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~ 341 ~
The Pharma Innovation Journal 2018; 7(10): 341-351
ISSN (E): 2277- 7695
ISSN (P): 2349-8242
NAAS Rating: 5.03
TPI 2018; 7(10): 341-351
© 2018 TPI
www.thepharmajournal.com
Received: 16-08-2018
Accepted: 18-09-2018
Maddumala Sowjanya
Department of Pharmaceutical
Chemistry, Sri Chundi
Ronganakulu College,
Chilakalurpet, Andhra Pradesh,
India
Baratam Anupama
Department of Pharmaceutical
Chemistry, KVSR Siddhartha
College of Pharmaceutical
Sciences, Vijayawada, Andhra
Pradesh, India
R Satyavani
Department of Pharmaceutical
Chemistry, KVSR Siddhartha
College of Pharmaceutical
Sciences, Vijayawada, Andhra
Pradesh, India
M Manoj Kumar
Department of Pharmaceutical
Chemistry, KVSR Siddhartha
College of Pharmaceutical
Sciences, Vijayawada, Andhra
Pradesh, India
KNV Chenchu Lakshmi
Assistant Professor,
Department of Pharmaceutical
Chemistry, KVSR Siddhartha
College of Pharmaceutical
Sciences, Vijayawada,
Andhra Pradesh, India
Correspondence
KNV Chenchu Lakshmi
Assistant Professor,
Department of Pharmaceutical
Chemistry, KVSR Siddhartha
College of Pharmaceutical
Sciences, Vijayawada,
Andhra Pradesh, India
Synthesis, characterisation, physiochemical properties
and biological evaluation of some novel 2-(3-oxo-
dihydro-2h-indol-2-ylidene) hydrazinecarboxmide
Schiff bases
Maddumala Sowjanya, Baratam Anupama, R Satyavani, M Manoj
Kumar and KNV Chenchu Lakshmi
Abstract Novel 2-(2-oxo-dihydro-2H-indol-2-ylidene) hydrazine carboxmide Schiff bases (1s-14s) were
synthesized by reacting various aliphatic and aromatic (substituted & unsubstituted) amines with isatin -
3-semicarbazone under strong basic conditions by conventional method. The purity and progress of
reaction was assessed by TLC and melting point. Synthesised compounds were characterised by various
spectroscopic methods such as IR, H1 &C13 NMR. Physical parameters such as isoelectric point, logP
and logD, pka, solubility (Log S and mg/ml) were determined by Chem Axon Chemicalize instant
Cheminformatics solution software. The synthesised Schiff bases were evaluated for their
antibacterial(two gram-positive bacteria Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC
6633 and two Gram-negative bacteria Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC
9027), antifungal (Aspergilus Niger MTCC 282 and Pencillium notatum NCIM 742,) and antioxidant
activities(DPPH Free radical scavenging assay). The results of Chem Axon revealed that compounds had
very low solubility in polar solvents, isoelectric point (6.5-8.5), log p (0-3.5), acidic pKa (8-9) basic pKa
(5-8).Antimicrobial studies revealed that compounds 3s, 5s, 7s and 12s possess good antibacterial and
antifungal properties. Compounds 5s, 7s, 8s, 11s, 12s exhibited better free radical scavenging assayof all
the compounds, 12s found to possess good antimicrobial and antioxidant activities. The study provides a
good scope for further development of novel targeted molecules.
Keywords: Schiff bases, anti-bacterial, anti-fungal, antioxidant, Chemaxon
1. Introduction
Schiff bases are condensation products of primary amines with carbonyl compounds and they
were first reported by Hugo Schiff [1] in 1864.The common structural features of these
compounds is the azomethine group with a general formula RHC=N-R1 where R & R1 are
alkyl, aryl, cyclo alkyl or heterocyclic group which may be variously substituted. These
compounds are also known as anils, imines or azomethines.
