Synthesis and biological activity of isoalantolactone - Tryptamine conjugates

Article abstract of DOI:10.1007/s11172-012-0058-x

Previously unknown adducts of substituted tryptamines with sesquiterpene lactones, viz., isoalantolactone and its epoxy derivative, were synthesized by the Michael reaction. The compounds obtained were tested for various types of biological activity.

Full text of DOI:10.1007/s11172-012-0058-x

Russian Chemical Bulletin, International Edition, Vol. 61, No. 2, pp. 409—415, February, 2012
409
Synthesis and biological activity of isoalantolactone—tryptamine conjugates
S. G. Klochkov,a S. V. Afanas´eva,a Yu. N. Bulychev,b M. E. Neganova,a and E. F. Shevtsovaa
a
Institute of Physiologically Active Compounds, Russian Academy of Sciences,
1 Severnyi proezd, 142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (496) 524 9508. Eꢀmail: klochkov@ipac.ac.ru
bResearch Institute for Experimental Tumor Diagnostics and Therapy,
N. N. Blokhin Russian Oncological Center, Russian Academy of Medical Sciences,
24 Kashirskoe shosse, 115478 Moscow, Russian Federation.
Fax: +7 (495) 324 22 74
Previously unknown adducts of substituted tryptamines with sesquiterpene lactones, viz.,
isoalantolactone and its epoxy derivative, were synthesized by the Michael reaction. The comꢀ
pounds obtained were tested for various types of biological activity.
Key words: isoalantolactone, sesquiterpenes, lactones, tryptamines, Michael reaction,
biologically active compounds.
Natural unsaturated ꢀlactones found among secondꢀ
ary metabolites of the most part of angiosperm plants have
a wide spectrum of biological activity, for example, antiꢀ
tumor,1 antiinflammatory, antibacterial, and antiprotoꢀ
zoal properties.2 The structure—biological activity relaꢀ
tionship has recently been studied for this series.3 The
modification of natural ꢀlactones can provide novel drugs
and solve the problem of their poor solubility in water and
polar solvents. To study possibilities of this modification,
we chose easily accessible objects: isoalantolactone (1)
isolated4 from elecampane roots (Inula helenium L.:
Asteraceae) and its epoxide 2. The latter has been syntheꢀ
sized previously5 by the selective oxidation of the exocyclic
double bond of the perhydronaphthalene fragment in
lactone 1.*
group. One of the routes for modifying such derivaꢀ
tives seems to be the Michael reaction, viz., addition of
nucleophiles to electronꢀdeficient alkenes.9 We used subsꢀ
tituted tryptamines (3ꢀ(2ꢀaminoethyl)indoles) to inꢀ
troduce an additional pharmacophoric fragment as
an Nꢀnucleophile into the lactone molecule. The
tryptamines are classified as physiologically active inꢀ
dole alkaloids and are intensively studied as neuroꢀ
modulators.10
The reactions of lactones 1 and 2 with unsubstituted
(3а) and substituted (3b—j) tryptamines occur on storage
of the reactants in methanol at ambient temperature for
several hours. The reaction is highly stereoselective: only
one stereoisomer of the corresponding 13ꢀtryptamine deꢀ
rivative of 11,13ꢀdihydroisoalantolactone 4 or 5 is formed
(Scheme 1).
The synthesis of adducts 4а,b and 5а,b has been deꢀ
scribed earlier.11 The hitherto unknown adducts of isoalanꢀ
tolactone 2 with other tryptamine derivatives 3с—j were
synthesized to expand the scope of studied compounds
with the aim to study the structure—biological activity
relationship (see Scheme 1). Compounds 3с—j contain
various substituents in the benzene ring (Me, Bun, Bus, Cl,
CF3) and/or methyl group in position 2 of the pyrrole
cycle. The duration of the reaction between lactones 1 or 2
and tryptamines 3 was almost independent of the nature
of substituents in their molecules. Preparative HPLC
was used for the isolation and purification of the obtained
products 4c—j.
It should be mentioned that the biological properties
of isoalantolactone 1 are well studied: it is used as an
antiinflammatory and antiulcerogenic agents6 and has a
high cytotoxic activity.7,8
The lactone cycle of compounds 1 and 2 contains
the exocyclic double bond activated by the carbonyl
1
An analysis of the Н NMR spectra combined with
1Нꢀ1Н COSY experiments proved the structures of the
synthesized compounds.
* Hereinafter traditional names and numeration of atoms in lacꢀ
tones are used.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 407—412, February, 2012.
1066ꢀ5285/12/6102ꢀ409 © 2012 Springer Science+Business Media, Inc.

410
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 2, February, 2012
Klochkov et al.
