Isolation, Synthesis, Structure-Activity Relationships of Bioactive Benzoquinones from Miconia lepidota from the Suriname Rainforest

Article abstract of DOI:10.1021/np000219r

Bioactivity-directed fractionation of an EtOAc extract from the leaves of Miconia lepidota afforded the two benzoquinones 2-methoxy-6-heptyl-1,4-benzoquinone (1) and 2-methoxy-6-pentyl-1,4-benzoquinone (primin) (2). This is the first reported isolation of

Full text of DOI:10.1021/np000219r

2
J . Nat. Prod. 2001, 64, 2-5
Full Papers
Isola tion , Syn th esis, a n d Str u ctu r e-Activity Rela tion sh ip s of Bioa ctive
Ben zoqu in on es fr om Micon ia lepid ota fr om th e Su r in a m e Ra in for est1
A. A. Leslie Gunatilaka,†,‡ J ohn M. Berger,† Randy Evans,§ J ames S. Miller,§ J an H. Wisse,
Kim M. Neddermann,| Isia Bursuker,| and David G. I. Kingston*,†
Department of Chemistry, M/ C 0212, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061,
Bedrijf Geneesmiddelen Voorziening Suriname, Commissaris Roblesweg, Geyersluit, Suriname, Missouri Botanical Garden,
P.O. Box 299, St. Louis, Missouri 63166-0299, and Bristol-Myers Squibb Pharmaceutical Research Institute, 5 Research
Parkway, Wallingford, Connecticut 06492-7660
Received May 3, 2000
Bioactivity-directed fractionation of an EtOAc extract from the leaves of Miconia lepidota afforded the
two benzoquinones 2-methoxy-6-heptyl-1,4-benzoquinone (1) and 2-methoxy-6-pentyl-1,4-benzoquinone
(primin) (2). This is the first reported isolation of 1. Both quinones 1 and 2 exhibited activity toward
mutant yeast strains based on Saccharomyces cerevisiae, indicative of their cytotoxicity and potential
anticancer activity. A number of previously synthesized and new analogues were prepared and tested in
the same strains. Compounds 1, 2, 2-methoxy-6-butyl-1,4-benzoquinone (5), and 2-methoxy-6-decyl-1,4-
benzoquinone (6) were tested in two cytotoxicity assays. In the M109 tumor cell lines, quinones 1, 2, and
6 had an IC50 value of 10 µg/mL. In the A2780 cell line, compounds 1, 2 and 5 had IC50 values of 7.9, 2.9,
and 3.2 µg/mL, respectively.
In our continuing efforts to uncover bioactive constitu-
ents from Suriname flora as part of an International
Cooperative Biodiversity Group (ICBG)2 program we ob-
tained a sample of the plant Miconia lepidota DC. (Mela-
stomataceae). Miconia is the largest genus of Melasto-
mataceae with about 1000 species widely distributed in the
New World tropics and one species in West Africa. Various
species of Miconia are common components of forest
understory throughout the neotropics, often with many
species occurring sympatrically (more than one species of
a genus at the same locality). M. lepidota is widespread in
northern South America, occurring in all of the Guianas,
adjacent Brazil, Venezuela, and Colombia. An EtOAc
extract of the leaves of this plant exhibited a positive
response to our bioassay using mutant yeast strains, which
have been shown to respond to known cytotoxic agents,2
and this extract was thus selected for detailed examination.
