Benzoquinone derivatives of Myrsine africana and Maesa lanceolata

Article abstract of DOI:10.1016/S0031-9422(03)00428-X

The fruits of Myrsine africana afforded two new benzoquinone derivatives, methylvilangin and methylanhydrovilangin. On the other hand, from the fruits of Maesa lanceolata two more novel compounds; 2,5-dihydroxy-3-(nonadec-14-enyl)-benzoquinone and lanciaq

Full text of DOI:10.1016/S0031-9422(03)00428-X

Phytochemistry 64 (2003) 855–862
www.elsevier.com/locate/phytochem
Benzoquinone derivatives of Myrsine africana and Maesa lanceolata
Lawrence O. Arot Manguroa,*, Jacob O. Midiwoa, Wolfgang Krausb, Ivar Ugic
aChemistry Department, University of Nairobi, PO Box 30197, Nairobi, Kenya
bUniversitaet Hohenheim, Institut fuer Chemie, Garbenstrasse 30, 70593-Stuttgart, Germany
cTechnische Universitaet Muenchen, Institut fuer Organische Chemie und Biochemie, Lichtenbergstrasse 4, Lehrstuhl 1, 85747-Garching, Germany
Received 25 July 2002; received in revised form 6 May 2003
Abstract
The fruits of Myrsine africana afforded two new benzoquinone derivatives, methylvilangin and methylanhydrovilangin. On the
other hand, from the fruits of Maesa lanceolata two more novel compounds; 2,5-dihydroxy-3-(nonadec-14-enyl)-benzoquinone and
lanciaquinone were isolated. Their structural elucidation was achieved by spectroscopic measurements including 2D NMR experi-
ments.
# 2003 Elsevier Ltd. All rights reserved.
Keywords: Myrsine africana; Maesa lanceolata; Myrsinaceae; Alkylhydroxy-1,4-benzoquinones
1. Introduction
2. Results and discussion
The family Myrsinaceae consists of nearly 1000 spe-
cies of trees and shrubs spread in 33 genera and is
characterized by the presence of 2,5-dihydroxy-3-alkyl-
benzoquinones and a number of triterpenoids based on
oleanane and/or ursane skeleton (Januaro et al., 1992).
In Kenya, the family is represented by five species
spread in four genera, namely: Myrsine, Maesa, Rapa-
nea and Embelia and are widely used in herbal medicine
(Kokwaro, 1976). In previous communications (Midiwo
et al., 1988, 1990, 1992; Midiwo and Manguro, 1996),
we reported the isolation of hydroxylated 1,4-benzo-
quinone derivatives from both Myrsine africana and
Maesa lanceolata parts. In a search for further related
chemical constituents of the plants, we now report the
isolation and structure determination of methylvilangin
(1), methylanhydrovilangin (2), from M. africana in
addition to 2,5-dihydroxy-3-(nonadec-14-enyl)-1,4-ben-
zoquinone (3) and a bisbenzoquinone, lanciaquinone (4)
from M lanceolata. All the compounds have been
reported for the first time as natural products. Their
structures were determined by physical, chemical and
spectroscopic methods.
Fractionation of the ethyl acetate extract of M. afri-
cana powdered fruits has led to the isolation and char-
acterization of two benzoquinone derivatives 1 and 2.
Compound 1 was isolated as an orange amorphous
ꢀ
powder, mp 129–130 C. Its mass spectrum obtained at
70 eV failed to show the molecular ion peak, but instead
afforded characteristic fragments at m/z 320 (C19H2804)
and 294 (C17H2604) (Fig. 1), suggesting the presence of a
bisbenzoquinone (Venkateswarlu and Rao, 1962). Also
evident from the spectrum was the base peak at m/z 154
and low abundant ions at m/z 180, 155 and 153.
Such fragmentation peaks have been reported in
vilangin (11) and other related hydroxylated 1,4-benzo-
quinones with an alkyl side chain (Ogawa and Natori,
1968; Venkateswarlu and Rao, 1962).
