J. Nat. Prod. 2005, 68, 1341-1344

1341

Structure of New Carotenoids from Corbicula Clam Corbicula japonica
Takashi Maoka,*,† Yasuhiro Fujiwara,‡ Keiji Hashimoto,§ and Naoshige Akimoto⊥Research Institute for Production Development, 15 Shimogamo-morimoto-cho, Sakyo-ku, Kyoto 606-0805, Japan, Kyoto
Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan, Nagahama Institute of
Bio-sciences and Technology, Tamura-cho, Nagahama, Shiga 526-0829, Japan, and Graduate School of Pharmaceutical
Sciences, Kyoto University, Yoshida-shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
Received April 11, 2005

Six new carotenoids, named corbiculaxanthin (1), corbiculaxanthin 3′-acetate (2), 6-epiheteroxanthin (3),7′,8′-didehydrodeepoxyneoxanthin (4), cyclopyrrhoxanthin (5), and hydratoperidinin (6), were isolated
from the corbicula clam (Shijimi in Japanese), Corbicula japonica. Their structures were determined bychemical and spectral data.
Corbicula clam (Shijimi in Japanese), Corbicula japonica,
which inhabits brackish water, is an important edible
shellfish in Japan. There have been several reports oncarotenoids in marine shellfish,1 but few studies on carotenoids in brackish and freshwater shellfish were carriedout.1 In the course of studies on the carotenoids inshellfish,2 six new carotenoids were isolated from C.
japonica as minor components along with β-carotene,alloxanthin, diadinoxanthin, diadinochrome, peridinin,
pyrrhoxanthin, and fucoxanthin. This paper reports theisolation and structural elucidation of these new carotenoids.3
Results and Discussion
The acetone (Me2CO) extract of the edible part of C.
japonica (450 g) was chromatographed on silica gel using
an increasing percentage of acetone (Me2CO) in hexane.
The fraction eluted with Me2CO-hexane (6:4) was subjected to HPLC on silica gel with Me2CO-hexane (6:4) andthen on ODS with CHCl3-MeCN (1:9) to yield 1 (0.2 mg),
2 (0.5 mg), 3 (1 mg), 4 (0.1 mg), 5 (1 mg), and 6 (0.03 mg).
Compound 1, named corbiculaxanthin, showed UV-vis
absorption maxima at 420, 443, and 472 nm. The molecular
formula of 1 was determined to be C40H56O4 by HRFABMS
data. The presence of three secondary hydroxy groups andone tertiary hydroxy group in 1 was consistent with theformation of a triacetate and a tetratrimethylsilyl ether of
1. The 1H NMR data of 1 indicated the presence of a 3,4(cis)-dihydroxy-β-end group, a 3,5-dihydroxy-β-end group,
and a polyene chain containing an allenic group (δ 6.03, s,H-8′).4 These partial structures were confirmed by 1H-1H
COSY and NOESY (Figure 1) experiments. The cis configuration of the 3,4-dihydroxy group was revealed by acoupling constant between H-3 and H-4 of 3.5 Hz4 and NOE
between H-3 and H-4. Furthermore, NOESY correlations
H-3/H-16, H-3/H-4, H-4/H-18, H-3′/H-16′, H-3′/Heq-2′(R),and H-3′/Heq-4′(R) revealed the relative stereochemistry of
both end groups (Figure 1). The overall E geometry of thepolyene chain was also confirmed by the NOESY data.
Therefore, the structure of 1 was determined to be 6′,7′didehydro-5′,6′-dihydro-β,β-carotene-3,4,3′,5′-tetrol. The CD* To whom correspondence should be addressed. Research Institute for
Production Development, 15 Shimogamo-Morimoto-Cho, Sakyou-ku, Kyoto
607-0805, Japan. Tel: +81-75-781-1107. Fax: +81-75-722-8694. E-mail:maoka@mbox.kyoto-inet.or.jp.
† Research Institute for Production Development.
‡ Kyoto Pharmaceutical University.
§ Nagahama Institute of Bio-sciences and Technology.
⊥ Kyoto University.

