Xanthones and benzophenones from Garcinia griffithii and Garcinia mangostana

Article abstract of DOI:10.1016/j.phytochem.2005.04.032

A new polyisoprenylated benzophenone, guttiferone I, together with the known compounds cambogin, 1,7-dihydroxyxanthone, 1,3,6,7-tetrahydroxyxanthone and 1,3,5,6-tetrahydroxyxanthone were isolated from the stem bark of Garcinia griffithii. The acetone extract of the heartwood of Garcinia mangostana contained one new diprenylated xanthone (mangoxanthone) and a new benzophenone (3′,6-dihydroxy-2,4,4′-trimethoxybenzophenone) as well as the known xanthones dulxanthone D, 1,3,7-trihydroxy-2-methoxyxanthone, 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthen-9-one. Their structures were established on the basis of spectroscopic studies and chemical correlation.

Full text of DOI:10.1016/j.phytochem.2005.04.032

PHYTOCHEMISTRY
Phytochemistry 66 (2005) 1718–1723
www.elsevier.com/locate/phytochem
Xanthones and benzophenones from Garcinia griffithii and
Garcinia mangostana
*
Nilar, Lien-Hoa D. Nguyen, Ganpathi Venkatraman, Keng-Yeow Sim, Leslie J. Harrison
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Republic of Singapore
Received 7 September 2004; received in revised form 21 April 2005
Available online 15 June 2005
Abstract
A new polyisoprenylated benzophenone, guttiferone I, together with the known compounds cambogin, 1,7-dihydroxyxanthone,
1,3,6,7-tetrahydroxyxanthone and 1,3,5,6-tetrahydroxyxanthone were isolated from the stem bark of Garcinia griffithii. The acetone
extract of the heartwood of Garcinia mangostana contained one new diprenylated xanthone (mangoxanthone) and a new benzophe-
none (30,6-dihydroxy-2,4,40-trimethoxybenzophenone) as well as the known xanthones dulxanthone D, 1,3,7-trihydroxy-2-meth-
oxyxanthone, 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthen-9-one. Their structures were established on the basis of
spectroscopic studies and chemical correlation.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Guttiferae; Garcinia griffithii; Garcinia mangostana; Polyisoprenylated benzophenones; Xanthones
1. Introduction
Garcinia mangostana L. is commonly found through-
out South and South East Asia where it is the source of
the mangosteen fruit as well as being utilised in tradi-
tional treatments for skin diseases (Burkill, 1966; Perry
and Metzger, 1980). We have previously reported the
isolation of 12 new xanthones from the hexane extract
of the heartwood of G. mangostana L. collected in
Myanmar (Nilar and Harrison, 2002). In a continuation
of our study of this species, we have now examined the
acetone extract and have obtained three known xant-
The genus Garcinia (Guttiferae) is known to produce
a variety of biologically active metabolites such as polyi-
soprenylated benzophenones (Gustafson et al., 1992;
Williams et al., 2003) and xanthones (Bennett and Lee,
1989). Garcinia griffithii T. Anders. is a medium-sized
tree found in South East Asia (Whitmore, 1972). No
medicinal uses are recorded for this species although it
has been used as a fruit tree (Burkill, 1966; Perry and
Metzger, 1980). As part of a phytochemical study of
South East Asian plants, we have previously reported
the presence of a cytotoxic bixanthone, griffipavixanth-
one, which is common to G. griffithii and Garcinia parvi-
folia (Xu et al., 1998) and now describe the isolation and
structural elucidation of further constituents of the stem
bark of G. griffithii collected in Singapore.
hones along with
benzophenone.
a new xanthone and a new
2. Results and discussion
Both hexane and EtOAc extracts of the stem bark of
G. griffithii were analysed. The latter gave the known
polyisoprenylated benzophenone, cambogin (Gustafson
et al., 1992) and three known xanthones, 1,7-dihydr-
oxyxanthone (Delle Monache et al., 1983), 1,3,6,7-tetra-
*
Corresponding author. Tel.: +65 6874 2687; fax: +65 6779 1691.
E-mail addresses: chmhl@nus.edu.sg, leslie@nus.edu.sg (L.J. Har-
rison).
