHCl3); UV (EtOH) λmax (log ꢀ) 231 (2.59), 244 (2.56), 257 (2.35)
8
9
nm; IR νmax (film) 3387, 2928, 2849, 2148 cm-1 13C and 1H
;
10
1.40 (m)
NMR, see Table 1; HREIMS m/z 387.3258 [M + H]+ (calcd for
C26H43O2, 387.3263).
11-13c
14
1.25-1.35 (m)
1.25-1.35 (m)
2.01 (q, 6.4)
29.73 (CH2)d
27.18 (CH2)e
129.8 (CH)f
130.0 (CH)f
27.20 (CH2)e
29.75 (CH2)d
Strongylodiol E (2): amorphous solid; [R]25D -1.8° (c 0.51,
CHCl3); UV (EtOH) λmax (log ꢀ) 223 (3.95), 257 (2.63) nm; IR
15
16
5.35 (m)
νmax (film) 3310, 2921, 2852, 2254, 2160 cm-1 13C and 1H NMR,
;
17
5.35 (m)
see Table 1; HREIMS m/z 453.3713 [M + H]+ (calcd for
C31H49O2, 453.3733).
18
2.01 (q, 6.4)
19
1.25-1.35 (m)
1.25-1.35 (m)
1.40 (m)
20-25c
26
Strongylodiol F (3): amorphous solid; [R]25D -5.3° (c 0.36,
CHCl3); UV (EtOH) λmax (log ꢀ) 221 (4.00), 256 (2.88) nm; IR
28.8 (CH2)b
30.3 (CH2)
146.3 (CH)
107.9 (CH)
80.6 (C)
27
2.32 (brq, 7.5)
6.00 (td, 7.5, 10.8)
5.44 (brd, 10.8)
νmax (film) 3296, 2926, 2849, 2251, 2168 cm-1 13C and 1H NMR,
;
28
see Table 2; HREIMS m/z 473.3333 [M + Na]+ (calcd for
C31H46O2Na, 473.3400).
29
30
Strongylodiol G (4): amorphous solid; [R]22D -3.9° (c 0.55,
CHCl3); UV (EtOH) λmax (log ꢀ) 229 (2.78), 243 (2.72), 257 (2.52)
31
81.1 (CH)
3.07 (d, 2.0)
1.70 (brs)
1.91 (brd, 5.3)
CH2OH
CHOH
nm; IR νmax (film) 3331, 2923, 2853, 2162 cm-1 13C and 1H
;
NMR, see Table 2; HREIMS m/z 385.3094 [M + Na]+ (calcd
a
13C NMR: 125 MHz, 1H NMR: 500 MHz. Assignments of the
13C and 1H signals were made on the basis of HMQC. b,d,e,f Values
with the same superscript are interchangeable. c The unassignable
13C signals [δC 29.16 (CH2 × 2), 29.19 (CH2), 29.30 (CH2), 29.33
(CH2), 29.4 (CH2), 29.53 (CH2), 29.55 (CH2), 29.60 (CH2)] were
observed for these carbons.
for C24H40O2Na, 385.3083).
Strongylodiol H (5): colorless oil; [R]22 -43.8° (c 0.35,
D
CHCl3); UV (MeOH) λmax (log ꢀ) 208 (3.79) nm; IR νmax (film)
3330, 2920, 2255, 2164, 1667 cm-1 13C and 1H NMR, see Table
;
3; HRESIMS m/z 379.3213 [M + Li]+ (calcd for C25H40O2Li,
379.3188).
Strongylodiol I (6): colorless oil; [R]22 -33.4° (c 0.13,
D
gel column. Stepwise elution with hexane (1500 mL), hexane-
EtOAc (4:1, 2000 mL), hexane-EtOAc (1:1, 1500 mL), EtOAc
(1500 mL), and MeOH (1000 mL) afforded five fractions. The
second fraction [8.51 g, eluted with hexane-EtOAc (4:1)] was
further subjected to flash column chromatography. Stepwise
elution with hexane-EtOAc (29:1 and 19:1) and EtOAc af-
forded three fractions. HPLC separation (reversed-phase,
CHCl3); UV (MeOH) λmax (log ꢀ) 208 (3.76) nm; IR νmax (film)
3332, 2921, 2854, 2255, 2164, 1667 cm-1 13C and 1H NMR,
;
see Table 3; HRESIMS m/z 393.3310 [M + Li]+ (calcd for
C26H42O2Li, 393.3345).