10.1021/np058053n CCC: $30.25

spectrum of 1 showed a weak negative cotton effect, which
was similar to that of deepoxyneoxanthin.5 On the basisof CD data, biosynthetic considerations, and the relative
stereochemistry of 3,4-dihydroxy group, a (3S,4R,3′S,5′R,6′R)configuration was postulated for 1.
Compound 2 showed the same absorption maxima as 1.
The molecular formula of 2 was determined to be C42H58O5© 2005 American Chemical Society and American Society of Pharmacognosy
Published on Web 08/13/2005

1342 Journal of Natural Products, 2005, Vol. 68, No. 9

Maoka et al.

Figure 2. Key HMBC correlations of 3 and 5.

Figure 1. Key NOESY correlations of 1, 2, 3, and 5.

by HRFABMS data. Compound 2 showed almost the same
1H NMR signals as 1 except for the presence of an acetylgroup at δ 2.04 and an acetylated oxymethine at δ 5.38
instead of a free oxymethine at δ 4.31 (H-3′) for 1. These
spectral data suggested that 2 was the 3′-acetate of 1. This
structure was confirmed by 1H-1H COSY and NOESY(Figure 1) experiments. Compound 2 showed also the same
CD spectrum as that of 1. Therefore, the structure of 2 wasdetermined to be (3S,4R,3′S,5′R,6′R)-3′-ethanoyloxy-6′,7′didehydro-5′,6′-dihydro-β,β-carotene-3,4,5′-triol, and thecompound was named corbiculaxanthin 3′-acetate.
Compound 3 showed UV-vis absorption maxima at 420,
443, and 472 nm. The molecular formula of 3 was determined to be C40H56O4 by HRFABMS data. The presence of
two secondary hydroxy groups and two tertiary hydroxygroups in 3 was revealed by acetylation, HRFABMS, 1H,
and 13C NMR data. 1H and 13C NMR of 3 showed thepresence of an alloxanthin moiety (C-1′ to C-20′).4 The
partial structure of the other end group (3,5,6-trihydroxy5,6-dihydro-β-end group) was elucidated by 1H-1H COSY,
HSQC, HMBC (Figure 2), and NOESY (Figure 1) experiments. Therefore, the structure of 3 was determined to be7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,5,6,3′-tetrol. Concerning the naturally occurring carotenoids with the 3,5,6trihydroxy-5,6-dihydro-β-end group, four kinds of stereoisomers [i.e., (3S,5R,6R), (3S,5S,6S), (3S,5S,6R), and(3S,5R,6S)] have been reported.6 The 1H and 13C NMR
spectral data of the 3,5,6-trihydroxy-5,6-dihydro-β-end
group in 3 do not coincide with those of the (3S,5R,6R),(3S,5S,6S), and (3S,5S,6R) configurations but coincide withthe (3S,5R,6S) configuration. Furthermore, NOESY correlations of H16/Heq-2(R), H-16/H-3, and H17/H7 also
supported this stereochemistry (Figure 1). Moreover, 3
showed a negative weak CD spectrum similar to that ofheteroxanthin.6a Therefore, the structure of 3 was determined to be (3S,5R,6S,3′R)-7′,8′-didehydro-5,6-dihydro-β,βcarotene-3,5,6,3′-tetrol. This structure corresponds to the
6-epimer of heteroxanthin. Therefore, compound 3 wasnamed 6-epiheteroxanthin.
Compound 4 showed UV-vis absorption maxima at 420,
443, and 472 nm. The molecular formula of 4 was determined to be C40H54O3 by HRFABMS data. 1H NMR of 4
