O- and N-substituted derivatives of planetol as valuable bioactive compounds

Article abstract of DOI:10.14233/ajchem.2014.16109

The compounds bearing sulfamoyl and acetamoyl groups have been found to show various biological activities. In the present research work, a series of O- and N-substituted derivatives were synthesized, starting with planetol (1). First N-methyl-4-hydroxyanilinium sulfate (1; planetol or metol) was treated with different aryl sulfonyl chlorides (2a-i) using aq. sodium carbonate solution as reaction medium to yield N-substituted derivatives 3a-i. The electrophile, N-(2,3-dihydro-1,4-benzodioxin-6-yl)-2-bromoacetamide (5) was prepared by the reaction of 2,3-dihydro-1,4-benzodioxin-6-amine (4) and 2-bromoacetylbromide in a weak basic aqueous medium. The target O-substituted molecules 6a-i, were synthesized by gearing up the electrophile 5, with the molecules 3a-i, in a polar aprotic solvent using LiH as an activator. The proposed structures of all the synthesized molecules were corroborated by IR,¹H NMR and EIMS spectral data. The in vitro enzyme inhibition and antibacterial studies rendered the synthesized molecules as better cholinesterase inhibitors and moderately better antibacterial agents. To explore the binding modes of the synthesized compounds, all of them were computationally docked against the active sites of acetyl cholinesterase (AChE), butyryl cholinesterase (BChE) and lipoxygenase (LOX). The compounds showed significant interactions and good correlation with the experimental data.

Full text of DOI:10.14233/ajchem.2014.16109

Asian Journal of Chemistry; Vol. 26, No. 4 (2014), 1151-1160
http://dx.doi.org/10.14233/ajchem.2014.16109
O- and N-Substituted Derivatives of Planetol as Valuable Bioactive Compounds
1
1,*
1
1
1
MISBAH IRSHAD , MUHAMMAD ATHAR ABBASI , AZIZ-UR-REHMAN , SHAHID RASOOL , SABAHAT ZAHRA SIDDIQUI ,
2
3
4
4
IRSHAD AHMAD , MUHAMMAD ASHRAF , MUHAMMAD ARIF LODHI and SYED BABAR JAMAL
1Department of Chemistry, Government College University, Lahore-54000, Pakistan
2Department of Pharmacy, The Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan
3Department of Biochemistry and Biotechnology, The Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan
4Computational Medicinal Chemistry Laboratory, Department of Biochemistry, Abdul Wali Khan University, Mardan-23200, Pakistan
*Corresponding author: Tel: +92 42 111000010; E-mail: atrabbasi@yahoo.com
Received: 27 July 2013;
Accepted: 3 November 2013;
Published online: 15 February 2014;
AJC-14719
The compounds bearing sulfamoyl and acetamoyl groups have been found to show various biological activities. In the present research
work, a series of O- and N-substituted derivatives were synthesized, starting with planetol (1). First N-methyl-4-hydroxyanilinium sulfate
(1; planetol or metol) was treated with different aryl sulfonyl chlorides (2a-i) using aq. sodium carbonate solution as reaction medium to
yield N-substituted derivatives 3a-i. The electrophile, N-(2,3-dihydro-1,4-benzodioxin-6-yl)-2-bromoacetamide (5) was prepared by the
reaction of 2,3-dihydro-1,4-benzodioxin-6-amine (4) and 2-bromoacetylbromide in a weak basic aqueous medium. The target O-substituted
molecules 6a-i, were synthesized by gearing up the electrophile 5, with the molecules 3a-i, in a polar aprotic solvent using LiH as an
activator. The proposed structures of all the synthesized molecules were corroborated by IR,1H NMR and EIMS spectral data. The in vitro
enzyme inhibition and antibacterial studies rendered the synthesized molecules as better cholinesterase inhibitors and moderately better
antibacterial agents. To explore the binding modes of the synthesized compounds, all of them were computationally docked against the
active sites of acetyl cholinesterase (AChE), butyryl cholinesterase (BChE) and lipoxygenase (LOX). The compounds showed significant
interactions and good correlation with the experimental data.
Keywords: 2,3-Dihydro-1,4-benzodioxin-6-amine, Antibacterial activity, Enzyme inhibition, Planetol, Computational methodology.
The synthesis of the compounds bearing poly-functional
groups has been increasing interest these days. In the demoed
work, molecules bearing sulfamoyl and acetamoyl function-
alities attached to 1,4-benzodioxane ring have been prepared
in good yields. The 1,4-benzodioxane moiety has valuable
importance in biological active compounds like silybin5,
americanin A6 and haedoxan A7 has antihepato-toxic and
insecticidal activity. The sulfonamides have gained interest of
researchers because of antimicrobial, antiinflammatory, anti-
thyroid, anticancer, antitumor, antiviral, etc. activities and as
inhibitors of carbonic anhydrase, cystein protease, cyclohydro-
genase, HIV protease, etc.8-11; and acetamides-possess anthel-
mintic, anticonvulsant, antioxidant, antiinflammatory, anti-
INTRODUCTION
Acetyl cholinesterase (AChE, EC 3.1.1.7) and butyryl
cholinesterase (BChE, EC 3.1.1.8) are the parts of serine
hydrolase enzymes. These are capable to terminate acetyl-
choline at cholinergic synapses. Because of the components
of cholinergic brain synapses and neuromuscular junctions,
these catalyze the hydrolysis of the neurotransmitter acetyl-
choline and so terminate the nerve impulse in cholinergic
synapses1. These cholinesterase inhibitors enhance acetyl-
choline for neuronal and neuromuscular transmission reversibly
or irreversibly2. In lipoxygenase type-1 (LOX, EC 1.13.11.12),
the Fe2+ is oxidized to the catalytically active Fe3+ by the reaction
product 15-hydroperoxy-eicosatetraenoic acid (15-HPETE)
and leukotrienes from arachidonic acid as a substrate and
13-hydroperoxy-octadecadienoic acid (13-HPODE) from
linoleic acid as a substrate3. Leukotrienes are important bio-
logically active mediators in variety of inflammatory events.