Schiff basesare used as substrates in the preparation of a number of industrial and biologically
active compounds via ring closure, cycloaddition and replacement reactions [2].Moreover,
Schiff bases derived from various heterocycles have been reported to possess cytotoxic [3],
anticonvulsant [4], antiproliferative [5], antimicrobial [6], anticancer [7], and antifungal [8]
activities. They have been encountered with antibacterial [9], anticancer, analgesic and anti-inflammatory, anticonvulsant, antimalarial, antiviral and CNS depressant activities. Isatin,
chemically known as 1H-indole-2, 3-dione, has become a popular topic due to its various uses. The
chemistry of Isatin and its derivatives is particularly interesting because of their potential
application in medicinal chemistry. Isatins are very important compounds due to their antifungal
properties. Schiff and Mannich bases of isatin derivatives are reported to show variety of biological
activities like antibacterial, antifungal [11], anti-convulsant, anti HIV, antidepressant, and anti-
inflammatory activities.
2. Materials and methods
Melting points were determined in open glass capillaries using Tempo (600) melting point
apparatus and were uncorrected. IR spectra (KBr discs) Bruker analysers were confirmed by
Shimadzu FT-IR Spectrophotometer using KBr pellets technique, Model No.8400S (Japan). 1H and
13C NMR spectra were recorded on Bruker 400 MHz NMR spectrometer (Switzerland) using
DMSO as solvent.
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The Pharma Innovation Journal
T.L.C. was run on silica gel G plates using ethyl acetate: n-
hexane (5:5) as developing solvent to assess the progress of
reaction and purity of the compounds. All other chemicals
used in the present study were of analytical grade.
2.1. Drugs and Chemicals Isatin-(LOBA-B.NO-0421100100), Semicarbazide-(LOBA-
B.NO-0568300100), Ortho phenylene diamine-(LOBA-
B.NO-0520700250), Sodium Hydroxide-(LOBA-B.NO-
0590000500), SilicagelG-(LOBA-B.NO-0570001000), Ethyl
Acetate-(LOBA-B.NO-0013702500), n-Hexane-(LOBA-
B.NO-0016102500), Dimethyl Sulphoxide -(LOBA-B.NO-
0012300500), 1-Naphthylamine- (SD FINE CHEM
LIMITED- B.NO- 1198/0598/3108/02), Ethyl amine-(LOBA-
B.NO-037180000), Methyl amine-(LOBA-B.NO-
4606H00500), Isopropyl amine-(Merck-B.NO-SH7B570229),
Aniline-(LOBA-B.NO-0003200500), 4-chloro aniline-
(LOBA-B.NO-0273300500), 4-Bromo aniline-(LOBA-B.NO-
0570001000), 4-Nitro aniline-(LOBA-B.NO-0492700250), 2-
Amino pyridine-(LOBA-B.NO-0570001024), 2Amino
pyrimidine-(Alderch-B.NO-A78608), 4-Amino phenol-(Otto-
B.NO-0117),6-Amino uracil-(), Hydroxyl amine
hydrochloride-(-B.NO-1402025), Ascorbic acid -(LOBA-
B.NO- 0154900500), Methanol-(FINAR CHEMICAL
LIMITED), Potassium Hydroxide-(OXFORD
LABORATARIES).
2.2 General procedure
Synthesis of (2z)-2-(3-oxo-dihydro-2H-indol-2-ylidene)
hydrazinecarboxmide Schiff bases [23-24]:
Isatin 3 Semicarbazone were prepared by condensation of
0.01 moles of Isatinwith 0.02 moles of Semicarbazide HCl in
presence glacial acetic acid and hot water. The reaction
mixture was refluxed for 4hr. The reaction mixture was
cooled; precipitate was filtered, dried, recrystallized from
methanol and confirmed by thin layer chromatography and
melting point.(2z)-2-(2-oxo-dihydro-2H-indol-2-ylidene)
hydrazine carboxmide Schiff bases synthesis was preceded by
condensation of equimoles (0.001moles) of step 1 with
various aliphatic &aromatic amines in methanol and few
drops of 40% KOH. The reaction mixture was refluxed for
4hr, cooled; the product formed was filtered, dried and
recrystallized from methanol. the progress and the purity of
the reaction was confirmed by thin layer chromatography and
melting point. The procedure was illustrated under Scheme
1&the physical data of the compounds were represented in
Table 1. The physical characteristics of the molecules were
assessed by Chem Axon’s Chemicalize instant
Cheminformatics solution software and the results were
tabulated in Tables 2, Table 3.The characterisation of the
molecules done by IR, C13NMR and H1 NMR data were
tabulated in Table 4, Table 5 and Table 6.