showed the presence of neoxanthin (H-2 to H-20′) andalloxanthin (H-2′ to H-20′) moieties.4 This was confirmedby the 1H-1H COSY experiment. Therefore, the structureof 4 was determined to be 6,7,7′,8′-tetradehydro-5,6-dihydro-β,β-carotene-3,5,3′-triol, and the compound was named
7′,8′-didehydrodeepoxyneoxanthin. The CD spectrum of 4
was almost the same as that of alloxanthin.2a Therefore,(3S,5R,6S,3′R) chirality was postulated for 4.
Compound 5 showed UV-vis absorption maxima at 455
and 475 nm. The molecular formula of 5 was determined
to be C39H48O6 by HRFABMS data. The 1H and 13C NMR
data of 5 were almost identical with those of pyrrhoxanthin4 except for the signals of the end group (C1 to C6
including C16, C17, and C18). The 1H and 13C NMR signalsof the remaining end group were similar to those of
cycloviolaxanthin, which has a (3S,5R,6R)-3,6-epoxy-5,6dihydro-5-hydroxy-β-end group.7 Thus, the structure 3,6epoxy-3′-ethanoyloxy-3-hydroxy-7′,8′-didehydro-5,6-dihydro12′,13′,20′-trinor-β,β-caroten-19,11-olide was postulated for
5. This structure was confirmed by 1H-1H COSY, TOCSY,NOESY (Figure 1), HSQC, and HMBC (Figure 2) experiments. The stereochemistry of 5 was elucidated fromNOESY and CD data by comparing it with those of
pyrrhoxanthin and cycloviolaxanthin.7 The CD spectrumof 5 was similar to that of pyrrhoxanthin. Therefore,(3S,5R,6R,3′R) chirality was postulated for 5. Compound
5 was named cyclopyrrhoxanthin after the presence of a3,6-epoxy end group, such as cycloviolaxanthin.
Compound 6 showed UV-vis absorption maxima at 455
and 475 nm. The molecular formula of 6 was determined
to be C39H52O8 by HRFABMS data. Acetylation of 6 gavea monoacetate. Because of the small amount of sample andcontamination of lipids, two-dimensional NMR experiments
could not be performed, so methylene signals in the end
groups could not be completely assigned. The 1H NMR data
for the methyl groups of H-20, 16′ to 19′, methine signal of
H-3′, and olefinic protons H-10 to H-8′ were almost thesame as those of peridinin.8 Positive ion FAB MS/MS
showed the characteristic product ions at m/z 630 [M H2O]+•, 612 [M - 2H2O]+•, 588 [M - AcOH]+•, and 570 [M- AcOH - H2O]+•., which were 18 mass units above thecorresponding ions of peridinin. These data clearly indicated that 6 is a hydrate product of peridinin. The presenceof a 3,5,6-trihydroxy-5,6-dihydro-β-end group in 6 wasdeduced from the HRFABMS, FAB MS/MS, and 1H NMR
data and the result of acetylation. Therefore, the planar
structure of 6 was deduced to be 3′-ethanoyloxy-3,5,6,5′tetrahydroxy-6′,7′-didehydro-5,6,5′,6′-tetrahydro-12′,13′,20′- trinor-β,β-caroten-19,11-olide, and the compound wasnamed hydratoperidinin. Concerning the peridinin derivatives with a 3,5,6-trihydroxy-5,6-dihydro-β-end group, hydratopyrrhoxanthinol, having (3S,5R,6R,3′R) chirality, wasisolated from marine shellfish, Mytilus edulis.9 The chemical shift values of methyl signals at H-16 and H-17 in 6