The absorption bands at 3320 and 1625 cmꢁ1 in the
IR spectrum coupled with the UV peaks at 430 and 290
nm further supported the presence of an enolic 1,4-
diketo system in which the OH groups are either 2,5- or
2,3-positioned on the ring (Midiwo et al., 1992;
Muhammad et al., 1993; Kiuchi et al., 1998a,b).
In the 1H NMR spectrum, the doublet peak of a
methyl on a tertiary carbon at ꢀ 1.58 and a quartet
methine proton at ꢀ 4.40 were similar to those pre-
viously reported for a corresponding synthetic deriva-
tive (Venkateswarlu and Rao, 1962). Furthermore, the
* Corresponding author.
0031-9422/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0031-9422(03)00428-X

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L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
multiplet resonance at ꢀ 1.50–1.20 on integration rela-
tive to the peak at ꢀ 4.40 corresponded to 36 protons
calculated for 18 methylenes. The remaining H NMR
and 116.20 for C-3 and C-6, respectively (Fig. 2). The
fluxional effect can be precluded if at least one of the
hydroxyl group is removed through structural modifi-
cation such as methylation or acetylation. Such modifi-
cations lead to observation of all the ring carbons as
shown in the 13C NMR spectra of 2,5-dimethox-
ymaesaquinone (10) (see Table 1). Further confirmation
of the structure 1 was achieved by chemical reaction.
Treatment of 1 with excess diazomethane at room tem-
perature gave 5 with a molecular ion peak at m/z 670
(C40H62O5), thus confirming free hydroxyl groups in the
benzoquinone derivative. Its 1H NMR spectrum was
similar to that of the parent compound except the
hydroxyl signals were replaced by four methoxy groups
at ꢀ 4.00 (6H) and ꢀ 3.85 (6H) while the 13C NMR data
(Table 1) clearly exhibited the characteristics of a meth-
oxylated 1,4-benzoquinone (Midiwo and Manguro,
1996). The relative positions of the methoxy groups in 5
was provided by NOESY experiments and further con-
firmed by HMBC correlations (Fig. 3). Saturation of the
methoxy signal at ꢀ 4.00 gave an NOE cross peak with
1
peaks at ꢀ 7.80, 2.43 and 0.88 were unequivocally
assigned to four hydroxyls, two benzylic methylenes and
two side chain terminal methyl groups, respectively.
From the foregoing evidences, compound 1 was con-
sidered to be a bisbenzoquinone in which the two ben-
zoquinone moieties are bridged by a tertiary carbon
holding a methyl function. The 13C NMR spectrum of
the compound did not exhibit all the ring carbon signals
but showed only two peaks at ꢀ 117.45 (C-3 and C-30)
and 114.50 (C-6 and C-60). Normally, the 13C NMR
spectra of 2,5- and/or 2,3-dihydroxy-3-alkyl-1,4-benzo-
quinones do not show the ring carbon peaks particu-
larly those attached to oxygen atoms due to fluxional
effect caused by intramolecular hydrogen bonding. The
result of this is long spin relaxation time which leads to
saturation of oxygen-carbon signals (Midiwo and Man-
guro, 1996). For instance, maesaquinone (7) showed
only two quinonoid carbon peaks above ꢀ 100 at 119.60

L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
857
Fig. 1. Fragmentation pattern of 1 in EIMS (70 eV).
the benzylic methylene (ꢀ 2.37), thus confirming the 2,5-
orientation of OH groups in compound 1. On the basis
of the above data, compound 1 was confirmed as a bis-
benzoquinone, methylvilangin.
above data, 2 was presumed to be a bisbenzoquinone
similar to compound 1 in which both an oxygen
atom and a tertiary carbon holding a methyl group
bridged the two benzoquinone moieties. This sugges-
tion was strongly supported by the molecular ion peak
at m/z 596, calculated for a formula of C36H52O7.
Compound 2, isolated as an orange amorphous solid
1
showed H NMR data which were strongly reminiscent
of those reported for compound 1 except for the shift of
peaks arising from two hydroxyls (ꢀ 7.04), a methine
proton (ꢀ 4.00) and a secondary methyl (ꢀ 1.30) upfleld.
