Cytotoxic activity of capnellene-8β,10α-diol derivatives from a Taiwanese soft coral Capnella sp.

Article abstract of DOI:10.1002/jccs.200800123

The sesquiterpene capnellene-8β,10α-diol (1) was isolated from non-polar extract of the soft coral Capnella sp. Ten acylation products of capnellene-8β,10α-diol were prepared: 10a-hydroxy-8β-O- benzoylcapnellene (2), 10α-hydroxy-8β-O-p-toluoylcapnellene (3), 10α-hydroxy-8β-O-4-chlorobenzoyl-capnellene (4), 10α-hydroxy- 8β-O-2-furoylcapnellene (5), 10α-hydroxy-8β-O-2- thiophenoylcapnellene (6), 10α-hydroxy-8β-O-4-fluorobenzoylcapnellene (7), 10α-hydroxy-8β-O-4-propylbenzoylcapnellene (8), 10α-hydroxy-8β-O-cinnamoylcapnellene (9), 10α-hydroxy-8β- O-4-nitrobenzoylcapnellene (10), and 10α-hydroxy-8β-O-4- anisoylcapnellene (11). The structures of capnellene-8β,10α-diol as well as its derivatives were established through standard spectroscopic analysis. The in vitro cytotoxic activities of the eleven compounds were evaluated against Hela, KB, Daoy, and WiDr human tumor cell lines.

Full text of DOI:10.1002/jccs.200800123

828
Journal of the Chinese Chemical Society, 2008, 55, 828-833
Cytotoxic Activity of Capnellene-8b,10a-diol Derivatives from a Taiwanese
Soft Coral Capnella sp.
Ya-Ching Shena* (
Yau-Haur Kuoc (
), Guo-Lin Tzengb (
),
) and Ashraf Taha Khalila
aSchool of Pharmacy, College of Medicine, National Taiwan University,
Jen-Ai Rd. Sec. 1, Taipei 100, Taiwan, R.O.C.
bInstitute of Marine Biotechnology and Resources, National Sun Yat-sen University,
70 Lien-Hai Road, Kaohsiung 80424, Taiwan, R.O.C.
cNational Research Institute of Chinese Medicine, Taipei, Taiwan, R.O.C.
The sesquiterpene capnellene-8b,10a-diol (1) was isolated from non-polar extract of the soft coral
Capnella sp. Ten acylation products of capnellene-8b,10a-diol were prepared: 10a-hydroxy-8b-O-ben-
zoylcapnellene (2), 10a-hydroxy-8b-O-p-toluoylcapnellene (3), 10a-hydroxy-8b-O-4-chlorobenzoyl-
capnellene (4), 10a-hydroxy-8b-O-2-furoylcapnellene (5), 10a-hydroxy-8b-O-2-thiophenoylcapnellene
(6), 10a-hydroxy-8b-O-4-fluorobenzoylcapnellene (7), 10a-hydroxy-8b-O-4-propylbenzoylcapnellene
(8), 10a-hydroxy-8b-O-cinnamoylcapnellene (9), 10a-hydroxy-8b-O-4-nitrobenzoylcapnellene (10),
and 10a-hydroxy-8b-O-4-anisoylcapnellene (11). The structures of capnellene-8b,10a-diol as well as its
derivatives were established through standard spectroscopic analysis. The in vitro cytotoxic activities of
the eleven compounds were evaluated against Hela, KB, Daoy, and WiDr human tumor cell lines.
Keywords: Capnella sp.; Capnellene-8b,10a-diol; Acyl derivatives; Cytotoxicity.