0031-9422/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.phytochem.2005.04.032

Nilar et al. / Phytochemistry 66 (2005) 1718–1723
1719
Table 1
1H (500 MHz), HMBC and 13C (125 MHz) NMR data for 1 in
CD3OD/TFA (J in Hz in parentheses)
hydroxyxanthone (Carpenter et al., 1969) and 1,3,5,6-
tetrahydroxyxanthone (Frahm and Chaudhuri, 1979)
which were identified by comparison of their physical
properties with reported values. The hexane extract of
the stem bark afforded mixtures of lipids and sterols as
well as griffipavixanthone (Xu et al., 1998) and a new
polyisoprenylated benzophenone, guttiferone I (1). The
mass spectrum of compound 1 showed a molecular ion
(m/z 602.3616) which established the molecular formula
as C38H50O6. UV absorptions at kmax 280 and 232 nm
revealed aromatic and conjugated carbonyl chromoph-
ores. The IR spectrum exhibited bands for hydroxyl
(3350 cmꢀ1) and both non-conjugated (1724 cmꢀ1) and
Position
dH
HMBC
dC
2J
3J
1
–
194.9
118.4
195.4
68.1
2
–
3
–
4
–
5
–
47.9
41.0
6
1.98 m
2.04 m
–
C-5, C-24
C-8
C-25
C-1, C-29
7
40.7
61.8
8
9
–
209.8
196.0
129.6
117.3
146.2
152.5
115.1
125.2
10
11
12
13
14
15
16
–
conjugated (1639 cmꢀ1
)
carbonyl groups. The 1H
–
NMR spectrum in CDCl3 was quite complex, but when
the spectrum was recorded in CD3OD/TFA only one set
of signals was obtained. This behaviour has been ob-
served for polyisoprenylated benzophenones from
Garcinia and Allanblackia species which undergo keto-
enol tautomerism (Gustafson et al., 1992; Fuller et al.,
7.19 d (1.9)
–
C-11, C-13
C-10, C-14, C-16
–
6.68 d (8.3)
6.98 dd
(1.9, 8.3)
2.54 m
2.75 br dd
(9.1, 13.5)
4.90 br t (9.1)
–
C-14, C-16
C-11, C-15
C-11, C-13
C-10, C-12, C-14
17
C-4, C-18
C-5, C-9, C-19
C-20, C-21
27.1
1
1999; Williams et al., 2003). The H NMR spectrum
(Table 1) revealed the presence of a 1,2,4-trisubstituted
benzene ring [dH 7.19 (1H, d, J = 1.9 Hz, H-12), 6.98
(1H, dd, J = 8.3 and 1.9 Hz, H-16), and 6.68 (1H, d,
J = 8.3 Hz, H-15)]. There were also resonances for two
tertiary methyl groups [dH 1.24 (3H, s, H3-22) and
1.02 (3H, s, H3-23)], four trisubstituted double bonds
[dH 4.90 (1H, br t, J = 9.1 Hz, H-18), 5.05 (1H, m, H-
25), 5.17 (1H, m, H-30), and 5.09 (1H, m, H-35)], seven
vinylic methyl groups [dH 1.69 (3H, s, H3-38), 1.68 (3H,
s, H3-21), 1.65 (6H, s, H3-20 and H3-27), 1.58 (3H, s, H3-
36), 1.53 (3H, s, H3-37), and 1.48 (3H, s, H3-28)] and 10
allylic methylene protons [dH 2.0–2.2 & 2.5–2.75 (10H,
m)] which suggested the presence of two 3-methylbut-
2-enyl and one 3,7-dimethylocta-2,6-dienyl side chains.