Scheme 1
Fig. 1. Main correlations in the 2D 1Нꢀ1H NOESY NMR specꢀ
trum of compound 4b. Chemical shifts are given in the  scale.
doublets at  2.83 and 3.08 with a high geminal spinꢀspin
coupling constant (interaction with each other, J1
=
= 11.74 Hz) and vicinal coupling constants for the interꢀ
action with the proton at the С(11) atom (J2 = 7.34 and
7.04 Hz). The signal from the Н(11) proton ( 2.34) is
a doublet of doublet of doublet of doublets in which
a farꢀrange constant of interaction with the axial proton at
the C(9) atom and with the proton at the C(3) atom can
be observed. The spectrum also exhibits signals from
the protons of the tryptamine fragments NСH2СH2 at
 3.0—3.05 and NСH2СH2 at  2.98, as well as the well
resolved signals from the heteroaromatic protons of tryptꢀ
amine: the signals from the protons at the С(2´) and С(4´)
atoms as a doublet of doublets at  7.05 (J = 2.35 Hz), at the
С(6´) atom as a doublet of doublets at  6.86 (J1 = 8.51 Hz,
J2 = 2.35 Hz), at the C(7´) atom as a doublet of doublets
at  7.25 (J = 8.80 Hz), and the broadened signal from the
indole NH group ( 7.95), which confirms the structure
proposed for compound 4b.
i. 1 or 2, MeOH, 20 C.
X + Y = CH2 (1, 4), OCH2 (2, 5); R1 = H, R2 = H (a), 5ꢀMeO (b),
5ꢀBun (e); R1 = Me, R2 = 5ꢀBnO (c), 5ꢀMeO (d), 7ꢀCF3 (f), H (g),
5ꢀBus (h), 5ꢀCl (i), 5,7ꢀMe2 (j).
As should be expected, the 1H NMR spectra of derivaꢀ
tives 4c—j exhibit signals from the protons of the tryptꢀ
amine moiety (ethylene bridge and heteroaromatic proꢀ
tons in the low field) and signals from the protons at the
С(11) and С(13) atoms at  2.8—3.0, whereas the signals
characteristic of the exocyclic =СH2 group (doublets at
 5.56 and 6.08) are absent.5 For example, the Н NMR
spectrum of compound 4b contains pronounced signals
from the protons at the C(13) atom as a doublet of
1
Table 1. Effect of compounds 1, 2, 4a—c,e,g—i, and 5a on the peroxide oxidation of lipids from the rat
brain homogenate initiated by the Fe3+ ion and tertꢀbutyl hydroperoxide and their Fe2+ꢀchelating and
antiradical activity
Comꢀ
pound
Inhibition of POL
Fe2+ꢀchelating
activitya,b
Antiradical
activity
(DPPH test)a (%)
Inductor of Fe3+
,
Inductor
of tBHPa (%)
(%)
IC50/mol L–1
c
c
c
1
2
4a
Prooxidant
Prooxidant
31.2 11.0
—
—
—
c
c
c
—
—
—
c
c
—
85.5 4.3
(30.6 3.2)b
81.5 2.6
(40.2 2.9)b
25.4 5.1
34.7 0.7
42.7 3.1
32.4 2.5
39.7 0.9
—
c
c
4b
13.9 1.1
—
—
4c
4e
4g
4h
4i
4.2 2.4
3.9 0.4
5.0 1.0
4.3 0.4
7.7 0.6
31.9 10.1
39.8 4.7
32.5 3.1
22.4 5.4
46.9 6.4
31.4 2.5
35.3 0.9
28.2 0.7
14.7 2.9
19.4 0.4
<10
c
c
5a
—
59.8 4.3
(83.02 4.3)b
—
a The concentration of the compound is 100 mol L–1
.
b The effective concentration ЕC50 (mol L–1) is given in parentheses.
c Under the experimental conditions, the corresponding activity was not observed.

Isoalantolactone—tryptamine conjugates
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 2, February, 2012
411
Stereochemistry of the new asymmetric center at the
C(11) carbon atom was determined from the data of 2D
1Нꢀ1Н COSY and 1Нꢀ1Н NOESY NMR experiments. The
main correlations in the NOESY spectrum of the alicyclic
fragment are presented in Fig. 1 for compound 4b as
an example. The intense crossꢀpeak between the Н(7)
(H 2.42, td, J1 = J2 = 6.16 Hz, J3 = 4.11 Hz) and Н(8)
protons (H 4.43) in the NOESY spectrum indicates that
the fiveꢀmembered lactone ring is cisꢀfused to the cycloꢀ
hexane ring. The NOESY spectrum exhibits the proꢀ
nounced crossꢀpeaks between the Н(8), Н(7), and Н(11)
protons, indicating ꢀorientation of the С(11)—С(13)
Ca2+
a
b
A
1.7
1.6
1.5
1.4
1.3
540 (arb. units)
S
A554—524 (arb. units)
Ca2+
4a
Ca2+
S
4a
–0.16
–0.18
–0.20
–0.22
–0.24
–0.26
Ca2+
1
2
3
4
5
1.2
1.1
1.0
3.5
7.0
10.5
14.0
17.5
21.0
t/min
3.5
7.0
10.5
14.0
17.5
21.0 t/min
A540 (arb. units)
5a
A554—524 (arb. units)
c
d
Ca2+
Ca2+
5a
1.7
–0.16
–0.18
–0.20
–0.22
–0.24
–0.26
S
S
Ca2+
Ca2+
1.6
1.5
1.4
1.3
1.2
1.1
1.0
3.5
7.0
10.5
14.0
17.5
21.0
t/min
3.5
7.0
10.5 14.0 17.5 21.0
t/min
Fig. 2. Effect of adducts 4a (a, b) and 5a (c, d) on the nonspecific permeability (a, c) and membrane potential (b, d) of mitochondria.