Structure of New Carotenoids from Corbicula japonica

were slightly different from those of hydratopyrrhoxanthinol. This fact indicated that the chirality of the 3,5,6trihydroxy-5,6-dihydro-β-end group in 6 was different fromthat of hydratopyrrhoxanthinol. The CD spectrum of 6 wassimilar to that of peridinin, having (3S,5R,6S,3′S,5′R,6′R)
chirality. On the basis of the CD data and biosynthetic
considerations of epoxide hydrolysis of peridinin, (3S,5R,6S,3′S,5′R,6′R) chirality was proposed for 6.
Experimental Section
General Experimental Procedures. The CD spectra wererecorded in Et2O at room temperature with a JASCO J-500
spectropolarimeter. The UV-vis spectra were recorded witha Shimadzu U-2001 spectrophotometer in diethyl ether (Et2O).
The 1H NMR (500 MHz) and 13C NMR (125 MHz) spectra were
measured with a Varian UNITY INOVA 500 spectrometer in
CDCl3 with TMS as an internal standard. Gradient (g) 1H1
H COSY, NOESY (mixing time 1.3 s), gHSQC (1JCH ) 142Hz), gHMBC (nJCH optimized for 8 Hz), and TOCSY (mixing
time 0.08 s) spectra were acquired using the standard Varianpulse programs with the Varian software, version 6.1A. All
two-dimensional NMR and 13C NMR spectra were measured
in 0.2 mL of CDCl3 solution using a SHIGEMI tube (Shigemi
Co., Ltd, Tokyo, Japan). The positive ion FAB-MS and CIDMS/MS spectra10 were recorded using a JEOL JMS-HX/HX
110A four-sector tandem mass spectrometer with m-nitrobenzyl alcohol (m-NBA) as a matrix. The CID-MS/MS was
performed with a FAB gun operated at 6 kV. A few microgramsof sample dissolved in CHCl3 was placed on a stainless steel
probe tip, and 1-2 µL of m-NBA was added as a matrix. The
sample was bombarded with xenon atoms, and the ionsproduced were accelerated through 10 keV. The radical cation
M+• selected as a precursor by MS1 was subjected to collisions
with argon gas in the collision cell, floated at a potential of 8kV, between MS1 and MS2. The amount of argon gas was
adjusted to attenuate the intensity of the precursor ion by 30%.
The resulting product ions were acquired with a JEOL ADS11 array detector on MS2. HPLC was performed on a Shimadzu LC-6AD with a Shimadzu SPD-6AV spectrophotometer
set at 450 nm. Acetylation and trimethyl silylations werecarried out using standard procedures.11
Animal Material. Corbicula clam, C. japonica (grown in
Lake Shinji, Shimane Prefecture), was purchased at a local
fish market in January and February. Voucher specimens havebeen deposited at the Research Institute for Production
Development.
Extraction and Isolation of Carotenoids. The Me2CO
extract of the edible parts of C. japonica (450 g) was partitioned
between diethyl ether (Et2O) and aqueous NaCl. The organic
layer was dried over Na2SO4 and then concentrated to dryness.
The residue was subjected to silica gel column chromatographyusing an increasing percentage of Me2CO in n-hexane. The
fraction eluted with Me2CO-hexane (6:4) was subjected to aseries of HPLCs on silica gel with Me2CO-hexane (6:4) andthen on ODS with CHCl3-MeCN (1:9) to yield 1 (0.2 mg), 2(0.5 mg), 3 (1 mg), 4 (0.1 mg), 5 (1 mg), and 6 (0.03 mg).
In the present investigation, the following known carotenoids were also isolated and identified: β-carotene (0.5 mg),
alloxanthin (2.0 mg), diadinoxanthin (1.0 mg), diadinochrome(3.5 mg), peridinin (9.0 mg), pyrrhoxanthin (1.0 mg), andfucoxanthin (0.5 mg).
Corbiculaxanthin (1): CD (20 µg/mL Et2O) λ (∆) nm 220(0), 235 (-5.0), 280 (-3.0), 330 (-2.8), 350 (0); UV-vis (Et2O)
λmax 420, 443, 472 nm, %III/II ) 50; 1H NMR (CDCl3, 500 MHz)δ 1.07 (6H, s, H-17, 17′), 1.09 (3H, s, H-16), 1.34 (1H,
overlapped, Hax-2′(β)), 1.34 (3H, s, H-16′), 1.35 (3H, s, H-18′),
1.41 (1H, dd, J ) 12.5, 12.5 Hz, Hax-4′(β)), 1.57 (1H, ddd, J )12.5, 4, 1 Hz, Heq-2(R)), 1.68 (1H, dd, J ) 12.5, 12.5 Hz, Hax2(β)), 1.80 (3H, s, H-19′), 1.90 (3H, s, H-18), 1.95 (1H,
overlapped, Heq-2′(R)), 1.97 (9H, s, H-20, 19′, 20′), 2.27 (1H,
ddd, J ) 12.5, 4.5, 2 Hz, Heq-4′(R)), 3.87 (1H, m, H-3), 3.96
(1H, d, J ) 3.5 Hz, H-4), 4.31 (1H, m, H-3′), 6.03 (1H, s, H-8′),