INTRODUCTION
Soft corals of the order Alcyonacea are the major con-
8b-O-benzoyl-capnellene (2), 10a-hydroxy-8b-O-p-tol-
uoyl-capnellene (3), 10a-hydroxy-8b-O-4-chlorobenzo-
yl-capnellene (4), 10a-hydroxy-8b-O-2-furoyl-capnellene
(5), 10a-hydroxy-8b-O-2-thiophenoyl-capnellene (6),
10a-hydroxy-8b-O-4-fluorobenzoyl-capnellene (7), 10a-
hydroxy-8b-O-4-propylbenzoyl-capnellene (8), 10a-hy-
droxy-8b-O-cinnamoyl-capnellene (9), 10a-hydroxy-8b-
O-4-nitrobenzoyl-capnellene (10), 10a-hydroxy-8b-O-4-
anisoyl-capnellene (11). The structure of 1 and its deriva-
tives was elucidated based on spectroscopic analysis, in-
cluding HRESIMS and 2D NMR. All compounds were
tested against a panel of human tumor cell lines. The cyto-
toxic activity of capnellene-8b,10a-diol as well as its ten
derivatives was evaluated against a panel of Hela, KB,
Daoy, and WiDr human tumor cell lines.
tributors to the biomass of many tropical reefs. Most of them
live in symbiotic relationship with intracellular algae that
play a major role in the biology of the colonies.1-3 These
corals have been widely studied as they produce a huge ar-
ray of skeletal classes of terpenes with unique substitution
patterns and functionalities.4,5 Capnella (Nephtheidae) is a
widely distributed genus of Alcyonacea that provide non-
isoprenoid sesquiterpenes with a 5-membered tricyclic
skeleton named capnellane, few xenicane-type diterpenes,
and no sterols.2,4 Some of the soft coral sesquiterpenoids
have demonstrated interesting biological activities but lit-
tle has been reported about the biological activities of
capnellene sesquiterpenes which have fused tricyclic rings
with an exo-double bond at C9.3 A chemical investigation
of Capnella sp. led to isolation of a capnellene derivative,
capnellene-8b,10a-diol (1), previously isolated from
Capnella imbricate,1,2,6 with reported cytotoxic activity
against K562 leukemia (IC50 = 0.7 mM).7 This major com-
pound was acylated to yield ten derivatives, 10a-hydroxy-
RESULTS AND DISCUSSION
Extraction of Capnella sp. and subsequent chro-
matographic fractionation of the CH2Cl2 extract yielded
capnellene-8b,10a-diol (1) that was characterized through
spectroscopic analysis and by comparison of its spectral
* Corresponding author. Tel: +886-2-2312-3456 ext. 2226; Fax: +886-2-02-2391-9098; E-mail: ycshen@ntu.edu.tw

Capnellene-8b,10a-diol Derivatives from Capnella sp.
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 829
data with published values.1,8-10 The acylation products
2-11 were prepared from 1 using different acid chlorides:
benzoyl chloride, toluoylchloride, 4-chlorobenzoyl chlo-
ride, 2-furoylcarbonyl chloride, 2-thienoylcarbonyl chlo-
ride, 4-fluorobenzoyl chloride, 4-propylbenzoyl chloride,
cinnamoyl chloride, 4-nitrobenzoyl chloride, and anisoyl
chloride, respectively. The structures of 2-11 were estab-
lished through analyses of their spectroscopic data, particu-
larly HRESIMS, 1H- and 13C NMR, DEPT, and 2 D NMR
(COSY, HMQC and HMBC). The spectral data of 1-11 are
included in the experimental section.
The cytotoxic activities of compounds 1-11 were
tested against human cervical epitheloid carcinoma (Hela),
human oral epidermoid (KB), human medulloblastoma
(Daoy), and human colon adenocarcinoma (WiDr) tumor
cell lines. Table 1 displays the assay results of the in vitro
cytotoxic activities, expressed as IC50 of 1-11. All tested
compounds showed significant activity against Hela and
KB cell lines. Compounds 1 and 5 exhibited the strongest
activity against the WiDr cell line with IC50 0.16 and 0.35,
respectively, while compounds 3 and 11 showed moderate
activity against the same cell line. Compounds 5 and 11

830 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Table 1. Cytotoxic activity of compounds 1-11a
Shen et al.
Animal Material
The soft coral Capnella sp. was collected on Green
Island, Taiwan, in June 2005. A voucher specimen (GSC-
25) was deposited at the School of Pharmacy, College of
Medicine, National Taiwan University, Taipei, Taiwan.