The moments of addition of the substrate (S), adducts, and calcium ions are shown by arrows. Concentrations of added adducts 4a and
5a: 0 (1), 1 (2), 10 (3), 50 (4), and 100 mol L–1 (5). Concentration of CaCl2: 6.25 nmol mL–1 (first addition) and 12.5 nmol mL–1
(second addition).

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Russ.Chem.Bull., Int.Ed., Vol. 61, No. 2, February, 2012
Klochkov et al.
bond in the addition product of tryptamine to the lactone
molecule. This stereoconfiguration is also confirmed by
the NOE correlation in the spectrum between the ꢀН(5)
proton (H 1.73, br.d, J = 12.32 Hz), axial Н(6) proton,
and ꢀproton at C(11).
The effect of the starting compounds 1, 2, and 3a and
obtained products 4a—c,e,g—j and 5a on the peroxide
oxidation of lipids (POL) of the rat brain homogenate
initiated by the Fe3+ ion or tertꢀbutyl hydroperoxide
(tBHP) was also studied (Table 1).
duct 4а. In the series of tryptamine derivatives of isoalanꢀ
tolactone, the suppression of calciumꢀinduced "swelling"
of mitochondria was observed only for compound 5a (see
Fig. 2, c). The data obtained suggest that the further
search for compounds increasing stability of mitoꢀ
chondria to the induction of nonspecific permeability of
mitochondria in the series of the tryptamine adducts of
epoxy isoalantolactone and isoalantolactone (to a less
extent) can reveal leader compounds, potential neuroꢀ
protectors.
The starting unsaturated ꢀlactones, viz., isoalantoꢀ
lactone (1) and its epoxidated derivative 2, exhibit no anꢀ
tioxidant activity; moreover, isoalantolactone and epoxy
isoalantolactone enhance the intensity of the Fe3+ꢀinduced
POL, i.e., they are prooxidants. Tryptamine 3а does not
exert antioxidant activity under our experimental condiꢀ
tions. It has earlier been shown12 that tryptamine 3a does
not almost exhibit antioxidant activity: it is active only in
millimolar concentrations (IC50 = 0.84 mmol L–1). The
more unexpected is the fact that the studied tryptamine
adducts 4 and 5 efficiently suppress the Fe3+ꢀinduced POL
(see Table 1), and for compounds 4c,e,g—i the activity is
comparable with that of the known antioxidant ionol.13
All adducts are chelating agents for the iron ion, although
no direct correlation is observed between the antioxidant
activity and ability to bind Fe2+ ions. The tryptamine deꢀ
rivatives of lactones are considerably less active towards
the tBHPꢀinduced POL. The antioxidant effect was reꢀ
vealed only for adducts 4c,e,g—i (as well as for unsubstiꢀ
Thus, the obtained tryptamine derivatives of isoalantoꢀ
lactones are interesting as efficient antioxidants, chelating
agents for the iron ion, and mitoprotectors. The use of
these compounds seems promising for the development of
novel neuroprotectors and, possibly, cytoprotectors of
a wide range of effect.
Experimental
Highꢀresolution mass spectra were recorded on a Thermo
Fisher Exactive mass spectrometer with an ORBITRAP mass
analyzer, the orthogonal ion injection, and an electrospray
ionization. Solutions of the starting compounds in acetonitrile
with the concentration 10–5 mol L–1 were taken for ionization,
and the obtained values of m/z corresponded to the peak of the
protonated molecular ion. Specific rotation was measured
on a Model 341 polarimeter (Perkin—Elmer), the values of rotaꢀ
tion were expressed in deg mL g–1 dm–1, and the solution conꢀ
centrations were expressed in g (100 mL)–1. IR spectra were
recorded on a Bruker ZFSꢀ113 instrument in KBr pellets. The
1Н NMR spectra of compounds 4c—j were measured on a Bruker
DPX 200 (200.13 MHz) instrument and those of compound 4b were
obtained on a Bruker AVANCE III instrument (500.13 MHz) in
CDCl3, the signals are given in the  scale relative to the signal
from the residual protons of the solvent ( 7.25). The 1Hꢀ1H
COSY and 1Hꢀ1H NOESY experiments were carried out on
a Bruker AVANCE III instrument (500.13 MHz).