Journal of Natural Products, 2005, Vol. 68, No. 9 1343

6.07 (1H, d, J ) 16 Hz, H-7), 6.10 (1H, d, J ) 11.5 Hz, H-10),
6.12 (1H, d, J ) 11.5 Hz, H-10′), 6.17 (1H, d, J ) 16 Hz, H-8′),
6.26 (1H, m, H-14′), 6.27 (1H, m, H-14), 6.34 (1H, d, J ) 15.5
Hz, H-12), 6.38 (1H, d, J ) 15.5 Hz, H-12′), 6.55 (1H, dd, J )15.5, 11.5 Hz, H-11), 6.63 (1H, dd, J ) 15.5, 11.5 Hz, H-11′),
6.64 (2H, m, H-15, 15′); HRFABMS m/z 600.4171 (C40H56O4,
calcd for 600.4178).
Acetylation of 1 in dry pyridine with Ac2O at room temperature produced a triacetate which showed molecular ion at m/z
726 by FABMS, and trimethyl silylation of 1 provided tetratrimethylsilyl ether of 1 which showed molecular ion at m/z
888 by FABMS.
Corbiculaxanthin 3′-acetate (2): CD (20 µg/mL Et2O) λ(∆) nm 220 (0), 235 (-5.0), 280 (-3.0), 330 (-2.8), 350 (0);UV-vis (Et2O) λmax 420, 443, 472 nm, %III/II ) 50; 1H NMR(CDCl3, 500 MHz) δ 1.07 (6H, s, H-17, 17′), 1.09 (3H, s, H-16),
1.35 (3H, s, H-18′), 1.38 (3H, s, H-16′), 1. 41 (1H, dd, J ) 12.5,
12.5, Hax-2′(β)), 1.51 (1H, dd, J ) 12.5, 12.5 Hz, Hax-4′(β)), 1.57
(1H, ddd, J ) 12.5, 4, 1 Hz, Heq-2(R)), 1.68 (1H, dd, J ) 12.5,
12.5 Hz, Hax-2(β)), 1.80 (3H, s, H-19′), 1.90 (3H, s, H-18), 1.97
(9H, s, H-20, 19′, 20′), 1.99 (1H, overlapped, Heq-2′(R)), 2.04
(3H, s, COCH3), 2.28 (1H, ddd, J ) 12.5, 4.5, 2 Hz, Heq-4′(R)),
3.87 (1H, m, H-3), 3.96 (1H, d, J ) 3.5 Hz, H-4), 5.38 (1H, m,H-3′), 6.05 (1H, s, H-8′), 6.07 (1H, d, J ) 16 Hz, H-7), 6.10
(1H, d, J ) 11.5 Hz, H-10), 6.15 (1H, d, J ) 11.5 Hz, H-10′),
6.17 (1H, d, J ) 16 Hz, H-8′), 6.26 (1H, m, H-14′), 6.27 (1H,m, H-14), 6.34 (1H, d, J ) 15.5 Hz, H-12), 6.38 (1H, d, J )15.5 Hz, H-12′), 6.55 (1H, dd, J ) 15.5, 11.5 Hz, H-11), 6.63
(1H, dd, J ) 15.5, 11.5 Hz, H-11′), 6.64 (2H, m, H-15, 15′);HRFABMS m/z 642.4290 (C42H58O5, calcd for 642.4285).
6-Epiheteroxanthin (3): CD (20 µg/mL Et2O) λ (∆) nm
230 (-1.0), 240 (-2.0), 250 (-3.0), 320 (-1.2), 370 (0); UVvis (Et2O) λmax 420, 443, 472 nm, %III/II ) 50; 1H NMR (CDCl3,
500 MHz) δ 0.82 (3H, s, H-17), 1.01 (3H, s, H-18), 1.14 (3H, s,
H-16′), 1.20 (3H, s, H-17′), 1.25 (3H, s, H-16), 1.45 (1H, dd, J) 12.5, 12.5 Hz, Hax-2′(β)), 1.54 (1H, dd, J ) 12.5, 12.5 Hz,
Hax-2(β)), 1. 61 (1H, dd, J ) 13.5, 11 Hz, Hax-4(β)), 1.77 (1H,
ddd, J ) 12.5, 4, 2.5 Hz, Heq-2(R)), 1.84 (1H, ddd, J ) 12.5, 4,
