960 J ournal of Natural Products, 2001, Vol. 64, No. 7
Notes
fraction afforded (+)-pinoresinol-â-glucoside (6) (3 mg), and the
hexane fraction afforded lupeol and stigmasterol. The struc-
tures of 1-4, 6, and betulinic acid were confirmed by compar-
ing their physical and spectral data with those reported in the
literature.5-9 Oleanolic acid, stigmasterol glucoside, and stig-
masterol were identified by direct TLC comparisons with
authentic samples. After removal of the above compounds, the
remainder of the CHCl3 fraction was washed with 2 N Na2-
CO3 and 2 N NaOH successively and then extracted with 2 N
HCl to give an alkaloid-containing fraction. After purification
with preparative TLC, harman (5) was confirmed by HPLC
analysis, where a peak corresponding to harman was detected
in this fraction [Allttima C18 (particle size 5 µm), 4.6 × 250
mm; ammonium acetate 25 mM adjusted with H3PO4 (pH
4.0): MeOH (40:60, v/v) at a flow rate of 1.0 mL/min; UV
detection at 287 nm; tR (min) 12.3 (harman)]. Compound 5 was
also identified by direct TLC comparison with an authentic
sample [Rf 0.5, CHCl3-MeOH (10:1)]. Harman was reported
previously from the related species S. racomosa Roxb.10
Compounds 7, 21, and 27 were obtained from Aldrich, Inc.
(Milwaukee, WI). The preparation of the remaining compounds
(5, 8-20, and 22-34) has been described in our previous
paper.11
lower activity. Thus, the 1-methyl group of 5 seems to be
important for activity in this series of compounds. (c) 3,4-
Dihydro â-carboline (21), produced by hydrogenation of 5,
had lower anti-HIV replication activity compared with the
unsaturated compound. (d) Bromination of 9 at C-6 gave
6-bromoharmine hydrobromide (24); this water-soluble
derivative showed the highest potency in this series of
compounds (EC50 0.22 µM, TI 26.6). The corresponding free
base (22) was not as potent as 24, perhaps due to limited
solubility in the assay buffer and media. (e) The fully
conjugated derivative (33) retained some activity. (f) Com-
pound 34, which possesses a benzimidazole in place of the
indole normally found in â-carbolines, displayed no activity.
Thus the â-carboline structure may be important for the
anti-HIV activity of these compounds. (g) Alkylation of the
indole nitrogen (17, 18, and 19) increased the anti-HIV
activity. Compound 19 (N-butyl) was more active than 18
(N-ethyl), indicating that the length of the alkyl chain at
this position is important to activity.
In summary, within the series of â-carboline derivatives
(5, 7-34), substitution of the parent compound harman (5)
with 1-methyl, 7-methoxy, or an alkyl group at the indole
nitrogen led to increased anti-HIV activity. Synthesis of
additional analogues of this type is currently ongoing in
our laboratory in an effort to identify more potent anti-
HIV inhibitors.
Ack n ow led gm en t. This investigation was supported by
a grant (AI 33066) from the National Institute of Allergy and
Infectious Diseases awarded to K.H.L.
Refer en ces a n d Notes
(1) For part 45, see: Xu, Z.; Chang, F. R.; Wang, H. K.; Kashiwada, Y.;
McPhail, A. T.; Bastow, K. F.; Tachibana, Y.; Cosentino, M.; Lee, K.
H. Anti-HIV Agents 45. Two New Sesquiterpenes, Leitneridanins A
and B, and the Cytotoxic and Anti-HIV Principles from Leitneria
floridana. J . Nat. Prod. 2000, 63, 1712.
(2) Kashiwada, Y.; Wang, H. K.; Nagao, T.; Kitanaka, S.; Yasuda, I.;
Fujioka, T.; Yamagishi, T.; Cosentino, L. M.; Kozuka, M.; Okabe, H.;
Ikeshiro, Y.; Hu, C. Q.; Yeh, E.; Lee, K. H. J . Nat. Prod. 1998, 61,
1090.
(3) Eich, E.; Schulz, J .; Trumm, S.; Sarin, P. S.; Maidhof, A.; Merz, H.;
Schro¨der, H. C.; Mu¨ller, W. E. G. Planta Med. 1990, 56, 506.
(4) Eich, E.; Pertz, H.; Kaloga, M.; Schulz, J .; Fesen, M. R.; Mazumder,
A.; Pommier, Y. J . Med. Chem. 1996, 39, 86.
(5) Rahman, M. M. A.; Dewick, P. M.; J ackson, D. E.; Lucas, J . A.
Phytochemistry 1990, 29, 1971.
(6) Miyazawa, M.; Kasahara, H.; Kameoka, H. Phytochemistry 1992, 31,
3666.
(7) Okuyama, E.; Suzumura, K.; Yamazaki, M. Chem. Pharm. Bull. 1995,
43, 2200.
(8) Bodesheim, U.; Ho¨lzl, J . Pharmazie 1997, 52, 386.
(9) Abe, F.; Yamauchi, T. Chem. Pharm. Bull. 1986, 34, 4340.
(10) Spa¨th, E. Monatsh. 1920, 41. 401.
(11) Ishida, J .; Wang, H. K.; Bastow, K. F.; Hu, C. Q.; Lee, K. H. Bioorg.
Med. Chem. Lett. 1999, 9, 3319.
Exp er im en ta l Section
P la n t Ma ter ia ls. S. setchuensis was collected in the Shi-
chuan Province, People’s Republic of China.
Extr a ction a n d Isola tion . The 95% EtOH extract (76.5
g) of the stems of S. setchuensis was adsorbed on Celite 521
and eluted successively with hexane, CHCl3, EtOAc, and
MeOH. Each fraction then was chromatographed repeatedly
on silica gel and ODS columns. The CHCl3 fraction (19.4 g)
was chromatographed on a silica gel column using CHCl3-
MeOH (1:0 f 0:1) as eluents to afford fractions 1-9. Fraction
2 gave betulinic acid (1 mg), oleanolic acid, and a mixture of
matairesinol (1) and (+)-pinoresinol (2) in a 5:2 ratio. Com-
pound 2 (10 mg) was isolated by acetylation of the mixture,
isolation of the diacetate, and deacetylation. Compound 1 was
isolated and identified as the aglycone of matairesinoside (3).
The diacetate (1a ) was generated by acetic anhydride-pyridine
acetylation of 1 at room temperature. Fractions 3, 4, and 5
afforded isolariciresinol (4) (18.1 mg), stigmasterol glucoside,
and matairesinoside (3) (550 mg), respectively. The MeOH
NP0101189