The proposal of the hydroxyl groups being at 2,20- and
not at 3,30-position on the ring was supported by ana-
lysis of relevant fragments in the mass spectrum. The
peaks at m/z 320 and 294, respectively were consistently
interpreted as outlined in Fig. 1. On the basis of the
Acetylation of 2 with acetic anhydride-pyridine pro-
duced 6, with a [M]+, 84 units more than that of the
parent compound, corresponding to addition of two
acetate units. The relative positions of the acetoxy units
in 6 was similarly provided by NOESY experiments.
Irradiation of the acetoxy peak at ꢀ 1.90 (6H) showed
an NOE effect on a benzylic methylene at ꢀ 2.44 (4H),
suggesting that the methylene and the acetoxy groups

858
L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
are vicinally oriented. Accordingly, from the above
results the structure of compound 2 was elucidated as
methylanhydrovilangin.
the presence of an hydroxylated-1,4-benzoquinone deri-
vative (Chandrasekhar et al., 1970; Kiuchi et al.,
1998a,b).
From the ethyl acetate extract of M. lanceolata fruits
were by repeated flash chromatography and recrystalli-
zation two more new compounds 3 and 4 isolated.
Compound 3, an orange amorphous powder showed IR
characteristic absorption bands at 3300 (hydrogen bon-
ded OH) and 1610 (chelated C¼O) cmꢁ1 which together
with the UV spectrum peaks at 426 and 290 nm signified
The structural similarity between 3 and maesaquinone
(7) previously reported from the plant (Midiwo et al.,
1992; Midiwo and Manguro, 1996) was indicated by the
resemblance of their 1H NMR spectra with a major
structural difference being the arrangement of the
substituents around the quinonoid ring. Comparison of
1
their H NMR spectra suggested the location of a pro-
ton at C-6 in 3, as evidenced by a singlet peak at ꢀ 6.0.
Furthermore, its molecular ion and base peaks at m/z
404 and 154, respectively compared to those at m/z [M]*
418 and 168 in 7 is explained by the presence of a qui-
nonoid methyl function in the latter (Ogawa and
Natori, 1968). As was the case in 7, the position of the
double bond in the side chain was identified to be
between C-14 and C-15 by alkaline hydrogen peroxide
oxidation reaction (Ogawa and Natori, 1968).
Treatment of 3 with excess diazomethane at room
temperature and after usual work up afforded 8. Its
1HNMR spectrum revealed the presence of two meth-
oxy groups at ꢀ 4.10 and 3.95 with corresponding 13C
NMR peaks at ꢀ 60.60 and 60.30, respectively. The MS
Fig. 2. The effect of intramolecular bonding on 13C NMR of 7.
Table 1
13C NMR assignment for the hydroxybenzoquinones
Carbon no.
1
2
3
4
5
6
7
8
9
10
1
–
178.90
151.07
120.15
182.05
154.40
127.00
178.90
151.07
120.15
182.05
154.40
127.00
22.14
–
–
184.60
155.80
132.30
183.40
158.80
130.00
184.60
155.80
132.30
183.40
158.80
130.00
28.40
184.43
151.91
122.80
183.90
160.10
122.80
184.43
151.91
120.80
183.90
160.10
120.80
29.40
–
184.30
157.70
182.50
155.90
130.80
183.60
158.90
105.40
181.40
155.60
130.80
181.00
126.30
108.50
–
181.70
157.70
2
–
117.45
–
117.60
–
–
119.60
3
119.50
–
126.70
184.70
127.20
182.55
4
–
–
–
5
–
–
102.40
–
–
116.20
156.00
108.60
151.85
119.50
6
114.50
–
101.20
179.80
155.30
117.30
175.50
118.30
104.10
–
10
–
–
–
–
20
–
–
–
–
–
30
117.45
–
–
–
–
–
40
–
–
–
–
50