1.5 Hz, Heq-2′(R)), 1.92 (6H, s, H-19, 18′), 1.96 (3H, s, H-20′),
1.97 (3H, s, H-20), 2.01 (3H, s, H-19′), 2.07 (1H, dd, J ) 18, 10
Hz, Hax-4′(β)), 2.11 (1H, ddd, J ) 13.5, 4, 2.5 Hz, Heq-4(R)),
2.43 (1H, ddd, J ) 18, 5, 1.5 Hz, Heq-4′(R)), 3.99 (1H, m, H-3′),
4.28 (1H, m, H-3), 5.87 (1H, d, J ) 16 Hz, H-7), 6.22 (1H, d, J
) 11.5 Hz, H-10), 6.27 (2H, m, H-14, H-14′), 6.36 (1H, d, J )15.5 Hz, H-12′), 6.38 (1H, d, J ) 15.5 Hz, H-12), 6.42 (1H, d,
J ) 16 Hz, H-8), 6.46 (1H, d, J ) 11.5 Hz, H-10′), 6.51 (1H,
dd, J ) 15.5, 11.5 Hz, H-11′), 6.62 (1H, dd, J ) 15.5, 11.5 Hz,
H-11), 6.65 (2H, m, H-15, 15′); 13C NMR (CDCl3, 125 MHz) δ
12.8 (q, C-20, 20′), 13.2 (q, C-19), 18.1 (q, C-19′), 22.5 (q, C-18′),
27.8 (q, C-18), 28.6 (q, C-17), 28.8 (q, C-16′), 29.7 (q, C-16),
30.5 (q, C-17′), 36.6 (s, C-1′), 39.7 (s, C-1), 41.5 (t, C-4′), 45.7
(t, C-4), 46.7 (t, C-2′), 46.9 (t, C-2), 64.4 (d, C-3), 64.9 (d, C-3′),
76.5 (s, C-5), 79.3 (s, C-6), 89.0 (s, C-7′), 98.6 (s, C-8′), 120.0(s, C-9′), 124.2 (d, C-11′), 124.8 (d, C-11), 124.9 (s, C-6′), 129.4(d, C-7), 130.1 (d, C-15 or 15′), 130.4 (d, C-15′ or 15), 132.0 (d,C-10), 132.8 (d, C-8), 133.1 (d, C-14 or 14′), 133.5 (d, C-14′ or14), 134.5 (s, C-9), 135.2 (d, C-10′), 136.3 (s, C-13′ or 13), 136.7(s, C-13 or C-13′), 137.3 (s, C-5′), 138.0 (d, C-12), 138.1 (d,C-12′); HRFABMS m/z 600.4174 (C40H56O4, calcd for 600.4178).
Acetylation of 3 in dry pyridine with Ac2O at room temperature produced a diacetate which showed molecular ion at m/z
684 by FABMS.
7′,8′-Didehydrodeepoxyneoxanthin (4): CD (20 µg/mL
Et2O) λ (∆) nm 240 (-1.5), 255 (-0.5), 280 (-2.0), 350 (0);UV-vis (Et2O) λmax 420, 443, 472 nm, %III/II ) 50; 1H NMR(CDCl3, 500 MHz) δ 1.07 (3H, s, H-17), 1.15 (3H, s, H-16′),
1.20 (3H, s, H-17′), 1.34 (1H, overlapped, Hax-2(β)), 1.34 (3H,s, H-16), 1.35 (3H, s, H-18), 1.41 (1H, dd, J ) 12.5, 12.5 Hz,
Hax-4(β)), 1.45 (1H, dd, J ) 12.5, 12.5 Hz, Hax-2′(β)), 1.80 (3H,s, H-19), 1.84 (1H, ddd, J ) 12.5, 4, 1.5 Hz, Heq-2′(R)), 1.92
(3H, s, H-19′), 1.95 (1H, overlapped, Heq-2(R)), 1.96 (6H, s,
H-20, 20′), 2.01 (3H, s, H-19′), 2.07 (1H, dd, J ) 18, 10 Hz,
Hax-4′(β)), 2.27 (1H, ddd, J ) 12.5, 4, 2 Hz, Heq-4(R)), 2.43 (1H,
ddd, J ) 18, 5, 1.5 Hz, Heq-4′(R)), 3.99 (1H, m, H-3′), 4.28 (1H,m, H-3), 6.03 (1H, s, H-8), 6.12 (1H, d, J ) 11.5 Hz, H-10),