NH
O
O + NH2
NH NH2
O Condensation
CH3COOH,H2O
KOH in Methanol
R/Ar-NH2
Condensation
IsatinSemicarbazide
Isatin
Heat,3-
Heat,
NH
O
N
NH
NH2
N
R/Ar
NH
N
O
NH
NH2
O
(1s-14s)
Scheme 1Compounds (1s-14s)
1s.—CH3, 2s.-C3H6, 3s.-C10H7, 4s.-C6H6, 5s.-C6H5, 6s.-C6H4Cl-p, 7s.-C6H4NO2,
8s.-C6H4Br, 9s.C5H4N, 10s.-C4H3N2, 11s.-C6H5O, 12s.-C6H7N2O213s.-OH14s.C2H5
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The Pharma Innovation Journal
Table 1: Physical Data
Compound IUPAC Name MF MW Physical state
MP(O)C %
ylide Colour State
1s (2z)-N1-methyl (-2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)hydrazine
carboximidamide C10H11N5O 217.23 Yellow solid 210 63
2s (2z)-N1,N1-DImethyl (-2-(3-oxo-1,2-dihydro-3H-indol-3-
ylidene)hydrazine-1- carboximidamide C12H15N5O 245.29 Yellow solid 240 65
3s (2z)-N1-(naphthalene-2-yl)
-2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)hydrazine carboximidamide C19H15N5O 329.36 Yellow solid 250 62
4s (2z)-N1-(4-aminophenyl)-2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)hydrazine carboximidamide C15H14N6O 294.32
Greenish
grey solid 240 70
5s (2z)- 2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)N1-
phenylhydrazinecarboximidamide C15H13N5O 279.30 Yellow solid 240 72
6s (2z)-N1-(4-chloro phenyl-2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)hydrazine carboximidamide C15H12ClN5O 313.75 Yellow solid 260 68
7s (2z)-N1-(4-nitro phenyl)-2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)hydrazine carboximidamide C15H12N6O3 324.30 Brown solid 260 80
8s (2z)-N1-(4-bromo phenyl)-2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)hydrazine carboximidamide C15H12BrN5O 358.20 Yellow solid 260 65
9s (2z)-2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)-N1-pyridin-3-yl)
hydrazine carboximidamide C14H12N6O 280.29 Yellow solid 250 67
10s (2z)-N1-(pyrimidin-4yl)-2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)hydrazine carboximidamide C13H11N7O 281.28 Yellow solid 260 66
11s (2z)-N1-(4-hydroxyphenyl)- 2-(3-oxo-1,3-dihydro-2H-indol-2-
ylidene)-hydrazine carboximidamide C15H13N5O2 295.30 Black solid 260 72
12s (2z)-N1-(2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)2-(3-oxo-1,3-
dihydro-2H-indol-2-ylidene)hydrazine carboximidamide C13H11N7O3 313.28 Yellow solid 290 77
13s (2z)-N1-hydroxy2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)hydrazine
carboximidamide C9H9N5O2 219.20 Yellow solid 240 67
14s (2z)-N1-ethyl (-2-(3-oxo-1,3-dihydro-2H-indol-2-ylidene)hydrazine
carboximidamide C11H13N5O 231.26 Yellow solid 230 69
Table 2: physico-chemical properties by Chem Axon chemicalize [10]
compound Elemental
composition
Solubility Pka
Log s mg/ml
1s
C%-55.29,
H%-5.1,
N%-32.2,
O%-7.3
2s
C%-58.76,
H%-6.16,
N%-28.5,
O%-6.5
3s
C%-69.2,
H%-4.5,
N%-21.2,
O%-4.8
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The Pharma Innovation Journal
4s
C%-61.2,
H%-4.7,
N%-28.5,
O%-5.4
5s
C%-64.5,
H%-4.6,
N%-25.08,
O%-5.7
6s
C%-57.4,
H%-3.8,
N%-11.3,
O%-5.1,
Cl%-11.3
7s
C%-55.5,
H%-3.7,
N%-25.9,
O%-14.8
8s
C%-50.3,
H%-3.3,
N%-19.5,
O%-4.4,
Br%-22.3
9s
C%-59.9,
H%-4.32,
N%-29.9,
O%-5.7
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The Pharma Innovation Journal
