A complex of perseitol and K+ ion from Scurrula fusca (Loranthaceae)

Article abstract of DOI:10.1016/S0040-4039(01)01403-4

A complex of perseitol (D-glycero-D-galacto-heptitol) and K⁺ ions in a molar ratio of 20:1 was isolated from the leaves of Scurrula fusca (Loranthaceae). The stereochemical structure of the complex was determined using several kinds of NMR techniques.

Full text of DOI:10.1016/S0040-4039(01)01403-4

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 6887–6889
A complex of perseitol and K+ ion from Scurrula fusca
(Loranthaceae)
Takashi Ishizu, Etsuji Tsujino, Hendig Winarno, Kazuyoshi Ohashi and Hirotaka Shibuya*
Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Sanzo, 1 Gakuen-cho, Fukuyama,
Hiroshima 729-0292, Japan
Received 28 March 2001; revised 13 July 2001; accepted 27 July 2001
Abstract—A complex of perseitol (D-glycero-D
-galacto-heptitol) and K+ ions in a molar ratio of 20:1 was isolated from the leaves
of Scurrula fusca (Loranthaceae). The stereochemical structure of the complex was determined using several kinds of NMR
techniques. © 2001 Elsevier Science Ltd. All rights reserved.
1
The leaves of a parasite plant, Scurrula fusca (BL.) G.
DON. (Loranthaceae), locally called benalu alus and
whose host-plant is Ficus riedelii MIQ. (Moraceae),
are traditionally used for the treatment of cancer in
Sumatra and the Sulawesi Islands, Indonesia.
the signal breadth in the H NMR spectrum of persei-
tol (1a) in H2O were observed by adding regular
amounts of KSCN as a potassium source to adjust the
molar ratio of 1a to the K+ ion from 23:1 to 16:1 (Fig.
1). The proton signals of 1a gradually broadened with
increases in the amount of K+ ions from 23:1 to 20:1,
and the signal breadth is widest at a molar ratio of
20:1. Thereafter, the widening proton signals of 1a
again became sharper from 20:1 to 16:1. These
findings indicated that the proton motions of 1a were
restricted due to complex formation with the K+ ion.
Furthermore, Fig. 2 shows that every methine and
methylene proton signal at a molar ratio of 20:1 shifts
upfield most prominently. These results indicated that
20 molecules of perseitol formed a complex with 1 mol
of the K+ ion in H2O solution state. Therefore, the
stoichiometry in complex 1 of perseitol with the K+
ion was confirmed to be 20:1.
The methanol extract of the dried leaves produced
precipitates, which were then treated with purified
water. The water-soluble phase was purified by HPLC
with a gel partition resin, resulting in a complex (1),
amorphous powder, mp 174–177°C, [h]D −2.0° (H2O),
in 1.4% yield from the leaves. Acetylation of 1 with
pyridine and acetic anhydride furnished a product
which was identified as perseitol heptaacetate1,2 by
comparison of the physicochemical properties includ-
ing the specific rotation [h]D −14.8° (MeOH). Further-
more, fluorescence X-ray analysis and atomic
absorption analysis indicated that complex 1 consisted
of perseitol (1a) and K+ ions in a molar ratio of 20:1,3
1
and did not contain other metal ions. The H NMR
Based on the observed coupling constants5 of the vici-
nal protons in H2O, it was found that perseitol (1a)
assumed a ‘zigzag’ conformation with a planar carbon
chain.6–8 There was no change in the coupling pattern
of perseitol (1a) in the 1H NMR spectrum observed
during the formation of complex 1 with K+ ions, indi-
cating that the perseitol moiety in complex 1 similarly
maintained a planar ‘zigzag’ conformation.
spectrum of the complex (1) gave a similar signal
pattern to that for perseitol (1a), except the signal
breadth.
To elucidate the stereochemical structure of 1, a
detailed NMR analysis4 was performed. Changes in
Changes in chemical shifts of the seven hydroxyl pro-
tons of 1a in the 1H NMR spectrum in DMSO-d6
were observed by adding regular amounts of KSCN to
adjust the molar ratio of the K+ ions to 1a from 0:1 to
Keywords: Scurrula fusca; Loranthaceae; perseitol; potassium ion;
complex.
* Corresponding author. Tel.: 0849-36-2111 (ext. 5252); fax: 0849-36-
2024; e-mail: shibuya@fupharm.fukuyama-u.ac.jp
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)01403-4

6888
T. Ishizu et al. / Tetrahedron Letters 42 (2001) 6887–6889
Figure 3. Interaction of perseitol (1a) with K+ ions.
1:1. The 3-hydroxyl proton signal shifted downfield
most prominently, before the 2-, 4- and 5-hydroxyl
proton signals shifted. The downfield shifts of 1-, 6-,
and 7-hydroxyl proton signals were not as prominent as
those of other hydroxyl proton signals. These facts
indicated that the 3-hydroxyl group of perseitol (1a)
most strongly attracted the K+ ion in forming complex
1, while the 2-, 4- and 5-hydroxyl groups attracted such
ions more strongly than the 1-, 6- and 7-hydroxyl
groups (Fig. 3).
As a result, it may be presumed that 20 molecules of
perseitol (1a), while maintaining a planar ‘zigzag’ con-
formation, associate with the surrounding K+ ion by
the above-mentioned interaction to form a complex (1)
having a spherical stereochemical structure in H2O
solution.9
Finally, it should be noted that complex 1 exhibits an
inhibitory effect (at 10−4 M, 40.3% inhibitory) on [3H]-
leucine incorporation in the Ehrlich ascites tumor cells
in mice, whereas perseitol (1a) did not show such
activity.
1
Figure 1. Changes in H NMR signals of perseitol (1a) (10.61
mg, 0.051 mmol) by addition of KSCN.
1
Figure 2. Shifts in H NMR signals of perseitol (1a) (10.61 mg, 0.051 mmol) by addition of KSCN.

T. Ishizu et al. / Tetrahedron Letters 42 (2001) 6887–6889
6889
References
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