Chemistry of Natural Compounds, Vol. 43, No. 3, 2007
ALKALOIDS OF Convolvulus subhirsutus FROM UZBEKISTAN
A. M. Gapparov, N. A. Razzakov, and S. F. Aripova
UDC 547.944/945
N
Convolvine, convolamine, convolidine, phyllalbine, and the new alkaloid phyllalbine -oxide and the
Convolvulus subhirsutus
aminoalcohol nortropine were isolated from the total alkaloids of
time from this plant.
and for the first
Key words: Convolvulus subhirsutus, alkaloids, isolation, phyllalbine N-oxide, nortropine.
Several tropane derivatives [1], mainlyconvolvine and convolamine [2], have been isolated previously from the aerial
part and roots of growing in Kazakhstan.
Convolvulus subhirsutus
The plant growing in Uzbekistan has not been investigated. We studied the aerial part of
[3] collected
C. subhirsutus
in Tashkent district at the start of flowering. The quantitative content of total alkaloids was 0.36% of the air-dried mass of the
aerial part. The total alkaloids obtained by extraction of the aerial part were divided into phenolic and nonphenolic parts.
Separation of the phenolic fraction over a column of Al O isolated two alkaloids with mp 209-210°C and 214-215°C, which
2
3
turned out to be phyllalbine and convolidine, respectively [4, 5]. The total bases of the nonphenolic part were separated by
citrate—phosphate buffer at pH 6.8 to afford a fraction consisting of crude convolvine. The fraction obtained by work up with
a buffer at pH 5.6 isolated convolamine with an impurity of convolvine.
Alkaloids in a basic aqueous solution were extracted with CHCl to produce a solution containing polar alkaloids that
3
were very soluble in water but nonextractable by organic solvents. The aqueous solution was evaporated to dryness. The solid
was chromatographed over a column of Al O . An amorphous base 1 was isolated from the first CHCl :CH OH eluents. The
2
3
3
3
IR spectrum of 1 exhibited absorption bands for active H at 3552-3451 cm−1; an aromatic ring, 1703, 1640, 1601, 874, 759;
and stretching and deformation vibrations of CH –, CH –, and CH–groups, 2962, 2838, 1439, 1323. The PMR spectrum of
3
2
1 showed signals for an N–CH group as a 3H singlet at 3.24 ppm and an aromatic methoxyl as a 3H singlet at 3.84. The range
3
1.75-2.25 ppm contained a broad 8H peak from four methylene protons. This was probably from protons of the tropane ring
in positions C2, C4, C6, and C7. A 1H signal appeared at 5.14 ppm for the C3 proton, which is diagnostic for tropane alkaloids
esterified at the C3 hydroxyl. Signals for aromatic protons (3H) were found in the range 6.75-7.55 ppm.
The spectral properties indicated that the isolated alkaloid was a tropane base esterified at the C3 hydroxyl by a
methoxy-substituted aromatic acid. Comparison of the spectral properties of 1 with those of phyllalbine showed that their
structures were similar. However, the N–CH signal in the PMR spectrum of 1 was shifted to weak field by 1 ppm compared
3
with that of phyllalbine. This indicated that there was an electronegative group on the N atom that was causing such a large
shift. Reduction of 1 with zinc in dilute HCl produced phyllalbine. Therefore, 1 was phyllalbine -oxide.
N
Continued separation of total alkaloids from the next CHCl :CH OH fractions isolated amorphous base 2 with 0.1
R
3
3
f
(system 2). The IR spectrum of 2 exhibited absorption bands for active H (3358-3350 cm−1), stretching and deformation
vibrations of CH – and CH– at 2885 and 1410, and an ether at 1028. The PMR spectrum of 2 contained signals for methylene
2
protons at 1.0-2.0 ppm as unresolved multiplets of intensity 8H. Base 2 was identified as nortropine, which we prepared by
hydrolysis of convolvine. Nortropine was isolated from the plant for the first time.
Thus, the aerial part of
growing in Tashkent district afforded six alkaloids: convolvine, convolamine,
C. subhirsutus
phyllalbine, convolidine, a newbase that turned out tobe phyllalbine -oxide, and nortropine, which was isolated from the plant
N
for the first time.
S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan,
Tashkent, fax (99871) 120 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 242-243, May-June, 2007.
Original article submitted January 18, 2006.
0009-3130/07/4303-0291 ©2007 Springer Science+Business Media, Inc.
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