Phragmalins from Xylocarpus moluccensis
Journal of Natural Products, 2009, Vol. 72, No. 9 1661
extracting with EtOAc (×3), the aqueous layer was acidified with HCl
to pH 3.0 and extracted with CH2Cl2 (×3). The organic layer was
combined, purified by Sephadex LH-20 CC (CH2Cl2-MeOH, 1:1), and
dried over anhydrous Na2SO4 to provide a mixture of 1:1 isobutanoic
acid and 2-methylbutyric acid (1.6 mg), which were identified on the
basis of their MS. Since isobutanoic acid is optically inactive, the
absolute configuration at C-2 in 2-methylbutyric acid was suggested
as S by the RD value [+10 (c 0.16, Me2CO)] of the above mixture. In
the same way, the absolute configuration of C-2 in the 2-methylbutyryl
group of moluccensins C-E (3-5) was also proved as S.
X-ray Crystallographic Analysis of Moluccensin A (1). A colorless
crystal of 1 was obtained in Me2CO. Crystal data were obtained on a
Bruker Smart 1000 CCD system diffractometer with graphite-mono-
chromated Mo KR radiation (λ ) 0.71073 Å) and operating in the ω
scan mode. The structure was solved by direct methods (SHELXS-97)
and refined using full-matrix least-squares difference Fourier techniques.
All non-hydrogen atoms were refined anisotropically, and all hydrogen
atoms were placed in idealized positions and refined as riding atoms
with the relative isotropic parameters. Crystallographic data for 1 have
been deposited with the Cambridge Crystallographic Data Centre with
the deposition number CCDC 743509. Copies of the data can be
obtained, free of charge, on application to the Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK [fax: +44(0)-1233-336033 or
Crystal Data of 1: orthorhombic, C35H44O11, space group P212121
with a ) 8.8804(4) Å, b ) 16.4376(8) Å, c ) 22.1252(10) Å, V )
3229.7(3) Å3, Z ) 4, Dcalcd ) 1.318 g/cm3, m ) 0.098 mm-1, and
F(000) ) 1368. Crystal size: 0.48 × 0.38 × 0.37 mm3. Independent
reflections: 3964 with Rint ) 0.0284. Observed reflections: 3964 with
[I > 4σ(I)]. The final indices were R1 ) 0.0374 and wR2 ) 0.0918 [I
> 2σ(I)].
Moluccensin A (1): colorless crystals (Me2CO); mp 88-90 °C;
1
[R]25 +1 (c 2.11, Me2CO); UV (MeCN) λmax 208.6, 255.9 nm; H
D
Figure 6. Diagnostic NOE correlations for moluccensin G (7).
and 13C NMR data (see Tables 1, 2); HR-TOFMS m/z 663.2782 [calcd
for C35H44O11Na [M + Na]+, 663.2776], HR-TOFMS m/z 641.2966
[calcd for C35H45O11 [M + H]+, 641.2962].
Experimental Section
Moluccensin B (2): white, amorphous powder; [R]25 -1 (c 3.56,
General Experimental Procedures. Melting points were measured
on an X4 micromelting point detector (Beijing Tech. Instrument Co.
Ltd., China). Optical rotations were recorded on a POLAPTRONIC
HNQW5 automatic high-resolution polarimeter (Schmidt & Haensch
Co. Ltd.). UV spectra were obtained on a Beckman DU-640 UV
spectrophotometer, and NMR spectra were recorded in CDCl3 using a
Bruker AV-400 spectrometer with TMS as the internal standard.
MALDITOFMS spectra were measured on a Bruker APEX II spec-
trometer in positive ion mode. Preparative HPLC was carried out on
ODS columns (250 × 10 mm i.d. and 250 × 4.6 mm i.d., YMC) with
a Waters 2998 photodiode array detector. For CC, silica gel (200-300
mesh) (Qingdao Marine Chemical Ind. Co. Ltd.) and RP C18 gel
(Cosmosil C18-PREP 140 µm, Nacalai Tesque, Kyoto, Japan) were
used.
Plant Material. The seeds of X. moluccensis were collected in
October 2007 at the mangrove wetlands in Krishna estuary, Andhra
Pradesh, India. The identification of the plant was performed by Mr.
Tirumani Satyanandamurty, principal at Government Degree College
at Amadala Valasa, Srikakulam Dist., Andhra Pradesh, India. A voucher
sample (No. IndianXM-01) is maintained in the Herbarium of the South
China Sea Institute of Oceanology.
