Anti-inflammatory neolignans from Piper kadsura

Article abstract of DOI:10.1021/np0505521

Two new neolignans, piperkadsin A (1) and piperkadsin B (2), as well as 11 known neolignans, three known alkaloids, the highly oxygenated compound (+)-crotepoxide, and stigmasterol were isolated from the stems of Piper kadsura. The anti-inflammatory activities of these compounds were evaluated. Compounds 1, 2, futoquinol (3), piperlactam S (4), and N-p-coumaroyl tyramine (5) showed potent inhibition of PMA-induced ROS production in human polymorphonuclear neutrophils with IC₅₀ values 4.3 ± 1.0, 12.2 ± 3.2, 13.1 ± 5.3, 7.0 ± 1.9, and 8.4 ± 1.3 μM, respectively.

Full text of DOI:10.1021/np0505521

842
J. Nat. Prod. 2006, 69, 842-844
Anti-inflammatory Neolignans from Piper kadsura
,|
Lie-Chwen Lin,*,†,‡, Chien-Chang Shen,† Yuh-Chiang Shen,†,§ and Tung-Hu Tsai*,
National Research Institute of Chinese Medicine, Taiwan, Graduate Institute of Integration Chinese and Western Medicine, China Medical
UniVersity, Taichung, Taiwan, Institute of Traditional Medicine, National Yang-Ming UniVersity, Taipei, Taiwan, Institute of Biomedical
Sciences, National Chung-Hshing UniVersity, Taichung, Taiwan, and Department of Education and Research, Taipei City Hospital,
Taipei, Taiwan, Republic of China
ReceiVed December 29, 2005
Two new neolignans, piperkadsin A (1) and piperkadsin B (2), as well as 11 known neolignans, three known alkaloids,
the highly oxygenated compound (+)-crotepoxide, and stigmasterol were isolated from the stems of Piper kadsura.
The anti-inflammatory activities of these compounds were evaluated. Compounds 1, 2, futoquinol (3), piperlactam S
(4), and N-p-coumaroyl tyramine (5) showed potent inhibition of PMA-induced ROS production in human
polymorphonuclear neutrophils with IC50 values 4.3 (1.0, 12.2 ( 3.2, 13.1 ( 5.3, 7.0 ( 1.9, and 8.4 ( 1.3 µM,
respectively.
Piper kadsura Ohwi (P. futokadsura) is a medicinal plant that
grows in the forests of Taiwan.1 The stems of P. kadsura, known
as haifengteng, are widely used in the Chinese herbal medicinal
prescriptions for the treatment of asthma and arthritic conditions.
A variety of compounds have been found in this plant, including
amides, lignans, neolignans, terpenes, and oxygenated cyclohex-
anes.2 Some of these compounds are reported to have anti-platelet
activating factor (PAF) activity. Among them, kadsurenone showed
remarkable PAF antagonist characteristics.3 However, there has been
relatively little information pertaining to its anti-inflammatory or
immunomodulating activities. We reinvestigated the active prin-
ciples of P. kadsura for their anti-inflammatory or immunomodu-
lating potentials. This paper deals with the structural investigation
of the new neolignans by spectroscopic means and their anti-
inflammatory activities.
The stems of P. kadsura were extracted with MeOH and
sequentially partitioned between H2O, CHCl3, and n-BuOH. With
repeated column chromatography the CHCl3 fraction gave two new
neolignans, piperkadsin A (1) and piperkadsin B (2), and 16 known
compounds.
