P. Shu, et al.
PhytochemistryLetters36(2020)32–36
Table 2
was performed using silica gel (Qingdao Marine Chemical Inc., China),
ODS (50 μm, Fuji Silysia Chemical Ltd., Japan), and Sephadex LH-20
(GE Healthcare Bio-Sciences AB, Sweden). TLC was performed with
silica gel 60 F254 (Yantai Chemical Industry Research Institute).
Inhibitory effects of compounds 1–12 and of kojic acid on mushroom tyr-
Compound
Tyrosinase
Compound
Tyrosinase inhibition
(%)
inhibition (%)
3.2. Plant material
1
2
3
4
5
6
9.75 0.72
8
9
10
The fresh roots of A. dahurica were collected in Xuchang, People’s
Republic of China, in April 2019. The botanical identification was made
by Prof. Lin Yang, School of Life Science and Engineering, Lanzhou
University of Technology. A voucher specimen (SPH2019A) was de-
posited in the herbarium of School of Chemistry and Chemical
Engineering, Xuchang University.
11
12
kojic acid (positive
control)
26.01 0.67
7
a
Tyrosinase inhibitions were measured at a derivative concentration of 25
μM, with L-tyrosine as the substrate. Results were expressed as means SEMs.
3.3. Extraction and isolation
b
NI: no inhibition.
The air-dried roots of A. dahurica (6.3 kg) were extracted with 95 %
EtOH at room temperature (3 × 15 L) to afford a crude extract of 93.8 g
after evaporation of the solvent under vacuum. The extract was sus-
pended in distilled H2O and partitioned with CH2Cl2 and n-BuOH, re-
spectively. The n-BuOH soluble portion (36.5 g) was subjected to silica
gel CC using CH2Cl2–MeOH (50:1 to 2:1) as eluent to give five fractions
A–E. Fraction B (5.3 g, eluted by CH2Cl2–MeOH 35:1) was subsequently
purified by Sephadex LH-20 column (CH2Cl2–MeOH 1:1) to give four
subfractions (FB-1 to FB-4). Fraction FB-1 was chromatographed on a
silica gel CC (CH2Cl2–MeOH 30:1) to give compound 12 (5.1 mg).
Fraction C (8.9 g, eluted by CH2Cl2–MeOH 25:1) was purified on a RP-
were connected to the C-2´´ and C-3´´ positions of 4, respectively
(Fig. 2; Fig. 40S, Supporting Information). On the basis of detailed 2D
NMR analysis, the structure of 4 was decided as 2´´,3´´-di-O-β-D-glu-
copyranosyl-(+)-byakangelicin, named as angelicoside IV.
According to the literatures, the two epimers at C-2´´, (R)-(+)-by-
akangelicin and (S)-(−)- byakangelicin, show opposite specific rota-
vided dextrorotatory aglycones, (+)-byakangelicin, suggesting the R
configuration at C-2´´.
C18 CC (MeOH–H2O, 50:50 to 100:0) to afford five subfractions (FC-1 to
The known compounds 5−12 were identified as tert-O-β-D-apio-
furanosyl-(1→6)-O-β-D-glucopyranosyl-byakangelicin (5) (Jia et al.,
the plants of angelica genus are rich in coumarins and related glycosides
are well consistent with the previous reports. Moreover, it is the first
time that furanocoumarin rhamnosides have been isolated from A.
dahurica, which would enriched our knowledge about the chemical
diversity of A. dahurica.
FC-5). Fraction C-1 was passed through a Sephadex LH-20 column
(MeOH) to give compounds 1 (2.7 mg) and 11 (5.7 mg). Fraction C-2
was chromatographed on a silica gel CC (CH2Cl2–MeOH 15:1) to give
compounds 6 (4.2 mg) and 8 (4.9 mg). Fraction D (11.4 g, eluted by
CH2Cl2–MeOH, 15:1 to 4:1) was purified on a Sephadex LH-20 column
(MeOH) to give four subfractions (FD-1 to FD-4). Fraction D-1 was
further purified by Sephadex LH-20 column (MeOH) to give compounds
2 (3.5 mg) and 7 (5.8 mg). Fraction D-2 was further purified by RP-C18
CC eluted with MeOH-H2O (20:80 to 50:50) to give compounds 3 (3.4
mg) and 5 (7.3 mg). Fraction D-3 was chromatographed on a silica gel
CC (CH2Cl2–MeOH 5:1) to give compound 10 (6.7 mg). Fraction D-4
was chromatographed on a RP-C18 CC (MeOH–H2O, 20:80 to 50:50) to
give compounds 4 (4.1 mg) and 9 (8.0 mg).
Angelicoside I (1): colorless oil; [ ]2D0 –24.4 (c 0.09, CH3OH); UV
λmax (MeOH) nm (log ε): 223 (4.0), 269 (3.7), 312 (3.7); IR (KBr) νmax
3434, 2927, 1720, 1592, 1481, 1349, 1272, 1170, 1035, 821 cm–1
;
1H
The mushroom tyrosinase inhibitory activities of compounds 1–12
and kojic acid (positive control) were evaluated at a concentration of 25
μM. However, only compounds 1, 2, and 11 showed moderate tyr-
osinase inhibition activities (Table 2). According to the previous re-
ports, entities with strong tyrosinase inhibitory activity usually con-
why compounds 1–12 showed weak or moderate activities. Moreover,
compared with the monoglycosides 1 and 2, the diglycosides 3–5 ex-
hibited weaker inhibition activities (inhibitory rate < 5 %). Perhaps the
polarity of tested compounds could influence the bioactivity.
NMR and 13C NMR data (CD3OD), see Table 1; HRESIMS m/z 503.1535
Angelicoside II (2): colorless oil; [ ]2D0 –22.2 (c 0.12, CH3OH); UV
λmax (MeOH) nm (log ε): 223 (4.2), 269 (4.0), 313 (3.8); IR (KBr) νmax
3446, 2931, 1700, 1606, 1481, 1353, 1218, 1145, 1074, 831 cm–1
;
1H
NMR and 13C NMR data (CD3OD), see Table 1; HRESIMS m/z 503.1530
Angelicoside III (3): colorless oil; [ ]2D0 [ ]D20 –30.0 (c 0.11, CH3OH);
UV λmax (MeOH) nm (log ε): 223 (4.0), 269 (3.8), 313 (3.6); IR (KBr)
νmax 3432, 2927, 1689, 1481, 1353, 1253, 1172, 1037, 836 cm–1
;
1H
NMR and 13C NMR data (CD3OD), see Table 1; HRESIMS m/z 649.2100
Angelicoside IV (4): colorless oil; [ ]2D0 –11.7 (c 0.14, CH3OH); UV
λmax (MeOH) nm (log ε): 222 (4.1), 268 (3.9), 313 (3.7); IR (KBr) νmax
3. Materials and methods
3426, 2927, 1720, 1589, 1477, 1353, 1170, 1072, 829 cm–1
;
1H NMR
3.1. General experimental procedures
and 13C NMR data (CD3OD), see Table 1; HRESIMS m/z 659.2181 [M
Optical rotations were determined on a Rudolph Autopol IV po-
larimeter (589 nm, 20 °C). FT-IR and UV spectra were determined using
FTIR-650 and Puxi TU-1950 instruments, respectively. NMR spectra
were recorded on a Bruker AM-400 spectrometer. High-resolution
electrospray ionization mass spectra (HRESIMS) were carried out on a
Waters Xevo G2-XS QTof spectrometer. Column chromatography (CC)
3.4. Acid hydrolysis of compounds 1–3
The acid hydrolysis of compounds 1–3 were conducted according to
35