Fullerene derivatized s-triazine analogues as antimicrobial agents

Article abstract of DOI:10.1016/j.ejmech.2008.10.036

A series of novel fullerene derivatives bearing s-triazine moiety have been synthesized by adopting 1,3 dipolar cycloaddition reaction of C₆₀ and azomethine ylides generated from the corresponding Schiff bases of 2,4,6 trisubstituted s-triazine

Full text of DOI:10.1016/j.ejmech.2008.10.036

European Journal of Medicinal Chemistry 44 (2009) 2178–2183
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Fullerene derivatized s-triazine analogues as antimicrobial agents
*
Anish Kumar, Shobhana Karuveettil Menon
Department of Chemistry, School of Sciences, Gujarat University, Navrangpura, Ahmedabad 380009, Gujarat, 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 fullerene derivatives bearing s-triazine moiety have been synthesized by adopting 1,3
dipolar cycloaddition reaction of C60 and azomethine ylides generated from the corresponding Schiff
bases of 2,4,6 trisubstituted s-triazine. All the compounds synthesized were characterized by elemental
analysis, FT-IR, 1H NMR, 13C NMR and FAB-MS. The compounds were then screened for their antibacterial
activity against both gram-positive (Staphylococcus aureus, Bacillus subtilis, Bacillus pumilis) and gram-
negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) bacteria by disc diffusion
method. All the compounds were found to be active against these strains at very low concentration and
were comparable to standard drug ciprofloxacin.
Received 29 July 2008
Received in revised form
24 September 2008
Accepted 22 October 2008
Available online 5 November 2008
Keywords:
Fulleropyrrolidine
s-Triazine
Ó 2008 Elsevier Masson SAS. All rights reserved.
Schiff base
Prato reaction
Antibacterial
1. Introduction
group or ionic part along with hydrophobic fullerene moiety so that
the dual purpose of interaction with cell wall of bacteria as well
Ever since its discovery, C60 has become a topic of considerable
interest in medicinal chemistry as a potential biologically active
compound. Its spherical shape together with its amazing physical
and chemical properties has prompted scientist world over to
exploit it in many areas ranging from material chemistry to bio-
logical sciences [1–4]. Interest in using C60 for diagnosis and ther-
apeutic use has been accelerated ever since it was discovered that
C60 derivatives could cross cell membranes [5]. Fullerene deriva-
tives have found potential application as neuroprotective agents
[6], anti-HIV agents [7,8], antimycobacterials [9], antibacterials
[10–12], bone-disorder drugs [13], X-ray contrast agents [14],
transfection vectors [15], photodynamic therapy agents [16], anti-
proliferative agents [17], drug delivery systems [18,19], inhibitors of
DNA enzymes [20], free radical sponge [21], anti-inflammatory
agents [22], anti-apoptosis agents [23], immunostimulatory agents
[24], vaccine against human papilloma virus [25], anticancer agents
[26], radiopharmaceuticals [27] and MRI contrast agents [28]. One
of the difficulties faced in using fullerene derivatives for biological
application is its low solubility in water or water miscible solvents.
This problem can be solved by introduction of (a) hydrophilic group
or (b) ionic species in the molecule. There are many reports
wherein fullerene derivatives have been used as antibacterials
[10–12]. These derivatives were having either hydrophilic functional
as their biological activity studies in water or water miscible
solvents becomes viable. Derivatized s-triazine molecules had been
proved efficient in inhibiting the growth of several strains of
bacteria [29–31]. Because of the increased bacterial resistance to
conventional antibiotics, there is an urgent need to design and
develop new antibiotics based on new chemical entities. Amphi-
philic peptides have shown great activity as antibacterials at
concentrations below mM range [32–34]. Activity of such class of
compounds has been attributed to electrostatic and hydrophobic
interactions with the bacterial membrane. Hence the presence of
both hydrophobic and hydrophilic groups is favorable for devel-
oping new chemical scaffolds as antibacterials. Moreover, the
presence of Schiff base has resulted in various compounds being
applicable to pharmaceutical and medicinal chemistry. Such
compounds had shown antibacterial, antifungal and antitumour
activities [35–37]. Some of the Schiff base derivatives with appre-
ciable cell membrane permeability were studied in cancer multi-
drug resistance studies. With these in view, we designed and
derivatized fullerene with substituted s-triazine having Schiff base
group between them so that the purpose of solubility for biological
studies as well as proper interaction with cell wall of bacteria could
be achieved efficiently.