Piperkadsin A (1) was obtained as a viscous oil. The IR (νmax
1660 cm-1) and UV (λmax 287 nm) spectra indicated a dienone
system. The molecular formula of 1 was consistent with C21H24O5
1
O-methyl groups. Comparison of the H and 13C NMR spectra of
from the HRFABMS spectrum, m/z 356.1629 [M]+. In the 1H NMR
1 with those of futoquinol (3)4,5 indicated that 1 bears a 4-hydroxy-
spectrum of 1, a set of three aromatic protons [δ 6.76 (d, J ) 1.5
3-methoxyphenyl substituent instead of the piperonyl group in
Hz, H-2), 6.78 (dd, J ) 1.5, 7.5 Hz, H-6), 6.84 (d, J ) 7.5 Hz,
futoquinol. HMBC correlations from H-2, H-5, and -OCH3 (δ 3.81)
H-5)], an olefinic proton (δ 6.91, H-7), and an allylic methyl singlet
to C-3 and from H-2, H-5, and H-6 to C-4 also confirmed the partial
(δ 1.65, H-9) suggested that a 3,4-dihydroxystyrene group was
structure of the 4-hydroxy-3-methoxyphenyl moiety. An NOE
present. Other methylene protons at δ 3.11 (H-7′) and olefinic
experiment performed on 1 showed an interaction between the
protons at δ 5.82 (m, H-8′), 5.06 (1H, dd, J ) 1.5, 5.5 Hz, H-9a′),
methyl and the aryl groups, but no interaction between methyl and
and 5.08 (1H, dd, J ) 12.0, 1.5 Hz, H-9b′) were assigned to the
H-7, suggesting that the aryl and the methyl groups are cis to each
allyl group. The singlets at δ 6.13 (s) and 5.80 (s) suggested two
other. The CD spectrum of 1 showed a strong positive couplet at
dienone protons at C-2′ and C-5′, respectively. As expected, the
248 nm and a negative one at 319 nm, which were in agreement
13C NMR chemical shifts at δ 139.2 (C-1′, s), 141.1 (C-2′, d), 105.3
with those of lancifolin C,6 thus establishing the 3′R configuration
(C-5′, d), 172.3 (C-4′, s), and 186.9 (C-6′, s) agreed with the dienone
of 1. On the basis of these data we propose the structure of 1 as
system. In addition, one aliphatic (δ 3.21) and two aromatic
(3′R)-4-hydroxy-3,3′,4′-trimethoxy-6′-oxo-∆-1′,4′,7,8′-8.3′-lignan.
O-methyl groups (δ 3.75 and 3.81) were also observed. The
Piperkadsin B (2) was also obtained as a viscous oil. IR (νmax
aliphatic methoxy is attached to a tertiary carbon, since no other
1740, 1631 cm-1) and UV (λmax 235, 280 nm) spectra showed
signal is found in the 3.5-5.0 ppm region except those of the
phenyl and R,â-unsaturated carbonyl absorption systems. The
molecular formula of 2 was consistent with C24H30O7 from the
* To whom correspondence should be addressed. E-mail:
HRFABMS spectrum, m/z 430.1983 [M]+. The 1H NMR spectrum
lclin@nricm.edu.tw. Tel: +886-2-28201999, ext. 7101. Fax: +886-2-
28264276.
of 2 revealed the presence of a veratryl ring system [three ABX
aromatic protons at δ 6.65 (d, J ) 1.5 Hz)/6.71 (dd, J ) 1.5, 8.0
Hz)/6.77 (d, J ) 8.0 Hz) and two O-methyl singlets at δ 3.81 and
3.84], an allyl group [methylene protons at δ 2.43 (dd, J ) 7.0,
13.0 Hz)/2.70 (dd, J ) 7.0, 13.0 Hz) and olefinic protons at δ 5.49
† National Research Institute of Chinese Medicine.
‡ China Medical University.
National Yang-Ming University.
§ National Chung-Hshing University.
| Taipei City Hospital.
10.1021/np0505521 CCC: $33.50
© 2006 American Chemical Society and American Society of Pharmacognosy
Published on Web 05/03/2006

Notes
Journal of Natural Products, 2006, Vol. 69, No. 5 843
spectra were measured with a Varian Inova-500 spectrometer with
deuterated solvents as internal standard. APCI-MS and HRFABMS were
recorded on Finnigan LCQ and Finnigan/Thermo Quest MAT spec-
trometers, respectively. Column chromatography was performed on
Sephadex LH-20 (Pharmacia) or silica gel 60 (70-230 or 230-400
mesh, Merck; or 12-26 µm, Eurochrom, Knauer) or Cosmosil 140
C18 OPN (Nacalai). Silica gel 60F254 (Merck) was used for TLC (0.25
mm).
Plant Material. The stems of Piper kadsura (Choisy) Ohwi were
collected in December 2003, in Taipei, Taiwan. Identification of plant
materials was confirmed by comparing with a voucher specimen (No.
197740) that had been deposited in the Herbarium of the Department
of Botany of National Taiwan University, Taipei, Taiwan.