The reaction course and purity of the synthesized compounds
were monitored by TLC on the Silufol UVꢀ254 plates (eluent
benzene—ethyl acetate, 3 : 2) and GLC (chromatograph Chrom 5,
column 3600×3 mm packed with Inerton Super 0.125—0.160 mm
with 5% ХЕꢀ60, flameꢀionization detector, detector and evapoꢀ
rator temperature 250 С, temperatureꢀprogrammed thermoꢀ
stat from 75 to 225 С). Individual components were isolated by
semipreparative HPLC (chromatograph Turbo LC 200 (Perꢀ
kin—Elmer), UV detection ( = 254 nm); analytical column
4×100 mm with Kromasil C18 (5 m); preparative column
10×250 mm with Kromasil C18 (5 m)); gradient elution was used
(eluent A: 0.1% trifluoroacetic acid in distilled water (pH 2.0),
eluent B: acetonitrile) with the elution rate 1 and 4 mL min–1 for
the analytical and preparative columns, respectively.
tuted tryptamine 3a) in the concentration 100 mol L–1
.
These compounds also exert antiradical activity in the tests
with the model stable radical diphenylpicrylhydrazyl
(DPPH).
The study of the effect of the synthesized tryptamine
adducts on the functional characteristics of mitochondria
(Fig. 2) revealed that epoxy isoalantolactone 2 and its
derivatives exerted no effect on the membrane potential of
mitochondria, whereas isoalantolactone 1 and its tryptꢀ
amine adducts induce the doseꢀdependent depolarization
of mitochondria and, correspondingly, prevent the potenꢀ
tialꢀdependent incorporation of calcium ions into mitoꢀ
chondria. Evidently, it is this phenomenon that is responꢀ
sible for the suppression of mitochondria "swelling" in the
presence of isoalantolactone or its tryptamine adducts
upon the addition of calcium ions to a suspension of mitoꢀ
chondria, which is a characteristic of the appearance of
nonspecific permeability of mitochondria. The typical
curves showing the effect of compounds 4a and 5a on
the membrane potential of mitochondria are presented in
Figs 2, b and d; other adducts 4 and 5 have similar depenꢀ
dences. The suppression of "swelling" of mitochondria
upon the addition of exogenic calcium in the presence of
isoalantolactone and its analogs, which correlates with
a decrease in the potential of mitochondria, does not qualꢀ
itatively differ from that presented in Fig. 2, a for adꢀ
Reagents from Aldrich, freshly distilled solvents, and pureꢀ
grade reagents were used. Isoalantolactone 1 was isolated
from roots of Inula helenium L. (family Asteraceae); separaꢀ
tion was carried out on a column impregnated with silver nitrate
as described,5 and the purity of compounds was monitored
by GLC.
Reaction of (epoxy)isoalantolactone with tryptamines (general
procedure). A mixture of lactone 1 or 2 (1 mmol) and the correꢀ

Isoalantolactone—tryptamine conjugates
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 2, February, 2012
413
sponding tryptamine 3 (1.1 mmol) was dissolved in methanol
with stirring, and the mixture was kept at ambient temperature.
After completion of the reaction (TLC monitoring), the solvent
was evaporated in vacuo, the residue was dissolved in acetoꢀ
nitrile and purified by HPLC. Compounds 4a and 5a,b have
been described earlier.11
(11R)ꢀ13ꢀ(5ꢀButyltryptamino)ꢀ11,13ꢀdihydroisoalantoꢀ
lactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(5ꢀnꢀbutylꢀ1Hꢀindolꢀ3ꢀ
yl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylidenedecahydronaphꢀ
tho[2,3ꢀb]furanꢀ2ꢀone) (4e). The yield was 96%, m.p. 89 С,
[]D20 +65 (c 0.1; CHCl3). MS (ESI), m/z: 449.3167 [М + H]+,
calculated for С29H40N2O2, [М + H]+, m/z: 449.3163. IR,
1
(11R)ꢀ13ꢀ(5ꢀMethoxytryptamino)ꢀ11,13ꢀdihydroisoalantoꢀ
lactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(5ꢀmethoxyꢀ1Hꢀindolꢀ3ꢀ
yl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylidenedecahydronaphꢀ
tho[2,3ꢀb]furanꢀ2ꢀone) (4b). The physicochemical characterisꢀ
/cm–1: 1762 (OC=O), 3480 (NH). Н NMR, : 0.73 (s, 3 H,
Н(15)); 0.89 (t, 3 H, (CH2)3CH3, J = 7.0 Hz); 0.98—1.47
(m, 7 H, Н(1), Н(2), Н(6), Нa(9)); 1.47—1.74 (m, 5 H, Н(5),
CH2(CH2)2CH3); 1.97—2.01 (m, 2 H, H(3)); 2.08 (dd, 1 H,
Нb(9), J1 = 1.2 Hz, J2 = 16.0 Hz); 2.26 (m, 1 H, H(7)); 2.28
(br.d, 2 H, H(13), J = 11.0 Hz); 2.70 (dt, 2 H, CH2(CH2)2Me,
J1 = 7.6 Hz, J2 = 14.9 Hz); 2.89 (t, 2 H, NСH2СH2, J = 6.1 Hz);
3.00 (t, 2 H, NСH2CH2, J = 6.1 Hz); 3.09 (dd, 1 H, H(11),
J1 = 5.3 Hz, J2 = 11.0 Hz); 4.36 (d, 1 Н, Нa(14), J = 1.4 Hz);
