PERGAMON
Phytochemistry 50 (1999) 345±348
Diterpenoid alkaloids from aconitum episcopale
Jing-Hua Yanga, *, Zi-Yan Lib, Liang Lia, Yun-Song Wangc
aDepartment of Chemistry, Yunnan University, Kunming, Yunnan Province 650091, People's Republic of China
bDepartment of Environmental Engineering, Kunming Institute of Science and Technology, Kunming, Yunnan Province 650093, People's Republic of
China
cYunnan Institute of Tobacco Industry, Kunming, Yunnan Province 650223, People's Republic of China
Revised 23 April 1998
Abstract
Three new diterpenoid alkaloids, liaconitine A (N-ethyl-1a,6a,16b,18-tetramethoxy-13b-ol-2,3-dehydroaconitane-8-acetate-14-
anisoylate), B (N-ethyl-1a,6a,16b,18-tetramethoxy-13b-ol-2,3-dehydroaconitane-8,14-dianisoylate and C (N-ethyl-1a,6a,16b,18-
tetramethoxy-8-ethoxy-13b-ol-2,3-dehydroaconitane-14-anisoylate) have been isolated from the roots of Aconitum episcopale. The
structures of the new compounds were established by spectroscopic methods and reduction of liaconitine A to the known
alkaloid, crassicauline A. # 1998 Published by Elsevier Science Ltd. All rights reserved.
Keywords: Aconitum episcopale; Ranunculaeae; Roots; Diterpenoid alkaloids; Liaconitines A-C; Crassicauline A
1. Introduction
HR mass spectrum (m/z 641.3188) and NMR spectral
chemical shifts (Tables 1 and 2). The 1H,13C NMR
and mass spectra showed that it is a C19-type diterpe-
noid alkaloid with an N-ethyl group, an acetyl group,
®ve methoxyl groups and an anisoyl group. Its spectral
characters were similar to the known compound, cras-
sicauline A (Wang & Fang, 1981). The main dier-
ences between liaconitine A and crassicauline A were
13C NMR chemical shifts of C(2),C(3) at d 125.1 and
137.5 that showed two methine carbons in place of
two methylene carbons of crassicauline A. In the 1H
NMR spectrum of liaconitine A, two ole®nic protons
indicated a one proton doublet at d 5.75 (J= 10 Hz)
and a one proton double doublet at d 6.08 (J= 10, 3.6
Hz). The latter is coupled to C(1)-bH (d 3.27, 1H, d,
J =3.6 Hz). This suggested the presence of a double
bond located at C(2),C(3) in liaconitine A. On the
basis of spectral data, the structure of liaconitine A
was assigned as 1 and con®rmed by reduction of liaco-
nitine A to crassicauline A, identical with an authentic
sample by comparison of TLC behavior, IR and 1H
NMR spectral signals (Wang & Fang, 1981).
Aconitum species have been used as a traditional
Chinese medicinal herb having analgesic activity. In
our studies of the alkaloids of the genus Aconitum,
three new C19 nordeterpenoid alkaloids, named liaco-
nitine A (1), B (2) and C (3) have been isolated from
the roots of A. episcopale, which was collected from
Lijiang, Yunnan Province, P.R. China. These novel al-
kaloids all bear a double bond at C(2),C(3). This type
of norditerpenoid alkaloid has not been reported from
Aconitum species native to Yunnan Province. 2,3-
Dehydrodelcosine was isolated earlier from A. japoni-
cum var. montanum Nakai in 1988 (Takayama et al.,
1988). The possibility that 3 is an artifact of the iso-
lation process has been addressed.
2. Results and discussion
Three new alkaloids were isolated from a CHCl3
extract by column chromatography over silica gel.
Liaconitine A was isolated as colourless needles and its
molecular formula C35H47NO11 was derived from the
Similarly, by their spectral data (Tables 1 and 2), lia-
conitine B and C were determined to be C19-type alka-
loids and all bearing a double bond at C(2),C(3) as in
1. Comparison of their NMR data indicated that the
only dierence among the three alkaloids was the C(8)
* Corresponding author.
0031-9422/98/$ - see front matter # 1998 Published by Elsevier Science Ltd. All rights reserved.
PII: S0031-9422(98)00387-2