this conclusion was supported by their mass spectra. Thus,
the EIMS of 1 showed a molecular ion at m/z 236, with
major fragment ions at m/z 179, 154, 153, 139, and 125,
consistent with the formation of the fragments C10H11O3,
C8H10O3, C8H9O3, C7H7O3, and C6H5O3.3 The EIMS of 2
showed a molecular ion at m/z 208 and contained the same
fragment ions as 1. Based on their 1H and 13C NMR data
(Tables 2 and 3) and confirmed by COSY, HETCOR, and
HMBC data, compounds 1 and 2 were assigned as the
benzoquinones 2-methoxy-6-heptyl-1,4-benzoquinone and
2-methoxy-6-pentyl-1,4-benzoquinone (primin), respec-
tively. These assignments were confirmed by comparison
with literature data.3
Quinone 1 has previously been synthesized as part of a
structure-activity relationship study of primin-type ben-
zoquinones as cell-mediated allergens causing contact
dermatitis3 and has been identified as a minor component
of Primula obconica,4 but it has not previously been isolated
as a homogeneous compound. Previous phytochemical
studies of various Miconia spp. have resulted in the
isolation of primin (2),5 its quinol analogue miconidin,5,6
and several triterpenes.7 Insect antifeedant,5 antimicro-
bial,6,8 and antineoplastic6,8 activities of primin and mi-
conidin have also been evaluated.
Resu lts a n d Discu ssion
The EtOAc extract was partitioned between hexane and
MeOH-H2O (80:20), and the aqueous layer was diluted
with H2O to MeOH-H2O (60:40) and extracted with CHCl3
to afford a bioactive CHCl3 fraction. Repeated chromatog-
raphy of this fraction on Si gel followed by reversed-phase
chromatography on a C-18-bonded phase afforded the two
bioactive compounds 1 and 2.
The bioactivity profiles for 1 and 2 in our yeast-based
bioassays are depicted in Table 1. Both compounds exhib-
ited moderate activity. However, it was interesting to note
that quinone 1, having two additional carbon atoms in the
side-chain, was significantly more active than its lower
homologue, primin (2), in the Sc-7 yeast strain. Because of
this apparent relationship between the length of the alkyl
side chain and activity in the Sc-7 yeast assay, we prepared
a number of additional 2-methoxy-6-alkyl-1,4-benzoquino-
nes to determine whether the relationship was a general
one. The previously reported quinones 1-7 were synthe-
1
The H and 13C NMR spectra of both 1 and 2 indicated
clearly that they were simple alkylated benzoquinones, and
* To whom inquiries should be addressed. Tel.: (540) 231-6570. Fax:
(540) 231-7702. E-mail: dkingston@vt.edu.
† Virginia Polytechnic Institute and State University.
‡ Present address: Bioresources Research Facility, Office of Arid Lands
Studies, University of Arizona, 250 E. Valencia Rd., Tucson, AZ 85706-
6800.
§ Missouri Botanical Garden.
Bedrijf Geneesmiddelen Voorziening Suriname.
| Bristol-Myers Squibb Pharmaceutical Research Institute.
10.1021/np000219r CCC: $20.00
© 2001 American Chemical Society and American Society of Pharmacognosy
Published on Web 11/23/2000

Bioactive Benzoquinones from Miconia
J ournal of Natural Products, 2001, Vol. 64, No. 1
3
Ta ble 1. Bioactivity Data of Alkyl Benzoquinones
cytotoxicity to
yeast strainsa
M109
A2780
compound
side chain
CH3
C2H5
C4H9
C5H11
C7H15
Sc-7
1138
1140
1353
(IC50, µg/mL)
(IC50, µg/mL)
3
4
5
530 ( 100
220 ( 50
80 ( 25
48 ( 1
580 ( 100
200 ( 30
220 ( 30
240 ( 40
120 ( 10
380 ( 180
630 ( 180
140 ( 20
150 ( 20
170 ( 40
130 ( 10
380 ( 180
830 ( 110
233 ( 20
210 ( 28
285 ( 40
220 ( 10
380 ( 180
NT
NT
NT
10
10
10
NT
NT
NT
NT
NTb
NT
3.2
2.9
7.9
NT
NT
NT
NT
ΝΤ
2 (primin)
1
6
7
8
9
16 ( 10
3 ( 1
>2000
180 ( 20
438 ( 121
NTb
C
C
10H21
19H39
>2000
>2000
>2000
CH2Ph
460 ( 80
536 ( 40
14
420 ( 150
430 ( 50
13
590 ( 80
577 ( 40
14
CH(OH)C4H9
nystatin
NAb
a
Yeast strain results are expressed as IC12 values (µg/mL), which is the concentration required to generate a kill-zone 12 mm in
b
diameter in yeast supported on an agar-based gel. NA ) not applicable; NT ) not tested.