4.40 (m, 1 Н, Н(8)); 4.71 (d, 1 Н, Нb(14), J = 1.4 Hz); 6.95
(br.s, 1 H, H(4´)); 6.97 (d, 1 H, H(6´), J = 6.5 Hz); 7.19
(d, 1 H, H(7´), J = 6.5 Hz); 7.35 (s, 1 Н, Н(2´)); 8.06 (br.s,
1 H, NH).
(11R)ꢀ13ꢀ(7ꢀTrifluoromethylꢀ2ꢀmethyltryptamino)ꢀ11,13ꢀ
dihydroisoalantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(7ꢀtriꢀ
fluoromethylꢀ2ꢀmethylꢀ1Hꢀindolꢀ3ꢀyl)ethylamino]methyl}ꢀ8aꢀ
methylꢀ5ꢀmethylidenedecahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4f).
The yield was 39%, m.p. 85—86 С, []D20 +27 (c 0.1; CHCl3).
MS (ESI), m/z: 475.2571 [М + H]+, calculated for С27H33F3N2O2,
[М + H]+, m/z: 475.2567. IR, /cm–1: 1090 (CF), 1762 (OC=O),
3471 (NH). 1Н NMR, : 0.76 (s, 3 H, Н(15)); 1.12—1.31 (m, 2 H,
Н(2)); 1.34—1.88 (m, 7 H, Н(1), Н(3), Н(6), Нa(9)); 2.02
(m, 1 H, Н(5)); 2.12 (dd, 1 H, Нb(9), J1 = 2.2 Hz, J2 = 14.7 Hz);
2.37 (m, 1 H, H(7)); 2.42 (s, 3 H, С(2´)Me); 2.67—2.91 (m, 2 H,
H(13)); 2.84 (t, 2 H, NСH2СH2, J = 5.7 Hz); 2.98 (t, 2 H,
NСH2CH2, J = 5.7 Hz); 3.04 (m, 1 H, H(11)); 4.37 (d, 1 Н,
Нa(14), J = 1.3 Hz); 4.42 (m, 1 Н, Н(8)); 4.73 (d, 1 Н, Нb(14),
J = 1.3 Hz); 7.10 (t, 1 Н, H(5´), J = 7.4 Hz); 7.33 (d, 1 H,
Н(6´), J = 7.4 Hz); 7.65 (d, 1 Н, Н(4´), J = 7.4 Hz); 8.21 (br.s,
1 H, NH).
1
tics of the compound are given in Ref. 11. Н NMR, : 0.77
(s, 3 H, Н(15)); 1.18 (m, 1 Н, Нa(6)); 1.24 (m, 1 Н, Нa(1)); 1.44
(dd, 1Н, Нa(9), J1 = 15.55 Hz, J2 = 4.40 Hz); 1.47—1.55 (m, 2 H,
Н(2)); 1.58 (m, 2 Н, Нb(1), Нb(6)); 1.73 (br.d, 1 H, Н(5),
J = 12.32 Hz); 1.98 (m, 1 H, Нa(3)); 2.15 (dd, 1 Н, Нb(9), J1 =
= 15.55 Hz, J2 = 2.05 Hz); 2.34 (dddd, 1 Н, Н(11), J1 = 2.35 Hz,
J2 = 4.11 Hz, J3 = 6.16 Hz, J4 = 12.73 Hz); 2.42 (td, 1 Н, Н(7),
J1 = J2 = 6.16 Hz, J3 = 4.11 Hz); 2.83 (dd, 1 H, Нa(13), J1 =
= 11.74 Hz, J2 = 7.34 Hz); 2.92 (q, 1 Н, Нb(3), J1 = J2 = J3 =
= 6.75 Hz); 2.98 (q, 2 Н, NCH2CH2, J1 = J2 = J3 = 2.93 Hz);
3.0—3.05 (m, 2 Н, NHCH2CH2); 3.08 (dd, 1 Н, Нb(13),
J1 = 11.74 Hz, J2 = 7.04 Hz); 3.87 (s, 3 Н, OMe); 4.40 (d, 1 Н,
Нa(14), J = 1.17 Hz); 4.43 (m, 1 Н, Н(8)); 4.73 (d, 1 Н, Нb(14),
J = 1.47 Hz); 6.86 (dd, 1 Н, Н(6´), J1 = 8.51 Hz, J2 = 2.35 Hz);
7.05 (s, 1 Н, Н(2´), 7.06 (s, 1 H, Н(4´)); 7.25 (d, 1 Н, Н(7´),
J = 8.80 Hz); 7.95 (br.s, 1 Н, NH).