Strongylodiol J (7): colorless oil; [R]22 -32.6° (c 0.44,
D
CHCl3); UV (MeOH) λmax (log ꢀ) 208 (3.79) nm; IR νmax (film)

Acetylenic Strongylodiols from a Petrosia Sponge
Journal of Natural Products, 2005, Vol. 68, No. 7 1005
3311, 2921, 2852, 2256, 2164, 1667 cm-1
;
13C and 1H NMR,
7, a solution of 2,4-dinitrophenylhydrazine (21.4 mg) in 5%
H3PO4-t-BuOH (1:1, 0.8 mL) was added. The mixture was
stirred for 30 min at room temperature. Excess EtOAc was
added to the reaction mixture, and the mixture was washed
with H2O and saturated aqueous NaCl, dried over anhydrous
MgSO4, and concentrated under reduced pressure. The crude
product was purified by HPLC [normal-phase, hexane-EtOAc
(85:15)] to afford 2,4-dinitrophenylhydrazone 11 (1.5 mg).
Similar degradation of 6 afforded the corresponding 2,4-
dinitrophenylhydrazone 12.
see Table 4; HRESIMS m/z 457.3689 [M + Li]+ (calcd for
C31H46O2Li, 457.3658).
Preparation of MNA Esters of 1. To a solution of 1 (1.0
mg) in dry CH2Cl2 (0.2 mL) were added successively tert-
butyldimethylsilyl chloride (0.3 mg), DMAP (1.9 mg), and NEt3
(10 µL). The mixture was stirred for 1 h at 0 °C under an argon
atmosphere. After addition of an excess of ether the reaction
mixture was washed with aqueous NaHCO3, aqueous NH4Cl,
and saturated aqueous NaCl, dried over anhydrous MgSO4,
and concentrated under reduced pressure. The crude product
was purified by silica gel column chromatography to afford
compound 8 (1.2 mg).
Compound 11: yellow powder; 1H NMR (500 MHz, CDCl3,
δ ppm) 0.89 (3H, t, J ) 5.4 Hz), 1.26-1.34 (10H, m), 1.62 (2H,
quint, J ) 7.4 Hz), 2.43 (2H, dt, J ) 5.4, 7.4 Hz), 7.53 (1H, t,
J ) 5.4 Hz), 7.93 (1H, d, J ) 9.6 Hz), 8.30 (1H, dd, J ) 2.9,
9.6 Hz), 9.12 (1H, d, J ) 2.9 Hz), 11.01 (1H, s, NH); 13C NMR
(125 MHz, CDCl3, δ ppm) 14.1 (CH3), 22.6 (CH2), 26.3 (CH2),
29.16 (CH2), 29.17 (CH2), 29.3 (CH2), 31.8 (CH2), 32.5 (CH2),
116.5 (CH), 123.5 (CH), 128.8 (C), 130.0 (CH), 137.8 (C), 145.2
(C), 152.6 (C); HREIMS m/z 323.1713 [M + H]+ (calcd for
C15H23N4O4, 323.1719).
To a solution of 8 (0.5 mg) in dry CH2Cl2 (0.2 mg) were added
successively (R)-MNA (1.5 mg), DMAP (0.9 mg), and EDC
hydrochloride (8.7 mg). The mixture was stirred for 2 h at room
temperature under an argon atmosphere. Excess ether was
added to the reaction mixture, and the mixture was washed
with 10% aqueous tartaric acid, aqueous NaHCO3, and satu-
rated aqueous NaCl, dried over anhydrous MgSO4, and
concentrated under reduced pressure. The crude product was
purified by silica gel column chromatography and HPLC to
afford (R)-MNA ester 9 (0.9 mg). (S)-MNA ester 10 (1.0 mg)
was similarly prepared from 1.
Compound 12: yellow powder; 1H NMR (500 MHz, CDCl3,
δ ppm) 0.87 (6H, t, J ) 6.6 Hz), 1.18 (2H, quint, J ) 7.1 Hz),
1.32 (4H, m), 1.40 (2H, quint, J ) 7.2 Hz), 1.57 (1H, m), 1.62
(2H, quint, J ) 7.5 Hz), 2.43 (2H, dt, J ) 5.5, 7.4 Hz), 7.53
(1H, t, J ) 5.4 Hz), 7.93 (1H, d, J ) 9.6 Hz), 8.30 (1H, dd, J )
2.8, 9.6 Hz), 9.12 (1H, d, J ) 2.8 Hz), 11.01 (1H, s, NH);
HREIMS m/z 337.1829 [M + H]+ (calcd for C16H25N4O4,
337.1876).