–
–
–
–
–
60
114.50
28.50
17.60
–
–
–
–
HꢁCꢁMe
H–C–Me
–
–
–
–
21.67
29.52
–
–
17.80
29.50
18.90
29.56
–
–
–
–
Benzylic-CH2 29.70
Chain-CH2
29.50
29.80
29.65
29.60
29.30
29.30
31.8, 29.5, 31.6, 29.3, 31.4, 29.4, 31.7, 29.7, 31.8, 29.4, 31.8, 29.4, 31.8, 29.9, 31.0, 29.4, 31.9, 29.6, 31.6, 29.3,
29.4, 29.3, 29.3, 27.9, 27.6, 25.7, 28.3, 28.2, 29.3, 29.2, 29.0, 28.6, 29.4, 29.5, 29.2, 28.6, 28.7, 27.8, 28.1, 27.7,
29.2, 22.9
22.6, 22.5
23.1, 22.1
22.6, 22.4
28.7, 22.9
28.2, 23.0
23.4, 22.5
8.70
25.5, 23.0
22.8, 22.7
23.9, 22.6
9.70
6-Me
50-Me
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
8.90
–
8.80
–
end-Me
2-OMe
20-OMe
5-OMe
50-OMe
–CH¼CH–
2-OAc
14.00
–
–
–
14.00
61.10
61.10
60.90
60.90
14.00
14.00
14.00
60.60
60.60
60.30
60.30
–
–
–
–
–
–
13.70
56.50
–
–
–
–
–
–
–
–
–
–
–
–
56.70
–
129.70
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
128.10
–
–
–
–
–
–
–
–
–
–
–
–
–
127.90
129.90
–
–
–
–
–
170.20
170.20
–
–
–
–
–
–
–
–
–
–
–
169.50
169.50
–
–
–
–
–
–
20-OAc
5-OAc
50-OAc
O¼CꢁMe
–
25.00
170.10
–

L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
859
data corroborated these findings by displaying a molec-
ular ion peak at m/z 432, calculated for C27H44O4. Pla-
cement of the OH groups at C-2 and C-5, respectively
and the proton at C-6 in 3 were established by NOESY
spectral data of the methylated derivative 8, which
showed connectivities between CH2-3 and MeO-2 and
between H-6 and MeO-5. This was further corroborated
by data generated from HMBC spectra as illustrated in
Fig. 3. On this basis compound 3 was identified as 2,5-
dihydroxy-3-(nonadec-14-enyl)-1,4-benzoquinone.
hydrogen and hydroxyl groups around it. Acetylation of
4 with acetic anhydride-pyridine mixture for 24 h at
room temperature gave a tri-acetyl derivative 9, which
was purified by column chromatography on silica gel. A
solution to clarify ambiguity concerning substitution
around the rings in the parent compound 4 was
obtained from HMQC, HMBC and NOESY experi-
ments on the triacetyl product 9. From the NOESY
correlation experiments (Fig. 3), cross peaks between
the proton at ꢀ 5.94 (H-6) and the acetyl group at ꢀ 2.20
confirmed that two OH groups are 2,5-positioned in one
ring. On the other hand, irradiation of a peak at ꢀ 6.01
(H-60) showed an NOE correlation with a peak at ꢀ 1.95
(Me-50), indicating that the two functionalities are ortho
positioned to each other. In the HMQC spectrum, the
methyl peak at ꢀH 1.95 was correlated with ꢀc 8.80, the
protons at ꢀH 5.94 and 6.01 with ꢀc 105.40 and 108.50,
respectively. In addition to these, the correlation spec-
troscopy via long range coupling (HMBC correlation,
J= 12 Hz) (Fig. 3) exhibited the following correlation
peaks; between the methyl at ꢀH 1.95 (Me-50) with car-
bons at ꢀc 126.30 (C-50), 108.50 (C-60) and 181.40 (C-10),
between the proton at ꢀH 6.01 (H-60) with ꢀc 108.50
(C-60), 126.30 (C-50), 181.00 (C-40) and 181.40 (C-10),
between the proton at ꢀH 5.94 (H-6) with carbons at ꢀc
182.50 (C-1), 183.60 (C-4), 158.90 (C-5), 155.90 (C-2),
and between the benzylic methylene at ꢀH 2.40 with
carbons ꢀc 155.90 (C-2), 130.80 (C-3 and C-30), 183.60
(C-4), 181.00 (C-40), 155.90 (C-2) and 155.60 (C-20). On
this basis compound 4, was thus designated as lancia-
quinone, a new natural product.