It has been found that these lipoxygenase products play a key
role in a variety of disorders such as bronchial asthma infla-
mmation4.
arthritic, anticancer, antibacterial and antifungal activities12-15
.
The synthesis of various sulfonamides and acetamides,
to inaugurate new less toxic and more efficient molecules,
prompted us to take into account the synthesis of such mole-
cules bearing both the moieties. The present work is the
protraction of our successful efforts for the synthesis of potent
bioactive sulfonamides, acetamides and heterocyclic comp-
ounds16-19. The series of synthesized molecules were found to

1152 Irshad et al.
Asian J. Chem.
be potentially more active against cholinesterase enzymes,
moderate against Gram-bacterial strains and less against
lipoxygenase enzyme.
(O-H stretching), 3061 (C-H stretching of aromatic ring), 2923
(-CH2- stretching), 1623 (C=C stretching of aromatic ring),
1376 (-SO2 stretching), 1154 (C-O-C stretching of ether); 1H
NMR (CD3OD, 300 MHz): δ (ppm) 7.64 (brd, J = 9.0 Hz, 2H,
H-2' & H-6'), 7.62-7.51 (m, 3H, H-3' to H-5'), 6.84 (d, J = 8.7
Hz, 2H, H-2 & H-6), 6.67 (d, J = 8.7 Hz, 2H, H-3 & H-5),
3.11 (s, 3H, CH3-1''), EIMS: m/z 263 [M]+, 199 [M-SO2]+, 141
[C6H5SO2]+, 122 [C7H8NO]+, 93 [C6H5O]+, 77 [C6H5]+, 51
[C4H3]+.
The docking method involves the prediction of ligand
conformation and orientation with in a targeted binding site.
Generally, there are two objectives of docking studies viz.,
precise structural modeling and accurate prediction of
activity20. Molecular docking can be used to explain the
mechanism of molecular recognition between the ligands and
its receptor. Some theoretic docking methods have been used
to study the interactions of molecular recognition.Among them
one is MOE-Dock21 method which allows the ligands to be
flexible during docking so that the ligands can adjust their
different conformations in the binding pocket of the receptor.
We have applied this method to find the best binding mode
between the synthesized compounds and cholinesterase (acetyl
cholinesterase, butyryl cholinesterase) and lipoxygenase.
N-(4-Hydroxyphenyl)-N,4-dimethylbenzenesulfo-
namide (3b): Light grey amorphous solid; Yield: 93 %; m.p.
125 °C; m.f.: C14H15NO3S; m.w.: 277 g mol-1; HR-MS: [M]+
277.3403 (Calcd. for C14H15NO3S; 277.3610); IR (KBr, νmax
,
cm-1): 3356 (O-H stretching), 3059 (C-H stretching of aromatic
ring), 2937 (-CH2- stretching), 1604 (C=C stretching of
aromatic ring), 1378 (-SO2 stretching), 1145 (C-O-C stretching
of ether); 1H NMR (CD3OD, 300 MHz): δ (ppm) 7.42 (d, J =
8.4 Hz, 2H, H-2' & H-6'), 7.34 (d, J = 8.1 Hz, H-3' & H-5'),
6.84 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.67 (d, J = 8.7 Hz, 2H,
H-3 & H-5), 3.01 (s, 3H, CH3-1''), 2.41 (s, 3H, CH3-4'); EIMS:
m/z 277 [M]+, 213 [M-SO2]+, 155 [CH3C6H5SO2]+, 122
[C7H8NO]+, 93 [C6H5O]+, 91 [CH3C6H5]+, 50 [C4H2]+.
EXPERIMENTAL
Melting points of the synthesized compounds were
recorded on open capillary tube Griffin and George melting
point apparatus and were uncorrected. Purity was checked out
by thin layer chromatography (layer chromatography) on pre-
coated silica gel G-25-UV254 plates with different polarity
solvent systems using ethyl acetate and n-hexane giving single
spot. Identification of spots was carried out at 254 nm UV
lamp and by ceric sulphate reagent on heating. The IR spectra
were recorded in KBr pellet method on a Jasco-320-A
spectrophotometer with wave number in cm-1. Nuclear magnetic
resonance spectra were recorded in CD3OD on a Bruker
spectrometers operating at 300 MHz. Chemical shifts are given
in ppm taking TMS as internal reference standard and coupling
constant (J) in Hz. The abbreviations used in 1H NMR were s
= singlet, d = doublet and dd = doublet of doublet. Mass spectra
(EIMS) were recorded on a JMS-HX-110 spectrometer, with
a data system. All the spectra were taken at 25 °C (r. temp.).
All the chemicals taken into account were purchased from
AlfaAesar, SigmaAldrick and Merck through local suppliers.
The solvents used in the discussed project were of analytical
grade.
4-(tert-Butyl)-N-(4-hydroxyphenyl)-N-methylben-
zenesulfonamide (3c): Blackish brown amorphous solid;
Yield: 90 %; m.p. 76 °C; m.f.: C17H21NO3S; m.w.: 319 g mol-1;
HR-MS: [M]+ 319.4207 (Calcd. for C17H21NO3S; 319.4371);
IR (KBr, νmax, cm-1): 3355 (O-H stretching), 3066 (C-H stre-
tching of aromatic ring), 2913 (-CH2- stretching), 1615 (C=C
stretching of aromatic ring), 1390 (-SO2 stretching), 1167 (C-
1
O-C stretching of ether); H NMR (CD3OD, 300 MHz): δ
(ppm) 7.58 (d, J = 8.7 Hz, 2H, H-2' & H-6'), 7.47 (d, J = 8.4
Hz, H-3' & H-5'), 6.86 (d, J = 9 Hz,2H, H-2 & H-6), 6.68 (d,
J = 8.7 Hz, 2H, H-3 & H-5), 3.10 (s, 3H, CH3-1''), 1.36 (s, 9H,
(CH3)3C-4'); EIMS: m/z 319 [M]+, 255 [M-SO2]+, 197
[(CH3)3CC6H5SO2]+, 133 [(CH3)3CC6H5]+, 122 [C7H8NO]+, 93
[C6H5O]+, 50 [C4H2]+.