Extraction and Isolation
IC50 (mg/mL)
Compound
Hela
KB
Daoy
WiDr
1
3.56
(-)
6.06
(-)
b(-)b
(-)
00.16
(-)
2
3
3.13
2.36
3.05
2.70
2.49
4.79
3.02
3.10
2.63
0.09
5.45
2.19
4.10
2.48
2.09
3.86
2.77
2.96
1.92
0.08
(-)
08.00
10.50
00.35
15.93
(-)
4
(-)
The soft coral Capnella sp. (4 kg, wet weight) was
homogenized with CH2Cl2/MeOH (1:1) twice (2 ´ 6 L).
After filtration and concentration under vacuum, the crude
extract (20 g) was partitioned between EtOAc/H2O to pro-
duce EtOAc extract. The EtOAc extract (5 g) was re-ex-
tracted with n-hexane/MeOH/H2O (4:3:1) to afford n-hex-
ane extract and a hydro-alcoholic mixture. Concentration
of the latter under vacuum led to isolation of 1 (2.8 g).
Capnellene-8b,10a-diol (1)
5
9.93
(-)
6
7
(-)
8
(-)
(-)
9
(-)
(-)
10
(-)
(-)
11
5.42
0.07
6.30
0.06
Mitomycin C
a Cell lines: Hela, human cervical epitheloid carcinoma; KB,
human oral epidermoid; Daoy, human medulloblastoma; WiDr,
human colon adenocarcinoma.
Colorless amorphous solid; [a]2D5 +40.8 (c 0.05,
CH2Cl2); UV lmax 207 nm; IR (CH2Cl2) nmax 3419 (OH),
1042 (OH) cm-1; EIMS m/z 218 [M-H2O]+; HRESIMS m/z
b (-): IC50 > 20 mg/mL.
259.1676 [M+Na]+ (calc for C15H24O2); H NMR (300
1
showed exclusive moderate cytotoxicity against the Daoy
cell line, while all other compounds were inactive. The
benzoyl ester 2 was inactive against all tested cell lines but
it seems that substitution at the p-position increased the
cytotoxic activity, especially against Hela and KB cells. All
tested compounds showed significant cytotoxicity against
Hela and KB cell lines with the exception of benzoyl ester
2. The activity of almost all esters against Hela and KB
cells was superior compared to the parent compound 1, es-
pecially in the case of 4, 7, and 11. This may be attributed to
greater penetration of the cytotoxic ester into the cancer
cells.
MHz, CDCl3) d 1.50 (2H, m, H-2), 1.71 (2H, m, H-3), 1.97
(m, Ha-5), 1.30 (m, Hb-5), 2.49 (m, H-6), 2.33 (m, Ha-7),
1.50 (m, Hb-7), 4.81 (m, H-8), 1.87 (s, H-11), 5.34 (2H, br
s, H-12), 1.08 (3H, s, H-13), 1.15 (3H, s, H-14), 1.26 (3H,
s, H-15); 13C NMR (75 MHz, CDCl3), d 44.0 (C-1), 43.2
(C-2), 42.0 (C-3), 49.9 (C-4), 46.2 (C-5), 49.6 (C-6), 38.1
(C-7), 73.6 (C-8), 162.4 (C-9), 90.2 (C-10), 65.7 (C-11),
109.8 (C-12), 32.8 (C-13), 31.4 (C-14), 24.1 (C-15).