Compound 4, also an orange amorphous powder
showed the presence of hydroxyl (3320 cmꢁ1), a, b-
conjugated carbonyl group (1650 cmꢁ1) and chelated
carbonyl (1610 cmꢁ1) groups in the IR spectrum. The
presence of these functionalities was supported by the
1
UV absorptions at 430 and 285 nm. Its H NMR data
suggested the presence of three hydroxyl groups (ꢀ 7.50,
D2O exchangeable), two protons (ꢀ 6.45 and 6.00), two
benzylic methylenes (ꢀ 2.40), a methyl (ꢀ 1.94) and side
chain methylenes (ꢀ 1.50–1.20). The molecular ion peak
at m/z 472 and the base peak at m/z 154 together with
another fairly strong one at m/z 152, showed that the
compound consisted of two benzoquinone moieties
which are not the same with regard to substitution
around the rings. This led to the assumption that one
ring is substituted with two hydroxyls which are either
2,5- or 2,3-positioned while the other has methyl,
3. Experimental
3.1. General experimental procedures
Melting points (uncorrected) were obtained on a hot
plate Reichert Thermovar, Buchi SMP-20. UV data
were recorded using Hewlett Packard Diode Array
8452A spectrophotometer while IR spectra were studied
on an infrared IMR-125 spectrophotometer. The NMR
spectra were obtained on a Brucker WM NMR spec-
trometer operating at 400 and 100 MHz, respectively in
CDC13 with tetramethylsilane as internal standard.
Mass spectrum data were obtained on MAT 8200 A
Varian MAT Bremen instrument. [ꢁ]D values were
obtained on a Jasco dip 360 apparatus. Silica gel for
column and tlc plates were impregnated with 2% oxalic
acid solution.
3.2. Plant material
Plant materials for research were identified and gath-
ered by Mr. Mathenge of Botany Department, Uni-
versity of Nairobi. Authentic specimens of the plants
Fig. 3. Pertinent correlations in HMBC and NOESY spectra of com-
pounds 5, 8 and 9.

860
L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
were deposited in the Department’s Herbarium. Their
identification was accomplished by comparison with
voucher specimens.
3.6. Methylation of 1
The compound (60 mg) in ether (30 ml) was treated
with excess diazomethane at room temperature for one
hour. Work up as usual afforded 5 as yellow needles
(crystallized from petroleum ether–dichloromethane,
3.3. Extraction and isolation of benzoquinones from
M. africana
25
9:1), 45 mg, mp 81–82 C; [ꢁ]D ꢁ11ꢀ (MeOH, c 1.0).
ꢀ
Powdered ground fruit (1 kg) was extracted with ethyl
acetate (3ꢂ21) at room temperature, the extracts com-
bined and removal of the solvent under reduced pressure
provided a dark brown material (50.5 g). A portion of it
(45 g) was chromatographed over silica gel with petroleum
ether containing increasing amounts of EtOAc and finally
with MeOH. Fractions (100 ml each) were collected and
their homogeneity monitored by tlc using solvent systems
petroleum ether–ethyl acetate (4:1, 3:2, 1:1) and petroleum
ether–ethyl acetate–acetic acid (85:15:5). This afforded
myrsinone (160 mg), embelin and/or rapanone (1000 mg)
and 5-O-methylembelin (70 mg) (Midiwo et al., 1992).
Fractions eluted as mixtures were further subjected to
medium pressure chromatography using petroleum ether–
ethyl acetate (3:2) to give methylvilangin (1) 200 mg and
methylanhydrovilangin (2) 90 mg.
