Regioselective synthesis and antimicrobial screening of novel ketocarbazolodispiropyrrolidine derivatives

Article abstract of DOI:10.1016/j.ejmech.2008.07.009

A series of novel dispiropyrrolidine derivatives have been synthesized through 1,3-dipolar cycloaddition reaction of azomethine ylide generated from sarcosin and di/tri ketone with the dipolarophile (E)-2-arylidine-1-keto-carbazoles. The cycloadducts keto

Full text of DOI:10.1016/j.ejmech.2008.07.009

European Journal of Medicinal Chemistry 44 (2009) 959–966
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European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Regioselective synthesis and antimicrobial screening of novel
ketocarbazolodispiropyrrolidine derivatives
,
b
Govindasami Periyasami a, Raghavachary Raghunathan a , Gangadharan Surendiran ,
*
Narayanasamy Mathivanan b
a Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu, India
b Center for Advanced Studies in Botany, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel dispiropyrrolidine derivatives have been synthesized through 1,3-dipolar cycloaddition
reaction of azomethine ylide generated from sarcosin and di/tri ketone with the dipolarophile
(E)-2-arylidine-1-keto-carbazoles.
The cycloadducts ketocarbazalo spiro N-methyl pyrrolidines showed the most interesting antimicrobial
activity at lower concentration.
Received 22 April 2008
Received in revised form 10 July 2008
Accepted 10 July 2008
Available online 18 July 2008
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords:
Keto-carbazole
Azomethine ylides
Cycloaddition
Dispiropyrrolidine
Bioactivity
1. Introduction
containing spiro ring systems [10]. Of particular interest, spi-
ropyrrolidinyloxindole ring systems are also found in a number of
Highly substituted pyrrolidines have gained much prominence
since they form the central skeleton of many natural products [1].
Generally, pyrrolidine derivatives adopt conformation of the
incipient oxocarbenium cation postulated as the transition state of
enzymatic glycoside hydrolysis and moreover, substituted poly-
hydroxylated pyrrolidine and piperidine alkaloids are one of the
most widespread secondary metabolite sugar mimics [2]. Plants in
the Hyacinthaceae are rich source of glycosidase inhibitors with
structural diversity, such as pyrrolidine, pyrrolizidine, piperidine
and their glycosides, which are receiving considerable attention
as potential therapeutic agents [3–5]. Furthermore, oral treat-
ment of lysosomal storage diseases with specific glycosidase and
glycosyl transfer inhibitors is attracting great interest [6,7]. Spiro
compounds represent an important class of naturally occurring
substances characterized by highly pronounced biological proper-
ties [8]. Natural product isopteropodine 1 (Fig. 1) has been shown
to modulate the function of muscarinic and serotonin receptors
while some of the synthetic compounds containing spirooxindole
as the core structure have potent non-peptide inhibitor of p53-
MDM2 interaction [9]. Gelsemine, pseudotabersonime, formosanine,
isoformosanine and mitraphylline are some of the alkaloids
alkaloids like elacomine, spirotryprostatins A and B, etc. Hence,
there has been renewed interest in the synthesis of such interesting
compounds.
Carbazole derivatives are known for their pharmacological
activities [11]. Carbomycines A and B have been found to be useful
as antibacterial and antifungal agents [12,13]. It has been reported
that pyridocarbazoles show marked anticancer and anti-HIV
activities [14–16]. One of the most important naturally occurring
alkaloid ellipticine and its isomer olivacine which are derived from
carbazole show antineoplastic activity [17]. Moreover, the deriva-
tives of carbazoles were able to intercalate with DNA [18] and it
was found to possess antileukemic activity [19]. In this context
of general interest, we describe here the synthesis of ketocarba-
zolodispiropyrrolidine derivatives by 1,3-dipolar cycloaddition of
azomethine ylides with substituted 2-arylbenzylidine-1,2,3,4-tet-
rahydro-1-keto-carbazoles as dipolarophile. We have screened
these compounds for antibacterial activity.
2. Results and discussion
2.1. Chemistry
The required dipolarophiles (E)-2-arylidene-1-keto-carbazoles
were prepared by the reaction of 1-keto-carbazole [20] (Scheme 1)
* Corresponding author. Tel.: þ91 4422202811; fax: þ91 4422300488.
E-mail address: ragharaghunathan@yahoo.com (R. Raghunathan).
0223-5234/$ – see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.07.009

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G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
Me
moderate yield of dispiro adducts 14a–f. (43–57%, Method A)
(Scheme 4).
H
N
O
As observed in the earlier case, the regio- and stereochemistry of
H
H
the cycloadducts were confirmed primarily by 1H NMR spectrum.
The compound 14b showed a triplet for the benzylic proton at
O
d
5.01 and the methylene proton of pyrrolidine ring showed
N
H
O
OMe
a doublet at
d
2.52 (J ¼ 14.0 Hz). The 13C NMR spectrum of 14b
1
exhibited two peaks at d 183.5 and 190.3 ppm for carbonyl carbons
for oxindole and keto-carbazole ring systems. Finally, the molecular
weight of compound 14b was also confirmed by a peak at m/z 461.5
(Mþ) in mass spectrum and the elemental analysis also showed
satisfactory results. The coupling constant (J value) of the benzylic
proton will remain the same irrespective of the stereochemistry of
the phenyl group as the proton is positioned adjacent to two
methylene protons.
We have carried out the above reactions under three different
conditions. (1) Refluxing in methanol (Method A). (2) Reacting in
microwave irradiation (600 W) with K-10 Montimorillonite clay
(Method B). (3) Reacting under microwave irradiation under neat
condition (Method C). Methods B and C were found to give better
yield of the products compared to Method A as shown in Tables 1, 2
and 3.
Isopeteropodine
Fig. 1. Representation of spiro compound.
with various substituted benzaldehydes and the geometry of
dipoloraphiles was assigned by using spectroscopic analysis. The
reaction of non-stabilized azomethine ylide (generated in situ from
decarboxylative condensation of triketone, ninhydrin 7 and sarco-
sine 6) with the dipolarophiles 5a–f in refluxing dioxane and
methanol (1:1) furnished dispiropyrrolidines 8a–f in moderate
yields (46–58% Method A, Scheme 2).