2. Chemistry
In the synthetic methodology, derivatives of 1,3,5-triazine
(1a–e) were synthesized from 2,4,6 trichloro 1,3,5 triazine and
* Corresponding author. Tel.: þ91 79 26302286; fax: þ91 79 26308545.
E-mail address: shobhanamenon07@gmail.com (S.K. Menon).
0223-5234/$ – see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.10.036

A. Kumar, S.K. Menon / European Journal of Medicinal Chemistry 44 (2009) 2178–2183
2179
different nucleophilic amines ranging from ammonia to N,N
dimethyl amine by reported procedures [38–40].
triazine derivatives (1a–e) were synthesized by condensation with
terephthalaldehyde. Fulleropyrrolidines (3a–e) were synthesized
from these Schiff bases by adopting Prato’s 1, 3 dipolar cycloaddition
reaction. IR spectra of compounds (3a–e) showed peaks between
3060 and 3070 cmꢂ1 due to aromatic C–H stretching. Other peaks
such as 2920–2925 cmꢂ1 corresponding to aliphatic C–H stretching
were observed in derivatives 3b–e. The peak corresponding to
azomethine linkage was observed in the range 1595–1615 cmꢂ1 in
case of all the fulleropyrrolidines. The peak between 3520 and
3240 cmꢂ1 for N–H stretching was observed in all the derivatives.
1H NMR spectra of all the derivatives (3a–e) showed a singlet in
In general, the first chlorine was displaced with temperature at
0 ꢀC or below and second chlorine was substituted with tempera-
ture between 25 ꢀand 50 ꢀC. The third chlorine in all the products
was replaced by hydrazine hydrate at reflux temperature of 80 ꢀC.
2,4,6 Trisubstituted 1,3,5-triazine was then treated with ter-
ephthalaldehyde in ethanol. Triazine derivative was added por-
tionwise slowly to an ethanolic solution of terephthalaldehyde.
Mixtures of products were obtained from which the desired
product was isolated by column chromatography using toluene/
methanol (50:1) as the eluant. The Schiff base containing free
aldehyde group was then reacted with C60 by Prato’s 1,3 dipolar
cycloaddition reaction [41] to get the desired products. The prod-
ucts were purified by column chromatography using toluene/ethyl
acetate as the eluant. Reaction sequence is given in Scheme 1. Ionic
derivative 3f was obtained by treatment of 3a with HCl solution in
methanol at 0 ꢀC. The yield and melting point of the series of full-
eropyrrolidines synthesized are given in Table 1.
the range
protons of the only benzene ring molecule appeared as doublets at
7.60 and
7.20 (J ¼ 8.4 Hz) each integrating for two protons,
respectively. A singlet at 3.85 integrating for one proton corre-
sponding to NH attached with azomethine linkage was observed in
all the synthesized fulleropyrrolidine. Other peaks such as 5.25
and 4.10 (J ¼ 9.3 Hz) appear as doublets for one proton each corre-
sponding to –CH2–N of the pyrrolidine ring. Peaks at 4.35 and 2.20
d 8.0–8.1 attributable to (CH]N) proton. Aromatic
d
d
d
d
d
have been observed in all the derivatives of fullerene, which can be
attributed to protons (–CH and N–CH3, respectively) involving the
3. Pharmocology
pyrrolidine ring. 13C NMR showed
d between 180.0 and 176.0 cor-
All the novel fullerene derivatives (3a–f) as well as the Schiff base
precursors (2a–e) were screened for their antibacterial activity
against bacterial strains of Escherichia coli, Staphylococcus aureus,
Bacillus subtilis, Bacillus pumilis, Pseudomonas aeruginosa and Kleb-
siella pneumoniae by disc diffusion method [42,43]. A standard
inoculum (1–2 ꢁ107 c.f.u/ml 0.5 McFarland standards) was intro-
duced onto the surface of sterile agar plates, and a sterile glass
spreader was used for even distribution of the inoculum. The disc
measuring 6.25 mm in diameter was prepared from Whatmann filter
paper and sterilized by dry heat at 140 ꢀC for 1 h. The sterile plates
previously soaked in a known concentration of the test compounds