N-(4-Hydroxyphenyl)-N-2,4,6-tetramethylbenzene-
sulfonamide (3d): Black amorphous solid;Yield: 84 %; m.p.
60 °C; m.f.: C16H19NO3S; m.w.: 305 g mol-1; HR-MS: [M]+
305.3934 (Calcd. for C16H19NO3S; 305.4106); IR (KBr, νmax
,
cm-1): 3364 (O-H stretching), 3069 (C-H stretching of aromatic
ring), 2924 (-CH2- stretching), 1604 (C=C stretching of
aromatic ring), 1395 (-SO2 stretching), 1159 (C-O-C stretching
of ether); 1H NMR (CD3OD, 300 MHz): δ (ppm) 6.95 (s, 2H,
H-3' & H-5'), 6.92 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.65 (d, J
= 9 Hz, 2H, H-3 & H-5), 3.19 (s, 3H, CH3-1''), 2.38 (s, 6H,
CH3-2' & 6'), 2.27 (s, 3H, CH3-4'); EIMS: m/z 305 [M]+, 241
[M-SO2]+, 183 [(CH3)3C6H5SO2]+, 122 [C7H8NO]+, 119
[(CH3)3C6H5]+, 93 [C6H5O]+.
General procedure for the synthesis of N-substituted
derivatives of planetol (3a-i): N-methyl-4-hydroxyanilinium
sulfate (1;10 mmol) was dissolved in 25 mL distilled water in
a 100 mL round bottom flask and basified to pH of 8-10 by
10 % aqueous Na2CO3 solution. The aryl sulfonyl chlorides
(2a-i; 10 mmol) were added to the reaction medium gradually
in 5-10 min. The reaction mixture was stirred for 4-5 h along
with monitoring by layer chromatography till the single spot.
At the end of reaction, dil. HCl (2 mL) was added slowly along
with vigorous hand shaking to adjust the pH to 3-5. The
precipitates were generated after a stay of 5-10 min which
were filtered, washed with distilled water and dried to afford
the title solid compounds, 3a-i in good yields. Recrystallization
was progressed in methanol.
4-(Acetylamino)-N-(4-hydroxyphenyl)-N-methyl-
benzenesulfonamide (3e): Grayish brown amorphous solid;
Yield: 91 %; m.p. 152 °C; m.f.: C15H16N2O4S; m.w.: 320 g
mol-1; HR-MS: [M]+ 320.3654 (Calcd. for C15H16N2O4S;
320.3849); IR (KBr, νmax, cm-1): 3369 (O-H stretching), 3073
(C-H stretching of aromatic ring), 2927 (-CH2- stretching),
1613 (C=C stretching of aromatic ring), 1379 (-SO2 stretching),
N-(4-Hydroxyphenyl)-N-methylbenzenesulfonamide
(3a): Light brown amorphous solid;Yield: 92 %; m.p. 106 °C;
m.f.: C13H13NO3S; m.w.: 263 g mol-1; HR-MS: [M]+ 263.3132
(Calcd. for C13H13NO3S; 263.3361); IR (KBr, νmax, cm-1): 3365
1
1153 (C-O-C stretching of ether); H NMR (CD3OD, 300
MHz): δ (ppm) 7.72 (d, J = 8.7 Hz, 2H, H-3' & H-5'), 7.47 (d,

Vol. 26, No. 4 (2014)
O- and N-Substituted Derivatives of Planetol as Valuable Bioactive Compounds 1153
J = 8.7 Hz, 2H, H-2' & H-6'), 6.86 (d, J = 8.7 Hz, 2H, H-2 &
H-6), 6.68 (d, J = 9 Hz, 2H, H-3 & H-5), 3.10 (s, 3H,
CH3CONH-4'), 2.14 (s, 3H, CH3-1''); EIMS: m/z 320 [M]+,
256 [M-SO2]+, 198 [CH3CONHC6H5SO2]+, 134
[CH3CONHC6H5]+, 122 [C7H8NO]+, 93 [C6H5O]+, 50 [C4H2]+.
4-Bromo-N-(4-hydroxyphenyl)-N-methylbenzen-esulfo-
namide (3f): Dark brown amorphous solid;Yield: 90 %; m.p.
78 °C; m.f.: C13H12NO3SBr; M.w.: 341 g mol-1; HR-MS: [M]+
Procedure for the synthesis of N-(2,3-dihydro-1,4-
benzodioxin-6-yl)-2-bromoacetamide (5): 2,3-Dihydro-1,4-
benzodioxin-6-amine (4; 110 mmol) was suspended in 100
mL distilled water in a 250 mL iodine flask and 10 % Na2CO3
solution was added to adjust the pH 8-10. The reaction mixture
was hand shaked for 5-10 min and then 2-bromoacetyl-
bromide (110 mmol) was poured drop wise along with
vigorous shaking till the formation of solid precipitates. After
complete addition, the iodine flask was kept on stirring for
further 15-20 min. The solid precipitates were verified through
thin layer chromatography giving single spot and acidified up
to pH of 3-5. The precipitates were filtered, washed with
distilled water and dried to yield the electrophile 5. Purplish
grey amorphous solid; Yield: 95 %; m.p. 56 °C; m.f.:
C10H10NO3Br; m.w.: 271 g mol-1; HR-MS: [M]+ 271.0952
(Calcd. for C10H10BrNO3; 271.1076); IR (KBr, νmax, cm-1): 3460
(N-H stretching), 3067 (C-H stretching of aromatic ring), 2919
(-CH2- stretching), 1618 (C=C stretching of aromatic ring),
341.2091 (Calcd. for C13H12BrNO3S; 341.2235); IR (KBr, νmax
,
cm-1): 3354 (O-H stretching), 3051 (C-H stretching of
aromatic ring), 2926 (-CH2- stretching), 1608 (C=C stretching
of aromatic ring), 1372 (-SO2 stretching), 1147 (C-O-C
1
stretching of ether); H NMR (CD3OD, 300 MHz): δ (ppm)
7.71 (d, J = 8.7 Hz, 2H, H-2' & H-6'), 7.44 (d, J = 8.4 Hz, 2H,
H-3' & H-5'), 6.87 (d, J = 9 Hz, 2H, H-2 & H-6), 6.69 (d, J =
9 Hz, 2H, H-3 & H-5), 3.12 (s, 3H, CH3-1''); EIMS: m/z 343
[M + 2]+, 341 [M]+, 277 [M-SO2]+, 219 [BrC6H5SO2]+, 155
[BrC6H5]+, 122 [C7H8NO]+, 93 [C6H5O]+, 50 [C4H2]+.