The structures of the products were confirmed on the basis of
their spectral and elemental analyses. In particular, the regio-
chemistry proposed for the product 8c was decided on the basis of
its 1H NMR spectrum exhibiting a triplet at
d 4.87 for the benzylic
2.1.1. Pharmacological studies
proton. If other isomer 9c was formed, one would expect a singlet
We have subjected all the synthesized compounds for bioac-
tivity studies against microorganisms and the results are shown
below.
The bioactivity studies were carried out against bacteria, Proteus
vulgaris; Proteus mirabilis; Staphylococcus aureus; and Salmonella
typhi, which were obtained from Microbial Metabolite Lab Culture
collection, University of Madras, Chennai.
instead of a triplet. The methylene protons of pyrrolidine ring
showed a doublet at
8c showed two peaks at
d
2.48 (J ¼ 14.5 Hz). The 13C NMR spectrum of
d
60.9 and 80.9 ppm reflecting the pres-
ence of two spiro carbons, the keto-carbazole and indanedione
carbonyl carbons exhibited peaks at 187.7, 199.6 and 200.9 ppm,
d
respectively. The mass spectrum of the compound showed a
molecular ion peak at m/z 490.5 (Mþ), which further confirmed the
formation of cycloadduct. Identical results were furnished by other
compounds with identical stereochemistry. The structure of 8d was
established by X-ray (Fig. 2) single crystal analysis [21], which also
proved the regiochemistry of cycloadduct.
2.1.2. Antimicrobial activity of dispiropyrrolidines (agar diffusion
assay)
The agar diffusion method [23] was used for the determination
of antibacterial activity of novel dispiropyrrolidines against
microorganism listed above. About 9 ml of nutrient agar media
were poured into petri plates (9 cm in diameter) and inoculated
with respective test organism. Wells are made with cork borer on
To enhance the scope of the above methodology, we reacted the
same dipolarophiles with azomethine ylide generated from the
diketone, acenathenequinone 10 and sarcosine 6. The reaction
yielded novel dispiropyrrolidine derivatives 11a–f in moderate
yield (43–60%) (Method A) via one pot three component reactions
the solid agar and loaded with 25–100
mg/ml of the test compound
with tetracycline as control. Petri dishes were incubated at 37 ꢀC for
24 h and the average diameter of the inhibition zone surrounding
the wells was measured after specified incubation period.
(Scheme 3). The 1H NMR spectrum of 11a showed a triplet at
d 5.18
for benzylic proton, which confirmed the regiochemistry of the
cycloadduct. The methylene protons of pyrrolidine ring showed as
The antibacterial activity of the carbazole derived compound
against human bacterial pathogens as determined by agar diffusion
method with tetracycline as reference control is presented in the
table. The maximum antimicrobial activity and inhibition zone
were observed for compounds derived from acenapthenequinone
(11d and f) followed by oxindole derivative (14d). The ninhydrin
derived compounds showed less activity (8c). All the compounds
showed good inhibitory activity in higher concentrations against
nearly all the test pathogens except 8d and b, which are void of
antimicrobial activity against S. aureus even in higher concentra-
tion. The acenapthenequinone derived compounds and isatin
derived compounds showed excellent activity against all the
a doublet at
regiochemistry of compound 11a. The 13C NMR spectrum showed
two peaks at 192.1 and 207.4 ppm for carbonyl carbons of keto-
d
2.34 (J ¼ 14.6 Hz). These results again confirm the
d
carbazole and acenapthenenone ring systems. The mass spectrum
of the product 11a showed a molecular ion peak at m/z 482 (Mþ)
and elemental analysis was also found to be satisfactory. The
structure of the adduct 11a was established by X-ray (Fig. 3) single
crystal analysis [22].
In the next series of experiments, we have examined the reac-
tions of the same dipolarophile with nonstablized azomethine ylide
generated from sarcosine 6 with diketone, isatin 13 which afforded
CHO
R
Ethanol / KOH
reflux
N
H
N
H
R
O
O
3
4a-f
5a-f
R = a) H, b) Me, c) OMe, d) Cl, e) Br, f) NO2
Scheme 1.

G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
961
O
O
O
CH3
CH2
OH
OH
CH3NHCH2COOH
N
R
O
7
6
N
H
O
5a-f
R
R
HN
HN
O
H
H
O
O
O
N
O
N
CH3
H3C
O
9a-f
8a-f
R = a) H, b) Me, c) OMe, d) Cl, e) Br, f) NO2
Scheme 2.
pathogens in low concentration, which is comparable to the
reference control. It was observed that all the antimicrobial activ-
ities of the present studied compounds are dose dependent. The
acenapthenequinone derived compounds 11d, f, a and b were
found to be effective in controlling all the test pathogens and very
effective in controlling P. vulgaris and P. mirabilis than the rest of the
compounds tested in the present study. The activity is very much
comparable to the reference control. Next to acenapthenequinone-
derived compounds, the isatin derived compounds 14d and c
exhibited good antimicrobial activity against P. vulgaris, P. mirabilis
and S. typhi which showed strong antimicrobial activity in higher
concentration. The ninihydrin derived compounds show less anti-
microbial activity, exhibits moderate antimicrobial activity against
P. vulgaris and P. mirabilis, and ineffective in controlling S. aureus
and S. typhi even in higher concentration. Further clinical studies
are required to validate the effective compounds of the present
study as an antimicrobial agent. The results are summarised in
Tables 4–7.
3. Conclusions
In conclusion, we have successfully synthesized a series of novel
dispiropyrrolidines and evaluated their structure–antimicrobial
activity relationship. The synthetic route involves 1,3-dipolar
cycloaddition reaction of azomethine ylide generated from di- and
tri ketones and sarcosine with (E)-2-aryledene-1-keto-carbazoles
as dipolarophiles. Among the various conditions employed, the
microwave irradiation method was found to be synthetically
useful in achieving high yields of the products with reduced
reaction time compared to conventional heating. Generally it was
found that all the synthetic spiropyrrolidines showed antimicro-
bial activity.
