Durinskiol B: A new Durinskiol congener from the symbiotic marine dinoflagellate Durinskia sp

Article abstract of DOI:10.1246/cl.2008.236

Durinskiol B (1) was isolated from the symbiotic marine dinoflagellate Durinskia sp., along with durinskiol A (2). The planar structure of 1 was determined by detailed NMR analysis. Durinskiol B (1) has structure similarity with durinskiol A (2) except for the existence of one methyl excess in the side chain of durinskiol B. Copyright

Full text of DOI:10.1246/cl.2008.236

236
Chemistry Letters Vol.37, No.3 (2008)
Durinskiol B: A New Durinskiol Congener
from the Symbiotic Marine Dinoflagellate Durinskia sp.
Eric Richard Oktavianus Siwu,1 Osamu Ohno,1 Masaki Kita,2;y and Daisuke Uemuraꢀ1;3
1Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602
2Research Center for Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602
3Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602
(Received November 15, 2007; CL-071270; E-mail: uemura@chem3.chem.nagoya-u.ac.jp)
Durinskiol B (1) was isolated from the symbiotic marine
wet weight)7 and durinskiol A (2, 0.004%). Interestingly, 1
and 2 did not show cytotoxicity against P388 murine leukemia
cells or B16 melanoma cells even at concentration 100 mg/mL.
1D NMR data of 1 in all regions were almost identical to
those of 2, however, 1 displayed one more doublet methyl and
the corresponding carbon than 2 (Figure 1). Molecular weight
dinoflagellate Durinskia sp., along with durinskiol A (2). The
planar structure of 1 was determined by detailed NMR analysis.
Durinskiol B (1) has structure similarity with durinskiol A (2)
except for the existence of one methyl excess in the side chain
of durinskiol B.
1
of 1 was also consistent with that of 2. H and 13C NMR data
revealed that 1 consists of eight methyls, 49 methylenes, four
methines, 41 oxymethines, one oxymethylene, four acetal
carbons, and a pair of terminal olefin carbons (see Supporting
Symbiotic marine dinoflagellates have been known as sour-
ces of various molecules with remarkable biological activities.
In particular, large polyol compounds which called as ‘‘super-
carbon-chain compounds’’1 have been isolated from these micro-
organisms such as symbiodinolide,2 karatungiols,3 zooxanthella-
toxins,4 and zooxanthelamides.5 In our continuing search for
polyol compounds from symbiotic marine dinoflagellates, we
examined the constituents of culture of Durinskia sp. isolated
from Okinawan nudibranch Chelidonura fulvipunctata. Recent-
ly, we reported the isolation and structure determination of a
long carbon-chain polyol compound with a molecular weight
of 2128 mu, durinskiol A (2). It caused a short body length,
abnormal pigment pattern, pericardiac and yolk-sac edema in
zebrafish at 188 mM.6 We describe here another congener of
durinskiol A (2) which is named durinskiol B (1) (Scheme 1).
The harvested cells (191 g wet weight from 400 L of culture)
were extracted with 80% ethanol. Ethanol extracts were initially
partitioned between EtOAc and water. Water-soluble material
was chromatographed by using a polystyrene gel TSK G-
3000S and ODS column chromatography, followed by re-
versed-phase HPLC to furnish durinskiol B (1, 0.0009% of
1
Information). On the basis of the H–1H COSY, TOCSY, and
HMBC correlations, the planar structure of 1 has been elucidated
except for the positions of two methyl groups (C93 and C94)
(Figure 2). Durinskiol B (1) contained a 6,5,6-bisspiroacetal
ring, a seven-membered ether ring, four six-membered ether
rings, and two sugar moieties (rhamnose and xylose) similar to 2.
To confirm the entire planar structure of 1, degradation reac-
tion was carried out. NaIO4 oxidation of 1 followed by NaBH4
reduction afforded the C1–C14 and the C15–C92 fragments.
On the basis of the 1H NMR and mass spectra, structure of
the C1–C14 fragment was established to be 13-tetradecenal,8
which suggested that both of the C93 and C94 methyl groups
were located on the other linear carbon-chain terminus. Despite
the detail 2D NMR analysis, however, the number of methylene
carbons between the spin systems including the isolated methyl
groups and those of the other part in 1 could not be established.
As in the case of durinskiol A (2),6 the C93 and C94 methyl
groups can be placed between C83 and C87 in 1, thus tentatively
connected to C86 and C83, respectively (Figure 2). The stereo-
chemistry of 1 could be suggested as the same as 2 due to the
identical spectroscopic data on both compounds especially in
the vicinal coupling constants.
OH
99
Me
O
OH
OH
1
A methyl moiety excess in 1 might be explained by the
28
17
14
15
O
O
OH
OH
H
H
33
OH
HO
H
O
H
38 OH
HO
H
41
OH
OH
97
98
O
HO
H
H
H
H
Me
Me
H
O
O
O
45
68
64 62
58
54
50
96
Me
HO
HO
OH
HO
OH
HO
O
1''
O
OH
OH
OH
1'
OH
O
O
95
6''
5'
Me
Me
OH
OH
OH
OH
93
l
94
1 : l+m+n = 3, R = Me
2 : l+m+n = 4, R = H
Me
m
n
92
(93)
Figure 1. Comparison of the doublet methyl signals between
durinskiols A and B in 1H NMR spectra (800 MHz for 1 and
600 MHz for 2).
R
Scheme 1.
Copyright ꢀ 2008 The Chemical Society of Japan