Ta ble 2. 1H NMR Spectral Data for Compounds 7-9a,b
δ
proton
H-3
7
8
9
5.86, d,
5.86, d,
5.89, d,
J ) 2.5
6.47, dt,
J ) 2.5, 1.3
2.41, dt,
J ) 7.9, 1.4
1.49, m
J ) 2.3
6.29, dt,
J ) 2.3, 1.6
3.74, d,
J ) 1.4
J ) 2.5
H-5
6.69, dt,
J ) 2.5, 1.2
4.69, m
H2-1′
H2-2′
H2-3′,4′
(CH2)n
CH3
1.7, m
1.38, m
1.24, m
0.87, t,
0.89, t,
F igu r e 1. General procedure for the synthesis of substituted 2-meth-
oxy-1,4-benzoquinones 1, 2, 4, and 8.
J ) 6.9
J ) 7.3
Ar-H-3′
Ar-H-4′
Ar-H-5′
7.19, br d,
J ) 6.7
strains. Compound 8 was previously reported as a minor
product of the oxidation of 2-benzyl phenol with 2,3-
dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in methanol.9
In the Sc-7 yeast assay, increasing the length of the
6-alkyl side chain results in increased potency up to the
decyl side chain (6), but potency decreases when the
significantly longer nonadecyl side chain is introduced
(compound 7). A similar trend has been noted in previous
investigations of benzoquinones as cell allergens.3
The compounds were also evaluated in the three yeast
strains 1138, 1140, and 1353, inasmuch as differential
activity in these strains is a predictor of activity against
the enzymes topoisomerase I and topoisomerase II.2c As it
turned out, the benzoquinones evaluated were not particu-
larly selective for any one of these three yeast strains, but
they did show a similar increase in potency with increasing
length of the alkyl side chain as they did with the Sc-7
assay. In this case, however, the greatest potency was
observed with the seven-carbon side chain of compound 1.
The four most potent compounds in the Sc-7 strain
(compounds 1, 2, 5, and 6) were also subjected to cytotox-
icity testing. In the M109 cell line compounds 1, 2, and 6
all had IC50 values of 10 µg/mL, and in the A2780 cell line
compounds 1, 2, and 5 had IC50 values of 7.9, 2.9, and 3.2
µg/mL, respectively. Although these compounds are thus
clearly cytotoxic, their potency is such that they are not
being evaluated any further as anticancer compounds.
7.31, br t,
J ) 7.1
7.24, tt,
J ) 7.3, 1.4
3.80, s
CH3O
3.81, s
3.81, s
a
b
In CDCl3
Coupling constants are reported from direct
measurement of peak splittings and will thus vary slightly from
their true values.
Ta ble 3. 13C NMR Spectral Data for Compounds 1-9a
δ compound
carbon
1
2
3
4
5
6
7
8
9
C-1
C-2
C-3
C-4
C-5
C-6
182.1 182.2 182.4 182.2 182.3 182.4 182.2 182.0 182.4
158.8 158.9 159.0 158.9 159.3 158.7 158.8 158.9 158.4
107.1 107.0 107.4 107.1 107.2 107.0 107.0 107.3 107.0
187.7 187.8 187.7 187.8 188.1 187.8 187.8 187.6 187.1
132.8 132.0 133.5 132.2 133.1 132.9 132.9 133.9 131.9
147.6 147.7 144.1 148.7 148.1 147.4 147.7 146.7 148.1
CH3O 56.4 56.4 56.4 55.9 56.4 55.8 56.4
56.5 56.4
35.0 68.4
28.5 27.8 27.7 136.4 35.9
22.4 29.3 29.3 129.5 27.7
29.6 29.4 128.9 22.2
C-1′
C-2′
C-3′
C-4′
C-5′
C-6′
C-7′
C-8′
C-9′
(CH2)
C-16′
C-17′
C-18′
CH3
28.7 28.8
27.7 27.5
29.0 31.5
29.2 22.4
31.7
21.9 29.8 28.8 28.8
29.6
29.4
29.4
32.0 29.6
22.7
127.1
22.6
29.8b
29.4
32.1
22.8
14.1 13.9 15.4 11.5 13.9 14.1 14.1
13.6
a
b
In CDCl3. Includes C-5′, C-6′, C-7′, C-9′ to C-15′.
