4
B.ꢀY. YANG ET AL.
3
.3. Extraction and isolation
The air-dried rattan stems of S. chinensis (13.5 kg) were extracted with 70% ethanol three
times, under reflux for 2 h each time. After solvent removal, the crude extract (1.82 kg) was
suspended in H O (26 L) and further extracted with petroleum ether (PE), EtOAc and BuOH,
2
successively, to obtain corresponding extracts after removal of the solvent. The n-butyl layer
(
110.6 g) was chromatographed on a silica gel column (200–300 mesh, 1 kg) using solvent
system CH Cl /MeOH (10:1 to 0:1) to give seven fractions (I-VII) based on TLC analysis. Fr. III
2
2
was subjected to silica gel chromatography, using solvent system CHCl /MeOH (200:1 to
2
0:1), to provide Fr. III-1 to III-11. Fr. III-3 was purified by preparative HPLC, to yield 2 (15 mg)
and 1 (5 mg). Fr. III-5 was purified by ODS chromatography to yield 3 (17 mg) and 7 (18 mg).
Fr. III-7 was purified by ODS chromatography to yield 12 (16 mg) and 11 (20 mg). Fr. IV was
subjected to ODS chromatography, to provide Fr. IV-1 to IV-10. Fr. IV-5 was purified by pre-
parative HPLC to yield 4 (23 mg). Fr. IV-6 was purified by preparative HPLC to yield 8 (9 mg)
and 5 (11 mg). Fr. VI was subjected to silica gel chromatography, using solvent system CHCl2/
MeOH (200:1 to 0:1), to provide Fr. VI-1 to VI-12. Fr. VI-7 was purified by preparative HPLC, to
yield 9 (22 mg), Fr. VI-8 was purified by preparative HPLC, to yield 6 (16 mg). Fr. VII was further
subjected to CC (Silica gel CHCl /MeOH 200:1 to 0:1) to resolve into compounds 13 (15 mg)
2
and 10 (19 mg).
2
2
Schilignan F (1): white amorphous powder.[ꢀ] + 11 (c 0.1, MeOH). UV (MeOH) λ 233,
D
max
+
+
1
2
84 nm. HRESIMS m/z 537.1973 [M + H] (Calcd for C H O , 537.1972). H NMR (400 MHz,
26
33 12
MeOH): δ 7.10 (1H, d, J = 1.6 Hz, H-2), 6.72 (1H, d, J = 8.0 Hz, H-5), 6.85 (1H, dd, J = 1.6, 8.0 Hz,
H
H-6), 4.37 (1H, s, H-7), 4.10 (1H, d, J = 10.0 Hz, H-9a), 4.03 (1H, d, J = 10.0 Hz, H-9b), 6.95 (1H,
d, J = 1.6 Hz, H-2′), 6.80 (1H, d, J = 8.0 Hz, H-5′), 6.79 (1H, dd, J = 1.6, 8.0 Hz, H-6′), 5.23 (1H, d,
J = 6.4 Hz, H-7′), 3.56 (1H, m, H-8′), 3.91 (1H, m, H-9′a), 3.21 (1H, m, H-9b), 4.65 (1H, d, J = 7.7 Hz,
H-1″), 3.09 (1H, m, H-2″), 3.38 (1H, m, H-3″), 3.26 (1H, m, H-4″), 3.29 (1H, m, H-5″), 3.80 (1H,
dd, J = 2.0, 12.0 Hz, H-6″a), 3.57 (1H, dd, J = 5.8, 12.0 Hz, H-6″b), 3.85 (3H, s, -OCH ), 3.86 (3H,
3
13
s, -OCH ). C NMR (100 MHz, MeOH): δ 128.4 (C-1), 113.9 (C-2), 148.4 (C-3), 147.6 (C-4), 115.2
3
C
(
(
(
C-5), 122.4 (C-6), 91.4 (C-7), 97.3 (C-8), 73.1 (C-9), 131.0 (C-1′), 110.4 (C-2′), 148.9 (C-3′), 146.7
C-4′), 116.1 (C-5′), 119.3 (C-6′), 83.1 (C-7′), 54.4 (C-8′), 69.5 (C-9′), 100.1 (C-1″), 75.2 (C-2″), 78.2
C-3″), 71.4 (C-4″), 77.9 (C-5″), 62.6 (C-6″), 56.4 (3-OCH ), 56.5 (3′-OCH ).
3
3
3
.4. Acid hydrolysis of new compound (1) and GC analysis
A solution of schilignan F (1, 2.0 mg) were treated with 2 mL H O and 1 mL 2 N aqueous HCl
2
at 80 °C for 4 h. After cooling, H O (5 mL) was added and neutralized with 2 N KOH. Then,
2
the reaction mixtures were extracted with EtOAc (3 mL × 3). The aqueous layer removed
under reduced pressure, and dissolved in anhydrous pyridine (5 mL) and treated with
L-cysteine methyl ester hydrochloride (1.5 mg). The mixture was stirred at 60 °C for 1 h, then
150 μL of HMDS-TMCS (hexamethyldisi lazane-trimethylchlorosilane, 3:1) was added, then
stirred for another 30 min at 60 °C. After centrifuged off, the supernatant was concentrated
2
2
3
(
1 μL) was analyzed by GC-MS (Wu et al. 2012; Tabopda et al. 2016; Yang et al. 2017), respec-
tively. The absolute configurations of D-glucose for compound 1 was determined by the
same retentions times (R ) of standard D-glucose (R at 16.3 min).
t
t