were placed in nutrient agar medium. Solvent and growth controls
were maintained. The plates were inverted and incubated for 24 h at
37 ꢀC. Ciprofloxacin was used as the standard drug. The inhibition
zones were measured and compared with the controls. The zone
responding to C of the triazine ring. The values between 160 and 120
are due to sp2C of the fullerene cage. The peak corresponding to sp3C
of fullerene cage could be found around
corresponding to C of the azomethine linkage was observed at
154.7. The mass spectrum of compound 3a showed molecular ion
d 73.0 and 68.0.The peak
d
peak at m/z 1004, in conformity with the molecular formula
C73N8H16. All the synthesized fulleropyrrolidines were screened for
antibacterial activity against both gram-positive and gram-negative
bacteria. Of all the derivatives tested for activity, it was the ionic
fullerene derivative with –NHþ3 groups, which was found to be the
most active against both classes of bacteria. The activity was found
to decrease on increasing the substitution on –NH2 group (Table 4).
5. Conclusion
developed by the solution of compound 3f (100
m
g/ml) in the plate
The investigation of antibacterial screening data revealed that
all the fullerene derivatives bearing s-triazine moiety showed
moderate to good bacterial inhibition.
against S. aureus and B. subtilis is as shown in Fig. 1. Bacterial inhi-
bition zone values for all the fulleropyrrolidines are given in Table 2.
Minimum inhibitory concentration (MIC) was evaluated by broth
dilution technique. The nutrient broth, which contained logarithmic
serially twofold diluted amount of test compound and controls, was
inoculated with approximately 5 ꢁ105 c.f.u of actively dividing
bacterial cells. The cultures were incubated for 24 h at 37 ꢀC and the
growth was monitored visually and spectrophotometrically. The
investigation of antibacterial screening revealed that all the fullerene
derivatives showed moderate to good bacterial inhibition. Bacterial
inhibition zones developed by fulleropyrrolidines (3a–f) were found
to be much bigger in size as compared to s-triazine based Schiff base
precursors (Table 3) indicating the contribution of fullerene moiety
towards antimicrobial activity of the synthesized fulleropyrrolidines.
The minimum inhibitory concentrations of various fullerop-
yrrolidines are given in given in Table 4. Compound 3f having with
ionic –NHþ3 group was found to be the most active followed by the
derivative inwhich both –NH2 group was free. The activity was found
to decrease on increasing the substitution on NH2 group. This
observation can be attributed to the fact that on increasing the
substitution on NH2 group, the hydrophilicity of the molecule as
a whole decreases which in turn decreases the disruption caused to
the negatively charged bacterial cell membrane (Fig. 2).
6. Experimental protocols
6.1. Apparatus
All the chemicals used were of analytical grade and purchased from
Sigma Aldrich and Merck Co. The cycloaddition reactions were per-
formed under argon. The cycloaddition reactions as well as other pre-
ceeding steps were monitored by TLC using Merck silica gel 60-F254
.
Silica gel (Merck, 0.040–0.063 mm) was used for column chromatog-
raphy. FAB-MS was recorded on Jeol SX-102/DA 600 mass spectrometer
using argon/xenon as the accelerating gas and nitrobenzylalcohol (NBA)
as the matrix. EI-MS was recorded on SHIMADZU QP-2020A. 1H NMR
spectra were recorded on a DRX 300 spectrophotometer operating at
400 MHz in CDCl3 with TMS as the internal standard. The absorption
spectra were recorded on Hitachi U – 3210 UV–vis spectrophotometer
using 10-mm quartz cell. Elemental analysis was done on a Carlo Erba
1108 analyzer. FT–IR spectra were recorded on a BRUKER-TENSOR 410
FT–IR spectrophotometer as KBr pellets. Melting point was taken on
Veego (VMP-DS) using a Mel-Temp apparatus.
