Journal of Natural Products
Article
Rehmachingiioside G (7): amorphous powder, [α]2D0 −123.0 (c
0.11, MeOH); UV (MeOH) λmax (log ε) 202 (4.56) nm; CD
(MeOH) 200 (Δε −17.27) nm; IR νmax 3374, 2931, 1658, 1374, 1178,
Copies of IR, MS, 1D and 2D NMR, and CD spectra for
1
1047, 952 cm−1; H NMR (methanol-d4, 500 MHz) and 13C NMR
AUTHOR INFORMATION
Corresponding Author
*Tel: +86-10-63165224. Fax: +86-10-63017757. E-mail:
(methanol-d4, 125 MHz), see Tables 1 and 2; (+)-HRESIMS m/z
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719.2746 [M + Na]+ (calcd for C30H48O18Na, 719.2733).
Rehmachingiioside H (8): amorphous powder, [α]2D0 −91.6 (c 0.10,
MeOH); UV (MeOH) λmax (log ε) 202 (4.59) nm; CD (MeOH) 200
(Δε −18.31) nm; IR νmax 3387, 2919, 1657, 1371, 1080, 1051, 950
cm−1; 1H NMR (methanol-d4, 500 MHz) and 13C NMR (methanol-d4,
125 MHz), see Tables 1 and 2; (+)-HRESIMS m/z 719.2750 [M +
Na]+ (calcd for C30H48O18Na, 719.2733).
Notes
The authors declare no competing financial interest.
Rehmachingiioside I (9): amorphous powder, [α]2D0 −135.3 (c 0.10,
MeOH); UV (MeOH) λmax (log ε) 202 (4.67) nm; CD (MeOH) 200
(Δε −24.49) nm; IR νmax 3379, 2928, 1657, 1375, 1079, 1048, 952
cm−1; 1H NMR (methanol-d4, 500 MHz) and 13C NMR (methanol-d4,
125 MHz), see Tables 1 and 2; (+)-HRESIMS m/z 719.2741 [M +
Na]+ (calcd for C30H48O18Na, 719.2733).
ACKNOWLEDGMENTS
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The authors gratefully acknowledge grants from the National
Natural Science Foundation of China (No. 81403076) and the
State Key Laboratory of Bioactive Substance and Function of
Natural Medicines (No. GTZC201201), Institute of Materia
Medica, Chinese Academy of Medical Sciences and Peking
Union Medical College.
Acid Hydrolysis of 1−9. Each compound (6 mg) was refluxed
individually in 6% HCl (5.0 mL) at 80 °C for 2 h. Then, each reaction
mixture was extracted with CHCl3 (3 × 6 mL), and the H2O phase
was dried using a N2 stream. The residues were separately subjected to
column chromatography over silica gel with CHCl3−MeOH−H2O
(7:4:1) as eluent to yield D-glucose and D-glucuronic acid, respectively,
with D-glucose exhibiting [α]D20 +41.3 to +58.9 (lit. [α]2D5 +43.2,
H2O)17 and D-glucuronic acid, [α]D20 +15.9 (c 0.08, H2O). The sugars
were confirmed as D-glucose and D-glucuronic acid by comparison with
an authentic sample on TLC (CHCl3−MeOH−H2O, 6:4:1, Rf 0.45
and Rf 0.05) and by measuring their optical rotations as shown above.
Cytotoxicity Assay. Compounds 1−25 were tested for cytotox-
icity against HCT-8 (human colon carcinoma), Bel-7402 (human liver
carcinoma), BGC-823 (human stomach carcinoma), A549 (human
lung carcinoma), and A2780 (human ovarian carcinoma) by means of
an MTT method described in the literature. Taxol was used as the
positive control.15
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Inhibitory Effects on NO Production in LPS-Activated
Microglia. Compounds 1−25 were tested for their ability to inhibit
LPS-activated NO production in the BV2 cell line. The murine
microglial BV2 cells were obtained from the Cell Culture Centre at the
Institute of Basic Medical Sciences, Chinese Academy of Medical
Sciences, and LPS was purchased from Sigma-Aldrich. The BV2 cells
were plated into a 96-well plate. After being preincubated for 24 h, the
cells were pretreated with 0.3 μg/mL LPS for an additional 24 h.
Nitrite, which is a soluble oxidation product of NO, was determined in
the culture supernatant using the Griess reaction. NaNO2 was used as
−
a standard to assay the NO2 concentration. The OD values of the
samples at 550 nm were measured. Cell viability was assessed using an
MTT assay. Curcumin was used as the positive control.14
Hepatoprotective Activity Assay. Human HepG2 hepatoma
cells were cultured in DMEM medium supplemented with 10% fetal
calf serum, 100 U/mL penicillin, and 100 μg/mL streptomycin at 37
°C in a humidified atmosphere of 5% CO2 + 95% air. The cells were
then passaged by treatment with 0.25% trypsin in 0.02% EDTA. The
MTT assay was used to assess the cytotoxicity of test samples.16 The
cells were seeded in 96-well multiplates. After an overnight incubation
at 37 °C with 5% CO2, 10 μM test samples and APAP (final
concentration of 8 mM) were added into the wells and incubated for
another 48 h. Then, 100 μL of 0.5 mg/mL MTT was added to each
well after the withdrawal of the culture medium and incubated for an
additional 4 h. The resulting formazan was dissolved in 150 μL of
DMSO after aspiration of the culture medium. The plates were placed
on a plate shaker for 30 min and read immediately at 570 nm using a
microplate reader. Bicyclol was used as the positive control.
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G. I. J. Nat. Prod. 2015, 78, 1543−1547.
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