Journal of Asian Natural Products Research
177
HR-TOF-MS: m/z 993.5748 [M þ Na]þ
above. The aqueous layer was concentrated
to dryness to give a residue which was
dissolved in pyridine (1 ml), and then
hexamethyldisilazane (0.4 ml) and tri-
methylchlorosilane (0.2ml) were added to
the solution to obtain the trimethylsilyl
(TMS) ethers. The mixture was kept at 208C
for 15min, and extracted with H2O (1 ml).
Each aqueous layer was examined by GC
(H2 flame ionization detector, column
temperature: 100–2808C, programmed
increase: 108C/min, carrier gas: N2
(1.5ml/min), injector and detector tempera-
ture: 2808C, injection volume: 1 ml, split
ratio: 10:1). The derivatives of L-arabinose,
D-xylose, L-rhamnose, and D-glucose were
detected. tR: 6.20, 8.84, 9.76, and 26.59 min,
respectively. The standard monosacchar-
ides were subjected to the same operation
and GC analysis under the same condition.
(calcd for C51H86O17Na, 993.5757).
3.3.3 (23S)-21R-O-n-Butyl-19-oxo-3b,
20j,21-trihydroxy-21,23-epoxydammar-
24-ene 3-O-[a-L-rhamnopyranosyl
(1 ! 2)][b-D-xylopyranosyl(1 ! 3)]-a-L-
arabinopyranoside (3)
White amorphous powder, Libermann–
Burchard and Molish reactions were
20
positive. MP 201–2038C, ½aꢀD þ21.7
(c ¼ 0.83, MeOH). IR (KBr): nmax 3438,
2942, 1702, 1651, 1540, 1453, 1384, 1259,
C
1041, 817, 783, 610 cm21. For 1H and 13
NMR spectral data see Table 3. HR-TOF-
MS: m/z 977.5448 [M þ Na]þ (calcd for
C50H82O17Na, 977.5444).
3.3.4 (23S)-21S-O-n-Butyl-19-oxo-3b,
20j,21-trihydroxy-21,23-epoxydammar-
24-ene 3-O-[a-L-rhamnopyranosyl
(1 ! 2)][b-D-xylopyranosyl(1 ! 3)]-a-L-
arabinopyranoside (4)
3.6 Antitumor bioassay
Antitumor activities were evaluated by
MTT assay [9] with Rg3 as the positive
control. Compounds 1–4 showed moder-
ate antitumor activities against HL-60,
Colon205, and Du145.
White amorphous powder, Libermann–
Burchard and Molish reactions were
20
positive. MP 203–2058C, ½aꢀD 211.0
(c ¼ 0.46, MeOH). IR (KBr): nmax 3430,
2929, 1707, 1637, 1384, 1043, 612 cm21
.
For 1H and 13C NMR spectral data see
Table 4. HR-TOF-MS: m/z 977.5443
[M þ Na]þ (calcd for C50H82O17Na,
977.5444).
References
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3.4 Acid hydrolysis of 1–4
Each compound (4 mg) was heated in 5 ml
of 2 M HCl–MeOH (4:1) at 908C for 6 h in
a water bath. After cooling, the reaction
mixture was diluted to 20 ml with water
and then extracted with CHCl3
(20 ml £ 3). After concentration, each
aqueous layer was examined by TLC
(CHCl3–MeOH–H2O 55:45:10) and com-
pared with the authentic samples.
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3.5 Determination of sugar components
The monosaccharide subunits were
obtained by HCl hydrolysis as described