Extraction and Isolation. The dried seeds (7.0 kg) of X. moluccensis
were extracted three times with 95% EtOH at room temperature. The
extract was concentrated under reduced pressure, followed by suspen-
sion in H2O and extraction with EtOAc. The resulting EtOAc extract
(320 g) was chromatographed on Si gel CC and eluted using a
CHCl3-MeOH system (100:0-5:1) to yield 230 fractions. Fractions
70 to 80 (19.0 g) were combined and further purified with RP C18 CC
(MeCN-H2O, 50:50-100:0) to afford 60 subfractions. Then subfrac-
tions 27 to 37 were combined and further purified with preparative
HPLC (YMC-Pack ODS-5-A, 250 × 20 mm i.d. and 250 × 4.6 mm
i.d., MeOH-H2O, 50:50 to 55: 45) to yield moluccensins A (1, 21.1
mg), B (2, 35.6 mg), C (3, 14.0 mg), D (4, 5.0 mg), E (5, 22.2 mg), F
(6, 19.3 mg), and G (7, 7.2 mg).
D
Me2CO); UV (MeCN) λmax 208.5, 254.7 nm; H and 13C NMR data
1
(see Tables 1, 2); HR-TOFMS m/z 677.2947 [calcd for C36H46O11Na
[M + Na]+, 677.2932], HR-TOFMS m/z 655.3153 [calcd for C36H47O11
[M + H]+, 655.3113].
Moluccensin C (3): white, amorphous powder; [R]25 +4 (c 1.4,
D
1
Me2CO); UV (MeCN) λmax 208.5, 254.7 nm; H and 13C NMR data
(see Tables 1, 2); HR-TOFMS m/z 677.2966 [calcd for C36H46O11Na
[M + Na]+, 677.2932], HR-TOFMS m/z 655.3131 [calcd for C36H47O11
[M + H]+, 655.3113].
Moluccensin D (4): white, amorphous powder; [R]25 -3 (c 0.1,
D
1
Me2CO); UV (MeCN) λmax 208.5, 254.7 nm; H and 13C NMR data
(see Tables 1, 2); HR-TOFMS m/z 693.2902 [calcd for C36H46O12Na
[M + Na]+, 693.2882], HR-TOFMS m/z 671.3075 [calcd for C36H47O12
[M + H]+, 671.3062].
Moluccensin E (5): white, amorphous powder; [R]25 -1 (c 2.22,
D
1
Me2CO); UV (MeCN) λmax 208.6, 255.9 nm; H and 13C NMR data
(see Tables 1, 2); HR-TOFMS m/z 671.3082 [calcd for C36H47O12 [M
+ H]+, 671.3062], HR-TOFMS m/z 688.3361 [calcd for C36H50O12N
[M + NH4]+, 688.3328].
Moluccensin F (6): white, amorphous powder; [R]25 +1 (c 1.93,
D
1
Me2CO); UV (MeCN) λmax 208.6, 255.9 nm; H and 13C NMR data
(see Tables 1, 2); HR-TOFMS m/z 663.2773 [calcd for C35H44O11Na
[M + Na]+, 663.2776], HR-TOFMS m/z 641.2988 [calcd for C35H45O11
[M + H]+, 641.2956].
Moluccensin G (7): white, amorphous powder; [R]25D + 16 (c 0.72,
1
Me2CO); UV (MeCN) λmax 208.6, 285.6 nm; H and 13C NMR data
(see Tables 1, 2); HR-TOFMS m/z 661.2635 [calcd for C35H42O11Na
[M + Na]+, 661.2619], HR-TOFMS m/z 639.2828 [calcd for C35H43O11
[M + H]+, 639.2805].
Acknowledgment. Financial support for this work from the Impor-
tant Project of Chinese Academy of Sciences (KSCX2-YW-R-093,
KZCX2-YW-216), the National High Technology Research and
Development Program of China (863 Program) (2007AA09Z407), the
National Natural Science Foundation of China (20772135), and the
Research Foundation for Young Talents from the South China Sea
Institute of Oceanology, Chinese Academy of Sciences (Min-Yi Li,
SQ200802), is gratefully acknowledged. We are grateful to Mr. T.
Absolute Configuration of C-2 in the 2-Methylbutyryl Group of
Moluccensins B-E (2-5). A portion of moluccensin B (2, 7 mg) was
dissolved in EtOH (0.5 mL) and treated with 6% KOH in H2O (1 mL)
with stirring at room temperature for 24 h. The reaction mixture was
concentrated and partitioned between EtOAc and H2O (3:1). After