10s
C%-55.5,
H%-3.9,
N%-34.8,
O%-5.6
11s
C%-61.01,
H%-4.4,
N%-23.7,
O%-10.8
12s
C%-49.8,
H%-3.5,
N%-31.3,
O%-15.3
13s
C%-61.2,
H%-4.7,
N%-28.5,
O%-5.4
14s
C%-57.1,
H%-5.6,
N%-30.2,
O%-6.9
Table 3: physic-chemical properties by Chem Axon
Compound Ionization constant Log p & Log D RF
1s
0.7
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2s
0.7
3s
0.7
4s
0.69
5s
0.7
6s
0.7
7s
0.7
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The Pharma Innovation Journal
78s
0.7
9s
0.7
10s
0.7
11s
0.7
12s
0.7
13s
0.7
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The Pharma Innovation Journal
14s
0.7
Table 4: Characteristics IR absorption bands of synthesized compounds
Compound C-H C-N C-OH N-H C=O 10- NH2 Ar-NO2 C-Cl C-Br
1s 3188.17 1349.62 3668.58 1791.21 3743.05, 3616.75
2s 3195.41 1100.58 3464.32 1701.00 3552.85, 3613.72
3s 3037.00 1283.10 3411.34 1735.61 3605.28, 3637.41
4s 3197.73 1386.27 3462.73 1694.87 3615.67, 3668.14
5s 3128.12 1344.30 3465.95 1694.75 3555.10, 3616.27
6s 3099.58 1345.27 3465.22 1703.86 3607.08, 3668.31 787.94
7s 3004.02 1299.48 3471.20 1704.76 3554.29, 3606.81 1394.17, 1578.82
8s 3085.30 1345.41 3467.58 1691.49 3615.70, 3666.61 668.38
9s 3129.09 1195.42 3465.34 1691.69 3553.34, 3615.79
10s 3189.32 1391.72 3464.70 1691.07 3615.19, 3675.05
11s 3000.66 1389.03 3220.16 3466.58 1706.92 3614.78, 3667.45
12s 3086.48 1234.96 3464.82 1719.12 3615.67, 3666.58
13s 3196.33 1387.32 3464.43 1703.44 3606.90, 3668.48
14s 3195.65 1390.22 3464.10 1690.97 3616.77, 3668.32
Table 5: C13NMR.
Compound C=O Aromatic Carbons (Ar-c) C-N C=N C-Cl C-OH C-NO2 C-Br
1s 206 111.8,125.2,122.3,125.2,123.4,125.3,122.3 125.2 140.1
2s 208 120.3,125.2,122.3,125.2,123.4,125.3,122.3 122.3 142
3s 199 125.2,125.2,122.3,125.2,123.4,125.3,122.3 125.2 146.3
4s 200 128.8,125.2,122.3,125.2,123.4,125.3,122.3 122.5 150
5s 202 122.3,125.2,122.3,125.2,123.4,125.3,122.3 124.3 152.8
6s 207 102.2,122.3,125.2,123.4,125.3,122.3,121.3 123.2 148.2 46.5
7s 205 121.3,120.3,125.2,122.3,125.2,123.4,125.3 126.3 145.6 76.2
8s 209 112.2,120.3,125.2,122.3,125.2,123.4,125.3 122.3 157.3 52.8
9s 214 124.3,120.3,125.2,122.3,125.2,123.4,125.3 125.3 153.9
10s 220 114.4,121.3,120.3,125.2,122.3,125.2,123.4, 124.3 150.0
11s 202 119.2,121.3,120.3,125.2,122.3,125.2,123.4, 122.3 155.3 150.2
12s 208 120.4,119.2,121.3,120.3,125.2,122.3, 125.2 122.2 149.2
13s 204 123.2,120.4,119.2,121.3,120.3,125.2,122.3 125.3 147.5
14s 201 125.2,114.4,121.3,120.3,125.2,122.3, 125.2, 123.2 154.7
Table 6: 1HNMR.
compound Hydrogens (n) δ(ppm) Multiplicity Solvents
1s
Ar
NH
NH2
CH=N
N-NH
6.771-7.422
9.109
1.764
4.120
8.816
(sx),(q)
Singlet
Singlet
Singlet
Singlet
DMSO
2s
Ar
NH,
NH2
C-CH
N-NH
6.771-7.422
8.744
1.981
1.191
8.853
(sx)(q)
Singlet
Singlet
Doublet
Singlet
DMSO
3s
Ar,
NH,
NH2
N-NH
6.441-7.839
9.764
1.810
12.751
(sx)(q)(t)
Singlet
Singlet
Singlet
DMSO
4s
Ar
NH,
NH2
6.637-7.422
10.244
1.934,4.695
(q),(d),(sx)
Singlet
Singlet
DMSO
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N-NH 12.784 Singlet
5s
Ar
NH
NH2
N-NH
6.771-7.422
9.325
2.709
12.758
(n)(q)(sx)(t)
Singlet
Singlet
Singlet
DMSO
6s
Ar
NH
NH2,
N-NH.