(11R)ꢀ13ꢀ(5ꢀBenzyloxyꢀ2ꢀmethyltryptamino)ꢀ11,13ꢀdihydroꢀ
isoalantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(5ꢀbenzyloxyꢀ2ꢀ
methylꢀ1Hꢀindolꢀ3ꢀyl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylꢀ
idenedecahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4с). The yield was
46%, m.p. 102—104 С, []D20 +32 (c 0.1; CHCl3). MS (ESI),
m/z: 513.3117 [М + H]+; calculated for С33H40N2O3, [М + H]+,
m/z: 513.3112. IR, /cm–1: 1762 (OC=O), 3471 (NH). 1Н NMR,
: 0.77 (s, 3 H, Н(15)); 1.19—1.31 (m, 2 H, Н(2)); 1.44—1.88
(m, 7 H, Н(1), Н(3), Н(6), Нa(9)); 1.84—2.06 (m, 1 H, Н(5));
2.17 (dd, 1 H, Нb(9), J1 = 1.5 Hz, J2 = 15.5 Hz); 2.41 (s, 3 H,
С(2´)Me); 2.56—2.75 (m, 3 Н, Н(7), H(13)); 2.81 (t, 2 H,
NСH2СH2, J = 7.4 Hz); 2.91 (t, 2 H, NСH2СH2, J = 7.4 Hz);
3.09 (dt, 1 H, H(11), J1 = 5.5 Hz, J2 = 10.9 Hz); 4.44 (d, 1 Н,
Нa(14), J = 1.4 Hz); 4.50 (m, 1 Н, Н(8)); 4.80 (d, 1 Н, Нb(14),
J = 1.4 Hz); 5.14 (br.s, 2 H, ОСH2); 6.88 (dd, 1 H, H(6´),
J1 = 1.9 Hz, J2 = 8.4 Hz); 7.12 (d, 1 H, H(4´), J = 1.9 Hz); 7.19
(d, 1 H, H(7´), J = 8.4 Hz); 7.26—7.61 (m, 5 H, Ar); 7.82 (br.s,
1 H, NH).
(11R)ꢀ13ꢀ(5ꢀMethoxyꢀ2ꢀmethyltryptamino)ꢀ11,13ꢀdihydroꢀ
isoalantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(2ꢀmethylꢀ5ꢀ
methoxyꢀ1Hꢀindolꢀ3ꢀyl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethꢀ
ylidenedecahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4d). The yield was
76%, m.p. 111—112 С, []D20 +75 (c 0.1; CHCl3). MS (ESI),
m/z: 437.2779 [М + H]+, calculated for С27H36N2O3, [М + H]+,
m/z: 437.2799. IR, /cm–1: 1762 (OC=O), 3470 (NH). 1Н NMR,
: 0.73 (s, 3 H, Н(15)); 1.19—1.31 (m, 2 H, Н(2)); 1.44—1.88
(m, 7 H, Н(1), Н(3), Н(6), Нa(9)); 1.84—2.06 (m, 1 H, Н(5));
2.08 (dd, 1 H, Нb(9), J1 = 2.1 Hz, J2 = 15.3 Hz); 2.66—2.75
(m, 3 Н, Н(7), H(13)); 2.32 (s, 3 H, С(2´)Me); 2.84 (t, 2 H,
NСH2СH2, J = 6.5 Hz); 2.98 (m, 1 H, H(11)); 3.02 (t, 2 H,
NСH2СH2, J = 6.5 Hz); 3.79 (s, 3 H, OMe); 4.34 (d, 1 Н,
Нa(14), J = 1.4 Hz); 4.38 (m, 1 Н, Н(8)); 4.70 (d, 1 Н, Нb(14),
J = 1.4 Hz); 6.70 (dd, 1 Н, H(6´), J1 = 2.3 Hz, J2 = 8.6 Hz); 6.92
(d, 1 H, Н(4´), J = 2.1 Hz); 7.08 (d, 1 Н, Н(7´), J = 8.6 Hz);
7.68 (br.s, 1 H, NH).