Chemistry Letters Vol.37, No.3 (2008)
237
OH
was isolated from Durinskia sp. The planar structure of 1 includ-
ing partial relative stereochemistry was almost identical with 2,
except for the existence of one more methyl excess in side chain
of 1. Considering of biogenetic pathway, 1 might be produced
from the same precursor with 2. Further studies on other durin-
skiol congeners are in progress.
99
Me
OH
OH
O
28
17
14
1
15
O
O
OH
OH
OH
33
OH
HO
O
38
HO
41
OH
This work was supported in part by a Grant-in-Aid for
Creative Scientific Research (No. 16GS0206) from JSPS and
by the 21st COE program (Establishment of COE on Material
Science) from MEXT, Japan. We are also indebted to Ono
Pharmaceutical Co., Ltd. for their financial support.
98
97
O
HO
Me
Me
O
O
O
54
45
OH
58
68
64 62
50
96
Me
HO
HO
OH
HO
OH
HO
O
1''
O
OH
OH
OH
1'
OH
OH
O
O
95
6''
5'
Me
Me
OH
References and Notes
OH
COSY, TOCSY
Selected HMBC
OH
y
1
2
Present address: Department of Chemistry, Graduate School
of Pure and Applied Sciences, University of Tsukuba, 1-1-1
Tennodai, Tsukuba 305-8571.
D. Uemura, Antitumor Polyethers. in Bioorganic Marine
Chemistry, ed. by P. J. Scheuer, Springer-Verlag, Berlin
Heidelberg, 1991, Vol. 4, pp. 1–31.
M. Kita, N. Ohishi, K. Konishi, M. Kondo, T. Koyama,
M. Kitamura, K. Yamada, D. Uemura, Tetrahedron 2007,
63, 6241.
83
94
86
Me
92
Me
93
Figure 2. Planar structure of 1 determined by 2D NMR spec-
troscopy.
Ad
S+
COO–
H
*
3
4
K. Washida, T. Koyama, K. Yamada, M. Kita, D. Uemura,
Tetrahedron Lett. 2006, 47, 2521.
H3C
*
+
NH3
SAM
a) H. Nakamura, T. Asari, A. Murai, Y. Kan, T. Kondo,
K. Yoshida, Y. Ohizumi, J. Am. Chem. Soc. 1995, 117,
550. b) H. Nakamura, T. Asari, K. Fujimaki, K. Maruyama,
A. Murai, Y. Ohizumi, Y. Kan, Tetrahedron Lett. 1995, 36,
7255.
carbocation intermediate
cation discharged
by formation of
cyclopropane ring
and loss of proton
precursor of durinskiols A and B
5
6
K. Onodera, H. Nakamura, Y. Oba, M. Ojika. Tetrahedron
2003, 59, 1067.
cation discharged by
addition of hydride
*
a) M. Kita, M. C. Roy, E. R. O. Siwu, I. Noma, T. Takiguchi,
M. Itoh, K. Yamada, T. Koyama, T. Iwashita, D. Uemura,
Tetrahedron Lett. 2007, 48, 3423. b) M. Kita, M. C. Roy,
E. R. O. Siwu, I. Noma, T. Takiguchi, K. Yamada, T.
Koyama, T. Iwashita, A. Wakamiya, D. Uemura, Tetra-
hedron Lett. 2007, 48, 3429.
*
bond cleavage
durinskiol B (1)
23
7
8
Colorless amorphous powder, ½ꢀꢁD þ8:5 (c 0.10, MeOH);
*
IR (KBr) 3400, 1650, 1636, 1458, 1051, 985 cmꢂ1; HR-
ESIMS [m=z (M + 2Na)2þ; found 1086.6692, calcd for
C55H99NaO19 (ꢀ þ1:4 mmu)].
durinskiol A (2)
Scheme 2. Plausible biogenetic pathway of the methyl excess
in 1. Ad, adenosyl.
1H NMR (CDCl3, 600 MHz) ꢁ 9.74 (1H, t, J ¼ 1:8 Hz), 5.79
(1H, m), 4.97 (1H, dt, J ¼ 17:0, 1.2 Hz), 4.90 (1H, dt,
J ¼ 10:0, 1.2 Hz), 2.39 (2H, td, J ¼ 7:2, 1.8 Hz), 2.01 (2H,
q, J ¼ 7:2 Hz), 1.60 (2H, pent., J ¼ 7:2 Hz), 1.34 (2H, m),
1.24 (14H, m); 13C NMR (CDCl3, 150 MHz) ꢁ 202.9 d,
139.2 d, 114.1 t, 43.9 t, 33.8 t, 29.5 t, 29.5 t, 29.4 t, 29.3 t,
29.1 t (ꢃ3), 28.9 t, 22.1 t; HRESIMS [m=z (M + Na)þ;
found 233.1906, calcd for C14H26NaO (ꢀ þ2:5 mmu)].
a) P. M. Dewick, in Medicinal Natural Products: A Bio-
synthetic Approach, 2nd ed., Wiley, Chicester, 2002, pp.
35–120. b) P. Metzger, E. Villarrealrosales, E. Casadevall,
Phytochemistry 1991, 30, 185.
plausible biogenetic pathway shown in Scheme 2. It is assumed
that the aliphatic chains on 1 and 2 are derived from an unsatu-
rated fatty acid chain. Cyclopropane ring formation on the dou-
ble bond are formed from a carbocation intermediate provided
by S-adenosylmethionine (SAM), followed by bond cleavage
to construct the methylene bond in 2. On the other hand, the
methylation mechanism from carbocation intermediate can be
postulated by accepting hydride from some reducing agents,
such as NADPH, giving 1.9
9
In summary, a new durinskiol congener, durinskiol B (1)
Published on the web (Advance View) January 29, 2008; doi:10.1246/cl.2008.236