6.2. General procedure for the synthesis of 2,4,6 trisubstituted 1,3,5
4. Results and discussion
s-triazines (1a–e)
2,4,6 Trisubstituted 1,3,5 s-triazines (1a–e) were synthesized by
reported procedure. Schiff bases (2a–e) of the corresponding
2,4,6 Trisubstituted 1,3,5 s-triazine derivatives were synthesized
by the reported procedure [27–29].

2180
A. Kumar, S.K. Menon / European Journal of Medicinal Chemistry 44 (2009) 2178–2183
CHO
R1
glac. acetic acid
N
N
NH2
EtOH,
Δ
R2
N
N
H
CHO
1
R1
CHO
N
N
N
N
R2
N
H
2
C60, Sarcosine
Toluene , Reflux 4h
R2
N
N
R1
N
HN
N
N
H3C
3
R1
R2
a
NH2
NH2
b
c
d
e
NHCH3
NH2
NHCH3
NHCH3
N (CH3)2
NHCH3
N (CH3)2
N (CH3)2
H2N
N
HN
3
N
N
N
NH2
NH
N
N
HN
N
3
HN
N
HCl , CH3OH , 0 °C
N
H3C
N
H3C
3a
3f
Scheme 1. Synthetic protocol of fulleropyrrolidines (3a–f).
6.3. Synthesis of Schiff bases (2a–e)
for a while and in the mean time 1a (2.82 g, 0.02 mol) was added
portionwise slowly for a period of half an hour. The yellow product
obtained was isolated and purified by column chromatography
(toluene/methanol 9:1). The solvent was then distilled out to get
To an ethanolic solution of terephthaldehyde (2.68 g, 0.02 mol)
was added 3–4 ml of glacial acetic acid. This mixture was refluxed

A. Kumar, S.K. Menon / European Journal of Medicinal Chemistry 44 (2009) 2178–2183
2181
Table 1
Characterization data of fulleropyrrolidines (3a–f)a.
Table 2
Zone of inhibition of fulleropyrrolidines (3a–f) (conc. 100
m
g/ml)a
Compound
R1
R2
Molecular formula
M.P. [ꢀC]
Yield [%]
Compound Staphylococcus Bacillus Bacillus Escherichia Pseudomonas Klebsiella
aureus
subtilis pumilis coli
aeruginosa
pneumoniae
3a
3b
3c
3d
3e
NH2
NH2
NH2
NHCH3
NHCH3
N (CH3)2
C73N8H16
C74N8H18
C75N8H20
C76N8H22
C77N8H24
215
212
208
205
201
33
39
38
40
39
NHCH3
NHCH3
N (CH3)2
N (CH3)2
3a
3b
3c
3d
3e
3f
20
19
16
15
13
22
28
27
23
21
15
32
38
28
24
20
18
13
31
36
25
24
21
20
14
25
27
24
22
18
16
15
25
32
16
15
14
12
b
–
a
Characterization data of fulleropyrrolidines (3a–e).
16
19
Standard 22
a
2a. Similarly 2b–e was synthesized by following the above
procedure.
Zone of inhibition of fulleropyrrolidines (100
Bacteria is resistant to compound.
mg/ml).
b
6.3.5. 2e (2-(4,6-Bis (dimethylamino)-1,3,5-triazin-2-yl)
hydrazinylidene) methyl benzaldehyde
6.3.1. 2a (2-(4,6 Diamino-1,3,5-triazin-2-yl) hydrazinylidene)
methyl benzaldehyde
Calcd for C15N7H19O (C: 57.5%, H: 6.0%, N: 31.3%). Found (C:
57.4%, H: 6.0%, N: 31.4%); IR (KBr,
cmꢂ1) 3090 (Ar–H), 1695 (CHO),
1595 (C]N); 1H NMR (
, DMSO-d6): 9.85 (s, 1H, CHO), 7.70 (d,
J ¼ 8.33, 2H, Ar–H), 7.50 (s, 1H, CH]N), 7.40 (d, J ¼ 8.33, 2H, Ar–H),
3.70 (s, 1H, NH), 2.40 (s, 12H, CH3); 13C NMR (
, 125 MHz, DMSO-d6)
190.0, 181.0, 176.5, 154.0, 139.0, 137.0, 129.0, 128.5, 44.5; mass (%)
Mþ 313 (58).