1
4-Chloro-N-(4-hydroxyphenyl)-N-methylbenzenesulfo-
namide (3g): Blackish grey amorphous solid; Yield: 94 %;
m.p. 100 °C; m.f.: C13H12NO3SCl; m.w.: 297 g mol-1; HR-MS:
[M]+ 297.3586 (Calcd. for C13H12NO3SCl; 297.3739); IR (KBr,
1157 (C-O-C stretching of ether); H NMR (CD3OD, 300
MHz): δ (ppm) 10.20 (s, 1H, NH), 7.20 (d, J = 2.1 Hz, 1H,
H-5), 6.95 (dd, J = 8.7, 2.1 Hz, 1H, H-7), 6.80 (d, J = 8.7 Hz,
1H, H-8), 4.19 (s, 4H, CH2-2 & CH2-3), 3.97 (s, 2H, CH2-2');
EIMS: m/z 273 [M + 2]+, 271 [M]+, 150 [C8H8NO2]+, 135
[C8H7O2]+, 122 [C6H4NO2]+, 121 [C2H2BrO]+, 107 [C6H3O2]+,
66 [C4H4N]+.
ν
aromatic ring), 2931 (-CH2- stretching), 1607 (C=C stretching
of aromatic ring), 1379 (-SO2 stretching), 1178 (C-O-C
max, cm-1): 3351 (O-H stretching), 3070 (C-H stretching of
1
stretching of ether); H NMR (CD3OD, 300 MHz): δ (ppm)
General procedure for the synthesis of O-substituted
derivatives (6a-i): N-(4-hydroxyphenyl)-N-methylarylsulfon-
amides (3a-i; 10 mmol) were homogeneously dissolved in N,N-
dimethylformamide (DMF; 10 mL) in a 100 mL RB flask and
activated by the addition of lithium hydride (10 mmol). The
mixture was stirred for 15-25 min and then the calculated
equimolar amount of electrophile, N-(2,3-dihydro-1,4-benzo-
dioxin-6-yl)-2-bromoacetamide (5) was added to reaction
mixture and further stirred for 5-6 h. The reaction progress
was supervised via layer chromatography till single spot.
Aqueous Na2CO3 solutionwas added to the flask and hand
shaked slowly. The target precipitated products were collected
by filtration, washed with distilled water and dried.
7.53 (d, J = 8.1 Hz, 2H, H-2' & H-6'), 7.45 (d, J = 8.1 Hz, 2H,
H-3' & H-5'), 6.87 (d, J = 8.4 Hz, 2H, H-2 & H-6), 6.69 (d,
J = 8.7 Hz, 2H, H-3 & H-5), 3.12 (s, 3H, CH3-1''); EIMS: m/z
299 [M + 2]+, 297 [M]+, 233 [M-SO2]+, 175 [ClC6H5SO2]+,
122 [C7H8NO]+, 111 [ClC6H5]+, 93 [C6H5O]+, 50 [C4H2]+.
2,5-Dichloro-N-(4-hydroxyphenyl)-N-methylbenzene-
sulfonamide (3h): Blackish grey amorphous solid; yield: 87
%; m.p. 76 °C; m.f.: C13H11NO3SCl2; mole-cular weight: 331
g mol-1; HR-MS: [M]+ 331.2035 (Calcd. for C13H11Cl2NO3S;
331.2148); IR (KBr, νmax, cm-1): 3375 (O-H stretching), 3072
(C-H stretching of aromatic ring), 2937 (-CH2- stretching),
1617 (C=C stretching of aromatic ring), 1379 (-SO2 stretching),
1170 (C-O-C stretching of ether); 1H NMR (CD3OD, 300MHz):
δ (ppm) 7.81 (s, 1H, H-6'), 7.71 (d, J = 8.4, 1H, H-3'), 7.58 (d, J =
8.4, 1H, H-4'), 6.87 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.69 (d, J = 9
Hz, 2H, H-3 & H-5), 3.12 (s, 3H, CH3-1''); EIMS: m/z 335 [M +
4]+, 333 [M + 2]+, 331 [M]+, 267 [M-SO2]+, 209 [Cl2C6H5SO2]+,
145 [Cl2C6H5]+, 122 [C7H8NO]+, 93 [C6H5O]+.