4. Experimental
4.1. General considerations
All melting points are uncorrected. IR spectra were recorded on
a SHIMADZU FT-IR 8300 instrument. 1H and 13C NMR spectra were
recorded in CDCl3 using TMS as an internal standard on JEOL
400 MHz, Mass spectra were recorded by JEOL-DX303 HF mass
spectrometer. Elemental analyses were carried out on a Perkin–
Elmer 2400B instrument.
Fig. 2. ORTEP diagram of 8d.

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G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
H2C
O
N
CH3
O
O
CH3NHCH2COOH
R
6
10
N
O
H
5a-f
R
R
H
HN
O
H
HN
O
N
O
CH3
N
O
H3C
12a-f
11a-f
R = a) H, b) Me, c) OMe, d) Cl, e) Br, f) NO2
Scheme 3.
4.2. General procedure for the synthesis of dispiro heterocylces
1-keto-carbazole (1 mmol) was ground with K-10 Montmorillonite
clay and irradiated under microwave conditions (600 W). After
completion of the reaction, the product was extracted with
dichloromethane and the organic layer was dried over MgSO4. The
solvent was then removed in vacuo and the crude product was
subjected to column chromatography using petroleum ether, ethyl
acetate mixture (8:2) as eluent.
Method C. A mixture of sarcosine 1 (1 mmol), ninhydrin 2/
acenapthenequionone 6/isatin 9 (1 mmol), and (E)-2-aryledene-
1-keto-carbazole (1 mmol) was ground and irradiated under
microwave conditions (600 W). After completion of the reaction,
the product was allowed to stand at room temperature until it gets
solidified and the crude product was subjected to column chro-
matography using petroleum ether, ethyl acetate mixture (8:2) as
eluent.
Method A. A mixture of sarcosine 1 (1 mmol), ninhydrin 2/ace-
napthenequionone 6/isatin 9 (1 mmol), and (E)-2-aryledene-1-
keto-carbazole was refluxed in dioxan:methanol (1:1). Completion
of the reaction was evidenced by TLC analysis. The solvent was
removed in vacuo and the crude product was subjected to column
chromatography using petroleum ether, ethyl acetate mixture (8:2)
as eluent.
Method B. A mixture of sarcosine 1 (1 mmol), ninhydrin 2/ace-
napthenequionone 6/isatin
9 (1 mmol), and (E)-2-aryledene-
4.2.1. 40-Phenyl-10-methyl-4,9-dihydrodispiro[carbazole-2,30-
pyrrolidine-20,200-indene]-1,100,300(3H)-trione (8a)
Pale yellow solid, mp 195–197 ꢀC; nmax (KBr) 1705, 1739,
3289 cmꢁ1
; dH (400 MHz, CDCl3) 1.73 (m, 2H, C(3)H2); 2.23 (s, 3H,
NCH3); 2.49 (d, 2H, J 19.5 Hz); 3.62 (t, 1H, C(4)H, J 9.32, 9.32 Hz);
3.84 (t, 1H, C(4)H, J 9.27, 9.28 Hz); 5.00 (t, 1H, benzylic H); 6.99–7.71
(m, 13H, ArH); 8.90 (s, 1H, NH). dC (100 MHz, CDCl3) 18.1, 27.9, 35.7,
46.4, 57.6, 61.1, 81.1, 112.4, 120.3, 121.2, 122.0, 122.7, 125.1, 127.0,
128.0, 128.4, 131.1, 131.4, 132.8, 135.6, 136.3, 140.9, .141.0, 188.0,
199.3, 200.7; EI-MS m/z 460.52 (Mþ); Anal. Calcd for C30H24N2O3: C,
78.24; H, 5.25; N, 6.08%. Found: C, 78.59; H, 5.51; N, 5.83%.
4.2.2. 40-(4-Methylphenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,200-indene]-
1,100,300(3H)-trione (8b)
Pale yellow solid, mp 208–210 ꢀC; nmax (KBr) 1704, 1740,
3285 cmꢁ1
; dH (400 MHz, CDCl3) 1.53 (m, 2H, C(3)H2); 2.16 (s, 3H,
NCH3); 2.30 (s, 3H, Ph-CH3); 2.51 (d, 2H, J 14.6 Hz); 3.56 (t, 1H,
C(4)H, J 9.19, 9.23 Hz); 3.79 (t, 1H, C(4)H, J 9.21, 9.23 Hz); 4.96 (t, 1H,
benzylic H); 7.01–7.86 (m, 12H, ArH); 8.92 (s, 1H, NH). dC (100 MHz,
CDCl3) 17.6, 26.9, 32.6, 34.7, 45.9, 58.2, 60.9, 80.9, 112.4, 120.3, 121.2,
Fig. 3. ORTEP diagram of 11a.

G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
963
O
O
CH3
CH3NHCH2COOH
O
N
N
H
N
H
CH2
R
13
1
N
H
5a-f
O
R
R
HN
H
HN
H
O
N
O
CH3
N
O
N
H
N
H3C
O
H
15a-f
14a-f
R = a) H, b) Me, c) OMe, d) Cl, e) Br, f) NO2
Scheme 4.
122.0,122.7,125.2, 128.1,129.0, 132.1,132.8,135.6,136.5,140.9, 141.1,
187.7, 199.1, 201.2; EI-MS m/z 474.1 (Mþ); Anal. Calcd for
C31H26N2O3: C, 78.46; H, 5.52; N, 5.90%. Found: C, 78.61; H, 5.72; N,
5.73%.
ArH); 8.90 (s, 1H, NH). dC (100 MHz, CDCl3) 18.6, 28.7, 35.7, 46.6,
57.6, 63.8, 81.1, 112.4, 120.4, 121.2, 122.1, 122.7, 125.1, 127.0, 128.4,
131.1, 131.4, 132.8, 135.6, 136.0, 136.4, 140.9, 141.2, 187.9, 199.4,
200.7; EI-MS m/z 494.97 (Mþ); Anal. Calcd for C30H23ClN2O3: C,
72.80; H, 4.68; N, 5.66%. Found: C, 72.69; H, 4.59; N, 5.79%.