Extraction and Isolation. The stems of P. kadsura (8.5 kg) were
crushed and extracted with MeOH (60 L × 3) under reflux. The MeOH
extract were evaporated to dryness and partitioned successively between
H2O and CHCl3, followed by n-BuOH (each 1.5 L × 3). The CHCl3
fraction (350 g) was subjected to column chromatography on silica
gel (10 × 120 cm), with a gradient of EtOAc in n-hexane, and 14
fractions (1-14) were collected. Fraction 6 (75.4 g) was rechromato-
graphed on a silica gel column using 15% EtOAc/n-hexane to give
two main fractions. Fraction 6-1 (35.3 g) was repeatedly purified with
silica gel (12-26 µm) column chromatography with 10% EtOAc/n-
hexane as eluent to give 6 (5.3 g), 7 (61 mg), and 8 (503 mg). Fraction
6-2 (20.9 g) was chromatographed on a Cosmosil 140 C18 OPN column
(60% MeOH/H2O) and on a silica gel column with 10% EtOAc/n-
hexane elution repeatedly to give 3 (5.5 g), 9 (476 mg), and 10 (1.2
g). A solid precipitate was separated from fraction 7 and recrystalized
from MeOH to give 11 (3.5 g). In the same manner, precipitates were
separated from fractions 9 and 14 and recrystalized from EtOAc/n-
hexane and MeOH to give 12 (450 mg) and 13 (14.4 g), respectively.
The filtrate of fraction 9 (13.5 g) was chromatographed on a Sephadex-
LH-20 (EtOAc) and on a silica gel (12-26 µm) column with 8%
EtOAc/benzene elution to give 1 (191 mg), 4 (30 mg), 12 (3.5 g), and
14 (893 mg). Fraction 11 (11.3 g) gave 2 (470 mg), 15 (215 mg), 17
(124 mg), and 18 (406 mg) after repeated silica gel (25% EtOAc/n-
hexane) and Sephadex LH-20 (EtOAc) column chromatography.
Fraction 12 was chromatographed on Sephadex-LH-20 (acetone) to give
5 (32 mg) and 19 (25 mg).
(m)/4.92 (dd, J ) 1.5, 10.0 Hz)/5.02 (dd, J ) 1.5, 17.0 Hz)], and
an acetoxy methyl at δ 2.10 (3H, s). Attachment of the allyl group
to an sp3-hybridized carbon atom was indicated by the shielded
chemical shift of the allylic-CH2 protons.7 In addition, the 1H NMR
spectrum of 2 exhibited two doublets at δ 0.78 (3H, J ) 6.5 Hz)
and 6.10 (1H) and a doublet-quartet at δ 2.27 (1H, J ) 1.5, 6.5
Hz), representing the typical AMX3-type signal of a CH3-CH-
CH-(O)- unit. The presence of the veratryl ring system, allyl
group, and CH3-CH-CH-(O)- unit was further confirmed by
the H-1H COSY spectrum. Along with these moieties, the H
NMR spectrum of 2 also revealed the presence of two methoxy
groups at δ 3.70 and 3.77, indicating their attachment to sp2-
hybridized carbon atoms, and two singlets at δ 5.22 and 5.44. This
finding was consistent with the 13C NMR signals at δ 55.7 (s, C-1′),
110.5 (d, C-2′), 147.6 (s, C-3′) 166.3 (s, C-4′), 102.5 (d, C-5′),
201.5 (s, C-6′), 55.1(-OCH3), and 56.3 (-OCH3), corresponding
to the 3,4-dimethoxy-6,6-disubstituted-cyclohexa-2,4-dienone group.
These subunits were connected by HMBC data. Correlations
observed in the HMBC spectrum from C-1 to H-8, H-7, H-2, and
H-5; from C-1′ to H-5′, H-7′, H-7, H-8, and H-9; from C-6′ to
H-2′, H-5′, and H-7′; and from acetyl carbonyl C-R to H-7 and
H-â confirmed the proposed structure of 2. The positions of the
3′- and 4′-OCH3 groups were reconfirmed by NOE experiments.