The 13C NMR spectrum (Table 1) showed resonances
for six aromatic carbons [dC 152.5 (C-14), 146.2 (C-
13), 129.6 (C-11), 125.2 (C-16), 117.3 (C-12), and 115.1
(C-15)] and a conjugated carbonyl group at dC 196.0
(C-10), which indicated the presence of a 3,4-dihydroxy-
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
120.8
135.7
25.9
1.65 s
1.68 s
1.24 s
1.02 s
2.09 m
5.05 m
–
C-19, C-21
C-19, C-20
C-5
C-18
C-18
18.2
23.2
C-4, C-6, C-23
C-4, C-6, C-22
C-26
C-5
C-6, C-25
C-24
27.3
30.1
C-28
125.4
133.7
26.3
1.65 s
1.48 s
2.52 m
5.17 m
–
C-26
C-8, C-30
C-25, C-27
C-31
C-38
18.1
31.8
120.5
139.2
27.7
2.00 m
1.99 m
5.09 m
–
27.8
C-36, C-37
125.1
132.2
25.9
1.58 s
1.53 s
1.69 s
C-35
C-35
C-31
C-34, C-37
C-34
C-30
17.8
16.8
1
benzoyl group. This was supported by H NMR signals
The C-17 methylene protons showed five correlations
3
for a 1,2,4-trisubstituted benzene ring (see above) and a
peak at m/z 137.0256 (C7H5O3) in the mass spectrum.
The presence of these structural features was supported
by the HMBC spectrum (see Table 1). The 13C NMR
spectrum also showed resonances for a non-conjugated
ketone [dC 209.8 (C-9)], two quaternary carbons [dC
68.1 (C-4) and 61.8 (C-8)] and an enolised 1,3-diketone
[dC 194.9 (C-1), 118.4 (C-2) and 195.4 (C-3)] which along
with quaternary [d 47.9 (C-5)], methine [d 41.0 (C-6)]
and methylene [d 40.7 (C-7)] carbons were characteristic
of the bicyclo[3.3.1]nonane ring system characteristic of
a polyisoprenylated benzophenone (Gustafson et al.,
1992).
(2J: C-4, C-18; J: C-5, C-9 and C-19) which required
the placement of one of the 3-methylbut-2-enyl groups
at C-4. The gem-dimethyl group at C-5 was indicated
by correlations between each set of methyl protons with
C-4, C-5 and C-6. The correlations of the C-24 methy-
lene protons (2J: C-6, C-25; 3J: C-26) required the place-
ment of the other 3-methylbut-2-enyl group at C-6.
Assignment of the relative stereochemistry of this group
was made by comparison of the 13C chemical shifts of
the methyl groups at C-22 and C-23 with those of guttif-
erones B (2), E (3) and F (4) (Gustafson et al., 1992; Ful-
ler et al., 1999). In guttiferone B (2), where the geranyl
side chain at C-6 is equatorial, the C-22 and C-23 methyl
resonances appeared at d 23.8 and 16.5, the C-23 methyl
The positions of the side chains were assigned from
the HMBC spectrum (Table 1) and nOe interactions.

1720
Nilar et al. / Phytochemistry 66 (2005) 1718–1723
being shielded by a c-gauche interaction with the geranyl
group. In both guttiferones E (3) and F (4), where the 3-
methylbut-2-enyl group at C-6 is axial, this shielding
interaction is absent for C-23 and hence the C-22 and
C-23 methyl signals appeared at d 23.2 and 27.3. In
the case of 1, the corresponding methyl resonances [dC
23.2 (C-22) and 27.3 (C-23)] established the axial nature
of the 3-methylbut-2-enyl group at C-6. The C-29 meth-
ylene protons showed two 2J couplings to C-8 and C-30
obtained from Polygala cyparissias (Pinheiro et al.,
1998).
The third compound, 1,3,5-trihydroxy-13,13-di-
methyl-2H-pyran[7,6-b]xanthen-9-one (8) has been
reported only as a transformation product of 1,3,5-tri-
hydroxy-6,60-dimethylpyrano-(20,30:6,7)-4-(1,2-dimethyl-
prop-2-enyl)-xanthone (9). This is the first report of 8 as
a natural product. 2D NMR studies (see Fig. 1) con-
firmed the structure and allowed the assignment of the
13C NMR spectrum (see Section 3) which has not previ-
ously been determined.
3
and a J coupling to C-31. They also showed an nOe
interaction with the C-38 methyl, while the C-30 olefinic
proton showed a correlation with C-38 and showed nOe
enhancements with the C-32 methylene protons. This
established that the 3,7-dimethylocta-2,6-dienyl group
was attached to C-8. The bicyclic ring system in com-
pound 1 requires that the C-4 and C-8 substituents be
equatorial. The absolute configuration of 1 remains
undetermined.
