D.T. Nga et al.
Phytochemistry Letters 27 (2018) 174–177
Fig. 3. Selected NOESY correlations of compound 1.
In the review of the phytochemical profile of Elaeocarpus genus,
to furnish compound 3 (8 mg), compound 4 (29 mg) and compound 5
(3.1 mg). Fraction F4 (12 g) was subjected to CC (240 g silica gel) with a
gradient of DCM-acetone to yield a mixture of compounds 4 and 6 (2:3),
compound 7 (13.5 mg) and compound 8 (17 mg), respectively.
Next, the n-BuOH residue (25 g) was subjected to a silica gel column
several cucurbitane-type triterpenes have been reported from E. chi-
nensis, E. hainanensis, etc. (Kinghorn et al., 1999; Meng et al., 2008), but
the oleanane-type triterpenes have not been identified from Elaeocarpus
sp. to date. These results propose a variation in the biosynthesis of the
triterpenoids in E. hainanensis and make a significant contribution to the
chemotaxonomic classification of the Elaeocarpus species.
2 2
(Φ60 mm × 80 mm) with stepwise gradient of CH Cl -MeOH (5:1→1:1,
v/v, 600 mL/fraction) to give 4 fractions (B1-B4). Fraction B1 (4.3 g) was
then loaded onto a silica gel column (Φ 45 mm × 350 mm) with an
3 2
eluent of CHCl -MeOH-H O (3:1:0.1, v/v/v, 1500 mL) to yield four sub-
fractions (B2.1-B2.4). Sub-fraction B2.2 (920 mg) was further purified on
3. Experimental
a reversed-phase C18 column (Φ30 mm × 350 mm) eluting with MeOH-
H O (1:1, v/v, 1400 mL) to furnish compound 1 (10.5 mg). Finally,
2
3.1. General experimental procedures
The silica gel 60 Å grade (40–63 μm) for column chromatography
compound 2 (12 mg) was obtained from sub-fraction B2.4 (1100 mg) by
using RP C18 column chromatography(Φ30 mm × 350 mm) with the
(
2
CC) was purchased from Merck (Darmstadt, Germany). Sephadex LH-
0 (25–100 μm) were purchased from Sigma-Aldrich (St Louis, MO).
Thin-layer chromatography (TLC) plates (silica gel 60 F254, 0.2 mm)
were obtained from Merck (Germany). Chemical spots on TLC plates
2
eluent of MeOH-H O (1:1, v/v, 1600 ml).
1α-Hydroxy-olean-12-en-3-O-β-D-xylopyranoside (1): white amor-
−
phous powder; C35
(calcd for 619.4215); H-NMR (CD
(CD OD, 125 MHz): See Table 1.
1α-Hydroxy-olean-12-en-3-O-β-L-arabinopyranoside (2): white amor-
58 6
H O ; HR-ESI-MS [M + HCOO] m/z 619.4212
1
13
after development were detected using 10% H
2
SO
4
in methanol. All
3
OD, 500 MHz) and
C-NMR
solvents were distilled and purified before use. The HR-MS spectra were
measured in the ESI mode on Agilent 6530 Accurate-Mass Q-TOF LC/
MS spectrometer (Agilent Technologies, USA). The 1H- and C NMR
spectra were recorded on a Bruker AM500 FT-NMR spectrometer
3
13
−
phous powder; C35
(calcd for 619.4215); H-NMR (CD
NMR (CD OD + CDCl , 125 MHz): See Table 1.
58 6
H O ; HR-ESI-MS [M + HCOO] m/z 619.4207
1
13
3
3
OD + CDCl , 500 MHz) and C-
(
Bruker Spin, Germany), resonating at 500 MHz and 125 MHz respec-
3
3
tively. Chemical shifts (δ) were expressed in ppm values with reference
to tetramethylsilane and coupling constants (J) were given in Hz. Gas
chromatography-GC (Shimadzu GC-2010 plus QP2020, Shimadzu
Corp., Japan) using a Shimadzu SH-Rxi-5 Sil capillary column (0.25 mm
ID × 30 mm) [column temperature 210 °C; detector temperature
Acid hydrolysis of 1 and 2: A solution of a compound (2.0 mg) in
HCl 1.0 M (3.0 mL) was heated under reflux for 2 h. Then, the reaction
mixture was concentrated in vacuum to dryness. The residue was ex-
3 2
tracted with CHCl and H O (5 mL each, 3 times). Next, the sugar re-
sidue obtained by concentration of the water layer was dissolved in dry
pyridine (0.1 mL). Then L-cysteine methyl ester hydrochloride in pyr-
idine (0.06 M, 0.1 mL) was added to the solution. After heating the
reaction mixture at 60 °C for 2 h, 0.1 mL of trimethylsilylimidazole was
added. Heating at 60 °C was continued for a further 2 h, and the mixture
was evaporated in vacuum to give a dried product, which was parti-
300 °C; injector temperature 270 °C; He gas flow rate 30 mL/min
(
splitting ratio: 1/30)] was used for sugar determination.
3.2. Plant material
tioned between n-hexane and H
using the GC procedure (General Procedures). The peaks of the hy-
drolysates of the respective glycosides were detected at t 8.21 min (D-
xylose) for 1 and at t 4.50 min (L-arabinose) for 2. The retention times
for the authentic samples (Sigma) after being treated similarly were
.21 min (D-xylose), 8.66 min (L-xylose), and 4.50 min (L-arabinose),
2
O. The n-hexane layer was analyzed
Elaeocarpus hainanensis Oliv. sample was collected in Ha Tinh pro-
vince, Vietnam and identified by Dr. Do Ngoc Dai, Department of
Forestry, Nghe An University of Economics. A voucher specimen (No.2-
MS.104.01–2014.34) has been deposited in the School of Chemical
Engineering, Hanoi University of Science and Technology.
R
R
8
respectively. Co-injection of the hydrolysates of the compounds with
standard D-xylose in 1 and L-arabinose in 2 gave single peaks.
3.3. Extraction and isolation
E. hainanensis sample (5.8 kg) was extracted with methanol (MeOH)
at room temperature (3 × 20 L × 24 h) and concentrated in vacuum at
5 °C. The obtained residue (354.2 g) was suspended in water (1000 mL)
Acknowledgement
5
and partitioned successively with n-hexane, dichloromethane (DCM),
and n-BuOH (each 3 × 1000 mL) to give residues of n-hexane (23.8 g),
DCM (80.4 g), and n-BuOH (28.70 g), respectively.
The work was completed with financial support from the project of
National Foundation for Science and Technology Development (104.01-
014.34.). We gratefully acknowledge the assistance of Dr. Nguyen
Xuan Nhiem, Department of Structural Research, Institute of Marine
Biochemistry (IMBC), Vietnam Academy of Science and Technology for
the HRESIMS measurement and Dr. Do Ngoc Dai, Department of
Forestry, Nghe An University of Economics, for the collection and
identification of the plant sample.
2
The DCM residue (60 g) was fractionated on a silica gel column
(
640 g silica gel) and eluting with a gradient of DCM-MeOH (1:0-0:1, v/
v) to give seven fractions (F1-F7). Fraction F3 (10 g) was repeatedly
chromatographed on a silica gel column (240 g silica gel) using mix-
tures of DCM-acetone to yield five fractions (F3.1-F3.5). Fraction F3.4
was purified by Sephadex LH-20 column chromatography with MeOH
176
Nga, Dao Thu