UV lmax (MeOH) nm: 290 (4.07). IR ꢂmax (KBr) cmꢁ1
:
2910, 2850 (C–H), 1645 (a, b-unsaturated C¼O), 1600
1
(C¼C), 1470, 1445, 1380, 775, 720. H NMR d ppm:
4.30 (q, J=7.5 Hz, H–C–Me), 4.00 (s, MeO-2, 20), 3.85
(s, MeO-5, 50), 2.37 (t, J=15.6, 7.7 Hz, CH2-3, 30), 1.60
(d, J=7.5 Hz, H–C–Me), 1.40–1.20 (m, 18CH2), 0.90 (t,
J=13.3, 6.2 Hz, terminal-Me). 13C NMR data: see
Table 1. MS (70 eV): m/z (%) M+ 670 (100), 625 (6),
530 (10), 483 (10), 361 (25), 221 (18), 165 (15), 83 (10),
68 (24).
3.7. Methylanhydrovilangin (2)
Obtained from petroleum ether–dichioromethane
(9:1) as orange crystals, mp 157–158 ꢀC; [ꢁ]D25 +47ꢀ
(CH2Cl2, c 1.0). UV lmax (MeOH) nm: 436 (2.43), 322
(3.3) and 262 (4.05). IR ꢂmax (KBr) cmꢁ1: 3380 (O–H),
2920, 2850 (C–H), 1640 (a,b-unsaturated C¼O), 1615
3.4. Extraction and isolation of compounds from M.
lanceolata
1
(C¼O, chelated), 1460, 1400, 1375, 1335, 1185, 760. H
NMR d ppm: 7.04 (s, OH-2, 20), 4.00 (q, J=7.6 Hz, H–
C–Me), 2.44 (t, J=15.4, 7.2 Hz, CH2-3, 30), 1.50–1.20
(m, 18CH2), 1.30 (d, J=7.4 Hz, H–C–Me), 0.88 (t, J=
13.2, 6.4 Hz, terminal-Me). 13C NMR: see Table 1. MS
(70 eV): m/z (%) M++2 598 (5), M+ 596 (100), 583
(11). 456 (10), 433 (5), 320 (21), 317 (10), 303 (12), 294
(25), 273 (3), 219 (5), 154 (20), 106 (3), 95 (15), 71(25),
69 (20), 57 (4).
Dried and finely powdered fruits (1 kg) was similarly
extracted with ethyl acetate as described for M. afri-
cana for 1 week to give 75 g of a semi solid brown
material. The extract (50 g) was fractionated by col-
umn chromatography, first with petroleum ether fol-
lowed by petroleum ether–EtOAc mixture containing
varying concentrations of the latter and concluded with
MeOH affording maesaquinone (9000 mg) (7), acetyl-
maesaquinone (3000 mg) and maesanin (1200 mg)
(Midiwo et al., 1988). Similarly fractions eluted as mix-
tures were combined and further purified by medium
pressure chromatography using petroleum ether–EtOAc
(3:2) with aliquots of 10 ml being collected. This proce-
dure afforded compounds 3 (70 mg) and 4 (45 mg),
respectively.
3.8. Acetylation of 2
The compound (20 mg) was treated with Ac2O (1 ml)
and pyridine (two drops) at room temperature for a
period of 24 h affording 6 as yellow amorphous powder,
mp 56–57 ꢀC; [ꢁ]D25 ꢁ23ꢀ (CH2CI2, c 1.0). UV lmax
(MeOH) nm: 465 (2.50) and 275 (4.10). IR ꢂmax (KBr)
cmꢁ1: 2920, 2850 (C–H), 1770 (C¼O, ester), 1675 (a, b-
unsaturated C¼O), 1375, 775. 1H NMR d ppm: 3.95 (q,
J=6.7 Hz, H–C–Me), 2.44 (t, J=15.3, 7.0 Hz, CH2-3,
30), 1.90 (s, OAc-2, 20), 1.50-1.15 (m, 18CH2), 1.35 (d,
J=6.7 Hz, H–C–Me), 0.89 (t, J=13.3, 7.6 Hz, terminal-
Me). 13C NMR data: see Table 1. ElMS (70 eV): m/z
(%) M+680 (9), 638 (5), 596 (60), 581 (100), 320 (19),
317 (15), 294 (20), 154 (40), 95 (15).
3.5. Methylvilangin (1)
The compound crystallized from methanol as orange
25
ꢀ
crystals, mp 129–130 C, [ꢁ]D +180 (CH2C12, c 1.0).