30,6-Dihydroxy-2,4,40-trimethoxybenzophenone (10)
was obtained as a pale yellow solid, C16H16O6 (m/z
304.0919), m.p. 161–162 ꢁC with UV (228, 280 and
312 nm) and IR absorptions [3400 (OH), 1618 (a
cross-conjugated C@O) and 1579 and 1514 (aromatic
rings) cmꢀ1] which were suggestive of an oxygenated
1
benzophenone. The H NMR spectrum contained sig-
nals for a chelated hydroxyl group [dH 11.72 (1H, s, 6-
OH)], two meta-coupled aromatic protons [dH 6.15
(1H, d, J = 2.3 Hz, H-5) and 5.95 (1H, d, J = 2.3 Hz,
H-3)], a 1,2,4-trisubstituted benzene ring [dH 7.17 (1H,
dd, J = 2.0 and 8.8 Hz, H-60), 7.17 (1H, d, J = 2.0 Hz,
H-20) and 6.83 (1H, d, J = 8.8 Hz, H-50)] and three meth-
oxyl groups [dH 3.93, 3.83 and 3.52 (3 Æ 3H, s, 40-OMe, 4-
OMe and 2-OMe)]. The 13C NMR spectrum (see Section
3) revealed the presence of sixteen carbon resonances
due to a carbonyl carbon, 12 aromatic carbons and three
methoxyl groups. These spectral data indicated that 10
was a benzophenone comprising 1,2,4-trisubstituted
and 1,2,3,5-tetrasubstituted benzene rings. Methylation
afforded a pentamethyl ether (11) which was identical
to that obtained by methylation of 40,6-dihydroxy-
2,30,4-trimethoxybenzophenone (12) from G. subelliptica
(Minami et al., 1994). The positions of the methoxyl
groups on 10 were determined using difference NOE
spectroscopy. The trisubstituted ring had only one
methoxyl since H-50 was enhanced upon irradiation of
the C-40 methoxyl group. Irradiation of the most
shielded methoxyl (2-OMe) enhanced H-3 whilst both
H-3 and H-5 were affected when the 4-OMe was irradi-
ated. The natural product was therefore 30,6-dihydroxy-
2,4,40-trimethoxybenzophenone (10).
R2
21
29
28
23
22
9
OH
13
17
24
38
HO
O
5O
3
7
37
10
1
A
15
11
R1
O
OH
1 R1=A, R2=H
2 R1=A, R2=preny1
3 R1=B, R2=H
B
22
23
OH
HO
O
5O
O
OH
4
The final compound, mangoxanthone (13) was iso-
lated as yellow needles, m.p. 195–197 ꢁC, [a]D ꢀ40.0.
A positive test with alcoholic FeCl3 showed it to be a
From G. mangostana, two compounds which have
previously been reported as natural products were iso-
lated. The first compound was a prenylated xanthone,
dulxanthone D (5), which has been isolated from G. dul-
cis and was identified by comparison with the literature
values (Ito et al., 1997). Methylation of 5 with diazome-
thane gave a trimethyl ether (6) [dH 3.97, 3.87 and 3.80
(each 3H, s)] which possessed a chelated hydroxyl [dH
13.44 (1H, s, 1-OH)] and was therefore the previously
unknown 1-hydroxy-3,6,7-trimethoxy-8-(3-methylbut-
2-enyl)-xanthone. The second known compound was
1,3,7-trihydroxy-2-methoxyxanthone (7) which has been
H
H
O
H
O
O
O
H
H
OH
OH
H
HMBC correlation
Fig. 1. HMBc correlations of 8.