6.771-7.422
9.364
2.926
12.749
(q)(d)(sx)
Singlet
Singlet
Singlet
DMSO
7s
Ar
NH
NH2
N-NH
6.771-7.889
10.241
2.916
12.795
(q)(d)(sx)
Singlet
Singlet
Singlet
DMSO
8s
Ar
NH,
NH2
N-NH
6.77-7.422
9.361
1.926
12.775
(q)(sx)(d)
Singlet
Singlet
Singlet
DMSO
9s
Ar
NH
NH2
N-NH
6.771-8.612
9.709
2.597
12.757
(q)(d)(sx)
Singlet
Singlet
Singlet
DMSO
10s
Ar
NH
NH2
N-NH
N=CH
6.771-7.422
9.489
1.490
9.664
8.763,8.767
(q)(d)(sx)
Singlet
Singlet
Singlet
(s)(d)
DMSO
11s
Ar
NH
NH2
OH
N-NH
6.690-7.422
9.751
2.931
9.360
12.765
(d)(q)(sx)
Singlet
Singlet
Singlet
Singlet
DMSO
12s
Ar
NH
NH2
C-CH2
N-NH
6.771-7.422
11.127,9.517
1.000
3.723
10.313
(q)(sx)
Singlet
Singlet
Singlet
Singlet
DMSO
13s
Ar
NH
NH2
N-OH
N-NH
6.771-7.422
9.482
3.097
13.037
9.136
(q)(sx)
Singlet
Singlet
Singlet
Singlet
DMSO
14s
Ar
NH
NH2
CH2,CH3
N-NH
6.771-7.422
9.140
1.460
3.331,1.190
9.189
(q)(sx)
Singlet
Singlet
(q)(t)
Singlet
DMSO
δ(ppm)-chemical shift in parts per million:
3. Biological Activities
3.1 Anti-Microbial Method [12]: Cup Plate method by
Diffusion principle: In vitro antibacterial& antifungal
activities were examined for all the compounds synthesized
(1s-14s) against an assortment of two gram positive bacteria
Staphylococcus aureus ATCC 6538,Bacillus subtilis ATCC
6633 and two gram negative bacteria Escherichia coli ATCC
8739and Pseudomonas aeruginosa ATCC 9027&two fungal
strains of Aspergilus Niger MTCC 282 and Pencillium
notatum NCIM 742.The prepared media was inoculated to
perform the assay with required quantity of suspension of the
microorganism. The media was inoculated with microbial
suspension at a temperature between 400c -500cand
immediately inoculated media was poured in to the petri
dishes to give a depth of 3-4mm.The known concentrations of
test samples were prepared with diluting solvent methanol and
introduced in to the cavities prepared in the agar media. The
petri plates were left for diffusion (1-2 hours) at room
temperature or at 40c for some period of time for the test
concentrations to diffuse into the media. After that the plates
were incubated for 18 hours for anti-bacterial activity &72
hours for anti-fungal activity at room temperature. The
diameter or area of the circular inhibition zones were
measured.
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Fig 1: Anti-fungal activity [27]
3.1.2 Anti-Oxidant [13]
Method: DPPH Free Radical Scavenging Assay: The
percentage of antioxidant activity (AA %) of each substance
was assessed by DPPH free radical assay. The samples were
reacted with the stable DPPH radical in an methanol solution.