Irradiation of 3′-OCH3 gave 7.9% enhancement on H-2′, and
irradiation of 4′-OCH3 gave 8.8% enhancement on H-5′. The
absolute configuration of C-7 in 2 was established by the modified
Mosher’s method. 8 Hydrolysis of 2 with alcoholic KOH gave the
alcohol 2a, which was subsequently esterified by (S)- and (R)-
MTPA chlorides to yield the (R)- and (S)-MTPA esters9 19 and
20, respectively. The ∆δ (δS-MTPA ester - δR-MTPA ester) values of
the C(9)H3, C(7′)H2, C(2′)H, and C(5′)H were positive and the ∆δ
values of C(2)H, C(5)H, and C(6)H were negative, indicating that
the configuration of C-7 in 2 was R. In addition, the absence of an
observable coupling between H-8 and H-7 in 2 and 2a indicates a
preferred dihedral angle close to 90°. Therefore, a 7R, 8S absolute
configuration was tentatively assigned on stable conformation
considerations. On the basis of the above data, we propose the
structure of 2 as (7R,8S)-7-acetoxy-3,3′,4,4′-tetramethoxy-6′-oxo-
∆-2′,4′,8′-8.1′-lignan. The configuration of C1′ remains unassigned.
In addition to 1 and 2, futoquinol (3),4,5 piperlactam S (4),10 N-p-
1
1
Piperkadsin A (1): oil; [R]24D -130.3 (c 0.43, CHCl3); UV (MeOH)
λ
max (log ꢀ) 238 (4.22), 287 (4.13) nm; IR (neat) νmax 3423, 1660, 1605,
1
1513 cm-1; H NMR (CDCl3, 500 MHz) δ 1.65 (3H, s, H-9), 3.11
(2H, m, H-7′), 3.21 (3H, s, 3′-OCH3), 3.75 (3H, s, 4′-OCH3), 3.81 (3H,
s, 3-OCH3), 5.06 (1H, dd, J ) 1.5, 5.5 Hz, H-9a′) and 5.08 (1H, dd, J
) 12.0, 1.5 Hz, H-9b′), 5.80 (1H, s, H-5′), 5.82 (1H, m, H-8′), 6.13
(1H, s, H-2′), 6.76 (1H, d, J ) 1.5 Hz, H-2), 6.78 (1H, dd, J ) 1.5, 7.5
Hz, H-6), 6.84 (1H, d, J ) 7.5 Hz, H-5), 6.91 (1H, s, H-7); 13C NMR
(CDCl3, 125 MHz) δ 13.8 (C-9), 32.5 (C-7′), 52.2 (3′-OCH3), 55.5
(3-OCH3), 55.9 (4′-OCH3), 79.6 (C-3′), 105.3 (C-5′), 111.8 (C-2), 114.0
(C-5), 116.8 (C-9′), 122.0 (C-6), 127.0 (C-7), 129.3 (C-1), 131.8 (C-
8), 134.8 (C-8′), 139.2 (C-1′), 141.1 (C-2′), 144.4 (C-4), 146.0 (C-3),
172.3 (C-4′), 186.9 (C-6′); APCIMS m/z 357 [M + H]+; HRFABMS
m/z 356.1629 [M]+ (calcd for C21H24O5, 356.1624); CD (4.8 mg/100
mL MeOH, 216-400 nm) [θ]216max +14 826, [θ]219 0, [θ]222min -11 829,
12
coumaroyl tyramine (5),11 kadsurin A (6),5 licarin D (7),
stigmasterol (8), kadsurin B (9),13 kadsurenone (10),13 galgravin
(11),14 (+)-crotepoxide (12),15 futoenone (13),16 liliflone (14),17
(7R,8R,3′R)-7-acetoxy-3′,4′-dimethoxy-3,4-methylenedioxy-6′-oxo-
∆-1′,4′,8′-8.3′-lignan (15),18 (7S,8S,1′R)-∆8′-1′-methoxy-3,4-methyl-
enedioxy-1′,6′-dihydro-6′-oxo-7-O-4′,8.3′-neolignan (16),19,20 burch-
ellin (17),21 and aristololactam AIIIa (18)22 were also isolated from
the stems of P. kadsura. The structures of known compounds were
established by comparison of physical properties with reported data.
The isolated compounds were evaluated for their anti-inflam-
matory and antioxidative properties. Phorbol-12-myristate-13-
acetate (PMA)-activated human polymorphonuclear neutrophils
(PMN) were used as target cells, and reactive oxygen species (ROS)
production was determined by a lucigenin-amplified chemilumi-
nescence.23,24 Our results showed that PMA (a PKC-dependent
activator) could induce greatly elevated ROS production up to 10-
20-fold higher than that of resting cells. Pretreatment with 1-50
µM of isolated compounds showed that 1-5 potently diminished
PMA-induced ROS production in a concentration-dependent man-
ner. The IC50 values of compounds 1-5 were 4.3 ( 1.0, 12.2 (
3.2, 13.1 ( 5.3, 7.0 ( 1.9, and 8.4 (1.3 µM, respectively.
max
min
[θ]231 0, [θ]248 +3201, [θ]271 0, [θ]274 0, [θ]319 -1683, [θ]351 0,
[θ]400 0.