Nilar et al. / Phytochemistry 66 (2005) 1718–1723
1721
phenol. The molecular formula was deduced to be
1
H
H
H
O
O
O
C23H24O6 from the HREI-MS (m/z 396.1602). The H
HO
H
and 13C NMR spectra (see Table 2) of 13 had signals
due to a chelated hydroxyl group [dH 13.08 (1H, s,
exchangeable with D2O, 1-OH)] with the corresponding
chelated carbonyl carbon [dC 182.2 (C-9)], a free pheno-
lic hydroxyl group [dH 9.00 1H, br s, exchangeable with
D2O, 7-OH], a 1,2,4-trisubstituted benzene ring [dH 7.56
(1H, d, J = 2.9 Hz, H-8), 7.48 (1H, d, J = 9.0 Hz, H-5)
and 7.34 (1H, dd, J = 9.0 and 2.9 Hz, H-6); dC 125.5
(C-6), 120.4 (C-5) and 109.9 (C-8)], a 3-methylbut-2-enyl
group [dH 5.30 (1H, t sept, J = 7.5 and 1.2 Hz, H-17),
3.48 and 3.41 (1H each, dd, J = 14.4 and 7.5 Hz, H2-
16), 1.86 (3H, br s, H3-20) and 1.66 (3H, br s, H3-19);
dC 132.7 (C-18), 123.5 (C-17), 23.3 (C-16), 18.7 (C-20)
and 26.5 (C-19)], a 2,3-dioxygenated-3-methylbutyl
group [dH 4.85 (1H, dd, J = 9.4 and 7.5 Hz, H-12),
3.22 (1H, dd, J = 15.6 and 7.5 Hz, H-11) and 3.16 (1H,
dd, J = 15.6 and 9.4 Hz, H-11), 1.28 (3H, s, H3-14) and
1.27 (3H, s, H3-15); dC 93.2 (C-12), 72.3 (C-13), 28.0
(C-11)], 26.8 (C-14) and 25.9 (C-15)], a hydroxyl group
[dH 3.82 (1H, br s, exchangeable with D2O, 13-OH)],
and nine substituted aromatic carbons, five of which
were oxygenated. The UV spectrum exhibited maxima
at 236, 266, 322, and 380 nm, characteristic of a oxygen-
ated xanthone.
O
OH
HMBC correlation
Fig. 2. HMBC correlations of 13.
The HMBC correlations of 13 (see Fig. 2) clearly
identified a 7-hydroxylated xanthone B ring and estab-
lished that the other ring was fully substituted. They also
confirmed the presence of a 3-methylbut-2-enyl group
and a 2,3-dioxygenated-3-methylbutyl group. Correla-
tions of the methylene protons of the latter group and
of the chelated hydroxyl proton established that C-2
was alkylated and a correlation from H-12 to C-3 re-
vealed that this alkyl group formed a 2-(1-hydroxy-1-
methylethyl)-2,3-dihydrofuran ring moiety with the
oxygen at C-3. The 3-methylbut-2-enyl group must by
default be attached to C-4 and this was confirmed by
the presence of a 3J correlation from the C-16 methylene
protons and C-3. The chemical shifts of the fully substi-
tuted ring agreed well with those of morusignin G (14)
(Hano et al., 1991). The compound was, therefore, man-
goxanthone (13) which is a new natural product.
Table 2
1H (500 MHz) and 13C (75 MHz) NMR data for 9 in acetone-d6 (J in
Hz in parentheses)
O
O
OH
O
OH
MeO
RO
HO
OMe
OH
Position
dH
dC
1
–
157.3
109.0
167.5
103.2
156.5
120.4
125.5
155.5
109.9
122.3
182.2
104.9
151.5
28.0
OR
O
2
–
3
–
5 R=H
6 R=Me
7
4
–
4a
5
–
7.48 d (9.0)
7.34 dd (9.0, 2.9)
6
O
OH
1
O
OMe
7
–
7.56 d (2.9)
11
8
R2O
R3O
8
9
8a
9
–
14
R1O
OMe
10a
–
O
O
OH
5
4
15
9a
10a
11
–
OH
R
–
10 R1=R2=H, R3=Me
11 R1=R2=R3=Me
12 R1=R3=H, R2=Me
8 R=H
9 R=
3.22 dd (15.6, 7.5)
3.16 dd (15.6, 9.4)
4.85 dd (9.4, 7.5)
–
1.27 sa
1.28 sa
Me
Me
12
13
14
15
16
93.2
72.3
26.8a
25.9a
23.3
O
OH
3.48 dd (14.4, 7.5)
3.41 dd (14.4, 7.5)
5.30 t sept (7.5, 1.2)
–
8
14
1
R1
11
9
15
17
18
123.5
132.7
26.5
O
10a
OH
O
4
5
16
R2
19
20
1.66 br s
1.86 br s
18.7
1-OH
7-OH
18-OH
a
13.08 s
9.00 br s
3.82 br s
19
20
13 R1=OH, R2=H
14 R1=H, R2=OH
Assignments within the same column are interchangeable.