Calcd for C11N7H11O (C: 51.4%, H: 4.3%, N: 38.1%). Found (C:
y
cmꢂ1) 3520 (N–H), 3240 (N–H),
y
51.2%, H: 4.4%, N: 38.2%); IR (KBr,
3090 (Ar–H), 1695 (CHO), 1595 (C]N); 1H NMR (
d
, DMSO-d6): 9.87
d
(s, 1H, CHO), 7.80 (d, J ¼ 8.32, 2H, Ar–H), 7.50 (s, 1H, CH]N), 7.40 (d,
J ¼ 8.32, 2H, Ar–H), 4.0 (s, 4H, –NH2), 3.85 (s, 1H, NH); 13C NMR (
d,
d
125 MHz, DMSO-d6) 190.0, 180.8, 176.0, 154.7, 139.0, 137.0, 129.8,
129.5; mass (%) Mþ 257 (68).
6.3.2. 2b (2-(4-Amino-6-(methylamino)-1,3,5-triazin-2-yl)
hydrazinylidene)methyl benzaldehyde
6.4. Synthesis of fulleropyrrolidines (3a–e)
Calcd for C12N7H13O (C: 53.1%, H: 4.8%, N: 36.2%). Found (C:
Schiff base 2a (25.7 mg, 0.1 mmol), N-methylglycine(5 mg) and
C60 (72 mg,0.1 mmol) were refluxed in dry toluene in inert atmo-
sphere for 6 h . The product was first purified by column chroma-
tography (toluene/ethyl acetate 9:1) to get pure product 3a. In
a similar way all other products (3b–e) were obtained by the above
procedure.
53.2%, H: 4.6%, N: 36.4%); IR (KBr,
y
cmꢂ1) 3525 (N–H), 3245 (N–H),
3090 (Ar-H), 1695 (CHO), 1595 (C]N); 1H NMR (
d, DMSO-d6): 9.86
(s, 1H, CHO), 7.80 (d, J ¼ 8.30, 2H, Ar-H), 7.50 (s, 1H, CH]N), 7.40 (d,
J ¼ 8.30, 2H, Ar-H), 4.0 (s, 2H, –NH2), 3.85 (s, 1H, NH), 3.65 (s, 1H,
NH), 2.50 (s, 3H, CH3); 13C NMR (
d, 125 MHz, DMSO-d6) 190.1, 182.4,
179.2, 176.0, 154.7, 139.0, 137.2, 129.8, 129.5, 35.3; mass (%) Mþ 271
(66).
6.4.1. Compound 3a. Calcd for C73N8H16 (C: 87.3%, H: 1.6%, N:
11.2%). Found (C: 87.2%, H: 1.6%, N: 11.2%); IR (KBr,
y
cmꢂ1) 3520 (N–
6.3.3. 2c (2-(4,-6-Bis (methylamino)-1,3,5-triazin-2-yl)
hydrazinylidene) methyl benzaldehyde
H), 3240 (N–H), 3090 (Ar–H), 1595 (C]N); 1H NMR (
d, 400 MHz,
DMSO-d6): 8.10 (s, 1H, CH]N), 7.60 (d, J ¼ 8.32, 2H, Ar–H), 7.20 (d,
J ¼ 8.32, 2H, Ar–H), 5.25 (d,1H, J ¼ 9.3, HHC–N of the pyrrolidine
ring), 4.35 (s, 1H, CH of the pyrrolidine ring), 4.10 (d,1H, J ¼ 9.3,
HHC–N of the pyrrolidine ring), 4.0 (s, 4H, –NH2), 3.85 (s, 1H, NH),
Calcd for C13N7H15O (C: 53.6%, H: 5.2%, N: 34.4%). Found (C:
53.5%, H: 5.2%, N: 34.4%); IR (KBr,
y
cmꢂ1) 3245 (N–H), 3090 (Ar–H),
1695 (CHO), 1595 (C]N); 1H NMR (
d, DMSO-d6): 9.86 (s, 1H, CHO),
7.75 (d, J ¼ 8.30, 2H, Ar–H), 7.50 (s, 1H, CH]N), 7.40 (d, J ¼ 8.30, 2H,
2.20 (s, 3H, CH3 linked to N of pyrrolidine ring); 13C NMR (