Piperkadsin B (2): oil; [R]24 34.7 (c 0.98, CHCl3); UV (MeOH)
D
λ max (log ꢀ) 235 (4.22), 280 (3.75), 318 (3.57) nm; IR (neat) ν
max
3448, 1740, 1631, 1582, 1517 cm-1; H NMR (CDCl3, 500 MHz) δ
1
0.78 (3H, d, J ) 6.5 Hz, H-9), 2.10 (3H, s, -COCH3), 2.27 (1H, dq,
J ) 1.5, 7.0 Hz, H-8), 2.43 (1H, dd, J ) 7.0, 13.0 Hz, H-7′a), 2.70
(1H, dd, J ) 7.0, 13.0 Hz, H-7′b), 3.70 (3H,s, -OCH3), 3.77 (3H,s,
-OCH3), 3.81 (3H,s, -OCH3), 3.85 (3H,s, -OCH3), 4.92 (1H, dd, J
) 1.5, 10.0 Hz, H-9′a), 5.02 (1H, dd, J ) 1.5, 17.0 Hz, H-9′b), 5.22
(1H, s, H-2′), 5.44 (1H, s, H-5′), 5.49 (1H, m, H-8′), 6.10 (1H, s, H-7),
6.65 (1H, d, J ) 1.5 Hz, H-2), 6.71 (1H, dd, J ) 1.5, 8.0 Hz, H-6),
6.77 (1H, d, J ) 8.0 Hz, H-5); 13C NMR (CDCl3, 125 MHz) δ 8.6
(C-9), 21.1 (-COCH3), 43.1 (C-7′), 48.4 (C-8), 55.1 (3′-OCH3), 55.8/
55.9 (3, 4-OCH3), 56.3 (4′-OCH3), 55.7 (C-1′), 74.0 (C-7), 102.5 (C-
5′), 108.9 (C-2), 110.5 (C-2′), 110.9 (C-5), 117.6 (C-6), 118.2 (C-9′),
132.5 (C-8′), 132.8 (C-1), 147.6 (C-3′), 148.2 (C-4), 148.7 (C-3), 166.3
(C-4′), 169.6 (-COCH3), 201.5(C-6′); APCIMS m/z 371 [M - CH3-
COO] +; HRFABMS m/z 430.1983 ([M] +, calcd for C24H30O7,
Experimental Section
General Experimental Procedures. IR spectra were obtained on a
Nicolet Avatar 320 IR spectrometer. UV spectra were measured on a
Hitachi U-3200 spectrophotometer in MeOH. Optical rotations were
recorded on a Jasco-DIP-370 polarimeter. Circular dichroism spectra
(CD) were recorded on Jasco J-715 spectrometer. 1H, 13C, and 2D NMR
max
430.1992); CD (3.2 mg/100 mL MeOH, 209-400 nm) [θ]209

844 Journal of Natural Products, 2006, Vol. 69, No. 5
Notes
min
max
+15529, [θ]211 0, [θ]213 -2582, [θ]218 0, [θ]223 +2345, [θ]228 0,
Acknowledgment. This study was supported by research grant
NSC94-2113-M-077-003 from the National Science Council, Taiwan.
min
max
[θ]233 -1710, [θ]236 0, [θ]242 +793, [θ]248 +427, [θ]281 +7590,
[θ]299 0, [θ]333 -5492, [θ]376 0, [θ]400 0.