2-{4-[Methyl(phenylsulfonyl)amino]phenoxy}-N-(2,3-
dihydro-1,4-benzodioxin-6-yl)acetamide (6a): Light brown
amorphous solid;Yield: 81 %; m.p. 157 °C; m.f.: C23H22N2O6S;
m.w.: 454 g mol-1; HR-MS: [M]+ 454.4975 (Calcd. for
C23H22N2O6S; 454.5031); IR (KBr, νmax, cm-1): 3462 (N-H
stretching), 3060 (C-H stretching of aromatic ring), 2921
(-CH2- stretching), 1621 (C=C stretching of aromatic ring),
1381 (-SO2 stretching), 1159 (C-O-C stretching of ether); 1H
NMR (CD3OD, 300 MHz): δ (ppm) 7.64 (dd, J = 7.8, 1.8 Hz,
2H, H-2' & H-6'), 7.51-7.41 (m, 3H, H-3' to H-5'), 7.17 (d, J =
2.4, 1H, H-5'''), 7.02 (dd, J = 8.4, 1.2 Hz, 1H, H-7'''), 6.99 (d,
J = 7.5 Hz, 1H, H-8'''), 6.97 (d, J = 8.1 Hz, 2H, H-2 & H-6),
6.78 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s, 4H, CH2-2''' &
CH2-3'''), 3.92 (s, 2H, CH2-2''''), 3.14(s, 3H, CH3-1''); EIMS:
m/z 454 [M]+, 390 [M-SO2]+, 150 [C8H8NO2]+, 141 [C6H5SO2]+,
135 [C8H7O2]+, 122 [C6H4NO2]+, 122 [C7H8NO]+, 107
[C6H3O2]+, 93 [C6H5O]+, 77 [C6H5]+, 66 [C4H4N]+, 51 [C4H3]+.
2-(4-{Methyl[(4-methylphenyl)sulfonyl]amino} phenoxy)-
N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide (6b): Light
grey amorphous solid; Yield: 80 %; m.p. 155 °C; m.f.:
N-(4-Hydroxyphenyl)-N-methyl-2-naphthalene-
sulfonamide (3i): Dark brown amorphous solid;Yield: 95 %;
m.p. 72 °C; m.f.: C17H15NO3S; m.w.: 313 gmol-1; HR-MS: [M]+
313.3725 (Calcd. for C17H15NO3S; 313.3834); IR (KBr, νmax
,
cm-1): 3347 (O-H stretching), 3058 (C-H stretching of aromatic
ring), 2927 (-CH2- stretching), 1609 (C=C stretching of aromatic
ring), 1391 (-SO2 stretching), 1164 (C-O-C stretching of ether);
1H NMR (CD3OD, 300 MHz): δ (ppm) 8.14 (s, 1H, H-1'),
7.96-7.90 (m, 2H, H-4' & H-5'), 7.87 (d, J = 8.1 Hz, 1H, H-3'),
7.64 (dd, J = 8.1, 2.1 Hz, 1H, H-8'), 7.52-7.47 (m, 2H, H-6' &
H-7'), 6.85 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.66 (d, J = 8.7
Hz, 2H, H-3 & H-5), 3.16 (s, 3H, CH3-1''); EIMS: m/z 313
[M]+, 249 [M-SO2]+, 191 [C10H7SO2]+, 127 [C10H7]+, 122
[C7H8NO]+, 93 [C6H5O]+.

1154 Irshad et al.
Asian J. Chem.
C24H24N2O6S; m.w.: 468 g mol-1; HR-MS: [M]+ 468.5234
(Calcd. for C24H24N2O6S; 468.5364); IR (KBr, νmax, cm-1): 3464
(N-H stretching), 3073 (C-H stretching of aromatic ring), 2911
(-CH2- stretching), 1610 (C=C stretching of aromatic ring),
1377 (-SO2 stretching), 1149 (C-O-C stretching of ether); 1H
NMR (CD3OD, 300 MHz): δ (ppm) 7.45 (d, J = 8.1 Hz, 2H,
H-2' & H-6'), 7.38 (d, J = 8.4 Hz, H-3' & H-5'), 7.19 (d, J =
2.4, 1H, H-5'''), 7.06 (dd, J = 8.1, 1.5 Hz, 1H, H-7'''), 6.89 (d,
J = 8.1 Hz, 2H, H-2 & H-6), 6.72 (d, J = 7.5 Hz, 1H, H-8'''),
6.69 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s, 4H, CH2-2'''&
CH2-3'''), 3.91 (s, 2H, CH2-2''''), 3.09 (s, 3H, CH3-1''), 2.42 (s,
3H, CH3-4'); EIMS: m/z 468 [M]+, 404 [M-SO2]+, 155
[CH3C6H5SO2]+, 150 [C8H8NO2]+, 135 [C8H7O2]+, 122
[C6H4NO2]+, 122 [C7H8NO]+, 107 [C6H3O2]+, 93 [C6H5O]+, 91
[CH3C6H5]+, 66 [C4H4N]+, 50 [C4H2]+.
(ppm) 7.72 (d, J = 8.7 Hz, 2H, H-2' & H-6'), 7.46 (d, J = 8.5
Hz, 2H, H-3' & H-5'), 7.18 (d, J = 2.4, 1H, H-5'''), 6.98 (dd,
J = 8.4, 1.8 Hz, 1H, H-7'''), 6.87 (d, J = 8.7 Hz,2H, H-2 & H-
6), 6.77 (d, J = 8.1 Hz, 1H, H-8'''), 6.68 (d, J = 8.7 Hz, 2H, H-
3 & H-5), 4.21 (s, 4H, CH2-2''' & CH2-3'''), 3.91 (s, 2H, CH2-
2''''), 3.11 (s, 3H, CH3CONH-4'), 2.98 (s, 3H, CH3-1''); EIMS:
m/z 511 [M]+, 447 [M-SO2]+, 198 [CH3CONHC6H5SO2]+, 150
[C8H8NO2]+, 135 [C8H7O2]+, 134 [CH3CONHC6H5]+, 122
[C6H4NO2]+, 122 [C7H8NO]+, 107 [C6H3O2]+, 93 [C6H5O]+, 66
[C4H4N]+, 50 [C4H2]+.