d,
Ar–H), 3.80 (s, 1H, NH), 3.65 (s, 2H, NH), 2.48 (s, 6H, CH3); 13C NMR
125 MHz, DMSO-d6) 180.8, 176.0, 166.5, 164.8, 164.0, 163.6, 156.2,
155.9, 154.7, 154.0, 152.9, 151.6, 150.5, 147.3, 146.2, 146.0, 144.4,
143.1, 143.0, 142.7, 142.5, 142.4, 142.1, 142.0, 141.8, 141.5, 140.2, 139.9,
139.4, 136.9, 136.7, 136.4, 135.9, 135.6, 132.6, 132.3, 131.1, 130.6,
129.9, 129.5, 129.1, 128.3, 127.7, 127.0, 122.6, 121.2, 120.3,118.9, 114.6,
114.4, 111.0, 82.0, 73.50 (sp3 C– of C60) 72.7, 72.4, 68.6 (sp3 C– of
C60),33.3; mass (%) Mþ 1004 (58).
(d, 125 MHz, DMSO-d6) 190.0, 180.8, 176.0, 154.5, 140.0, 138.3, 136.5,
130.0, 129.0, 35.0; mass (%) Mþ 285 (70).
6.3.4. 2d 2-((4-Dimethyamino)-6-(methylamino)-1,3,5-triazin-2-
yl) hydrazinylidene methyl benzaldehyde
Calcd for C14N7H17O (C: 56.1%, H: 5.6%, N: 32.8%). Found (C:
56.0%, H: 5.6%, N: 32.7%); IR (KBr,
y
cmꢂ1) 3245 (N–H), 3090 (Ar–H),
1695 (CHO), 1595 (C]N); 1H NMR (
d, DMSO-d6): 9.85 (s, 1H, CHO),
6.4.2. Compound 3b. Calcd for C74N8H18 (C: 87.3%, H: 1.6%, N:
7.70 (d, J ¼ 8.34, 2H, Ar–H), 7.50 (s, 1H, CH]N), 7.40 (d, J ¼ 8.34, 2H,
11.2%). Found (C: 87.2%, H: 1.6%, N: 11.2%); IR (KBr,
y
cmꢂ1) 3520 (N–
Ar–H), 3.80 (s, 1H, NH), 3.65 (s, 1H, NH), 2.45 (s, 3H, CH3), 2.35 (s,
H), 3240 (N–H), 3090 (Ar–H), 1595 (C]N); 1H NMR (
d, 400 MHz,
6H, CH3); 13C NMR (
d
, 125 MHz, DMSO-d6) 190.1, 180.7, 178.2, 176.0,
DMSO-d6): 8.00 (s, 1H, CH]N), 7.55 (d, J ¼ 8.33, 2H, Ar–H), 7.20 (d,
154.7, 139.0, 137.0, 129.0, 128.5, 44.0, 35.8; mass (%) Mþ 299 (58).
Table 3
Zone of inhibition of Schiff base precursors (2a–e) (conc. 100
m
g/ml)a.
Compound Staphylococcus Bacillus Bacillus Escherichia Pseudomonas Klebsiella
aureus
subtilis pumilis coli
aeruginosa
pneumoniae
b
2a
2b
2c
2d
2e
09
09
11
10
09
16
18
12
10
10
38
15
13
10
11
10
36
15
15
14
12
–
27
11
13
11
10
–
32
–
15
14
12
b
b
b
–
Standard 22
19
a
Fig. 1. The zone developed by the solution of compound 3f (100
against S. aureus (1a) and B. subtilis (1b).
mg/ml) in the plate
Zone of inhibition of s-triazine Schiff bases(100 mg/ml).
Bacteria is resistant to compound.
b

2182
A. Kumar, S.K. Menon / European Journal of Medicinal Chemistry 44 (2009) 2178–2183
Table 4
131.1, 130.6, 129.9, 129.5, 129.1, 128.3, 127.7, 127.0, 122.6, 121.2,
MIC results of fulleropyrrolidines (3a–e)a.