min
Hydrolysis of Piperkadsin B (2). To a solution of 2 (45 mg) in
EtOH (5 mL) was added 4 N aqueous KOH (2 mL), and the solution
was stirred at room temperature for 40 min. Then the solution was
diluted with H2O and extracted with Et2O. The Et2O layer was washed
with H2O, dried with Na2SO4, and evaporated in vacuo. The residue
was purified by preparative TLC (benzene/EtOAc/acetone, 4:2:0.5) to
yield 2a: oil; [R]24D 67.4 (c 0.42, CHCl3); UV (MeOH) λ max (log ꢀ)
234 (4.32), 276 (3.93), 316 (3.52) nm; 1H NMR (CDCl3, 500 MHz) δ
0.67 (3H, d, J ) 7.0 Hz, H-9), 2.25 (1H, q, J ) 6.5 Hz, H-8), 2.62
(1H, dd, J ) 7.0, 12.5 Hz, H-7′a), 2.78 (1H, dd, J ) 7.0, 12.5 Hz,
H-7′b), 3.76 (3H,s, -OCH3), 3.81 (3H,s, -OCH3), 3.87 (3H,s, -OCH3),
3.89 (3H,s, -OCH3), 4.97 (1H, d, J ) 10.0 Hz, H-9′a), 5.06 (1H, d, J
) 17.0 Hz, H-9′b), 5.22 (1H, s, H-7), 5.51 (1H, s, H-5′), 5.58 (1H, m,
H-8′), 5.80 (1H, s, H-2′), 6.84 (3H, s, H-2, 5, 6); 13C NMR (CDCl3,
125 MHz) δ 7.7 (C-9), 43.0 (C-7′), 48.9 (C-8), 55.4 (-OCH3), 55.9
(-OCH3 × 2), 56.4(-OCH3), 56.6 (C-1′), 72.5 (C-7), 102.5 (C-5′),
108.9 (C-2), 110.9 (C-5), 113.0 (C-2′), 117.5 (C-6), 117.9 (C-9′), 133.0
References and Notes
(1) Lin, T. T.; Lu, S. Y. Piperaceae. In Flora of Taiwan, 2nd ed.; Editorial
Committee of the Flora of Taiwan: Taipei, 1996; Vol. II, pp 624-
631.
(2) Parmar, V. S.; Jain, S. C.; Bisht, K. S.; Jain, R.; Taneja, P.; Jain, A.;
Tyagi, O. D.; Prasad, A. K.; Wengel, J.; Olsen, C. E.; Boll, P. M.
Phytochemistry 1997, 46, 597-673.
(3) Shen, T. Y.; Hussaini, I. M. Methods Enzymol. 1990, 187, 446-
454.
(4) Takahashi, S.; Ogiso, A. Chem. Pharm. Bull. 1970, 18, 100-104.
(5) Tyagi, O. D.; Jensen, S.; Boll, P. M.; Sharma, N. K.; Bisht, K. S.;
Parmar, V. S. Phytochemistry 1993, 32, 445-448.
(6) Diaz, P. P.; Yoshida, M.; Gottlieb, O. R. Phytochemistry 1980, 19,
285-288.
(7) Gottlieb, O. R.; Silva, M. L. D.; Ferreira, Z. S. Phytochemistry 1975,
14, 1825-1827.
(8) Ohtani, I.; Kusumi, T.; Kashman, Y.; Kakisawa H. J. Am. Chem.
Soc. 1991, 113, 4092-4096.
(9) Dale, J. A.; Dull, D. L.; Mosher, H. S. J. Org. Chem. 1969, 34, 2543-
2549.
(C-8′), 136.8 (C-1), 146.9 (C-3′), 147.9/148.8 (C-3, 4), 166.7 (C-4′),
+
203.1 (C-6′); APCIMS m/z 371 [M - H2O + H]
.
Reaction of Alcohol 2a with (R)-MTPA.8,9 (R)-MTPA (25 mg) and
thionyl chloride (1 mL) were refluxed for 3 h. After excess thionyl
chloride was removed by vacuum evaporation, a solution of 2a (9 mg)
in 4 mL of dry CH2Cl2, (dimethylamino)pyridine (12.3 mg), and
triethylamine (0.1 mL) were added and the solution was stirred for 16
h at room temperature. The reaction mixture was concentrated and
purified by preparative TLC (benzene/EtOAc, 4:2) to yield the (R)-
MTPA ester 19: 1H NMR (CDCl3, 500 MHz) δ 0.78 (3H, d, J ) 7.0
Hz, H-9), 2.30 (1H, dd, J ) 2.0, 13.0 Hz, H-7′a), 2.49 (1H, dd, J )
3.0, 7.0 Hz, H-8), 2.63 (1H, dd, J ) 3.0, 13.0 Hz, H-7′b), 3.54 (3H, s,
MTPA-OCH3), 3.55 (3H,s, -OCH3), 3.77 (3H,s, -OCH3), 3.80 (3H,s,
-OCH3), 3.86 (3H,s, -OCH3), 4.90 (1H, d, J ) 8.5 Hz, H-9′a), 4.93
(1H, d, J ) 15.5 Hz, H-9′b), 5.19 (1H, s, H-2′), 5.41 (1H, m, H-8′),
5.47 (1H, s, H-5′), 6.29 (1H, d, J ) 3.0 Hz, H-7), 6.81 (3H, s, H-2, 5,
6).