1344 Journal of Natural Products, 2005, Vol. 68, No. 9

6.26 (1H, m, H-14), 6.27 (1H, m, H-14′), 6.36 (1H, d, J ) 15.5
Hz, H-12′), 6.38 (1H, d, J ) 15.5 Hz, H-12), 6.46 (1H, d, J )11.5 Hz, H-10′), 6.55 (1H, dd, J ) 15.5, 11.5 HZ, H-11), 6.63
(1H, dd, J ) 15.5, 11.5 HZ, H-11), 6.64 (2H, m, H-15, 15′);HRFABMS m/z 582.4078 (C40H54O3, calcd for 582.4073).
Cyclopyrrhoxanthin (5): CD (20 µg/mL Et2O) λ (∆) nm
230 (-1.5), 250 (-2.5), 275 (-1.0), 350 (0); UV-vis (Et2O) λmax
455 and 475 nm, %III/II ) 9; 1H NMR (CDCl3, 500 MHz) δ
0.89 (3H, s, H-17), 1.18 (3H, s, H-16′), 1.20 (3H, s, H-17′), 1.22
(3H, s, H-18), 1.47 (3H, s, H-16), 1.57 (1H, dd, J ) 12.5, 12.5
Hz, Hax-2′(β)), 1.63 (1H, d, J ) 12 Hz, Heq-2(β)), 1.71 (1H, d, J
) 12 Hz, Heq-4(β)), 1.84 (2H, overlapped, Hax-2(R) and Heq-2′(R)), 1.91 (3H, s, H-18′), 2.00 (3H, s, H-20), 2.04 (1H, ddd, J )12, 6, 2 Hz, Hax-4(R)), 2.05 (3H, s, CH3CO), 2.13 (1H, dd, J )18, 9 Hz, Haq-4′(β)), 2.24 (3H, s, H-20), 2.50 (1H, ddd, J ) 18,
5.5, 2 Hz, Heq-4′(R)), 4.41 (1H, t, J ) 6 Hz, H-3), 5.40 (1H, m,H-3′), 5.72 (1H, s, H-12), 6.41 (1H, dd, J ) 14.5, 11.5 Hz, H-14′),
6.44 (1H, d, J ) 16 Hz, H-8), 6.44 (2H, d, J ) 11.5 Hz, H-10′,
H-14), 6.50 (1H, dd, J ) 14.5, 11.5 Hz, H-15), 6.57 (1H, dd, J) 14.5, 11.5 Hz, H-11′), 6.64 (1H, dd, J ) 14.5, 11.5 Hz, H-15),
6.96 (1H, d, J ) 16 Hz, H-7), 7.01 (1H, s, H-10′); 13C NMR(CDCl3, 125 MHz) δ 15.5 (q, C-20), 18.1 (q, C-19′), 21.4 (q,COCH3), 22.4 (q, C-18′), 25.5 (q, C-16), 28.7 (q, C-16′), 30.2 (q,C-17′), 31.5 (q, C-18), 32.0 (q, C-17), 36.1 (s, C-1′), 37.5 (t, C-4′),
42.3 (t, C-2′), 44.0 (s, C-1), 47.5 (t, C-4), 48.4 (t, C-2), 67.9 (d,C-3′), 75.5 (d, C-3), 82.3 (s, C-5), 90.0 (s, C-7′), 91.9 (s, C-6),