General Procedure for the Preparation of 2-11
0.1 mL of an appropriate acid chloride (benzoyl chlo-
ride, toluoylchloride, 4-chlorobenzoyl chloride, 2-furoyl-
carbonyl chloride, 2-thienoylcarbonyl chloride, 4-fluoro-
benzoyl chloride, 4-propylbenzoyl chloride, cinnamoyl
chloride, 4-nitrobenzoyl chloride, and anisoyl chloride)
was added to a solution of 1 (50 mg, 0.212 mmole) in anhy-
drous pyridine (2 mL) at 50° C and stirred for 21 h. After
completion of the reaction (as monitored by TLC) the reac-
tion mixture was poured into ice-water and stirred for 45
min and then extracted with CH2Cl2. The organic layer was
washed with NaHCO3 solution, then with sufficient water,
dried over anhydrous Na2SO4, and the solvent was re-
moved under vacuum. The crude product was first purified
through a Sephadex LH-20 column using CH2Cl2-MeOH
(1:1) to afford the pure products. The respective products
were 2 (23 mg, yield 32%), 3 (15.5 mg, yield 21%), 4 (35.7
mg, yield 45%), 5 (44 mg, yield 63%), 6 (46 mg, yield
EXPERIMENTAL SECTION
General Methods
Optical rotations were recorded on a JASCO DIP-
1000 polarimeter. IR and UV spectra were measured on a
Hitachi T-2001 and a Hitachi U-3210 spectrophotometer,
respectively. Mass spectra were recorded on a VG Quattro
5022 mass spectrometer. NMR spectra were run on a
Bruker FT-300 NMR instrument. The chemical shifts are
given in d (ppm) and coupling constants in Hz. Multiplici-
ties and assignments were monitored by DEPT and HMBC
techniques. Sephadex LH-20 was obtained from Amersham
Pharmacia Biotech AB, Uppsala, Sweden. Other chemicals
were obtained from E. Merck (Germany) unless otherwise
specified.

Capnellene-8b,10a-diol Derivatives from Capnella sp.
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 831
(C-7), 76.2 (C-8), 158.6 (C-9), 90.2 (C-10), 66.1 (C-11),
113.9 (C-12), 32.5 (C-13), 31.3 (C-14), 23.7 (C-15), 165.4
(C-1¢), 128.7 (C-2¢), 130.9 (C-3¢,7¢), 128.9 (C-4¢,6¢), 139.4
(C-5¢).
63%), 7 (24 mg, yield 33%), 8 (17.8 mg, yield 22%), 9 (34
mg, yield 44%), 10 (32.4 mg, yield 40%), 11 (27 mg, yield
34%).11
10a-Hydroxy-8b-O-benzoylcapnellene (2)
[a]2D5 +108.7 (c 0.05, CH2Cl2); UV lmax 255, 273 nm;
IR (CH2Cl2) nmax 3503 (OH), 1716 (C=O ester) cm-1; EIMS
m/z 340; HRESIMS m/z 363.1938 [M+Na]+ (calc for
10a-Hydroxy-8b-O-2-furoylcapnellene (5)
[a]2D5 +68.0 (c 0.05, CH2Cl2); UV lmax 248, 260 nm;
IR (CH2Cl2) nmax 3497 (OH), 1713 (C=O ester) cm-1; EIMS
m/z 330; HRESIMS m/z 353.1728 [M+Na]+ (calc for
1
C22H28O3); H NMR (300 MHz, CDCl3) d 1.51 (2H, m,
1
C20H26O4); H NMR (300 MHz, CDCl3) d 1.50 (2H, m,
H-2), 1.71 (2H, m, H-3), 1.94 (m, Ha-5), 1.43 (m, Hb-5),
2.67 (m, H-6), 2.49 (m, Ha-7), 1.53 (m, Hb-7), 5.48 (dd, J =
4.8, 1.5 Hz, H-8), 1.92 (s, H-11), 5.48 (2H, br s, H-12), 1.13
(3H, s, H-13), 1.20 (3H, s, H-14), 1.27 (3H, s, H-15), 8.04
(2H, d, J = 7.3 Hz, H-3¢,7¢), 7.45 (2H, d, J = 7.3 Hz,
H-4¢,6¢), 7.57 (t, J = 7.3 Hz, H-5¢); 13C NMR (75 MHz,
CDCl3), d 44.1 (C-1), 43.4 (C-2), 42.4 (C-3), 49.8 (C-4),
45.5 (C-5), 49.3 (C-6), 35.1 (C-7), 76.0 (C-8), 158.8 (C-9),
90.3 (C-10), 66.1 (C-11), 113.8 (C-12), 32.5 (C-13), 31.3
(C-14), 23.8 (C-15), 166.3 (C-1¢), 130.5 (C-2¢), 129.6 (C-
3¢,7¢), 128.4 (C-4¢,6¢), 132.9 (C-5¢).
