DSpace at VNU: A new guaianolide fromArtemisia roxburghiana

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A new guaianolide from Artemisia
roxburghiana
a

a

a

Phan Minh Giang , Tran Thi Thanh Nhan , Phan Tong Son ,
b

Katsuyoshi Matsunami & Hideaki Otsuka

b

a

Faculty of Chemistry, VNU University of Science, Vietnam
National University, 19 Le Thanh Tong Street, Hanoi, Vietnam
b

Graduate School of Biomedical Sciences, Hiroshima University,
1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
Published online: 22 Feb 2013.

To cite this article: Phan Minh Giang, Tran Thi Thanh Nhan, Phan Tong Son, Katsuyoshi Matsunami
& Hideaki Otsuka (2013) A new guaianolide from Artemisia roxburghiana, Natural Product Research:
Formerly Natural Product Letters, 27:20, 1856-1858, DOI: 10.1080/14786419.2013.768991
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Natural Product Research, 2013
Vol. 27, No. 20, 1856–1858, />
A new guaianolide from Artemisia roxburghiana
Phan Minh Gianga*, Tran Thi Thanh Nhana, Phan Tong Sona, Katsuyoshi Matsunamib and
Hideaki Otsukab
a
Faculty of Chemistry, VNU University of Science, Vietnam National University, 19 Le Thanh Tong Street,
Hanoi, Vietnam; bGraduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima 734-8553, Japan

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(Received 11 October 2012; final version received 25 December 2012)
A new member of 5a H,6b H,7a H,11a H-guaian-12,6a-olides, 11-epi-8a-hydroxyarborescin, together with a mixture of (24R)- and (24S)-cycloart-25-en-3b,24-diols,
palmitic acid and 1-octacosanol were isolated from the leaves of Artemisia
roxburghiana Bess. (Asteraceae) of Vietnam. Their structures were determined on
the basis of spectroscopic methods.
Keywords: Artemisia roxburghiana; Asteraceae; sesquiterpene lactone; guaianolide

1. Introduction
In the chemistry of Artemisia plants of Asteraceae family, sesquiterpene lactones including
guaianolides, eudesmanolides and germacranolides are the molecules of interest (Kelsey &
Shafizadeh 1979; Tan et al. 1998). The guaiane-type sesquiterpene lactones are recognised as a
diverse group of natural compounds with varied stereochemical and functional groups
(Budeˇsˇ´ınsky´ & Sˇaman 1995). Artemisia roxburghiana Bess. (Vietnamese name: Ngải ru`’ng) is a
subshrub of 50– 100 cm tall and is used to treat fever and intestinal worms (Hayat et al. 2009). As
a part of our study of sesquiterpene lactones from species of the family Asteraceae
A. roxburghiana was investigated. The study showed the accumulation of guaianolides with the
exclusive H-5a, H-6b, H-7a and H-11a stereochemistry in this plant (Phan et al. 2012). In the
search for minor guaianolides, a new guaianolide, 11-epi-8a-hydroxyarborescin (1), together
with a mixture of two known epimeric cycloartane triterpenoids, (24R)- and (24S)-cycloart25-en-3b,24-diols (3), palmitic acid (4) and 1-octacosanol (5) were isolated from the leaves of

A. roxburghiana.

2. Results and discussion
The dried leaves of A. roxburghiana were extracted with MeOH, and the resulting MeOH extract
was sequentially fractionated using solvents of increasing polarities to give n-hexane-, CH2Cl2and EtOAc-soluble fractions. The CH2Cl2-soluble fraction was fractionated by repeated silica
gel column chromatography (CC) to give compounds 1 –5. The structures of the known
compounds 2 – 5 were determined by comparing their spectroscopic data with the reported
literature values (Levy 1976; Pei et al. 2007).
Compound 1 was isolated as a white amorphous powder (½aŠ24
D þ 215.5, CHCl3) and its
molecular formula was determined as C15H20O4 on the basis of the HR-ESI-TOF-MS spectrum

*Corresponding author. Email:
q 2013 Taylor & Francis


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Natural Product Research

1857

of 1. The 1H, 13C NMR and HSQC spectroscopic data of 1 revealed the presence of three methyl
groups, two sp3 methylenes, five sp3 methines including two oxymethines [dH 4.29 (1H, t,
J ¼ 10.5 Hz) and dC 79.0 (d), and dH 3.86 (1H, ddd, J ¼ 10.5, 10.5, 3.5 Hz) and dC 64.6 (d); IR:
nmax 3454 cm21], two oxygenated tertiary carbons of an epoxide ring [dC 72.3 (s) and 60.6 (s)],
two olefinic carbons of a trisubstitued double bond [dH 5.56 (1H, br s); dC 140.6 (s) and 124.8
(d)] and a lactone carbonyl group [dC 179.6 (s); IR: nmax 1759 cm21]. Thus, the spectroscopic
data of 1 agreed well with a sesquiterpene lactone of the guaiane type (Budeˇsˇ´ınsky´ & Sˇaman
1995) and HMBC correlations (Figure 1) supported the same planar structure of 1 as that of 8ahydroxyarborescin (Wong & Brown 2002). However, 1 was determined to be an epimer of 8ahydroxyarborescin at C-11, since the 13C NMR chemical shifts at C-11 (dC 38.3) and C-13 (dC