sized by previously reported methods3 (Figure 1) and were
evaluated for bioactivity in the Sc-7 and other yeast strains.
Two related benzoquinones, 2-methoxy-6-benzyl-1,4-ben-
zoquinone (8) and 2-methoxy-5-(1-hydroxy)pentyl-1,4-ben-
zoquinone (9), were also synthesized and tested in these

4
J ournal of Natural Products, 2001, Vol. 64, No. 1
Gunatilaka et al.
Exp er im en ta l Section
benzyl bromide in 8 mL of THF to 0.629 g (0.026 mol) of
magnesium turnings in a vented 20-mL vial with vigorous
shaking until the addition was complete. o-Vanillin (0.5 g,
0.003 mol) in 8 mL of THF was slowly added with vigorous
shaking at 0 °C until either the addition was complete or until
the yellow color (indicative of unreacted o-vanillin) persisted.
The vial was allowed to stand at room temperature overnight.
The reaction was worked up with 100 mL of 10% HCl in H2O,
extracted with 200 mL of Et2O, and the Et2O layer dried over
Na2SO4. The solvent was removed under reduced pressure to
afford the crude addition product as an oil. This crude product
was purified with 25% EtOAc in hexane over Si gel; if
necessary further purification was performed using a reversed-
phase 5g Varian C18 SPE with a gradient of 70-100% MeOH
in H2O.
Gen er a l Exp er im en ta l P r oced u r es. Melting points were
determined on a Kofler hot stage apparatus equipped with a
microscope and are uncorrected. All NMR spectra were
recorded at 400 MHz for H and 100 MHz for 13C spectra on a
1
Varian Unity 400 instrument or at 500 MHz for 1H and 125
MHz for 13C spectra on a J EOL Eclipse instrument. MS were
obtained on a VG7070E-HF, a VG Quattro, or a Hewlett-
Packard HP-5890-5970-GC/MSD instrument. Gel filtration
chromatography used Sephadex LH-20 (25-100 µM), and
column chromatography employed Si gel 60 (230-400 mesh)
for normal-phase chromatography and Varian 5g ODS SPE
cartridges and Whatman LRP-2 column packing for reversed-
phase chromatography.
The addition product obtained as described above was
hydrogenated with an equal weight of 5% Pd/C in 50 mL of
MeOH over a period of 2-5 days at atmospheric pressure and
room temperature. The reaction was monitored by TLC until
it was complete or 5 days had passed. The reaction mixture
was filtered over Celite, and the Celite was washed with
additional MeOH. The combined MeOH solution was evapo-
rated under reduced pressure to yield a homogeneous product
in most cases; if further purification was necessary, it was
carried out by preparative TLC on Si gel with 25% EtOAc in
hexane.
The deoxy product thus obtained (50-100 mg) was oxidized
to the benzoquinone by oxidation with 0.5 g of Fremy’s salt in
either 100 mL aqueous 5% Na2CO3 or 20 mL pH 9 phosphate
buffer in 80 mL H2O with vigorous stirring overnight. The
resulting solution was extracted twice with 100 mL of CHCl3
and the CHCl3 layer dried over Na2SO4, filtered, and solvent
removed under reduced pressure. The crude product was then
purified by Si gel preparative TLC with 25% EtOAc in hexane
and/or recrystallization with hexane-CHCl3 or hexane-
EtOAc. Compound 3 was synthesized by direct reduction of
o-vanillin with hydrogen over 5% Pd/C, followed by oxidation
with Fremy’s salt.3
Yea st Bioa ssa y. The Sc-72a and 1138/1140/13532c yeast
bioassays were performed as previously reported. Samples
were prepared and incubated for 48 h for the 1138, 1140, and
1353 strains, or 72 h for the Sc-7 strain. The zones of inhibition
were measured, and IC12 values and standard deviations were
obtained from the results of three individual experiments.