2-{4-[[(4-Bromophenyl)sulfonyl](methyl)amino]phenoxy}-
N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide (6f): Light
grey amorphous solid; Yield: 81 %; m.p. 83 °C; m.f.:
C23H21N2O6SBr; M.w.: 532 g mol-1; HR-MS: [M]+ 532.3937
(Calcd. for C23H21N2O6SBr; 532.4032); IR (KBr, cm-1) νmax
:
2-{4-[{[4-(tert-Butyl)phenyl]sulfonyl}(methyl)amino]
phenoxy}-N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide
(6c): Light brown amorphous solid;Yield: 79 %; m.p. 71 °C;
m.f.: C27H30N2O6S; m.w.: 510 g mol-1; HR-MS: [M]+ 510.6034
(Calcd. for C27H30N2O6S; 510.6166); IR (KBr, νmax, cm-1): 3459
(N-H stretching), 3063 (C-H stretching of aromatic ring), 2921
(-CH2- stretching), 1621 (C=C stretching of aromatic ring),
1390 (-SO2 stretching), 1168 (C-O-C stretching of ether); 1H
NMR (CD3OD, 300 MHz): δ (ppm) 7.58 (d, J = 8.4 Hz, 2H,
H-2' & H-6'), 7.47 (d, J = 8.4 Hz, H-3' & H-5'), 7.17 (d, J =
1.8, 1H, H-5'''), 6.95 (dd, J = 8.1, 1.5 Hz, 1H, H-7'''), 6.86 (d,
J = 8.7 Hz,2H, H-2 & H-6), 6.77 (d, J = 8.7 Hz, 1H, H-8'''),
6.68 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s, 4H, CH2-2''' &
CH2-3'''), 3.91 (s, 2H, CH2-2''''), 3.10 (s, 3H, CH3-1''), 1.34 (s,
9H, (CH3)3C-4'); EIMS: m/z 510 [M]+, 446 [M-SO2]+, 197
[(CH3)3CC6H5SO2]+, 150 [C8H8NO2]+, 135 [C8H7O2]+, 133
[(CH3)3CC6H5]+, 122 [C6H4NO2]+, 122 [C7H8NO]+, 107
[C6H3O2]+, 93 [C6H5O]+, 66 [C4H4N]+, 50 [C4H2]+.
3446 (N-H stretching), 3072 (C-H stretching of aromatic ring),
2908 (-CH2- stretching), 1606 (C=C stretching of aromatic
ring), 1376 (-SO2 stretching), 1177 (C-O-C stretching of ether);
1H-NMR (CD3OD, 300 MHz): δ (ppm) 7.76 (d, J = 8.7 Hz,
2H, H-2' & H-6'), 7.51 (d, J = 8.4 Hz, 2H, H-3' & H-5'), 7.15
(d, J = 2.1, 1H, H-5'''), 6.93 (dd, J = 8.4, 1.8 Hz, 1H, H-7'''),
6.87 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.77 (d, J = 8.1 Hz, 1H,
H-8'''), 6.69 (d, J = 8.4 Hz, 2H, H-3 & H-5), 4.21 (s, 4H, CH2-
2''' & CH2-3'''), 3.91 (s, 2H, CH2-2''''), 2.98 (s, 3H, CH3-1'');
EIMS: m/z 534 [M+2]+, 532 [M]+, 468 [M-SO2]+, 219
[BrC6H5SO2]+, 155 [BrC6H5]+, 150 [C8H8NO2]+, 135 [C8H7O2]+,
122 [C6H4NO2]+, 122 [C7H8NO]+, 107 [C6H3O2]+, 93 [C6H5O]+,
66 [C4H4N]+, 50 [C4H2]+.
2-{4-[[(4-Chlorophenyl)sulfonyl](methyl)amino]phenoxy}-
N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide (6g): Dark
brown amorphous solid; Yield: 87 %; m.p. 84 °C; m.f.:
C23H21N2O6SCl; m.w.: 488 g mol-1; HR-MS: [M]+ 488.5415
(Calcd. for C23H21N2O6SCl; 488.5516); IR (KBr, νmax, cm-1):
3447 (N-H stretching), 3072 (C-H stretching of aromatic ring),
2934 (-CH2- stretching), 1606 (C=C stretching of aromatic
ring), 1378 (-SO2 stretching), 1161 (C-O-C stretching of ether);
1H NMR (CD3OD, 300 MHz): δ (ppm) 7.74 (d, J = 8.4 Hz,
2H, H-2' & H-6'), 7.52 (d, J = 8.1 Hz, 2H, H-3' & H-5'), 7.12
(d, J = 2.1, 1H, H-5'''), 6.95 (dd, J = 8.4, 2.1 Hz, 1H, H-7'''),
6.88 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.79 (d, J = 8.4 Hz, 1H,
H-8'''), 6.68 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s, 4H, CH2-
2''' & CH2-3'''), 3.92 (s, 2H, CH2-2''''), 2.98 (s, 3H, CH3-1'');
EIMS: m/z 490 [M + 2]+, 488 [M]+, 424 [M-SO2]+, 175
[ClC6H5SO2]+, 150 [C8H8NO2]+, 135 [C8H7O2]+, 122
[C6H4NO2]+, 122 [C7H8NO]+, 111 [ClC6H5]+, 107 [C6H3O2]+,
93 [C6H5O]+, 66 [C4H4N]+, 50 [C4H2]+.