1722
Nilar et al. / Phytochemistry 66 (2005) 1718–1723
3. Experimental
Removal of the solvent gave a crude extract (29.1 g)
which was subjected to CC (silica gel, acetone–hexane
1
step gradient) to give 19 frs. TLC and H NMR spec-
3.1. General experimental details
troscopy showed that only fr 7 was worth further
examination. The fr (3.56 g) was subjected to GPC,
CC (silica gel, 30% EtOAc–hexane) and HPLC (silica
gel, 30% EtOAc - hexane) to give dulxanthone D (5)
(7 mg), 306-dihydroxy-2440-trimethoxybenzophenone (10)
(55 mg), 1,3,7-trihydroxy-2-methoxyxanthone (7) (10 mg),
1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]-xanthen-
9-one (8) (8 mg), and mangoxanthone (13) (6.2 mg).
Mp uncorr. IR: CHCl3 unless otherwise specified.
UV: EtOH. 1H NMR and 13C NMR: Bruker
DPX300, Bruker AMX500 or Bruker DRX500 relative
to TMS at d 0.0. EIMS: 70 eV Finnigan TSQ-7000
LC/triple quadrupole MS.
CC was carried out on normal phase silica gel 60
(Merck, 63–200 lm) or reversed phase silica gel (Baker
C18, 40 lm). GPC: Sephadex LH-20 (CHCl3–MeOH
1:1 as eluant). HPLC: Lichrosorb silica, 10 lm,
4.5 · 250 mm or 9.0 · 250 mm, RI detection.
3.4.1. 1-Hydroxy-3,6,7-trimethoxy-8-(3-methylbut-2-
enyl)-xanthone (6)
3.2. Plant material
Dulxanthone D (5) (4 mg) was methylated with ethe-
real CH2N2 to give the trimethyl ether (6) as a pale yel-
low gum. UV kmax nm (log e): 244 (4.33), 254 (4.37), 308
(4.17), 346 (3.75). IR mmax cmꢀ1: 1649 (C@O), 1596 (Ar),
1457, 1427, 1269, 1208, 1160, 1128. 1H NMR (500 MHz,
CDCl3) dH 13.44 (1H, s, 1-OH), 6.76 (1H, s, H-5), 6.32
(1H, d, J = 2.3 Hz, H-4), 6.31 (1H, d, J = 2.3 Hz, H-2),
5.25 (1H, t sept, J = 6.6 and 1.3 Hz, H-12), 4.13 (2H,
br d, J = 6.6 Hz, H2-11), 3.97 (3H, s, OMe), 3.87 (3H,
s, OMe), 3.80 (3H, s, OMe), 1.85 (3H, s, H3-15), 1.69
(3H, br s, H3-14). 13C NMR (125 MHz, CDCl3) dC
182.1 (C), 165.8 (C), 163.7 (C), 158.3 (C), 156.8 (C),
155.6 (C), 144.2 (C), 137.4 (C), 132.0 (C), 123.1 (CH),
112.0 (C), 104.1 (C), 98.4 (CH), 96.8 (CH), 91.9 (CH),
61.0 (CH3), 56.1 (CH3), 55.7 (CH3), 26.2 (CH2), 25.9
(CH3), 18.2 (CH3). EIMS m/z (rel. int.): 370 [M]+ (39),
355 (36), 341 (8), 327 (100), 313 (9), 299 (11), 283 (8),
257 (5), 195 (23), 170 (11), 135 (2), 77 (44), 41 (5).
HR-EIMS m/z 370.1410 (C21H22O6 requires m/z
370.1416).