Cytotoxicity Bioa ssa y. In vitro antitumor cytotoxicity
assays were performed at Bristol-Myers Squibb using the
Madison Lung Carcinoma (M109)10 murine cell line as previ-
ously reported.11
P la n t Ma ter ia l. The leaves of M. lepidota were collected
in Suriname by a team from Missouri Botanical Gardens and
given the collector’s number Evans 1848. The collection was
made in the Para district in northern Suriname in low-
elevation wet forest along the road from Zanderij to Kraka,
4.4 km from its intersection with Zanderij Highway, 0.5 km
before the bridge over Sabakoe Creek, at an elevation of 25
m. Identification of the plant was carried out by Suzanne
Renner. Voucher specimens are deposited in the National
Herbarium of Suriname, Paramaribo, Suriname, and the
Missouri Botanical Garden, St. Louis, MO. Extracts for
screening were prepared with EtOAc and MeOH by Bedrijf
Geneesiddelen Voorziening, Suriname, and sent for bioassay
and isolation work to Virginia Polytechnic Institute and State
University; the EtOAc extract was designated E 940138.
Bioa ctivity-Gu id ed F r a ction a tion a n d Isola tion . The
EtOAc extract E 940138 (6.7 g) was found to be bioactive in
our Sc-7 yeast assay and was partitioned between hexane and
80% MeOH in H2O. The hexane fraction (4.57 g) was found to
be weakly active and subsequently was found to contain minor
quantities of the bioactive compounds isolated from the more
active aqueous MeOH fraction and was therefore not further
investigated. Water was added to the bioactive 80% MeOH in
H2O fraction to give a 60% MeOH in H2O solution, which was
thoroughly extracted with CHCl3 to yield 1.03 g of the bioactive
CHCl3 fraction. The remaining aqueous MeOH fraction was
found to be inactive and was not further investigated. The
CHCl3 fraction was subjected to column chromatography (CC)
on Si gel, eluting with CHCl3, 2% i-PrOH in CHCl3, and 50%
CHCl3 in MeOH. The bioactive fractions of the 2% i-PrOH in
CHCl3 eluates were combined (428 mg) and submitted to CC
on Si gel using a solvent gradient from 1 to 2.5% of i-PrOH in
hexane with the bioactive fraction (369 mg) eluting with 1%
i-PrOH in hexane. The bioactive fraction was then subjected
to RP-CC on LRP-2 and eluted with 50-100% MeOH in H2O
to give quinones 1 (158 mg) and 2 (34.2 mg).
2-Meth oxy-6-h ep tyl-1,4-ben zoqu in on e (1): yellow solid,
mp 64-66 °C (from hexane-CHCl3); lit. 63 °C;3 overall yield
6%; 13C NMR, see Table 3; anal. C 70.92%, H 8.56%, calcd for
C
14H20O3, C 71.16%, H 8.53%.
2-Meth oxy-6-pen tyl-1,4-ben zoqu in on e (pr im in ) (2): yel-
low solid, mp 62-64 °C (from hexane-CHCl3); lit. 62-63 °C;3
overall yield 8%; 13C NMR, see Table 3; anal. C 68.99%, H
7.74%, calcd for C12H16O3, C 69.21%, H 7.74%.
2-Meth oxy-6-m eth yl-1,4-ben zoqu in on e (3): tan-yellow
solid, mp 144-145 °C (from hexane-CHCl3); lit. 150 °C;3
overall yield 20%; 13C NMR, see Table 3; anal. C 60.49%, H
5.36%, calcd for C8H8O3‚1/3H2O, C 60.76%, H 5.52%.