H-2), 1.70 (2H, m, H-3), 1.91 (m, Ha-5), 1.41 (m, Hb-5),
2.66 (m, H-6), 2.44 (m, Ha-7), 1.59 (m, Hb-7), 6.02 (br d, J
= 6.9 Hz, H-8), 1.89 (s, H-11), 5.47 (s, Ha-12), 5.46 (d, J =
1.1 Hz, Hb-12), 1.10 (3H, s, H-13), 1.18 (3H, s, H-14), 1.25
(3H, s, H-15), 7.59 (br s, H-4¢), 6.50 (t, J = 3.1 Hz, H-5¢),
7.12 (d, J = 3.1 Hz, H-6¢); 13C NMR (75 MHz, CDCl3) d
44.1 (C-1), 43.4 (C-2), 42.4 (C-3), 49.8 (C-4), 45.5 (C-5),
49.3 (C-6), 35.0 (C-7), 76.0 (C-8), 158.6 (C-9), 90.3 (C-
10), 66.3 (C-11), 114.2 (C-12), 32.5 (C-13), 31.3 (C-14),
23.8 (C-15), 158.6 (C-1¢), 144.9 (C-2¢), 146.4 (C-4¢), 111.7
(C-5¢), 117.7 (C-6¢).
10a-Hydroxy-8b-O-p-toluoylcapnellene (3)
[a]2D5 +114.2 (c 0.05, CH2Cl2); UV lmax 243, 251 nm;
IR (CH2Cl2) nmax 3497 (OH), 1713 (C=O ester), 1611, 1455
cm-1; EIMS m/z 354; HRESIMS m/z 377.2092 [M+Na]+
10a-Hydroxy-8b-O-2-thiophenoylcapnellene (6)
[a]2D5 +78.4 (c 0.05, CH2Cl2); UV lmax 253, 278 nm;
IR (CH2Cl2) nmax 3503 (OH), 1701 (C=O ester), 1593, 1488
cm-1; EIMS m/z 346; HRESIMS m/z 369.1502 [M+Na]+
(calc for C20H26O3S); 1H NMR (300 MHz, CDCl3) d 1.50
(2H, m, H-2), 1.71 (2H, m, H-3), 1.90 (m, Ha-5), 1.40 (m,
Hb-5), 2.64 (m, H-6), 2.44 (m, Ha-7), 1.48 (m, Hb-7), 6.00
(d, J = 7.8 Hz, H-8), 1.90 (s, H-11), 5.49 (s, Ha-12), 5.47 (s,
Hb-12), 1.12 (3H, s, H-13), 1.19 (3H, s, H-14), 1.25 (3H, s,
H-15), 7.55 (d, J = 4.8 Hz, H-4¢), 7.09 (t, J = 4.0 Hz, H-5¢),
7.79 (d, J = 3.6 Hz, H-6¢); 13C NMR (75 MHz, CDCl3) d
44.1 (C-1), 43.4 (C-2), 42.5 (C-3), 49.9 (C-4), 45.4 (C-5),
49.3 (C-6), 35.0 (C-7), 76.2 (C-8), 158.7 (C-9), 90.3 (C-
10), 66.3 (C-11), 114.5 (C-12), 32.5 (C-13), 31.3 (C-14),
23.7 (C-15), 161.9 (C-1¢), 127.7 (C-2¢), 134.1 (C-4¢), 132.4
(C-5¢), 133.3 (C-6¢).
1
(calc for C23H30O3); H NMR (300 MHz, CDCl3) d 1.48
(2H, m, H-2), 1.70 (2H, m, H-3), 1.97 (m, Ha-5), 1.30 (m,
Hb-5), 2.64 (m, H-6), 2.48 (m, Ha-7), 1.50 (m, Hb-7), 6.04
(d, J = 7.8 Hz, H-8), 1.91 (s, H-11), 5.47 (s, Ha-12), 5.46 (s,
Hb-12), 1.12 (3H, s, H-13), 1.20 (3H, s, H-14), 1.27 (3H, s,
H-15), 7.92 (2H, d, J = 7.8 Hz, H-3¢,7¢), 7.24 (2H, d, J = 7.8
Hz, H-4¢,6¢), 2.41 (s, H-8¢); 13C NMR (75 MHz, CDCl3), d
44.1 (C-1), 43.4 (C-2), 42.4 (C-3), 49.8 (C-4), 45.5 (C-5),
49.3 (C-6), 35.1 (C-7), 75.7 (C-8), 158.9 (C-9), 90.3 (C-
10), 66.1 (C-11), 113.8 (C-12), 32.5 (C-13), 31.3 (C-14),
23.8 (C-15), 166.4 (C-1¢), 127.7 (C-2¢), 129.6 (C-3¢,7¢),
129.1 (C-4¢,6¢), 143.6 (C-5¢), 21.6 (C-8¢).