120.3,118.9, 114.6, 114.4, 111.0, 82.0, 73.1 (sp3 C– of C60), 72.7, 72.4,
68.0 (sp3 C– of C60), 33.3; mass (%) Mþ 1032 (45).
Compound Staphylococcus Bacillus Bacillus Escherichia Pseudomonas Klebsiella
aureus
subtilis pumilis coli
aeruginosa
pneumoniae
3a
3b
3c
3d
3e
3f
10
12
25
25
50
6.25
0.1
0.1
0.50
0.50
1.0
1.0
5.0
10
12.
12.5
12.5
25
25
25
12.5
12.5
12.5
25
–
12.5
12.5
6.4.4. Compound 3d. Calcd for C76N8H22 (C: 87.3%, H: 1.6%, N:
11.2%). Found (C: 87.2%, H: 1.6%, N: 11.2%); IR (KBr,
y
cmꢂ1) 3520 (N–
0.5
0.5
1.0
0.08
0.06
12.5
12.5
25
12.5
6.25
H), 3240 (N–H), 3090 (Ar–H), 1595 (C]N); 1H NMR (
d, 400 MHz,
b
DMSO-d6): 8.00 (s, 1H, CH]N), 7.45 (d, J ¼ 8.33, 2H, Ar–H), 7.15 (d,
J ¼ 8.33, 2H, Ar–H), 5.20 (d, 1H, J ¼ 9.3, HHC–N of the pyrrolidine
ring) 4.35 (s, 1H, CH of the pyrrolidine ring), 4.00 (d, 1H, J ¼ 9.3,
HHC–N of the pyrrolidine ring), 3.75 (s, 1H, NH), 3.65 (s, 1H, NH),
2.50 (s, 3H, CH3), 2.35 (s, 6H, CH3), 2.20 (s, 3H, CH3 linked to N of
0.25
0.25
12.5
6.25
Standardc 6.25
a
MIC results of fulleropyrrolidines(3a–e).
Bacteria is resistant to compound.
Ciprofloxacin is used as the standard drug.
b
c
pyrrolidine ring); 13C NMR (
d, 125 MHz, DMSO-d6) 180.8, 176.0,
166.5, 164.8, 164.0, 163.6, 156.2, 155.9, 154.7, 154.0, 152.9, 151.6,
150.5, 147.3, 146.2, 146.0, 144.4, 143.1, 143.0, 142.7, 142.5, 142.4,
142.1,142.0,141.8,141.5,140.2,139.9,139.4,136.9,136.7,136.4,135.9,
135.6, 132.6, 132.3, 131.1,130.6, 129.9, 129.5, 129.1, 128.3, 127.7, 127.0,
122.6, 121.2, 120.3,118.9, 114.6, 114.4, 111.0, 82.0, 73.0 (sp3 C– of C60),
72.7, 72.4, 68.0 (sp3 C– of C60), 33.3; mass (%) Mþ 1046 (50).
J ¼ 8.33, 2H, Ar–H), 5.20 (d, 1H, J ¼ 9.3, HHC–N of the pyrrolidine
ring), 4.35 (s, 1H, CH of the pyrrolidine ring), 4.10 (d, 1H, J ¼ 9.3,
HHC–N of the pyrrolidine ring), 4.0 (s, 2H, –NH2), 3.80 (s, 1H, NH),
3.65 (s, 1H, NH), 2.50 (s, 3H, CH3), 2.20 (s, 3H, CH3 linked to N of
pyrrolidine ring); 13C NMR (
d, 125 MHz, DMSO-d6) 180.8, 176.0,
166.5, 164.8, 164.0, 163.6, 156.2, 155.9, 154.7, 154.0, 152.9, 151.6,
150.5, 147.3, 146.2, 146.0, 144.4, 143.1, 143.0, 142.7, 142.5, 142.4,
142.1,142.0,141.8,141.5,140.2,139.9,139.4,136.9,136.7,136.4,135.9,
135.6,132.6, 132.3, 131.1, 130.6, 129.9, 129.5, 129.1,128.3, 127.7, 127.0,
122.6, 121.2, 120.3,118.9, 114.6, 114.4, 111.0, 82.0, 73.2 (sp3 C– of C60),
72.7, 72.4, 68.3 (sp3 C– of C60), 33.3; mass (%) Mþ 1018 (42).