2-Meth oxy-6-eth yl-1,4-ben zoqu in on e (4): bright yellow
solid, mp 109-111 °C (from hexane-CHCl3); lit. 106 °C;3
overall yield 24%; 13C NMR, see Table 3; anal. C 64.82%, H
6.21%, calcd for C9H10O3, C 65.05%, H 6.07%.
2-Meth oxy-6-bu tyl-1,4-ben zoqu in on e (5): bright yellow
solid, mp 52-54 °C (from hexane-CHCl3); lit. 55 °C;3 overall
yield 19%; 13C NMR, see Table 3; anal. C 67.74%, H 7.19%,
calcd for C11H14O3, C 68.02%, H 7.26%.
2-Meth oxy-6-decyl-1,4-ben zoqu in on e (6): tan-yellow solid,
mp 62-63 °C (from hexane-EtOAc); lit. 60-61 °C;3 overall
yield 17%; 13C NMR, see Table 3; EIMS m/z 278 (M+, 48), 193
(13), 179 (27), 166 (17), 154 (98), 153 (100), 139 (14), 124 (19),
109 (10), 69 (43); HREIMS m/z 278.1884 (calcd for C17H26O3,
278.1881). anal. C 71.98%, H 9.33%, calcd for C17H26O3‚1/3H2O,
C 71.80%, H 9.45%.
2-Meth oxy-6-h ep tyl-1,4-ben zoqu in on e (1): yellow crys-
tals; 13C NMR, see Table 3; EIMS m/z (rel int) 236 (M+, 55),
193 (15), 179 (39), 166 (18), 153 (100), 139 (17), 125 (40), 108
(19), 95 (8), 81 (8), 69 (45), and 53 (18).3
2-Meth oxy-6-pen tyl-1,4-ben zoqu in on e (p r im in ) (2): yel-
low crystals; 13C NMR, see Table 3; EIMS m/z (rel int) 208
(M+, 40), 179 (37), 153 (100), 139 (16), 124 (54), 109 (36), 95
(16), 91 (11), 81 (17), 69 (78), and 53 (20).3
Gen er a l P r oced u r es for th e Syn th esis of Alk yl a n d
Ben zyl Ben zoqu in on es. Selected 2-methoxy-6-alkyl-1,4-ben-
zoquinones were synthesized in a manner similar to that
reported by Konig et al.3 Alkyl and benzyl Grignard reagents
were prepared by the slow addition of 0.009 mol of alkyl or
2-Meth oxy-6-n on a d ecyl-1,4-ben zoqu in on e (7): tan-yel-
low waxy solid, mp 86-87 °C (from EtOH); lit. 93.5 °C (from
1
EtOH);12 overall yield 10%; H NMR, see Table 2; 13C NMR,
see Table 3; EIMS m/z 404 (M+, 75), 193 (6), 179 (12), 166 (11),
154 (100), 153 (99), 139 (13), 124 (15), 109 (12), 69 (37), lit.
404 (11), 154 (100), 153 (92);13 HREIMS m/z 404.3297 (calcd
for C26H44O3, 404.3290).
2-Meth oxy-6-ben zyl-1,4-ben zoqu in on e (8): bright yellow
solid, mp 128-130 °C (from hexane-CHCl3); overall yield 7%;
1H NMR, see Table 2; 13C NMR, see Table 3; EIMS m/z (rel

Bioactive Benzoquinones from Miconia
J ournal of Natural Products, 2001, Vol. 64, No. 1
5
int) 228 (M+, 80), 213 (70), 196 (50), 185 (20), 168 (22), 157
(28), 143 (44), 129 (36), 128 (28), 115 (90), and 69 (100); anal.
C 73.37%, H 5.32%, calcd for C14H12O3, C 73.67%, H 5.30%.
2-Meth oxy-5-(1-h yd r oxyp en tyl)-1,4-ben zoqu in on e (9).