UV lmax (MeOH) nm: 430 (4.26) and 290 (4.10). IR
ꢂmax (KBr) cmꢁ1: 3320 (O–H), 2920, 2850 (C–H), 1625
1
(chelated C¼O), 1570, 1120, 715. H NMR d ppm: 7.80
(s, OH-2, 20, 5, 50), 4.40 (q, J= 7.5 Hz, H–C–Me), 2.43
(t, J=15.1, 7.1 Hz, CH2-3, 30), 1.58 (d, J=7.5 Hz, H–
C–Me), 1.50–1.20 (m, 18CH2), 0.88 (t, J=13.3, 6.2 Hz,
end-Me). 13C NMR data: see Table 1. ElMS (70 eV):
m/z (%) 320 (20), 294 (25), 182 (5), 180 (42), 155 (15),
154 (100), 153 (35), 142 (16), 139 (69), 125 (25), 69 (30).
3.9. 2,5-Dihydroxy-3-(nonadec-14-enyl)-1,4-benzoqui-
none (3)
Crystallized from MeOH as yellow brown crystals,
25
ꢀ
mp 138–139 C; [ꢁ]D ꢁ40ꢀ (CH2Cl2, c 1.0). UV lmax

L.O. Arot Manguro et al. / Phytochemistry 64 (2003) 855–862
861
(MeOH) nm: 426 (2.60) and 290 (4.25). IR ꢂmax (KBr)
cmꢁ1: 3300 (O–H), 2920, 2830 (C–H), 1610 (chelated
ꢁ17.5ꢀ (CH2Cl2, c 1.0). UV lmax (MeOH) nm: 276 (4.0).
IR ꢂmax (KBr) cmꢁ1: 1765 (C¼O, ester), 1650 (a, b-
1
I
C¼O), 1590 (C¼C), 1330, 1180. H NMR d ppm: 7.70
unsaturated C¼O), 1570 (C¼C), 1300, 1025, 760. H
(s, OH-2, 5), 6.0 (s, H-6), 5.40 (m, –CH¼CH–), 2.40 (t,
J=15.3, 7.5 Hz, CH2-3), 2.0 (m, –CH2CH¼CH2ꢁ),
1.50–1.10 (m, 14CH2), 0.90 (t, J=13.5, 6.7 Hz, terminal-
Me). ElMS (70 eV): m/z (%) M+ 404 (15), 155 (40), 154
(100), 153 (10), 125 (15), 105 (12), 80 (30), 55 (80). 13C
NMR data are in Table 1.
NMR ꢀ ppm: 6.01 (s, H-60), 5.94 (s, H-6), 2.40 (t,
J=15.3, 7.7 Hz, CH2-3, 30), 2.20 (s, OAc-2, 5), 2.10 (s,
OAc-20), 1.95 (s, Me-50), 1.50–1.20 (m, 12CH2). 13C
NMR: see Table 1. ElMS (70 eV): m/z (%) M+ 598 (8),
556 (5), 322 (3), 154 (65), 152 (15), 138 (20), 69 (55), 55
(100), 43 (90).
3.10. Methylation of 3
3.14. Maesaquinone (7)
Approximately 20 mg was methylated using similar
procedures described for 1 to give a yellow compound 8
An orange amorphous powder from MeOH, mp 129–
25
ꢀ
131 C; [ꢁ]D ꢁ22ꢀ (CH2CI2, c 1.0). UV lmax (MeOH)
25
ꢀ
(15.5 mg), crystallized in MeOH, mp 44 C; [ꢁ]D 59ꢀ
nm: 424 (2.8) and 286 (4.50). IR n max (KBr) cmꢁ1
:
(CH2Cl2, c 1.0). UV (max (MeOH) nm: 440 (2.70) and
272 (4.50). IR (max (KBr) cmꢁ1: 2920, 2840 (C–H),
3320 (O–H), 1610 (C¼O, chelated), 1370, 1180, 1120,
1
1055, 765. H NMR ꢀ ppm: 7.60 (s, OH-2, 5), 5.30 (m,
1
1660 (C¼O), 1600 (C¼C). H NMR d ppm: 5.90 (s,
–CH¼CH–), 2.40 (t, J=15.0, 7.5 Hz, CH2-3), 2.0 (m,
–CH2CH¼CHCH2–), 1.95 (s, Me-6), 1.50–1.20 (m,
14CH2), 0.85 (t, J=13.2, 74 Hz, terminal-Me). 13C
NMR data: see Table 1. ElMS (70 eV): m/z (%) M+
418 (12), 169 (55), 168 (100), 139 (30), 55 (35).