(11R)ꢀ13ꢀ(2ꢀMethyltryptamino)ꢀ11,13ꢀdihydroisoalantoꢀ
lactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(2ꢀmethylꢀ1Hꢀindolꢀ3ꢀ
yl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylidenedecahydronaphꢀ
tho[2,3ꢀb]furanꢀ2ꢀone) (4g). The yield was 83%, m.p. 83—85 С,
[]D20 +98 (c 0.1; CHCl3). MS (ESI), m/z: 407.2697 [М + H]+,
calculated for С26H34N2O2, [М + H]+, m/z: 407.2693. IR,
1
/cm–1: 1760 (OC=O), 3480 (NH). Н NMR, : 0.81 (s, 3 H,
Н(15)); 1.05—1.35 (m, 2 H, Н(2)); 1.34—1.87 (m, 7 H, Н(1),
Н(3), Н(6), Нa(9)); 2.00 (m, 1 H, Н(5)); 2.12 (d, 1 H, Нb(9),
J = 15.5 Hz); 2.25—2.39 (m, 3 Н, Н(7), H(13)); 2.41 (s, 3 H,
С(2´)Me); 2.89 (t, 2 H, NСH2СH2, J = 6.1 Hz); 2.98 (t, 2 H,
NСH2CH2, J = 6.1 Hz); 3.09 (dd, 1 H, H(11), J1 = 2.7 Hz,
J2 = 10.0 Hz); 4.44 (d, 1 Н, Нa(14), J = 1.4 Hz); 4.49 (m,
1 Н, Н(8)); 4.80 (d, 1 Н, Нb(14), J = 1.4 Hz); 7.12 (dt,
2 Н, H(5´), H(6´), J1 = 7.6 Hz, J2 = 10.2 Hz); 7.28 (d, 1 H,
Н(7´), J = 7.6 Hz); 7.54 (d, 1 Н, Н(4´), J = 7.6 Hz); 8.14 (br.s,
1 H, NH).
(11R)ꢀ13ꢀ[5ꢀ(Butꢀ2ꢀyl)ꢀ2ꢀmethyltryptamino]ꢀ11,13ꢀdihydroꢀ
isoalantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{2ꢀ[5ꢀ(butꢀ2ꢀyl)ꢀ2ꢀ
methylꢀ1Hꢀindolꢀ3ꢀyl)ethylamino)ꢀ8aꢀmethylꢀ5ꢀmethylideneꢀ
decahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4h). The yield was 83%,
20
m.p. 83—85 С, []D +38 (c 0.1; CHCl3). MS (ESI), m/z:
463.3325 [М + H]+; calculated for С30H42N2O2, [М + H]+,
m/z: 463.3319. IR, /cm–1: 1761 (OC=O), 3470 (NH). 1Н NMR,
: 0.73 (s, 3 H, Н(15)); 0.78 (t, 3 H, CH2CH3, J = 7.2 Hz); 1.22

414
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 2, February, 2012
Klochkov et al.
(d, 3 H, СHCH3, J = 6.8 Hz); 1.27—1.98 (m, 10 H, Н(1), Н(2),
Н(3), Н(5), Н(6), Нa(9)); 1.61 (dq, 2 H, СНCH2CH3, J1 = 7.2 Hz,
J2 = 14.5 Hz); 2.07 (dd, 1 H, Нb(9), J1 = 2.1 Hz, J2 = 7.5 Hz);
2.25 (m, 1 H, H(7)); 2.32 (s, 3 H, С(2´)Me); 2.60 (dd, 1 H,
СHMe, J1 = 6.8 Hz, J2 = 12.9 Hz); 2.62—2.75 (m, 2 Н, H(13));
2.83 (t, 2 H, NСH2СH2, J = 7.2 Hz); 2.89 (t, 2 H, NСH2CH2,
J = 7.2 Hz); 3.00 (m, H(11), 1 H); 4.34 (d, 1 Н, Нa(14),
J = 1.4 Hz); 4.41 (m, 1 Н, Н(8)); 4.70 (d, 1 Н, Нb(14), J = 1.4 Hz);
6.89 (d, 1 H, H(6´), J = 4.0 Hz); 7.12 (d, 1 H, H(7´), J = 4.0 Hz);
7.24 (s, 1 Н, Н(4´)); 7.68 (br.s, 1 H, NH).
firmed by the UV spectra of ferrozine in the pure form and in the preꢀ
sence of the studied substance recorded in the 300—800 nm range.
Radicalꢀbinding activity of compounds 4 and 5 were deterꢀ
mined using the model stable radical diphenylpicrylhydrazyl
(DPPH) by a known procedure.17
Effect of compounds 4 and 5 on the functional characteristics
of mitochondria. Rat brain mitochondria were isolated by a stanꢀ
dard method of differential centrifugation. The effect of comꢀ
pounds 4 and 5 on the functional characteristics of mitochondria
were examined by two parameters: a change in the membrane
potential and calciumꢀinduced "swelling" of mitochondria caused
by a change in the mitochondrial shape due to opening of special
pores of nonspecific permeability. Mitochondrial "swelling" was
measured as a decrease in the absorbance (A540) of a suspension
of mitochondria after the addition of calcium ions (Fig. 2, a, c).