(R)-MNA ester 9: colorless oil; 1H NMR (500 MHz, CDCl3,
δ ppm) 0.090 (6H, s), 0.86 (6H, d, J ) 6.6 Hz), 0.89 (9H, s),
1.21-1.39 (24H, m), 1.49 (1H, m), 1.77 (2H, m, H-7), 2.13 (4H,
m), 3.47 (3H, s), 4.33 (2H, s, H-1), 4.96 (1H, s), 5.45 (1H, t, J
) 6.7 Hz, H-6), 7.47-7.56 (3H, m), 7.82-7.92 (4H, m);
HRFABMS m/z 705.4884 [M + Li]+ (calcd for C45H66O4SiLi,
705.4890).
Supporting Information Available: Copies of 1H and 13C NMR
spectra of strongylodiols D-J (1-7). These materials are available free
of charge via the Internet at http://pubs.acs.org.
(S)-MNA ester 10: colorless oil; 1H NMR (500 MHz, CDCl3,
δ ppm) 0.12 (6H, s), 0.86 (6H, d, J ) 6.7 Hz), 0.90 (9H, s),
0.88-1.52 (25H, m), 1.59 (2H, m, H-7), 2.13 (2H×2, q, J ) 6.7
Hz), 3.47 (3H, s), 4.37 (2H, s, H-1), 4.95 (1H, s), 5.46 (1H, t, J
) 6.5 Hz, H-6), 7.47-7.54 (3H, m), 7.81-7.91 (4H, m);
HRFABMS m/z 705.4902 [M + Li]+ (calcd for C45H66O4SiLi,
705.4890).
References and Notes
(1) Faulkner, D. J. Nat. Prod. Rep. 2002, 19, 1-48, and previous papers
in this series.
(2) Blunt, J. W.; Copp, B. R.; Munro, M. H. G.; Northcote, P. T.; Prinsep,
M. R. Nat. Prod. Rep. 2004, 21, 1-49, and the previous paper in this
series.
∆δ values (δR-ester - δS-ester) between (R)-MNA ester 9
and (S)-MNA ester 10 for 1: -0.04 ppm for H-1 and +0.18
ppm for H-7. These data indicated an R configuration at C-6
for the major enantiomer of 1.
Preparation of MNA Esters of 2-7. (R)- and (S)-MNA
esters of strongylodiols E (2)-J (7) were prepared by a method
similar to that for strongylodiol D (1).
∆δ values (δR-ester - δS-ester) (ppm): -0.04 (H-1) and +0.18
(H-7) for 2; -0.04 (H-1) and +0.17 (H-7) for 3 and 4; -0.05
(H-1), +0.20 (H-7), +0.19 (H-8), and +0.15 (H-9) for 5, 6, and
7. These data indicated each R configuration at C-6 of the
major enantiomer for 2-7.
Oxidative Degradation of 5. To a solution of 5 (5.0 mg)
in t-BuOH-H2O (1:1, 0.34 mL) were added successively OsO4
(0.68 mg), H5IO4 (18.4 mg), and one drop of 30% aqueous
AcOH. The mixture was stirred for 80 min at room tempera-
ture. After neutralization with 0.05 M aqueous NaOH to pH
(3) Watanabe, K.; Tsuda, Y.; Yamane, Y.; Takahashi, H.; Iguchi, K.;
Naoki, H.; Fujita, T.; Van Soest, R. W. M. Tetrahedron Lett. 2000,
41, 9271-9276.
(4) Ohtani, I.; Kusumi, T.; Kashman, Y.; Kakisawa, H. J. Am. Chem.
Soc. 1991, 113, 4092-4096.
(5) Kusumi, T.; Takahashi, H.; Xu, P.; Fukushima, T.; Asakawa, Y.;
Hashimoto, T.; Kan Y.; Inouye, Y. Tetrahedron Lett. 1994, 35, 4397-
4400.
(6) Kusumi, T.; Takahashi, H.; Hashimoto, T.; Kan Y.; Asakawa, Y.
Chem. Lett. 1994, 1093-1094.
(7) De Haan, J. W.; Van de Ven, L. J. M. Org. Magn. Reson. 1973, 5,
147-153.
(8) Niwa, M.; Iguchi, M.; Yamamura, S. Chem. Pharm. Bull. 1980, 28,
997-999.
(9) Mori, K.; Nakazono, Y. Tetrahedron 1986, 42, 283-290.
(10) Kobayashi, M.; Kawazoe, K.; Kitagawa, I. Chem. Pharm. Bull. 1989,
37, 1676-1678.
(11) Hooper, J. N. A., Van Soest, R. W. M., Eds. Systema Porifera; Kluwer
Academic/Plenum Publishers: New York, 2002; Vol. 1, pp 911-916.
NP040233U