afford Frs. C1–C9. Fraction C2 (52 mg) was further purified by semipreparative HPLC (MeCN–H O, 10:90) to afford
2
compounds 3 (23 mg) and 4 (14 mg). Fraction C4 (19 mg) was further purified by semipreparative HPLC (MeCN–H O,
2
25:75) to afford compound 1 (11 mg). Fraction C5 (65 mg) was further purified by semipreparative HPLC (MeCN–H O,
2
10:90) to afford compound 5 (6.1 mg). Fraction G (1.2 g) was purified on silica gel CC eluted with CH Cl –MeOH (100:0 to
2
2
70:30) to afford Frs. G1–G13. Fraction G2 (47 mg) was further purified by semipreparative HPLC (MeCN–H O, 30:70) to
2
afford compounds 6 (9.4 mg) and 7 (4.2 mg). Fraction G5 (77 mg) was further purified by semipreparative HPLC (MeCN–H O,
2
25:75) to afford compounds 8 (10 mg) and 9 (23 mg). Fraction G8 (113 mg) was further purified by semipreparative HPLC
(MeCN–H O, 20:80) to afford compound 10 (39 mg). Fraction I (34 mg) was further purified by semipreparative HPLC
2
(MeCN–H O, 15:85) to afford compounds 2 (19 mg) and 11 (7.4 mg).
2
25
Compound 1, amorphous powder; [α] +0.7° (c 0.4, MeOH). UV (MeOH, λ , nm): 230, 282. CD (MeOH, mdeg):
Δε nm – 3.7, Δε nm –1.2. IR (KBr, ν , cm ): 3442, 2928, 2852, 1670, 1616, 1561, 1508, 1466, 1230, 1024. H and
C NMR data, see Table 1. HR-ESI-MS m/z 315.1307 [M – H] (calcd for C H O , 315.1311).
Compound 2, amorphous powder; [α] –18.1° (c 0.31, MeOH). UV (MeOH, λ , nm): 230, 280. IR (KBr, ν ,
cm ): 3410, 1596, 1512, 1230, 1126, 1073. H and C NMR data, see Table 2. HR-ESI-MS m/z 713.2728 [M – H]
D
max
–1
1
230
282
max
13
–
18 19
5
25
D
max
max
–1
1
13
–
(calcd for C H O , 713.2735).
33 45 17
Antioxidant Activity Evaluation. The antioxidant activities of the samples were determined by theABTS and DPPH
radical scavenging assay [12]. The scavenging ability of the sample was expressed as EC values.
50
Acid Hydrolysis of Compound 2. A solution of compound 2 (11 mg) was hydrolyzed in HCl–MeOH (4:1, 10 mL) at
85°C for 2 h. Then the reaction mixture was diluted with H O and extracted with CH Cl (10 mL × 2). The CH Cl layer was
2
2
2
2
2
subjected to silica gel CC (CH Cl –MeOH, 95:5) to give the aglycone as analyzed by NMR. The water layer was neutralized
2
2
with 5% NaOH solution to give the sugar fraction. The sugar fraction was analyzed by GC. Identification of D-glucose was
done by co-injection of the hydrolysate with standard silylated samples.
ACKNOWLEDGMENT
Mengyue Wang and Lili Wu contributed equally to this work. This study was financially supported by grants from the
National Natural Science Fund of China (No. 81374067) and the Region Collaborative Innovation Center of Tibetan Medicine
(2017XTCX004).
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