Constituents of Agave americana and Agave barbadensis

Article abstract of DOI:10.1016/j.fitote.2005.04.013

An investigation of Agave americana and Agave barbadensis resulted in the isolation of a new homoisoflavanoid, 7-hydroxy-3-(4-methoxybenzyl)-chroman (3), together with known compounds 7-hydroxy-3-(4-methoxybenzyl)-chroman-4-one (1), 5,7-dihydroxy-3-(4-methoxybenzyl)-chroman-4-one (2), cantalasaponin-1 (4), and 2-hydroxy-butanedioic acid-1-methyl ester (5).

Full text of DOI:10.1016/j.fitote.2005.04.013

Fitoterapia 76 (2005) 594–597
www.elsevier.com/locate/fitote
Phytochemical communication
Constituents of Agave americana
and Agave barbadensis
a
b
b
W.F. Tinto a, , J.L. Simmons-Boyce , S. McLean , W.F. Reynolds
*
aDepartment of Biological and Chemical Sciences, University of the West Indies, Cave Hill, Campus, P.O. Box 64,
Bridgetown, WI, Barbados
bDepartment of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6
Received 31 March 2004; accepted 30 April 2005
Available online 23 June 2005
Abstract
An investigation of Agave americana and Agave barbadensis resulted in the isolation of a new
homoisoflavanoid, 7-hydroxy-3-(4-methoxybenzyl)-chroman (3), together with known compounds
7-hydroxy-3-(4-methoxybenzyl)-chroman-4-one (1), 5,7-dihydroxy-3-(4-methoxybenzyl)-chroman-
4-one (2), cantalasaponin-1 (4), and 2-hydroxy-butanedioic acid-1-methyl ester (5).
D 2005 Elsevier B.V. All rights reserved.
Keywords: Agave americana; Agave barbadensis; Homoisoflavanoid
1. Plant
We used Agave americana (Agavaceae) aerial parts and Agave barbadensis rhizomes,
collected in 2000 in the parishes of St. Phillip and St. Lucy, respectively, in Barbados. Dr.
Claire Durant identified the plants and voucher specimens (Agave-2 and Agave-1,
respectively) deposited in Tanaud Ireland, Inc., University of the West Indies, Cave Hill
Campus.
* Corresponding author.
E-mail address: wtinto@uwichill.edu.bb (W.F. Tinto).
0367-326X/$ - see front matter D 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.fitote.2005.04.013

W.F. Tinto et al. / Fitoterapia 76 (2005) 594–597
595
2. Uses in traditional medicine
Several Agave spp. have been used in the treatment of scabies, tumors, syphilis, and
dysentery, and as insecticides. They are also a source of fiber and produce steroidal
sapogenins and saponins, the raw materials for steroid hormone synthesis [1].
3. Previously isolated constituents
Previously isolated constituents are steroidal sapogenins and saponins [2,3], chro-
mones, alcohols, and esters [4–6]. No phytochemical study on A. barbadensis has been
reported.
4. Newly isolated constituents
Newly isolated constituents from the EtOAc extract of A. barbadensis rhizomes were:
7-hydroxy-3-(4-methoxybenzyl)-chroman-4-one (1) (yield: 0.0007%) [7,8], 5,7-dihy-
droxy-3-(4-methoxybenzyl)-chroman-4-one (2) (yield: 0.0004%) [9], 7-hydroxy-3-(4-
methoxybenzyl)-chroman (3) (yield: 0.0003%), and cantalasaponin-1 (4) (yield: 0.014%)
[10]. Newly isolated constituent from the EtOAc extract of the aerial part of A. americana
was 2-hydroxy-butanedioic acid-1-methyl ester (5) (yield: 0.025%).
OCH
HO
O
7
3
2
1'
5
4
9
R
R
1
R
R1
O
1
2
3
H
OH
H
O
H2
25
21
O
1
3
18
COOCH3
ROOC
19
OH
O
OH
OH
3
O
R
HO
HO
O
6
5
6
H
O
OH
OH
CH3
O
HO
HO
4
OH