9.7) clearly indicated the H-11a orientation (Budeˇsˇ´ınsky´ and Sˇaman 1995). The chemical shifts
of C-11 and C-13 reported for 8a-hydroxyarborescin are dC 40.9 and 16.1, respectively (Wong
& Brown 2002). NOESY spectrum also supported the stereochemical assignments of the
stereocenters of 1 as H-5a, H-6b, H-7a and H-8b on the basis of the correlations between H3-13
(dH 1.28) and H-6b (dH 4.29), between H-5a (dH 2.86) and H-7a (dH 1.99) and between H-8b
(dH 3.86) and H3-13; no correlations were observed between H3-13 and H-5a/H-7a (Figure 1).
Therefore, the structure of 1 was determined to be 11-epi-8a-hydroxyarborescin. A
diastereomeric compound of 1, deacetylglobicin, was isolated from A. absinthium (Lee et al.
1971; Kasamov et al. 1984).

3. Experimental
3.1 General experimental procedures
Optical rotations were measured on a JASCO P-1030 digital polarimeter. FT-IR spectra were
recorded on a Horiba FT-710 spectrophotometer. HR-ESI-TOF-MS spectra were measured on
an Applied Biosystem QSTAR XL mass spectrometer. 1H (500 MHz), 13C NMR and DEPT
(125 MHz) spectra were recorded on a Bruker Avance 500 NMR spectrometer. Silica gels
(0.063 – 0.200 mm, 0.040 – 0.063 mm and 0.015 – 0.040 mm) (Merck, Darmstadt, Germany) were
used for open-CC and flash chromatography. Thin-layer chromatography (TLC) was carried out
on TLC silica gel 60 F254 (Merck, Darmstadt, Germany) and detected by spraying with 1%
vanillin in concentrated H2SO4, followed by heating on a hot plate at 2008C.

3.2 Plant material
The leaves of A. roxburghiana Bess. (Asteraceae) were collected in Ha Giang province, Vietnam
in November 2008. The plant was identified by Mr Nguyen Quoc Binh, a botanist of the Institute
of Biological Resources and Ecology, Vietnam Academy of Science and Technology, Hanoi,
14

O
2

1

3

6

H

O

9
8

5

4

H

O
10

OH
H
H

OH

OH

7

H
15

H

11

O
1

12

O

13

H

O
O

1

Figure 1. Structure, NOESY and HMBC correlations of compound 1.

HMBC
NOESY

O
O


1858

P.M. Giang et al.

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Vietnam. Voucher specimen of the plant (voucher number: VMN-B0000302) was deposited at
the same Institute.
3.3 Extraction and isolation
The powdered dried leaves of A. roxburghiana (6 kg) were extracted with MeOH at room
temperature (three times, each time for three days). The MeOH extract was successively
partitioned between water and n-hexane, CH2Cl2 and EtOAc to give the corresponding soluble
fractions. Part of the CH2Cl2-soluble fraction (42 g) was subjected to silica gel CC using nhexane/acetone 49:1, 29:1, 19:1, 6:1, 3:1 and 1:1 to give eleven fractions. Silica gel CC of
fraction 9 (3.3 g) eluting with n-hexane/acetone 9:1, 6:1, 3:1 and 1:1 gave compound 1 (15 mg).
Repeated silica gel CC of fraction 7 (3.8 g) eluting with n-hexane/EtOAc 19:1, 9:1, 6:1, 3:1 and
1:1 gave a mixture of compounds 2 and 3 (5 mg), and compound 4 (3 mg). Compound 5 (3 mg)
were obtained from fractions 3 (0.33 g) on washing with a mixture of n-hexane/acetone.
11-epi-8a-Hydroxyarborescin (1): white amorphous powder; ½aŠ24
D þ 215.5 (c 0.11, CHCl3);
IR (film) nmax cm21: 3454, 1759, 1441, 1381, 1261, 1222, 1181; 1H NMR (CDCl3): d 1.28 (3H,
d, J ¼ 7.5 Hz, 13-CH3), 1.35 (3H, s, 14-CH3), 1.93 (3H, br s, 15-CH3), 1.99 (1H, ddd, J ¼ 10.5,
10.5, 7.0 Hz, H-7), 2.12 (1H, d, J ¼ 18.0 Hz, H-2a), 2.16 (1H, dd, J ¼ 14.5, 10.5 Hz, H-9b),
2.33 (1H, dd, J ¼ 14.5, 3.5 Hz, H-9a), 2.76 (2H, m, H-2b, H-11), 2.86 (1H, d, J ¼ 10.5 Hz, H5), 3.86 (1H, ddd, J ¼ 10.5, 10.5, 3.5 Hz, H-8), 4.29 (1H, t, J ¼ 10.5 Hz, H-6), 5.56 (1H, br s, H3). 13C NMR (CDCl3): d 9.7 (C-13), 18.2 (C-15), 22.7 (C-14), 38.3 (C-11), 39.2 (C-2), 43.5 (C9), 51.6 (C-5), 56.2 (C-7), 60.6 (C-10), 64.6 (C-8), 72.3 (C-1), 79.0 (C-6), 124.8 (C-3), 140.6 (C4), 179.6 (C-12); Positive-ion HR-ESI-TOF-MS: m/z 287.1255, [M þ Na]þ (calcd for
C15H20O4Na: 287.1253).
Acknowledgements
This work was supported by the National Foundation for Science and Technology Development

(NAFOSTED, Hanoi, Vietnam).

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