4.2.3. 40-(4-Methoxyphenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,200-indene]-
1,100,300(3H)-trione (8c)
4.2.5. 40-(4-Bromophenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,200-indene]-
1,100,300(3H)-trione (8e)
Pale yellow solid, mp 212 ꢀC; nmax (KBr) 1705, 1739, 3283 cmꢁ1
;
dH (400 MHz, CDCl3) 1.51 (m, 2H, C(3)H2); 2.09 (s, 3H, NCH3); 2.48
(d, 2H, J 14.5 Hz); 3.49 (t, 1H, C(4)H, J 9.21, 9.23 Hz); 3.72 (t, 1H,
C(4)H, J 9.23, 9.25 Hz); 3.82 (s, 3H, OCH3) 4.87 (t, 1H, benzylic H);
6.92–7.761 (m, 12H, ArH); 8.61 (s, 1H, NH). dC (100 MHz, CDCl3) 17.6,
26.9, 32.6, 34.7, 45.9, 58.2, 60.9, 80.9, 112.4,120.3, 121.2, 122.0, 122.7,
125.2, 128.1, 129.0, 132.2, 132.7, 135.6, 136.5, 140.9, 141.1, 187.7, 199.6,
200.9; EI-MS m/z 490.5 (Mþ); Anal. Calcd for C31H26N2O4: C, 75.90;
H, 5.34; N, 5.71%. Found: C, 75.69; H, 5.42; N, 5.81%.
Yellow solid, mp 198 ꢀC; nmax (KBr) 1702, 1740, 3282 cmꢁ1
; dH
(400 MHz, CDCl3) 1.77 (m, 2H, C(3)H2); 2.21 (s, 3H, NCH3); 2.49 (d,
2H, J 16.01 Hz); 3.60 (t, 1H, C(4)H, J 9.32, 9.32 Hz); 3.85 (t, 1H, C(4)H,
J 9.26, 9.28 Hz); 4.98 (t, 1H, benzylic H); 6.88–7.71 (m, 12H, ArH);
8.90 (s, 1H, NH). dC (100 MHz, CDCl3) 18.4, 28.6, 35.7, 46.6, 57.6, 61.6,
80.1, 112.0, 120.4, 121.2, 122.1, 122.7, 125.1, 126.9, 127.2, 130.0, 131.5,
132.7, 135.7, 136.1, 141.0, 141.2, 187.9, 199.3, 200.6; EI-MS m/z 539.42
(Mþ); Anal. Calcd for C30H23BrN2O3: C, 66.80; H, 4.30; N, 5.19%.
Found: C, 67.01; H, 4.46; N, 5.35%.
4.2.4. 40-(4-Chlorophenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,200-indene]-
1,100,300(3H)-trione (8d)
4.2.6. 40-(4-Nitrophenyl)-10-methyl-4,9-dihydrodispiro[carbazole-
2,30-pyrrolidine-20,200-indene]-1,100,300(3H)-trione (8f)
Yellow solid, mp 204 ꢀC. nmax (KBr) 1704, 1740, 3285 cmꢁ1
;
dH
Yellow solid, mp 210–212 ꢀC; nmax (KBr) 1704, 1738, 3289 cmꢁ1
;
(400 MHz, CDCl3) 1.78 (m, 2H, C(3)H2); 2.35 (s, 3H, NCH3); 2.52
(d, 2H, J 16.64 Hz); 3.62 (t, 1H, C(4)H, J 9.32, 9.33 Hz); 3.89 (t, 1H,
C(4)H, J 9.28, 9.21 Hz); 5.09 (t, 1H, benzylic H); 6.97–7.70 (m, 12H,
dH (400 MHz, CDCl3) 1.65 (m, 2H, C(3)H2); 2.19 (s, 3H, NCH3); 2.42
(d, 2H, J 16.01 Hz); 3.58 (t, 1H, C(4)H, J 9.28, 9.27 Hz); 3.75 (t, 1H,
C(4)H, J 9.25, 9.28 Hz); 5.06 (t, 1H, benzylic H); 6.79–7.68 (m, 12H,
Table 1
Table 2
Influence of conventional heating and microwave irradiation on 1,3-dipolar cyclo-
Influence of conventional heating and microwave irradiation on 1,3-dipolar cyclo-
addition reaction of 5a–f with 6 and 7
addition reaction of 5a–f with 6 and 10
Cycloadduct 8
Method A
Method B
Method C
Cycloadduct 11
Method A
Method B
Method C
Yield in 6 h (%)
Yield in 15 min (%)
Yield in 15 min (%)
Yield in 6 h (%)
Yield in 15 min (%)
Yield in 15 min (%)
a
b
c
d
e
f
48
53
50
58
54
46
78
71
84
95
86
75
85
82
88
95
89
86
a
b
c
d
e
f
51
43
52
60
55
43
82
79
85
96
94
81
89
83
91
93
96
85
Method A: conventional reflux; Method B: K-10 Montmorillonite clay/MW; Method
C: neat/MW.
Method A: Conventional reflux; Method B: K-10 Montmorillonite clay/MW; Method
C: neat/MW.

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G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
Table 3
Table 5
Influence of conventional heating and microwave irradiation on 1,3-dipolar cyclo-
Effect of dispiropyrrolidines on the growth of human pathogen Proteus mirabilis
addition reaction of 5a–f with 6 and 13
Organism
Compound
Concentration of the compound (
m
g/ml)
100
Cycloadduct 10
Method A
Method B
Method C
25
50
75
Yield in 6 h (%)
Yield in 15 min (%)
Yield in 15 min (%)
Zone of inhibition (mm)
a
b
c
d
e
f
50
48
57
43
45
52
78
80
88
90
93
86
84
89
83
96
94
81
Proteus mirabilis
8a
8b
8c
8d
8e
8f
11a
11b
11c
11d
11e
11f
14a
14b
14c
14d
14e
14f
–
9
13
–
9
9
13
14
17
14
14
18
22
18
20
24
18
17
14
16
16
18
16
16
28
15
18
20
23
16
21
32
21
22
36
22
21
16
11
15
9
11
13
13
14
16
16
15
13
12
14
13
15
14
13
24
9
Method A: Conventional reflux; Method B: K-10 Montmorillonite clay/MW; Method
C: neat/MW.