596
W.F. Tinto et al. / Fitoterapia 76 (2005) 594–597
7-Hydroxy-3-(4-methoxybenzyl)-chroman (3): white solid; [a]2D0 + 34.38 (c 0.01,
CHCl3); IR bands (film): 3421, 1647 cmÀ 1; UV max: 282 (loge 3.63), 224 (4.10), 210
1
(4.22) nm; H-NMR (500 MHz, CD3OD): y 7.10 (2H, d, J 8.9 Hz, H2V and H6V), 6.85
(3H, m, H-5, H-3V, and H-5V), 6.34 (1H, dd, J 8.1 and 2.5 Hz, H-6), 6.30 (1H, d, J 2.5 Hz,
H-8), 4.15 (1H, ddd, J 10.8, 2.8, and 1.4 Hz, H-2a), 3.80 (3H, s, 4V-OMe), 3.78 (1H, dd, J
10.8 and 2.3 Hz, H-2b), 2.71 (1H, dd, J 15.6 and 5.7 Hz, H-4a), 2.63 (1H, dd, J 14.1 and
7.1 Hz, H-9a), 2.55 (1H, dd, J 14.1 and 7.1 Hz, H-9b), 2.42 (1H, dd, J 15.6 and 8.5 Hz, H-
4b), 2.24 (1H, m, H-3); 13C-NMR (125 MHz, CD3OD): y 158.1 (C-4V), 155.3 (C-8a),
154.7 (C-7), 131.4 (C-1V), 130.5 (C-5), 129.9 (C-2V and C-6V), 113.8 (C-3V, C-4a, C-5V),
107.8 (C-6), 103.1 (C-8), 70.0 (C-2), 54.9 (4V-OMe), 37.2 (C-9), 34.3 (C-3), 30.4 (C-4);
HRMS: [M]+ m/z: 270.1251. Calc. for C17H18O3 270.1256.
1
The H-NMR data for 3 closely resembled that for 1 [11], except that it showed a
multiplet at y 2.24 and a double doublet at y 2.42 ( J 3.6, 9.1 Hz) and both protons showed
correlations with C-4 (y 30.4). This suggested the presence of a methylene group at C-4
instead of a carbonyl group. The isolation of compounds 1–3 from the genus Agave is the
second report of flavanoid-type compounds being isolated from this genus, the first report
being that of agamanone [4].
Compound 5 from A. americana is a methyl ester of malic acid, a product of the
tricarboxylic acid cycle [12], but extensive literature searches failed to provide references
with NMR data for this compound.
2-Hydroxy-butanedioic acid 1-methylester (5): pale yellow solid; [a]2D0 À 4.08 (c 0.63,
CH3OH); IR bands (film): 3446, 1739, 1636 cmÀ 1; UV max 268 (loge 1.96), 208 (2.75)
nm; 1H-NMR (300 MHz, CD3OD): y 5.08 (1H, s, OH), 4.50 (1H, dd, J 8.5 and 4.7 Hz, H-
2), 3.74 (3H, s, OMe), 2.78 (1H, dd, J 16.5 and 4.7 Hz, H-3a), 2.67 (1H, dd, J 16.5 and
8.5 Hz, H-3b); 13C-NMR (75 MHz, CD3OD): y 173.9 (C-1), 172.7 (C-4), 67.5 (C-2), 51.7
(C-OMe), 38.8 (C-3); HREIMS: [M+H]+ m/z: 149.0446. Calc. for C5H9O5 149.0450.
Compound 6 was prepared by methylation of 5.
2-Hydroxy-butanedioic acid dimethylester (6): colourless solid; [a]2D0 + 1.18 (c 1.34,
CHCl3); IR bands (film): 3440, 1644 cmÀ 1; UV max : 214 (loge 2.51 nm); 1H-NMR (300
MHz, CD3OD): y 4.51 (1H, dd, J 6.2 and 4.7 Hz, H-2), 3.81 (3H, s, 4-OMe), 3.71 (3H, s,
1-OMe), 2.88 (1H, dd, J 14.1 and 4.7 Hz, H-3a), 2.78 (1H, dd, J 14.1 and 6.2 Hz, H-3b);
13C-NMR (75 MHz, CD3OD): y 173.8 (C-1), 171.1 (C-4), 67.5 (C-2), 53.1 (4-OMe), 52.3
(1-OMe), 38.8 (C-3); EIMS: [M+H]+ m/z 163, 146, 131, 114, 103, 71.
Acknowledgements
The authors thank Dr. Alex Young of the Department of Chemistry, University of
Toronto, for MS measurements, and Dr. Claire Durant Tanaud Research Unit, a subsidiary
of Shire-Biochem, for assistance with the collection and identification of the plants.
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