10a-Hydroxy-8b-O-4-chlorobenzoylcapnellene (4)
[a]2D5 +60.0 (c 0.05, CH2Cl2); UV lmax 237, 252 nm;
IR (CH2Cl2) nmax 3494 (OH), 1715 (C=O ester), 1593, 1488
cm-1; EIMS m/z 374; HRESIMS m/z 397.1548 [M+Na]+
(calc for C22H27ClO3); 1H NMR (300 MHz, CDCl3) d 1.50
(2H, m, H-2), 1.70 (2H, m, H-3), 1.93 (m, Ha-5), 1.38 (m,
Hb-5), 2.65 (m, H-6), 2.46 (m, Ha-7), 1.46 (m, Hb-7), 6.03
(d, J = 7.8 Hz, H-8), 1.90 (s, H-11), 5.46 (2H, br s, H-12),
1.11 (3H, s, H-13), 1.19 (3H, s, H-14), 1.26 (3H, s, H-15),
7.95 (2H, d, J = 7.1 Hz, H-3¢,7¢), 7.40 (2H, d, J = 7.1 Hz,
H-4¢,6¢); 13C NMR (75 MHz, CDCl3), d 44.1 (C-1), 43.4
(C-2), 42.3 (C-3), 49.7 (C-4), 45.5 (C-5), 49.3 (C-6), 35.1
10a-Hydroxy-8b-O-4-fluorobenzoylcapnellene (7)
[a]2D5 +124.0 (c 0.05, CH2Cl2); UV lmax 241 nm; IR
(CH2Cl2) nmax 3502 (OH), 1715 (C=O ester), 1603, 1508
(Ar.) cm-1; EIMS m/z 358; HRESIMS m/z 381.1847
[M+Na]+ (calc for C22H27FO3); 1H NMR (300 MHz,
CDCl3) d 1.50 (2H, m, H-2), 1.75 (2H, m, H-3), 1.93 (m,
Ha-5), 1.39 (m, Hb-5), 2.66 (m, H-6), 2.48 (m, Ha-7), 1.47
(m, Hb-7), 6.04 (br d, J = 6.5 Hz, H-8), 1.91 (s, H-11), 5.47
(2H, br s, H-12), 1.12 (3H, s, H-13), 1.20 (3H, s, H-14),
1.27 (3H, s, H-15), 8.04 (2H, d, J = 6.6 Hz, H-3¢,7¢), 7.12
(2H, d, J = 6.6 Hz, H-4¢,6¢); 13C NMR (75 MHz, CDCl3), d

832 J. Chin. Chem. Soc., Vol. 55, No. 4, 2008
Shen et al.
44.2 (C-1), 43.4 (C-2), 42.4 (C-3), 49.8 (C-4), 45.5 (C-5),
49.3 (C-6), 35.1 (C-7), 76.1 (C-8), 158.7 (C-9), 90.2
(C-10), 66.1 (C-11), 113.9 (C-12), 32.5 (C-13), 31.3
(C-14), 23.8 (C-15), 165.3 (C-1¢), 126.7 (C-2¢), 132.1
(C-3¢,7¢), 115.5 (C-4¢,6¢), 164.0 (C-5¢).