2-{4-[(Mesitylsulfonyl)(methyl)amino]phenoxy}-N-
(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide (6d): Black
sticky solid;Yield: 81 %; m.f.: C26H28N2O6S; m.w.: 496 g mol-1;
HR-MS: [M]+ 496.5764 (Calcd. for C26H28N2O6S; 496.5824);
IR (KBr, νmax, cm-1): 3468 (N-H stretching), 3062 (C-H stretching
of aromatic ring), 2936 (-CH2- stretching), 1625 (C=C stretching
of aromatic ring), 1395 (-SO2 stretching), 1162 (C-O-C
1
stretching of ether); H NMR (CD3OD, 300 MHz): δ (ppm)
7.11 (d, J = 2.4, 1H, H-5'''), 6.97 (s, 2H, H-3' & H-5'), 6.94
(dd, J = 8.4, 2.1 Hz, 1H, H-7'''), 6.87 (d, J = 8.4 Hz, 2H, H-2 &
H-6), 6.76 (d, J = 8.1 Hz, 1H, H-8'''), 6.67 (d, J = 8.4 Hz, 2H,
H-3 & H-5), 4.21 (s, 4H, CH2-2''' & CH2-3'''), 3.93 (s, 2H,
CH2-2''''), 2.99 (s, 3H, CH3-1''), 2.38 (s, 6H, CH3-2' & 6'), 2.27
(s, 3H, CH3-4'); EIMS: m/z 496 [M]+, 432 [M-SO2]+, 183
[(CH3)3C6H5SO2]+, 150 [C8H8NO2]+, 135 [C8H7O2]+, 122
[C6H4NO2]+, 122 [C7H8NO]+, 119 [(CH3)3C6H5]+, 107
[C6H3O2]+, 93 [C6H5O]+, 66 [C4H4N]+.
2-{4-[[(2,5-Dichlorophenyl)sulfonyl](methyl)amino]
phenoxy}-N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide
(6h): Black amorphous solid;Yield: 82 %; m.p. 146 °C; m.f.:
C23H20N2O6SCl2; m.w.: 522 g mol-1; HR-MS: [M]+ 522.3865
(Calcd. for C23H20Cl2N2O6S; 522.3987); IR (KBr, νmax, cm-1):
3476 (N-H stretching), 3059 (C-H stretching of aromatic ring),
2937 (-CH2- stretching), 1606 (C=C stretching of aromatic
ring), 1393 (-SO2 stretching), 1151 (C-O-C stretching of ether);
1H NMR (CD3OD, 300 MHz): δ (ppm) 7.81 (s, 1H, H-6'),
7.71 (d, J = 8.4 Hz 1H, H-3'), 7.44 (d, J = 8.4 Hz 1H, H-4'),
7.17 (d, J = 2.4, 1H, H-5'''), 6.94 (dd, J = 8.4, 2.4 Hz, 1H, H-
7'''), 6.87 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.77 (d, J = 8.7 Hz,
1H, H-8'''), 6.69 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s, 4H,
2-{4-[{[4-(Acetylamino)phenyl]sulfonyl}(methyl)
amino]phenoxy}-N-(2,3-dihydro-1,4-benzodioxin-6-
yl)acetamide (6e): Brownish grey amorphous solid; Yield:
85 %; m.p. 140 °C; m.f.: C25H25N3O7S; M.w.: 511 g mol-1;
HR-MS: [M]+ 511.5488 (Calcd. for C25H25N3O7S; 511.5574);
IR (KBr, νmax, cm-1): 3467 (N-H stretching), 3034 (C-H
stretching of aromatic ring), 2936 (-CH2- stretching), 1602
(C=C stretching of aromatic ring), 1386 (-SO2 stretching), 1162
(C-O-C stretching of ether); 1H NMR (CD3OD, 300 MHz): δ

Vol. 26, No. 4 (2014)
O- and N-Substituted Derivatives of Planetol as Valuable Bioactive Compounds 1155
CH2-2''' & CH2-3'''), 4.12 (s, 2H, CH2-2''''), 3.10 (s, 3H, CH3-
1''); EIMS: m/z 526 [M + 4]+, 524 [M + 2]+, 522 [M]+, 458
[M-SO2]+, 209 [Cl2C6H5 SO2]+, 150 [C8H8NO2]+, 145
[Cl2C6H5]+, 135 [C8H7O2]+, 122 [C6H4NO2]+, 122 [C7H8NO]+,
107 [C6H3O2]+, 93 [C6H5O]+, 66 [C4H4N]+.
USA.All reactions were performed in triplicates. The positive
and negative controls were included in the assay. Baicalein
(0.5 mM well-1) was used as a positive control. The percentage
inhibition (%) and IC50 values were calculated by the same
method as described cholinesterase enzymes.
2-{4-[Methyl(2-naphthylsulfonyl)amino]phenoxy}-N-
(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide (6i): Light
brown amorphous solid; Yield: 89 %; m.p. 90 °C; m.f.:
C27H24N2O6S; m.w.: 504 g mol-1; HR-MS: [M]+ 504.5552
(Calcd. for C27H24N2O6S; 504.5625); IR (KBr, νmax, cm-1): 3475
(N-H stretching), 3070 (C-H stretching of aromatic ring), 2937
(-CH2- stretching), 1612 (C=C stretching of aromatic ring),
1376 (-SO2- stretching), 1182 (C-O-C stretching of ether); 1H
NMR (CD3OD, 300 MHz): δ (ppm) 8.14 (s, 1H, H-1'), 7.99-
7.93 (m, 2H, H-4' & H-5'), 7.67 (d, J = 8.1 Hz, 1H, H-3'), 7.59
(dd, J = 8.1, 2.1 Hz, 1H, H-8'), 7.49-7.42 (m, 2H, H-6' & H-
7'), 7.17 (d, J = 2.4, 1H, H-5'''), 6.93 (dd, J = 8.7, 2.1 Hz, 1H,
H-7'''), 6.85 (d, J = 8.7 Hz, 2H, H-2 & H-6), 6.78 (d, J = 8.4
Hz, 1H, H-8'''), 6.67 (d, J = 8.7 Hz, 2H, H-3 & H-5), 4.21 (s,
4H, CH2-2''' & CH2-3'''), 3.91 (s, 2H, CH2-2''''), 3.16 (s, 3H,
CH3-1''); EIMS: m/z 504 [M]+, 440 [M-SO2]+, 191 [C10H7SO2]+,
150 [C8H8NO2]+, 135 [C8H7O2]+, 127 [C10H7]+, 122 [C6H4NO2]+,
122 [C7H8NO]+, 107 [C6H3O2]+, 93 [C6H5O]+, 66 [C4H4N]+.