6.4.5. Compound 3e. Calcd for C77N8H24 (C: 87.3%, H: 1.6%, N:
11.2%). Found (C: 87.2%, H: 1.6%, N: 11.2%); IR (KBr,
y
cmꢂ1) 3520 (N–
H), 3240 (N–H), 3090 (Ar–H), 1595 (C]N); 1H NMR (
d, 400 MHz,
DMSO-d6): 8.00 (s, 1H, CH]N), 7.40 (d, J ¼ 8.35, 2H, Ar–H), 7.20 (d,
J ¼ 8.35, 2H, Ar–H), 5.25 (d, 1H, J ¼ 9.3, HHC–N of the pyrrolidine
ring) 4.35 (s, 1H, CH of the pyrrolidine ring), 3.90 (d,1H, J ¼ 9.3,
HHC–N of the pyrrolidine ring), 3.65 (s, 1H, NH), 2.40 (s, 12H, CH3),
6.4.3. Compound 3c. Calcd for C75N8H20 (C: 87.3%, H: 1.6%, N:
2.20 (s, 3H, CH3 linked to N of pyrrolidine ring); 13C NMR (
d,
11.2%). Found (C: 87.2%, H: 1.6%, N: 11.2%); IR (KBr,
y
cmꢂ1) 3520 (N–
125 MHz, DMSO-d6) 180.8, 176.0, 166.5, 164.8 164.0, 163.6, 156.2,
155.9, 154.7, 154.0, 152.9, 151.6, 150.5, 147.3, 146.2, 146.0, 144.4,
143.1, 143.0, 142.7, 142.5, 142.4, 142.1, 142.0, 141.8, 141.5, 140.2, 139.9,
139.4, 136.9, 136.7, 136.4, 135.9, 135.6, 132.6, 132.3, 131.1, 130.6,
129.9, 129.5, 129.1, 128.3, 127.7, 127.0, 122.6, 121.2, 120.3,118.9, 114.6,
114.4, 111.0, 82.0, 72.9 (sp3 C– of C60), 72.7, 72.4, 67.9(sp3 C– of C60),
33.3; mass (%) Mþ 1060 (48).
H), 3240 (N–H), 3090 (Ar–H), 1595 (C]N); 1H NMR (
d, 400 MHz,
DMSO-d6): 8.00 (s, 1H, CH]N), 7.50 (d, J ¼ 8.34, 2H, Ar–H), 7.20 (d,
J ¼ 8.34, 2H, Ar–H), 5.20 (d,1H, J ¼ 9.3, HHC–N of the pyrrolidine
ring) 4.35 (s, 1H, CH of the pyrrolidine ring), 4.00 (d,1H, J ¼ 9.3,
HHC–N of the pyrrolidine ring) 3.75 (s, 1H, NH), 3.65 (s, 2H, NH),
2.50 (s, 6H, CH3), 2.20 (s, 3H, CH3 linked to N of pyrrolidine ring);
13C NMR (
d, 125 MHz, DMSO-d6) 180.8, 176.0, 166.5, 164.8, 164.0,
163.6, 156.2, 155.9, 154.7, 154.0, 152.9, 151.6, 150.5, 147.3, 146.2,
146.0, 144.4, 143.1, 143.0, 142.7, 142.5, 142.4, 142.1, 142.0, 141.8, 141.5,
140.2, 139.9, 139.4, 136.9, 136.7, 136.4, 135.9, 135.6, 132.6, 132.3,
Acknowledgement
Authors are thankful to SAIF, CDRI Lucknow for spectral analysis.
Authors would also like to thank Department of Microbiology,
Gujarat University for antimicrobial studies and Prof. K.H. Chikha-
liya, Gujarat University for his support. One of the authors, Anish
Kumar is grateful to CSIR, New Delhi for Junior Research Fellowship.
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