11
11
14
12
13
9
9
11
9
13
11
12
18
ArH); 8.92 (s, 1H, NH). dC (100 MHz, CDCl3) 18.2, 27.9, 35.6, 45.3,
58.8, 60.6, 81.0, 112.0, 120.6, 121.3, 122.1, 122.6, 124.4, 125.6, 126.9,
128.8, 130.6, 132.2, 135.1, 135.4, 141.7, 141.8, 188.2, 199.1, 201.2;
EI-MS m/z 502.52 (Mþ); Anal. Calcd for C30H23N3O5: C, 71.28; H,
4.59; N, 8.31%. Found: C, 71.45; H, 4.36; N, 8.51%.
18
21
22
18
20
>40
4.2.7. 10-Methyl-40-phenyl-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11a)
Tetracycline
Yellow crystalline solid, mp 222 ꢀC; nmax (KBr) 1638, 1702,
3351 cmꢁ1
; dH (400 MHz, CDCl3) 1.46 (m, 1H, C(3)H); 1.86 (m, 1H,
1H, benzylic H); 6.79–7.80 (m, 14H, ArH); 9.15 (s, 1H, NH). dC
(100 MHz, CDCl3) 19.2, 32.4, 34.7, 47.0, 58.4, 62.6, 80.1, 112.2, 119.7,
120.3, 120.9, 122.3, 124.8, 125.0, 126.6, 126.7, 127.5, 127.8, 128.2,
128.6, 130.0, 130.4, 131.6, 131.7, 137.0, 138.0, 138.8, 142.5, 192.2,
206.5; EI-MS m/z 496.6 (Mþ); Anal. Calcd for C34H28N2O2: C, 82.23;
H, 5.68; N, 5.64%. Found: C, 82.42; H, 5.75; N, 5.48%.
C(3)H); 2.07 (s, 3H, NCH3); 2.34 (d, 2H, J 14.64 Hz); 3.63 (t, 1H,
C(4)H, J 8.80, 8.28 Hz); 4.17 (t, 1H, C(4)H, J 10.30, 9.3 Hz); 5.19 (t, 1H,
benzylic H); 6.81–7.89 (m, 15H, ArH); 9.15 (s, 1H, NH). dC (100 MHz,
CDCl3) 19.2, 32.4, 34.7, 47.0, 58.4, 62.6, 80.1,112.2,119.8,120.3,120.9,
122.5, 124.9, 125.1, 126.6, 126.8, 127.6, 127.8, 128.2, 128.3, 130.1,
130.4, 131.6, 131.7, 137.0, 138.0, 139.1, 142.1, 192.1, 207.4; EI-MS m/z
482.58 (Mþ); Anal. Calcd for C33H26N2O2: C, 82.13; H, 5.43; N, 5.81%.
Found: C, 82.31; H, 5.58; N, 5.71%.
4.2.9. 10-Methyl-40-(4-methoxyphenyl)-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11c)
4.2.8. 10-Methyl-40-(4-methylphenyl)-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11b)
Yellow solid, mp 190 ꢀC; nmax (KBr) 1642, 1705, 3351 cmꢁ1
; dH
(400 MHz, CDCl3) 1.42 (m, 1H, C(3)H); 1.80 (m, 1H, C(3)H); 2.03 (s,
3H, NCH3); 2.23 (d, 2H, J 14.02 Hz); 3.56 (t, 1H, C(4)H, J 8.68,
8.65 Hz); 3.62 (s, 3H, OCH3); 4.09 (t, 1H, C(4)H, J 9.28, 9.30 Hz); 5.14
(t, 1H, benzylic H); 6.71–7.68 (m, 14H, ArH); 9.13 (s, 1H, NH). dC
(100 MHz, CDCl3) 19.2, 32.4, 34.6, 46.9, 58.3, 62.6, 80.1, 112.2, 119.7,
Pale yellow solid, mp 210 ꢀC; nmax (KBr) 1644, 1705, 3349 cmꢁ1
;
dH (400 MHz, CDCl3) 1.44 (m, 1H, C(3)H); 1.84 (m, 1H, C(3)H); 2.05
(s, 3H, NCH3); 2.28 (d, 2H, J 14.31 Hz); 2.30 (s, 3H, PhCH3); 3.60 (t,
1H, C(4)H, J 8.70, 8.68 Hz); 4.10 (t, 1H, C(4)H, J 9.28, 9.31 Hz); 5.16 (t,
Table 6
Effect of dispiropyrrolidines on the growth of human pathogen Staphylococcus
Table 4
aureus
Effect of dispiropyrrolidines on the growth of human pathogen Proteus vulgaris
Organism
Compound
Concentration of the compound (
25 50 75
Zone of inhibition (mm)
m
g/ml)
100
Organism
Compound
Concentration of the compound (
m
g/ml)
100
25
50
75
Zone of inhibition (mm)
Staphylococcus aureus
8a
8b
8c
8d
8e
8f
11a
11b
11c
11d
11e
11f
14a
14b
14c
14d
14e
14f
–
9
9
9
14
14
13
11
12
14
19
18
16
18
14
16
13
13
14
14
15
11
24
16
18
15
16
19
18
21
23
21
22
18
21
16
16
17
18
18
14
28
20
21
20
19
21
18
26
27
30
34
22
31
18
20
20
21
22
20
>40
Proteus vulgaris
8a
8b
8c
8d
8e
8f
11a
11b
11c
11d
11e
11f
14a
14b
14c
14d
14e
14f
11
–
13
–
9
12
–
15
–
18
9
21
12
21
24
18
18
21
20
17
>40
22
>40
26
21
20
26
21
22
>40
15
14
13
17
14
14
12
18
16
22
16
16
13
18
14
13
24
16
18
16
18
18
16
13
24
20
27
20
18
18
24
18
18
28
–
11
14
14
9
14
11
9
11
9
12
9
11
9
19
12
13
12
12
11
9
11
9
18
11
–
22
Tetracycline
Tetracycline

G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
965
Table 7
125.4, 126.2, 126.9, 127.8, 128.6, 129.6, 130.4, 130.6, 131.8, 131.9,
132.3, 134.8, 136.1, 136.4, 138.8, 142.6, 192.0, 206.5; EI-MS m/z
527.58 (Mþ); Anal. Calcd for C33H25BrN2O2: C, 75.13; H, 4.78; N,
7.96%. Found: C, 75.32; H, 4.63; N, 8.12%.