Stem bark of G. griffithii was collected in Singapore
and identified by Prof. Le Cong Kiet of the Botany
Department, University of Ho Chi Minh City, Vietnam.
A herbarium sample (LJHGG1) is deposited in the
National University of Singapore Herbarium (SINU).
Hexane-extracted G. mangostana heartwood (1 kg) was
available from an earlier study of the hexane soluble
material (Nilar and Harrison, 2002).
3.3. Extraction and isolation of compounds from
G. griffithii
Air-dried and ground bark (950 g) was extracted with
hot hexane (35 g of extract) and then hot EtOAc (30 g of
extract). CC of the hexane extract over silica gel yielded
1
7 frs. H NMR showed that frs 1–2 contained triglycer-
ides and b-sitosterol and they were not investigated
further. Frs 4–7 showed a single spot on TLC and after
RP-CC over C18 silica gel [Me2CO–H2O–TFA
(74.95:24.95:0.1)] yielded guttiferone I (1) (40 mg). CC
of the EtOAc extract over silica gel (EtOAc–hexane gra-
dient) gave, in order of elution, cambogin (35 mg), 1,7-
dihydroxyxanthone (10 mg), 1,3,6,7-tetrahydroxyxanth-
one (12 mg) and 1,3,5,6-tetrahydroxyxanthone (15 mg).
3.4.2. 1,3,5-Trihydroxy-13,13-dimethyl-2H-pyran[6,7-
b]-xanthen-9-one (8)
Yellow solid; m.p. 275–277 ꢁC. UV kmax nm (log e):
274 (4.79), 328 (4.29), 362 (4.19). IR mmax cmꢀ1 3438
(OH), 1654 (C@O), 1578 (Ar), 1474, 1340, 1253, 1167,
1
3.3.1. Guttiferone I (1)
Bright yellow solid, m.p. 60–62ꢁ. [a]D ꢀ68 (c 1.2,
1136. H NMR (500 MHz, acetone-d6) dH 13.10 (s, 1-
OH, exchangeable with D2O), 7.41 (s, H-8), 6.56 (d,
J = 9.9 Hz, H-11), 6.44 (d, J = 2.1 Hz, H-4), 6.23 (d,
J = 2.1 Hz, H-2), 5.88 (d, J = 9.9 Hz, H-12), 1.49 (s,
H3-14 and H3-15); 13C NMR (125 MHz, acetone-d6)
dC 180.9 (C-9), 164.6 (C-1), 166.1 (C-3), 158.7 (C-4a),
146.8 (C-10a), 146.6 (C-6), 134.3 (C-5), 132.4 (C-12),
122.1 (C-11), 119.3 (C-7), 115.3 (C-8a), 113.2 (C-8),
103.2 (C-9a), 98.9 (C-2), 94.8 (C-4), 78.8 (C-13), 28.3
(C-14), 28.3 (C-15). EIMS m/z (rel. int.): 326 [M]+
(57), 311 (100), 297 (5), 274 (17), 259 (22), 231 (14),
203 (6), 156 (40), 141 (7), 115 (3), 69 (5), 59 (14), 43
(32). HR-EIMS m/z 326.0791 (C18H14O6 requires m/z
326.0790).
CHCl3); UV kmax nm (e): 280 (26,700), 232 (20,600);
IR mmax 3350, 1724, 1639, 1505 cmꢀ1 1H NMR and
;
13C NMR (CD3OD/0.1% TFA) (Table 1); HR-EIMS
m/z (rel. int.) 602.36158 [M+] (6), 533.15925 (10),
465.20163 (35), 231.98515 (21), 137.02560 (30),
69.07056 (100).
3.4. Extraction and isolation of compounds from
G. mangostana
The dried and powdered plant material was ex-
tracted by continuous percolation with hot Me2CO.

Nilar et al. / Phytochemistry 66 (2005) 1718–1723
1723
3.4.3. 30,6-Dihydroxy-2,4,40-trimethoxybenzophenone
(10).
Pale yellow solid; m.p. 161–162 ꢁC. UV kmax nm (log
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Acknowledgements
We thank the National University of Singapore for
financial support.
Garcinia griffithii and G. pavifolia. Tetrahedron Lett. 39, 9103–
9106.