2-Methoxy-5-(1-hydroxypentyl)phenol was partially hydroge-
nated by the same procedure described above, followed by
oxidation with Fremy’s salt, to give 2-methoxy-5-(1-hydroxy-
pentyl)-1,4-benzoquinone in an overall yield of 21%: yellow-
60, 1294-1297. (c) Abdel-Kader, M. S.; Bahler, B. D.; Malone, S.;
Werkhoven, M. C. M.; van Troon, F.; David, M.; Wisse, J . H.;
Burkuser, I.; Neddermann, K. M.; Mamber, S. W.; Kingston, D. G. I.
J . Nat. Prod. 1998, 61, 1202-1208. (d) Yang, S.-W.; Zhou, B.-N.;
Wisse, J . H.; Evans, R.; van der Werff, H.; Miller, J . S.; Kingston, D.
G. I. J . Nat. Prod. 1998, 61, 901-906. (e) Yang, S.-W.; Abdel-Kader,
M.; Malone, S.; Werkhoven, M. C. M.; Wisse, J . H.; Bursuker, I.;
Neddermann, K.; Fairchild, C.; Raventos-Suarez, C.; Menendez, A.
T.; Lane, K.; Kingston, D. G. I. J . Nat. Prod. 1999, 62, 976-983. (f)
Yang, S.-W.; Zhou, B.-N.; Malone, S.; Werkhoven, M. C. M.; van
Troon, F.; Wisse, J . H.; Kingston, D. G. I. J . Nat. Prod. 1999, 62,
1173-1174.
1
tan solid; mp 94-95 °C (from hexane-CHCl3); H NMR, see
Table 2; 13C NMR, see Table 3; EIMS m/z (rel int) 224 (M+, 5),
196 (8), 195 (7), 182 (30), 168 (98), 167 (100), 159 (15), 158
(22), 140 (42), 139 (78), 125 (36), 122 (22) and 69 (62); anal. C
64.02%, H 7.18%, calcd for C12H16O4, C 64.27%, H 7.19%.
(3) Konig, W. A.; Faasch, H.; Heitsch, H.; Colberg, C.; Hausen, B. M. Z.
Naturforsch. B., Chem. Sci. 1993, 48, 387-393.
(4) Schlegel, R.; Ritzau, M.; Ihn, W.; Stengel, C.; Gra¨fe, U. Nat. Prod.
Lett. 1995, 6, 171-176.
Ack n ow led gm en t. This work was supported by an Inter-
national Cooperative Biodiversity Grant, number U01 TW/CA-
00313 from the Fogarty Center, NIH, and this support is
gratefully acknowledged, as is the advice and encouragement
of Dr. J oshua Rosenthal of the Fogarty Center and Dr. J ames
Rodman of the National Science Foundation. Mass spectra
were obtained by Mr. Kim Harich and Ms. Ann Campbell of
Virginia Polytechnic Institute and State University. We thank
Dr. Y.-Z. Shu at Bristol Myers-Squibb for his assistance in
obtaining the M109 cytotoxicity data.
(5) Bernays, E.; Lupi, A.; Bettolo, R. M.; Mastrofrancesco, C.; Tagliatesta,
P. Experientia 1984, 40, 1010-1011.
(6) Marini-Bettolo, G. B.; Delle Monache, F.; Goncalves da Lima, O.; de
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Refer en ces a n d Notes
(1) Biodiversity Conservation and Drug Discovery in Suriname, Part 8.
For Part 7, see: Abdel-Kader, M. S.; Bahler, B. D.; Malone, S.;
Werkhoven, M. C. M.; Wisse, J . H.; Neddermann, K.; Bursuker, I.;
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Prod. 1997, 60, 1287-1293. (b) Abdel-Kader, M. S.; Wisse, J . H.;
Evans, R.; van der Werff, H.; Kingston, D. G. I. J . Nat. Prod. 1997,
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(13) Marner, F.-J .; Horper, W. Helv. Chim. Acta 1992, 75, 1557-1562.
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