Effect of dispiropyrrolidines on the growth of human pathogen Salmonella typhi
Organism
Compound
Concentration of the compound (
25 50 75
Zone of inhibition (mm)
m
g/ml)
100
4.2.13. 40-Phenyl-10-methyl-4,9-dihydrodispiro[carbazole-2,30-
Salmonella typhi
8a
8b
8c
8d
8e
8f
11a
11b
11c
11d
11e
11f
14a
14b
14c
14d
14e
14f
9
13
9
14
14
16
16
18
13
20
21
18
21
21
18
13
14
18
17
13
18
28
18
16
21
19
19
18
28
29
26
31
30
25
18
16
21
18
pyrrolidine-20,300-indole]-1,200(3H)-dione (14a)
–
Yellow solid, mp 120–122 ꢀC; nmax (KBr) 3281, 1704, 1656 cmꢁ1
;
–
9
–
11
13
9
dH (400 MHz, CDCl3) 1.63 (m, 1H, C(3)H); 1.91 (m, 1H, C(3)H); 2.21(s,
3H, NCH3); 2.58 (d, 2H, J 14.21 Hz); 3.58 (t, 1H, C(4)H, J 8.71, 8.69 Hz);
4.12 (t, 1H, C(4)H, J 10.18, 9.83 Hz); 5.19 (t, 1H, benzylic H); 6.81–7.58
(m, 13H, ArH); 8.17 (s, 1H, NH); 9.18 (s, 1H, NH). dC (100 MHz, CDCl3)
19.1, 21.1, 32.6, 34.8, 46.5, 57.7, 61.3, 81.8, 109.4, 112.3, 121.2, 122.4,
126.5, 126.8, 128.6, 128.9, 129.1, 130.4, 133.8, 136.4, 138.2, 140.7, 183.6,
190.3; EI-MS m/z 447.5 (Mþ); Anal. Calcd for C29H25N3O2: C, 77.83; H,
5.63; N, 9.39%. Found: C, 77.71; H, 5.75; N, 9.20%.
9
11
14
15
15
16
14
14
11
12
14
15
9
11
12
13
13
9
11
9
9
4.2.14. 40-(4-Methylphenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,300-indole]-1,200(3H)-
dione (14b)
12
11
–
16
22
>40
9
18
16
22
Yellow solid, mp 132 ꢀC; nmax (KBr) 3281, 1702, 1643 cmꢁ1
; dH
Tetracycline
(400 MHz, CDCl3) 1.55 (m, 1H, C(3)H); 1.85 (m, 1H, C(3)H); 2.17 (s,
3H, NCH3); 2.3 (s, 3H); 2.52 (d, 2H, J 14.00 Hz); 3.53 (t, 1H, C(4)H, J
8.72, 8.69 Hz); 4.04 (t, 1H, C(4)H, J 9.91, 9.73 Hz); 5.01 (t, 1H,
benzylic H); 6.65–7.71 (m, 12H, ArH); 8.17 (s, 1H, NH); 9.03 (s, 1H,
NH). dC (100 MHz, CDCl3) 18.8, 21.0, 32.4, 34.7, 46.5, 57.7, 61.3, 81.8,
109.3, 112.2, 121.2, 122.4, 126.5, 126.8, 128.6, 128.9, 129.2, 130.4,
135.8, 136.5, 138.2, 140.7, 183.5, 190.3; EI-MS m/z 461.5 (Mþ); Anal.
Calcd for C30H27N3O2: C, 78.07; H, 5.90; N, 9.10%. Found: C, 77.89; H,
5.73; N, 9.22%.
120.1, 120.8, 122.3, 124.8, 125.0, 126.6, 126.7, 127.4, 127.8, 128.1,
128.2,130.1,130.2,131.3,131.6,137.1,138.0,138.6,142.3,191.9, 206.5;
EI-MS m/z 512.6 (Mþ); Anal. Calcd for C34H28N2O3: C, 79.67; H, 5.51;
N, 5.46%. Found: C, 79.80; H, 5.40; N, 5.54%.
4.2.10. 10-Methyl-40-(4-chlorophenyl)-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11d)
4.2.15. 40-(4-Methoxyphenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,300-indole]-1,200(3H)-
dione (14c)
Pale yellow solid, mp 198 ꢀC; nmax (KBr) 1639, 1705, 3348 cmꢁ1
;
dH (400 MHz, CDCl3) 1.42 (m,1H, C(3)H); 1.85 (m,1H, C(3)H); 2.15 (s,
3H, NCH3); 2.30 (d, 2H, J 17.2 Hz); 3.61 (t, 1H, C(4)H, J 8.79, 8.18 Hz);
4.07 (t, 1H, C(4)H, J 10.28, 9.96 Hz); 5.12 (t, 1H, benzylic H); 6.81–
7.89 (m, 14H, ArH); 9.21 (s, 1H, NH). dC (100 MHz, CDCl3) 19.2, 29.7,
32.5, 34.6, 46.4, 58.5, 62.5, 80.0, 112.2, 119.9, 120.9, 122.0, 125.0,
125.1, 126.7, 127.7, 127.9, 128.2, 128.4, 130.1, 130.6, 131.8, 131.9, 132.6,
135.3, 136.8, 137.8, 138.1, 142.1, 191.9, 207.4; EI-MS m/z 517.02 (Mþ);
Anal. Calcd for C33H25ClN2O2: C, 76.66; H, 4.87; N, 5.42%. Found: C,
76.48; H, 5.01; N, 5.55%.