The reaction mixture consisted of adding 1 mL of test samples
(1s-14s) in methanol, 1 mL of DPPH radical solution in
methanol. When DPPH reacts with an antioxidant compound,
which can donate hydrogen, it is reduced. The changes in
colour (from deep violet to light yellow) were read
[Absorbance (Abs)] at 517 nm after 100 min of reaction using
a UV-VIS spectrophotometer (DU 800; Beckman Coulter,
Fullerton, CA, USA). The mixture of methanol (1 mL) and
sample (Ascorbic acid) (1 mL) serve as blank. The control
solution was prepared by mixing methanol (1 mL) and DPPH
radical solution (1 mL). The scavenging activity percentage
(AA %) was determined by
% Inhibition = O.D of 𝑐𝑜𝑛𝑡𝑟𝑜𝑙−O.D of test
O.D of control
IC-50 values were determined from the % Inhibition and
were tabulated
Table 7: Anti-oxidant activity
Compound %inhibition IC 50
values 2.5µg/ml 5µg/ml 7.5µg/ml 10µg/ml
Std 37.39 66.08 53.04 25.21 3.93
1s 98.26 89.56 96.52 93.04 -
2s 87.82 91.30 91.30 91.30 -
3s 39.13 40.86 44.34 43.47 18.80
4s 46.95 40 45.21 48.69 17.7
5s 46.08 50.43 48.69 50.43 8.67
6s 48.69 42.60 34.78 50.43 -
7s 49.56 48.69 50.43 50.43 7.52
8s 43.47 51.30 51.30 47.82 9.17
9s 54.78 53.91 52.17 51.30 12.48
10s 50.43 53.91 49.56 53.04 -
11s 46.95 39.13 26.95 28.69 0.81
12s 52.17 49.56 53.04 53.91 0.028
13s 53.04 49.56 52.17 50.43 12.5
14s 37.39 14.78 4.34 0 -
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4. Discussion
Synthesis of Schiff bases: The compounds synthesised by
conventional method and their characterisation by
spectroscopic methods, their physical parameters assessment
by online software Chemaxon [10] Cheminformatics software
reveal that the compounds possess very low solubility, highly
basic as their Pka values range from (8-9),log P (0-3.5)
provides basic information and support to the results obtained
practically. The spectroscopic features IR data reveal the
presence of NH2 (3700 Cm-1 to 3600 Cm-1), NH (3400 Cm-1 to
3500Cm-1), CH (2900-3100 Cm-1) stretching, C=O (1700 Cm-
1), C=N (1550-1490 Cm-1). Proton NMR reveals the presence
of two NH singlet’s between 10-12ppm, one singlet NH2 (4-
5ppm).
4.1 Antimicrobial activities
Cup plate diffusion method is preferred method for
antimicrobial studies.All the Schiff bases were moderately
active towards gram positive, gram negative and fungal
microorganisms as the inhibition zones were prominently
observed at concentrations above 250µg /ml of which the
compounds are more susceptible towards gram positive
organisms. Compounds 3s, 5s, 7s and 12s possess good
antibacterial and antifungal properties.
4.1.2 Antioxidant activity
The 2,2-diphenyl-1-picrylhydrazyl (DPPH) method is a
preferred method because it is fast, easy and reliable and does
not require a special reaction and device. Ascorbic acid
showed dose dependent antioxidant activity in DPPH assay.
Isatin compounds showed dose dependent free radical
scavenging activity in DPPH method. 5s, 7s, 8s, 11s, 12s
compounds showed higher % inhibition when compared with
other compounds.
In drug discovery, the development of hybrid molecules
through the combination of different pharmacophores leads to
compounds with interesting biological profiles. In this study,
synthesised isatin compounds (1s-14s) were selected and
screened antimicrobial and in vitro antioxidant activity. Isatin
Schiff bases showed dose dependent in-vitro antioxidant
activity in DPPH assay. 5s, 7s, 8s, 11s, 12s compounds
showed dose dependent antioxidant activity. The antioxidant
activity study provides a basis for further screening of other
pharmacological activities mainly anti-inflammatory etc.
5. Conclusion
A series of new novel 2-(3-oxo-dihydro-2H-indol-2-
ylidene)hydrazine carboxmide schiff base sderivatives were
prepared by conventional method and evaluated for their
antimicrobial, DPPH free radical scavenging assay for which
the mechanisms underlying this process remain to be fully
elucidated. It is intended that the results from these studies
will assist in elucidating their precise mechanism of action
and provide an approach for further optimization and
development to get new leads in the treatment of microbial
infections.
6. Acknowledgements The authors are thankful to the Siddhartha Academy for
General and Technical Education for providing necessary
facilities to carry out this research work.
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