98.5 (s, C-8′), 118.8 (d, C-12), 119.6 (d, C-8), 120.9 (s, C-9′),
124.3 (s, C-6′), 125.2 (s, C-9), 129.9 (d, C-15′), 130.5 (d, C-11′),132.3 (d, C-7), 133.8 (d, C-14′), 134.6 (s, C-13), 135.7 (d, C-10′),136.7 (d, C-10 and C-15), 137.2 (d, C-5′), 137.5 (d, C-14), 147.0(s, C-11), 168.8 (s, C-19), 170.7 (s, COCH3); HRFABMS m/z
612.3444 (C39H48O6, calcd for 612.3451).
Hydratoperidinin (6): CD (40 µg/mL Et2O) λ (∆) nm 240(-2.5), 253 (-4.0), 325 (-2.0), 350 (0); UV-vis (Et2O) λmax 455
and 475 nm, %III/II ) 9; 1H NMR (CDCl3, 500 MHz) δ 0.83
(3H, s, H-16 or 17), 1.07 (3H, s, H-17′), 1.12 (3H, s, H-16 or17), 1.35 (3H, s, H-18′), 1.39 (3H, s, H-16′), 1.43 (3H, s, H-18),
1.80 (3H, s, H-19′), 2.04 (3H, s, CH3CO), 2.23 (3H, s, H-20),
4.24 (1H, m, H-3), 5.38 (1H, m, H-3′), 5.73 (1H, s, H-12), 6.06
(1H, s, H-8′), 6.12 (1H, d, J ) 11.5 Hz, H-10′), 6.39 (1H, dd, J) 14.5, 11.5 Hz, H-14′), 6.45 (1H, d, J ) 11.5 Hz, H-14), 6.51

Maoka et al.

(1H, dd, J ) 14.5, 11.5 Hz, H-15′), 6.56 (1H, d, J ) 16 Hz,
H-8), 6.61 (2H, dd, J ) 14.5, 11.5 Hz H-15, 11′), 7.03 (1H, s,
H-10), 7.09 (1H, d, J ) 16 Hz, H-7); HRFABMS m/z 648.3671(C39H52O8, calcd for 648.3662); FAB MS/MS m/z 630 [M H2O]+•, 612 [M - 2H2O]+•, 588 [M - AcOH]+•, 570 [M - AcOH
- H2O]+•, and 552 [M - AcOH - 2H2O]+•.
Acetylation of 6 in dry pyridine with Ac2O at room temperature produced a monoacetate which showed molecular ion atm/z 690.3767 (C41H54O9, calcd for 690.3768) by HRFABMS.
Supporting Information Available: FAB MS/MS of M+• of
hydratoperidinin (6) and peridinin. This material is available freecharge via the Internet at http://pubs.acs.org.

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