Pale yellow solid, mp 132 ꢀC; nmax (KBr) 3284, 1703, 1643 cmꢁ1
;
dH (400 MHz, CDCl3) 1.53 (m, 1H, C(3)H); 1.87 (m, 1H, C(3)H); 2.06
(s, 3H, NCH3); 2.48 (d, 2H, J 14.10 Hz); 3.21 (t, 1H, C(4)H, J 8.68,
8.70 Hz); 3.68 (s, 3H, OCH3); 3.96 (t, 1H, C(4)H, J 9.80, 9.91 Hz); 4.95
(t, 1H, benzylic H); 6.64–7.70 (m, 12H, ArH); 8.11 (s, 1H, NH); 9.03 (s,
1H, NH). dC (100 MHz, CDCl3) 18.7, 20.9, 32.4, 34.7, 36.2, 57.6, 61.3,
81.8, 109.4, 112.2, 121.1, 122.4, 126.4, 126.8, 128.6, 128.9, 129.0, 131.0,
135.1, 136.3, 137.9, 140.3, 183.5, 190.3; EI-MS m/z 477.56 (Mþ); Anal.
Calcd for C30H27N3O3: C, 75.45; H, 5.70; N, 8.80%. Found: C, 75.63;
H, 5.52; N, 9.02%.
4.2.11. 10-Methyl-40-(4-bromophenyl)-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11e)
4.2.16. 40-(4-Chlorophenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,300-indole]-1,200(3H)-
dione (14d)
Pale yellow solid, mp 194 ꢀC; nmax (KBr) 1644, 1704, 3343 cmꢁ1
;
dH (400 MHz, CDCl3) 1.40 (m, 1H, C(3)H); 1.83 (m, 1H, C(3)H); 2.03
(s, 3H, NCH3); 2.30 (d, 2H, J 16.91 Hz); 3.62 (t, 1H, C(4)H, J 8.78,
8.92 Hz); 4.05 (t, 1H, C(4)H, J 10.29, 9.98 Hz); 5.09 (t, 1H, benzylic
H); 6.82–7.89 (m, 14H, ArH); 9.22 (s, 1H, NH). dC (100 MHz, CDCl3)
19.2, 29.7, 32.6, 34.7, 46.4, 58.5, 62.5, 80.0, 112.3, 119.9, 120.7, 122.0,
124.9,125.0,126.6,127.7,127.9,128.1,128.4,130.3,130.6, 131.8,131.9,
132.6, 135.3, 136.7, 137.7, 138.0, 142.1, 190.9, 207.4; EI-MS m/z 561.47
(Mþ); Anal. Calcd for C33H25BrN2O2: C, 70.59; H, 4.49; N, 4.99%.
Found: C, 70.81; H, 4.56; N, 5.12%.
Pale yellow solid, mp 162 ꢀC; nmax (KBr) 3284, 1706, 1656 cmꢁ1
;
dH (400 MHz, CDCl3) 1.51 (m, 1H, C(3)H); 1.83 (m, 1H, C(3)H); 2.10 (s,
3H, NCH3); 2.50 (d, 2H, J 14.21 Hz); 3.20 (t, 1H, C(4)H, J 8.67, 8.69 Hz);
3.98 (t, 1H, C(4)H, J 9.80, 9.76 Hz); 5.24 (t, 1H, benzylic H); 6.88–7.88
(m, 12H, ArH); 8.23 (s, 1H, NH); 9.10 (s, 1H, NH). dC (100 MHz, CDCl3)
18.2, 20.3, 32.4, 33.1, 45.9, 56.8, 61.1, 81.2, 109.1, 112.0, 120.9, 122.1,
125.7, 125.9, 128.3, 128.5, 129.3, 130.6, 135.2, 136.1, 137.0, 140.2, 182.9,
190.0; EI-MS m/z 481.98 (Mþ); Anal. Calcd for C29H24ClN3O2: C,
71.27; H, 5.02; N, 8.72%. Found: C, 71.16; H, 5.19; N, 9.01%.
4.2.12. 10-Methyl-40-(4-nitrophenyl)-400,900-dihydro-2H-
dispiro[acenapthylene-1,20-pyrrolidine-30,200-carbazole]-100,2(300H)-
dione (11f)
4.2.17. 40-(4-Bromophenyl)-10-methyl-4,9-
dihydrodispiro[carbazole-2,30-pyrrolidine-20,300-indole]-1,200(3H)-
dione (14e)
Yellow solid, mp 202–204 ꢀC; nmax (KBr) 1648, 1706, 3346 cmꢁ1
;
dH (400 MHz, CDCl3) 1.38 (m,1H, C(3)H); 1.79 (m,1H, C(3)H); 2.11 (s,
3H, NCH3); 2.28 (d, 2H, J 16.53 Hz); 3.48 (t, 1H, C(4)H, J 8.52,
8.68 Hz); 4.28 (t, 1H, C(4)H, J 10.11, 9.97 Hz); 5.18 (t, 1H, benzylic H);
6.99–7.98 (m, 14H, ArH); 9.54 (s, 1H, NH). dC (100 MHz, CDCl3) 18.6,
28.6, 32.9, 33.5, 45.9, 59.2, 61.6, 80.8, 112.3, 119.9, 120.5, 121.8, 124.6,
Pale yellow solid, mp 186–188 ꢀC; nmax (KBr) 3281, 1703,
1654 cmꢁ1
; dH (400 MHz, CDCl3) 1.48 (m, 1H, C(3)H); 1.68 (m, 1H,
C(3)H); 2.00 (s, 3H, NCH3); 2.11 (d, 2H, J 14.21 Hz); 3.08 (t,1H, C(4)H,
J 8.59, 8.60 Hz); 3.42 (t, 1H, C(4)H, J 9.80, 9.78 Hz); 4.87 (t, 1H,
benzylic H); 6.61–7.68 (m, 12H, ArH); 8.06 (s, 1H, NH); 9.01 (s, 1H,

966
G. Periyasami et al. / European Journal of Medicinal Chemistry 44 (2009) 959–966
[2] Y. Toru, Y. Kayo, K. Harushisa, K. Yukihiko, A.W. Alison, J.N. Robert,
W.J.F. George, A. Naoki, J. Nat. Prod. 65 (2002) 1875.
[3] A.A. Watson, R.J. Nash, M.R. Wormald, D.J. Harvey, S. Dealler, E. Lees, N. Asano,
H. Kizu, A. Kato, R.C. Griffiths, A.J. Cairns, G.W.J. Fleet, Phytochemistry 46
(1997) 255.