1.56 (m, Hb-7), 6.04 (d, J = 7.8 Hz, H-8), 1.91 (s, H-11),
5.50 (s, Ha-12), 5.48 (s, Hb-12), 1.11 (3H, s, H-13), 1.19
(3H, s, H-14), 1.26 (3H, s, H-15), 8.18 (2H, d, J = 8.5 Hz,
H-3¢,7¢), 8.29 (2H, d, J = 8.5 Hz, H-4¢,6¢); 13C NMR (75
MHz, CDCl3), d 44.2 (C-1), 43.2 (C-2), 42.3 (C-3), 49.7
(C-4), 45.5 (C-5), 49.3 (C-6), 35.1 (C-7), 77.1 (C-8), 158.4
(C-9), 90.2 (C-10), 66.1 (C-11), 114.3 (C-12), 32.6 (C-13),
31.3 (C-14), 23.7 (C-15), 164.4 (C-1¢), 135.8 (C-2¢), 130.6
(C-3¢,7¢), 123.5 (C-4¢,6¢), 150.5 (C-5¢).
10a-Hydroxy-8b-O-4-propylbenzoylcapnellene (8)
[a]2D5 +74.2 (c 0.05, CH2Cl2); UV lmax 234, 250 nm;
IR (CH2Cl2) nmax 3481 (OH), 1714 (C=O ester), 1610, 1457
(Ar.) cm-1; EIMS m/z 382; HRESIMS m/z 405.2408 [M+
Na]+ (calc for C25H34O3); 1H NMR (300 MHz, CDCl3) d
1.50 (2H, m, H-2), 1.69 (2H, m, H-3), 1.92 (2H, m, Ha-5),
1.46 (m, Hb-5), 2.65 (m, H-6), 2.45 (m, Ha-7), 1.49 (m,
Hb-7), 6.04 (d, J = 7.7 Hz, H-8), 1.92 (s, H-11), 5.47 (s,
Ha-12), 5.46 (s, Hb-12), 1.13 (3H, s, H-13), 1.20 (3H, s,
H-14), 1.27 (3H, s, H-15), 7.95 (2H, d, J = 8.0 Hz, H-3¢,7¢),
7.25 (2H, d, J = 8.0 Hz, H-4¢,6¢), 2.64 (2H, t, J = 7.4 Hz,
H-8¢), 1.65 (m, H-9¢), 0.94 (t, J = 7.3 Hz, H-10¢); 13C NMR
(75 MHz, CDCl3), d 44.1 (C-1), 43.4 (C-2), 42.4 (C-3),
49.8 (C-4), 45.4 (C-5), 49.3 (C-6), 35.1 (C-7), 75.7 (C-8),
158.9 (C-9), 90.3 (C-10), 66.1 (C-11), 113.8 (C-12), 32.5
(C-13), 31.3 (C-14), 23.8 (C-15), 166.4 (C-1¢), 127.9
(C-2¢), 129.6 (C-3¢,7¢), 128.5 (C-4¢,6¢), 148.3 (C-5¢), 38.0
(C-8¢), 24.2 (C-9¢), 13.7 (C-10).
10a-Hydroxy-8b-O-4-anisoylcapnellene (11)
[a]2D5 +100.3 (c 0.05, CH2Cl2); UV lmax 255, 273 nm;
IR (CH2Cl2) nmax 3488 (OH), 1711 (C=O ester), 1606, 1511
(Ar.) cm-1; EIMS m/z 370; HRESIMS m/z 393.2040
[M+Na]+ (calc for C23H30O4); 1H NMR (300 MHz, CDCl3)
d 1.50 (2H, m, H-2), 1.71 (2H, m, H-3), 1.92 (m, Ha-5),
1.46 (m, Hb-5), 2.54 (m, H-6), 2.46 (m, Ha-7), 1.54 (m, Hb-
7), 6.02 (d, J = 7.1 Hz, H-8), 1.91 (s, H-11), 5.47 (s, Ha-12),
5.46 (s, Hb-12), 1.12 (3H, s, H-13), 1.19 (3H, s, H-14), 1.27
(3H, s, H-15), 7.99 (2H, d, J = 8.7 Hz, H-3¢,7¢), 6.92 (2H, d,
J = 8.7 Hz, H-4¢,6¢), 3.86 (3H, s, H-8¢); 13C NMR (75 MHz,
CDCl3), d 44.1 (C-1), 43.4 (C-2), 42.4 (C-3), 50.0 (C-4),
45.5 (C-5), 49.3 (C-6), 35.1 (C-7), 75.6 (C-8), 163.3 (C-9),
90.2 (C-10), 66.1 (C-11), 113.6 (C-12), 32.5 (C-13), 31.3
(C-14), 23.8 (C-15), 166.0 (C-1¢), 122.9 (C-2¢), 131.6 (C-
3¢,7¢), 113.7 (C-4¢,6¢), 159.0 (C-5¢), 55.4 (OCH3).