H-6), 5.35 (m, –CH¼CH–), 4.10 (s, MeO-2), 3.95 (s,
MeO-5), 2.40 (t, J¼ 15.4, 7.1 Hz, CH2-3), 2.0 (m,
–CH¼CH2ꢁ), 1.50–1.20 (m, 14CH2), 0.90 (t, J¼13.0,
7.3 Hz, terminal-Me). ElMS (70 eV): m/z (%) M+
432 (100), 185 (2), 183 (4), 154 (4), 153 (7), 139 (6), 123
(80), 111 (2). 13C NMR data: see Table 1.
3.15. Methylation of maesaquinone
3.11. Alkaline hydrogen peroxide oxidation of 3 and gas
chromatography of fatty acids
Approximately 500 mg in dry acetone (150 ml) was
treated with excess diazomethane for one hour at room
temperature. Work up as described for 1 afforded 10
(450 mg), yellow needles, mp 46–48 ꢀC; [ꢁ]D25 ꢁ37ꢀ
(CH2C12, c 1.0). UV lmax (MeOH) nm: 284 (4.25). IR
ꢂmax (KBr) cmꢁ1 : 2920, 2850 (C–H), 1660 (a, b-unsa-
turated C¼O), 1600 (C¼C), 1460. 1H NMR ꢀ ppm: 5.31
(m, –CH¼CH–), 3.80 (MeO-2), 3.60 (MeO-5), 2.40 (t,
J=14.7, 7.5 Hz, CH2-3), 2.0 (m, –CH2CH¼CHCH2–),
1.88 (s, Me-6), 1.60–1.25 (m,14CH2), 0.90 (t, J=13.6,
7.4 Hz, terminal-Me). ElMS (70eV): m/z (%) 446 (100),
418 (5), 197 (30), 181 (35), 167 (32), 154 (25), 137 (15).
13C NMR spectral data are in Table 1.
To the compound (4 mg) dissolved in n-KOH was
added H2O2 (30%, 0.2 ml) under slight warming on a
water bath (Ogawa and Natori, 1968). After 3 h the
reaction mixture was acidified and extracted with ether.
The ethereal layer was dried, evaporated and methyl-
ated with CH2N2 in ether. The product was subjected to
gas chromatography and the retention times compared
with the methyl ester from 7 and also those from
authentic fatty acids.
3.12. Lanciaquinone (4)
Crystallized as yellow brown crystals from MeOH,
25
Acknowledgements
ꢀ
mp 141–143 C; [ꢁ]D +29ꢀ (CH2Cl2, c 0.5). UV lmax
(MeOH) nm: 430 (2.80) and 285 (4.40). IR ꢂmax (KBr)
L. Manguro is thankful to German Academic
Exchange Services (DAAD) and Alexander von Hum-
boldt Foundation for PhD scholarship and fellowship,
respectively. Dr. Rudolf Hermann of Technische Uni-
versitaet Muenchen and Frau Betina Wundrack of
Universitaet Hohenheim are both acknowledged for
providing NMR data.
cmꢁ1: 3320 (O–H), 1650 (a, b-unsaturated C¼O), 1610
(chelated C¼O). H NMR ꢀ ppm: 7.50 (s, OH-2, 20, 5),
1
6.45 (s, H-60), 6.0 (s, H-6), 2.40 (t, J=15.3, 7.6 Hz, CH2-
3, 30), 1.94 (s, Me-50), 1.50–1.20 (m, 12CH2). 13C NMR
data: see Table 1. ElMS (70 eV): m/z (%) M+ 472 (20),
320 (12), 154 (100), 152 (80), 139 (15), 69 (45), 55 (75),
43 (65).
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