[4] A. Kato, I. Adachi, M. Miyauchi, K. Ikeda, T. Komae, H. Kizu, Y. Kameda,
A.A. Watson, R.J. Nash, M.R. Wormald, G.W.J. Fleet, N. Asano, Carbohydr. Res.
316 (1999) 95.
[5] N. Asano, H. Kuroi, K. Ikeda, H. Kizu, Y. Kameda, A. Kato, I. Adachi, A.A. Watson,
R.J. Nash, G.W.J. Fleet, Tetrahedron Asymmetry 11 (2000) 1.
[6] J.Q. Fan, S. Ishii, N. Asano, Y. Suzuki, Nat. Med. 5 (1999) 112.
[7] F.M. Platt, G.R. Neises, G. Reinkensmeier, M.J. Townsend, V.H. Perry, R.L. Proia,
B. Winchester, R.A. Dwek, T. Butters, Science 276 (1997) 428.
[8] J. Kobayashi, M. Touda, K. Agemi, H. Shiegemori, M. Ishibashi, T. Saski,
Y. Mikami, Tetrahedron 47 (1991) 6617.
[9] K. Ding, Y. Lu, N.Z. Coleska, S. Qiu, Y. Ding, W. Gao, J. Stuckey, K. Krajewski,
P.P. Roller, Y. Tomita, D.A. Parrish, J.R. Deschamps, S. Wang, J. Am. Chem. Soc.
127 (2005) 10130.
[10] D.M. Jamess, H.B. Kunze, D.J. Faulkner, J. Nat. Prod. 54 (1991) 1137.
[11] R.D. Fabio, R. Giovannini, B. Bertani, M. Borriello, A. Bozzoli, D. Donati, A. Falchi,
D. Ghirlanda, C.P. Leslie, A. Pecunioso, G. Rumboldt, S. Spada, Bioorg. Med.
Chem. Lett. 16 (2006) 1749.
[12] D.N. Chowdhury, S.K. Basak, B.P. Das, Curr. Sci. 47 (1978) 490.
[13] K. Sakano, K. Ishimaru, S. Nakamura, J. Antibiot. 33 (1980) 683.
[14] D.L. Borek, E. Frei, M. Stiborova, Chem. Commun. 69 (2004) 603.
[15] M.J.E. Hewlins, A.M.O. Campos, P.V.R. Shannon, Synthesis (1984) 289.
[16] K. Hirata, C. Ito, H. Furukawa, M. Itogiawa, C.L. Mark, K.H. Lee, Bioorg. Med.
Chem. Lett. 9 (1999) 119.
NH). dC (100 MHz, CDCl3) 17.4, 18.6, 28.2, 31.7, 32.9, 42.3, 56.1, 60.9,
80.0, 109.1, 112.0, 120.8, 121.4, 124.2, 125.6, 126.8, 127.8, 128.1, 130.8,
134.2, 135.2, 136.8, 140.2, 182.9, 190.1; EI-MS m/z 526.43 (Mþ) Anal.
Calcd for C29H24BrN3O2: C, 66.17; H, 4.60; N, 7.98%. Found: C, 66.38;
H, 4.72; N, 8.12%.
4.2.18. 40-(4-Nitrophenyl)-10-methyl-4,9-dihydrodispiro[carbazole-
2,30-pyrrolidine-20,300-indole]-1,200(3H)-dione (14f)
Yellow solid, mp 198–200 ꢀC; nmax (KBr) 3282, 1705, 1652 cmꢁ1
;
dH (400 MHz, CDCl3) 1.39 (m,1H, C(3)H); 1.60 (m,1H, C(3)H); 2.13 (s,
3H, NCH3); 2.20 (d, 2H, J 14.10 Hz); 2.98 (t, 1H, C(4)H, J 8.62,
8.61 Hz); 3.38 (t, 1H, C(4)H, J 9.79, 9.78 Hz); 5.14 (t, 1H, benzylic H);
6.92–7.86 (m, 12H, ArH); 8.15 (s, 1H, NH); 9.23 (s, 1H, NH). dC
(100 MHz, CDCl3) 17.3, 18.2, 26.2, 30.5, 32.2, 42.6, 56.8, 61.2, 80.4,
109.2, 112.2, 120.8, 122.3, 124.6, 124.9, 125.2, 126.6, 128.0, 128.1,
130.6, 135.4, 135.8, 136.2, 140.3, 182.2, 190.6; 492.54; EI-MS m/z
492.54 (Mþ); Anal. Calcd for C29H24N4O4: C, 70.72; H, 4.91; N,
11.38%. Found: C, 70.49; H, 4.75; N, 11.51%.
Acknowledgements
[17] N. Haider, J. Heterocycl. Chem. 39 (2002) 511.
[18] R. Miri, K. Javidnia, B. Hemmateenejad, A. Azarpira, Z. Amirghofran, Bioorg
Med Chem 12 (2004) 2529.
[19] H. Galski, H. Sivan, P. Lazarovici, A. Nagler, Leuk. Res. 30 (2006) 1151.
[20] N.I. Andreeva, Chem. Abstr. 68 (1968) 57793.
[21] B.K. Satis Kumar, D. Gayathri, D. Velmurugan, K. Ravikumar, G. Periyasami,
Acta Crystallogr. E62 (2006) o50757.
GPS & Prof. RR thank the Department of Science and Technology
(DST), New Delhi, India, for financial support. We also acknowledge
Dr. D. Velmurugan, Department of Crystallography and Biophysics,
University of Madras, for the X-ray crystal analysis. The authors
thank SAIF, IIT, Chennai, for spectral data.
[22] B.K. Satis Kumar, D. Gayathri, D. Velmurugan, K. Ravikumar, G. Periyasami,
Acta Crystallogr. E63 (2007) o843.
[23] M.W. Jenny, Methods for Testing the Antimicrobial Activity of Extracts, in:
I. Ahmad, F. Aqil, M. Owais (Eds.), Modern Phytomedicine, Turning Medicinal
Plants into Drugs, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2006, p.
157.
References
[1] J.W. Daly, T.W. Spande, N. Whittaker, R.J. Highet, D. Feigl, N. Noshimori,
T. Tokuyama, C.W. Meyers, J. Nat. Prod. 46 (1986) 210.