The membrane potential of mitochondria was measured with
the potentialꢀdependent indicator safranine18 (Fig. 2, b, d) in
the presence of the inhibitor of complex I in the respiratory
chain of rotenone mitochondria (1 mol L–1) after the addition
of the substrate of complex II succinate (0.5 mmol L–1). The
opening of special mitochondrial pores was induced by to sucꢀ
cessive additions of calcium ions: 6.25 and 12.5 nmol mL–1
CaCl2.
(11R)ꢀ13ꢀ(5ꢀChloroꢀ2ꢀmethyltryptamino)ꢀ11,13ꢀdihydroꢀ
isoalantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(5ꢀchloroꢀ2ꢀmeꢀ
thylꢀ1Hꢀindolꢀ3ꢀyl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylꢀ
idenedecahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4i). The yield was
20
64%, m.p. 95—96 С, []D +53 (c 0.1; CHCl3). MS (ESI),
m/z: 441.2312 [М + H]+; calculated for С26H33ClN2O2,
[М + H]+, m/z: 441.2303. IR, /cm–1: 850 (ССl), 1762 (OC=O),
3472 (NH). 1Н NMR, : 0.81 (s, 3 H, Н(15)); 1.10—1.32 (m, 2 H,
Н(2)); 1.37—1.89 (m, 7 H, Н(1), Н(3), Н(6), Нa(9)); 1.84—2.06
(m, 1 H, Н(5)); 2.17 (d, 1 H, Нb(9), J = 16.0 Hz); 2.40 (s, 3 H,
С(2´)Me); 2.66—2.75 (m, 3 Н, Н(7), H(13)); 2.83 (t, 2 H,
NСH2СH2, J = 6.4 Hz); 2.94 (m, 1 H, H(11)); 3.05 (t, 2 H,
NСH2CH2, J = 6.4 Hz); 4.44 (d, 1 Н, Нa(14), J = 1.3 Hz); 4.48
(m, 1 Н, Н(8)); 4.79 (d, 1 Н, Нb(14), J = 1.32 Hz); 7.07 (d, 1 Н,
H(6´), J = 8.4 Hz); 7.18 (d, 1 Н, Н(7´), J = 8.4 Hz); 7.49 (br.s,
1 H, H(4´)), 8.16 (br.s, 1 H, NH).
The statistical processing of the results was performed using
the Excelꢀ5 statistical program package.
This work was financially supported by the Presidium
of the Russian Academy of Sciences (Program for Basic
Research "Fundamental Sciences for Medicine").
(11R)ꢀ13ꢀ(2,5,7ꢀTrimethyltryptamino)ꢀ11,13ꢀdihydroisoꢀ
alantolactone ((3R,3aR,4aR,8aR,9aR)ꢀ3ꢀ{[2ꢀ(2,5,7ꢀtrimethylꢀ
1Hꢀindolꢀ3ꢀyl)ethylamino]methyl}ꢀ8aꢀmethylꢀ5ꢀmethylideneꢀ
decahydronaphtho[2,3ꢀb]furanꢀ2ꢀone) (4j). The yield was 70%,
m.p. 138—140 С, []D20 +110 (c 0.1; CHCl3). MS (ESI), m/z:
435.3021 [М + H]+; calculated for С28H38N2O2, [М + H]+,
m/z: 435.3006. IR, /cm–1: 1762 (OC=O), 3475 (NH). 1Н NMR,
: 0.76 (s, 3 H, Н(15)); 1.19—1.31 (m, 2 H, Н(2)); 1.34—1.92
(m, 7 H, Н(1), Н(3), Н(6), Нa(9)); 1.94—2.06 (m, 1 H, Н(5));
2.11 (dd, 1 H, Нb(9), J1 = 1.5 Hz, J2 = 14.5 Hz); 2.38 (s, 9 H,
С(2´)Me, С(5´)Me, С(7´)Me); 2.82 (t, 2 H, NСH2СH2,
J = 6.0 Hz); 2.83—2.90 (m, 3 Н, Н(7), H(13)); 2.94 (t, 2 H,
NСH2CH2, J = 6.0 Hz); 3.04 (dd, 1 H, H(11), J1 = 5.3 Hz,
J2 = 10.4 Hz); 4.37 (d, 1 Н, Нa(14), J = 1.3 Hz); 4.43 (m, 1 Н, Н(8));
4.74 (d, 1 Н, Нb(14), J = 1.3 Hz); 6.73 (br.s, 1 H, H(6´)); 7.13
(br.s, 1 H, H(4´)); 7.65 (br.s, 1 H, NH).
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in revised form October 14, 2011