(10) Wu, Q. L.; Wang, S. P.; Tu, G. Z.; Feng, Y. X.; Yang, J. S.
Phytochemistry 1997, 44, 727-730.
(11) Chang, F. R.; Chen, C. Y.; Hsieh, T. J.; Cho, C. P.; Wu, Y. C. J.
Chin. Chem. Soc. 2000, 47, 913-920.
(12) Wenkert, E.; Gottlieb, H. E.; Gottlieb, O. R.; Pereira, M. O. da S.;
Formiga, M. D. Phytochemistry 1976, 15, 1547-1551.
(13) Chang, M. N.; Han, G. Q.; Arison, B. H.; Springer, J. P.; Hwang, S.
B.; Shen, T. Y. Phytochemistry 1985, 24, 2079-2082.
(14) Holloway, D.; Scheinmann, F. Phytochemistry 1974, 13, 1233-1236.
(15) Takahashi, S. Phytochemistry 1970, 18, 199-202.
(16) Ogiso, A.; Kurabayashi, M.; Takahashi, S.; Mishima, H.; Woods,
M. C. Chem. Pharm. Bull. 1970, 18, 105-114.
(17) Iida, T.; Ito, K. Phytochemistry 1983, 22, 763-766.
(18) Prasad, A. K.; Tyagi, O. D.; Wengel, J.; Boll, P. M.; Olsen, C. E.;
Sharma, N. K.; Bisht, K. S.; Gupta, S.; Parmar, V. S. Tetrahedron
1994, 50, 2231-2240.
(19) Khan, M. R.; Gray, A. I.; Waterman, P. G. Phytochemistry 1987,
26, 1155-1158.
(20) Joshi, N.; Garg, H. S.; Bhakuni, D. S. J. Nat. Prod. 1990, 53, 479-
482.
(21) Engler, T. A.; Wei, D. D.; Letavic, M. A.; Combrink, K. D.; Reddy,
J. P. J. Org. Chem. 1994, 59, 6588-6599.
(22) Priestap, H. A. Phytochemistry 1985, 24, 849-852.
(23) Shen, Y. C.; Chiou, W. F.; Chou, Y. C.; Chen, C. F. Eur. J.
Pharmacol. 2003, 465, 171-181.
Reaction of Alcohol 2a with (S)-MTPA.8,9 (S)-MTPA (25 mg) and
thionyl chloride (1 mL) were refluxed for 3 h. After excess thionyl
chloride was removed by vacuum evaporation, a solution of 2a (9 mg)
in 4 mL of dry CH2Cl2, (dimethylamino)pyridine (12.3 mg), and
triethylamine (0.1 mL) were added and the solution was stirred for 16
h at room temperature. The reaction mixture was concentrated and
purified by preparative TLC (benzene/EtOAc, 4:2) to yield the (S)-
MTPA ester 20: 1H NMR (CDCl3, 500 MHz) δ 0.81 (3H, d, J ) 7.0
Hz, H-9), 2.41 (1H, dd, J ) 2.5, 13.0 Hz, H-7′a), 2.46 (1H, dd, J )
2.5, 7.0 Hz, H-8), 2.71 (1H, dd, J ) 2.5, 13.0 Hz, H-7′b), 3.47 (3H, s,
MTPA-OCH3), 3.60 (3H,s, -OCH3), 3.70 (3H, s, -OCH3), 3.78 (3H,s,
-OCH3), 3.85 (3H, s, -OCH3), 4.96 (1H, d, J ) 10.5 Hz, H-9′a),
5.03 (1H, d, J ) 17.0 Hz, H-9′b), 5.35 (1H, s, H-2′), 5.49 (1H, s, H-5′),
5.50 (1H, m, H-8′), 6.32 (1H, d, J ) 2.5 Hz, H-7), 6.63 (1H, d, J )
2.0 Hz, H-2), 6.71 (1H, dd, J ) 2.0, 8.0 Hz, H-6), 6.76 (1H, d, J ) 8.0
Hz, H-5).
(24) Parij, N.; Nagy, A.-M.; Fondu, P.; Neve, J. Eur. J. Pharmacol. 1998,
352, 299-305.
NP0505521