10a-Hydroxy-8b-O-cinnamoylcapnellene (9)
[a]2D5 +105.6 (c 0.05, CH2Cl2); UV lmax 280, 305 nm;
IR (CH2Cl2) nmax 3481 (OH), 1705 (C=O ester), 1636 (dou-
ble bond), 1457 cm-1; EIMS m/z 366; HREIMS 389.2092
Cytotoxicity Assay
The cytotoxicity assay depends on the binding of
methylene blue to fixed monolayers of four human tumor
cell lines (Hela, KB, Daoy, and WiDr), respectively. Sam-
ples and control standard drugs were prepared at a concen-
tration of 1, 10, 40, and 100 mg/mL. After seeding 2880
cells/well in a 96-well microtiter plate for 3 h, 20 L of sam-
ple or standard agent was placed in each well and incubated
at 37 °C for 3 days. The absorbance was measured on a
microtiter plate reader (Dynatech, MR 7000) at 650 nm.
The IC50 value was defined, by comparison with the un-
treated cells, as the concentration of a test sample resulting
in 50% reduction of absorbance. Mitomycin C was used as
a positive control.
1
m/z [M+Na]+ (calc for C24H30O3); H NMR (300 MHz,
CDCl3) d 1.47 (2H, m, H-2), 1.69 (2H, m, H-3), 1.91 (m,
Ha-5), 1.37 (m, Hb-5), 2.63 (m, H-6), 2.44 (m, Ha-7), 1.51
(m, Hb-7), 5.94 (d, J = 6.8 Hz, H-8), 1.90 (s, H-11), 5.43
(2H, br s, H2-12), 1.12 (3H, s, H-13), 1.19 (3H, s, H-14),
1.27 (3H, s, H-15), 6.46 (d, J = 16.0 Hz, H-2¢), 7.69 (d, J =
16.0 Hz, H-3¢), 7.53 (2H, m, H-5¢,9¢), 7.39 (3H, m, H-
6¢,7¢,8¢); 13C NMR (75 MHz, CDCl3) d 44.1 (C-1), 43.3
(C-2), 42.3 (C-3), 49.8 (C-4), 45.4 (C-5), 49.4 (C-6), 35.0
(C-7), 75.4 (C-8), 158.7 (C-9), 90.2 (C-10), 66.0 (C-11),
113.2 (C-12), 32.5 (C-13), 31.4 (C-14), 23.8 (C-15), 166.7
(C-1¢), 113.2 (C-2¢), 144.8 (C-3¢), 134.3 (C-4¢), 128.1
(C-5¢,9¢), 128.8 (C-6¢,8¢), 118.4 (C-5¢).
10a-Hydroxy-8b-O-4-nitrobenzoylcapnellene (10)
[a]2D5 +91.2 (c 0.05, CH2Cl2); UV lmax 255, 276 nm;
IR (CH2Cl2) nmax 3525 (OH), 1722 (C=O ester), 1607,
1529, 1347 (NO2) cm-1; EIMS m/z 385; HRESIMS m/z
408.1784 [M+Na]+ (calc for C22H27NO5); 1H NMR (300
MHz, CDCl3) d 1.47 (2H, m, H-2), 1.72 (2H, m, H-3), 1.95
(m, Ha-5), 1.38 (m, Hb-5), 2.66 (m, H-6), 2.50 (m, Ha-7),
ACKNOWLEDGMENT
The authors thank the Office of National Science and
Technology Program for Biotechnology and Pharmaceuti-
cal, and the National Science Council, Taipei, Taiwan (NSC
95-2323-B-002-018) for providing financial support.
Received December 25, 2007.

Capnellene-8b,10a-diol Derivatives from Capnella sp.
J. Chin. Chem. Soc., Vol. 55, No. 4, 2008 833
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Wallace, H. M. Tetrahedron 1998, 54, 12953.
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