Cholinesterase assays: The acetyl cholinesterase and
butyryl cholinesterase inhibition activities were executed
according to the reported method22 with small modifications.
A volume of 100 µL comprising 60 µL Na2HPO4 buffer with
concentration of 50 mM (pH 7.7), 10 µL test compound (0.5
mM well-1) and 10 µL (0.005 unit well-1 for acetyl choline-
sterase and 0.5 unit well-1 for butyryl cholinesterase) enzyme
was developed. This homogeneous mixture was pre-read at
405 nm followed by pre-incubation for 10 min at 37 ºC. The
reaction was started by the addition of 10 µL of 0.5 mM well-1
substrate (acetylthiocholine iodide for acetyl cholinesterase
and butyrylthiocholine chloride for BChE) and the addition
of 10 µL DTNB (0.5 mM well-1). After 15 min of incubation
at 37 ºC absorbance was measured at 405 nm using 96-well
plate reader Synergy HT, Biotek, USA. All experiments were
carried out with their respective controls in triplicate. Eserine
(0.5 mM well-1) was used as a positive control. The percent
inhibition was calculated by the following equation
Antibacterial assay: The antimicrobial activity was
determined following the principle that increased absorbance
of broth medium is directly related to log phase of growth and
was performed in sterile 96-wells microplates under aseptic
conditions24,25. Three Gram-negative (Escherichia coli,
Pseudomonas aeruginosa and Salmonella typhii) and two
Gram-positive bacteria (Bacillus subtilis, Staphylococcus
aureus) were included in the study and were maintained on
stock culture agar medium. The test samples (with suitable
solvents and dilutions) 20 µg/well and 180 µL fresh bacterial
culture (with suitable dilution by fresh nutrient broth) was
poured into wells to make a volume of 200 µL. The initial
absorbance of the culture was kept 0.12-0.19 at 540 nm. The
absorbance was measured at 540 nm using microplate reader,
before and after incubation at 37 °C for 16-24 h with lid on
the microplate. The difference was related to bacterial growth.
The percent inhibition was calculated using the formula,
X – Y
Inhibition (%) =
×100
X
where, X is absorbance in control with bacterial culture and
Y is absorbance in test sample. Results are mean of triplicate
(n = 3, sem). Ciprofloxacin was taken as reference standard.
Minimum inhibitory concentration (MIC) was measured with
suitable dilutions (5-30 µg/ well) and results were calculated
using EZ-Fit Perrella Scientific Inc. Amherst USA software.
Statistical analysis:All the measurements were executed
in triplicate and statistical analysis was performed by microsoft
excel 2010. Results are presented as mean sem.
Protein preparation: The protein molecules included in
our study, acetyl cholinesterase, butyryl cholinesterase and
lipoxygenase were retrieved from protein data bank. Water
molecules were removed and the 3D protonation of the protein
molecule was performed using MOE applications. The energy
of the protein molecules were minimized via energy mini-
mization algorithm of MOE tool. The following parameters
were used for energy minimization; gradient: 0.05, Force Field:
MMFF94X+Solvation, Chiral Constraint: Current Geometry.
Energy minimization was terminated when the root mean
square gradient falls below the 0.05. The minimized structure
was used as the template for Docking.
Control – Test
Inhibition (%) =
×100
Control
where control is the activity without inhibitor and test is the
activity in the presence of test compound. IC50 values were
calculated using EZ-Fit Enzyme kinetics software (Perrella
Scientific Inc. Amherst, USA). The IC50 values were the
average of three independent experiments.
Molecular docking: The binding mode of the ligands
into the binding pocket of protein molecule was predicted by
MOE-Dock implemented in MOE. After the completion of
docking we analyze the best poses for hydrogen bonding/π-π
interactions by using MOE applications21.
Lipoxygenase assay: Lipoxygenase (LOX) activity was
assayed according to the reported method of Baylac & Racine23
with small modifications. Total volume of lipoxygenase assay
mixture was 200 µL containing 150 µL Na3PO4 buffer (100
mM and pH 8), 10 µL test compound (0.5 mM well-1) and
15 µL (600 units well-1) enzyme. The contents were mixed,
pre-read at 234 nm and pre-incubated for 10 min at 25 °C.
The reaction was initiated by addition of 25 µL substrate
solution. The change in absorbance was observed after 6 min
at 234 nm using 96-well plate reader Synergy HT, Biotek,
RESULTS AND DISCUSSION
The sulfamoyl and acetamoyl functionalities have been
successfully geared up through a series of benignant methods
by the protocol sketched in Scheme-I.All the procedures with
reaction conditions are mentioned in experimental section. The
synthesized molecules were evaluated for the anti-enzymatic
and antibacterial activities and found to be valuable potent

1156 Irshad et al.
Asian J. Chem.
CH3
NH
1''
CH3
N
R
O
O
I
5
1
S
S
O
O
3
Cl
R
HO
HO
3a-i
1
2a-i
2'
CH2
1'
O
O
4
NH
NH2
II
5
C
Br
1
O
8
O
O
III
5
4
1''
CH3
R
N
2'''
S
1
5
1'''
O
4'''
NH
CH2
O
3
O
5'''
8'''
C
O
1''
O
O
6a-i
Reagents and conditions: (I) Na2CO3/H2O, stirring for 4-5 h, pH = 8-10 (II)
Na2CO3/H2O, 2-bromoacetyl bromide stirring for 30 min, pH = 8-10 (III) LiH/DMF,
stirring for 5-6 h
Compd.
3a,6a
R
Compd.
3e,6e
R
Compd.
3i,6i
R
6'
6'
O
1'
4'
7'
9'
2'
2'
4'
4'
5'
N
H
H3C
6'
6'
2'
4'
2'
3b,6b
3c,6c
3d,6d
3f.6f
3g,6g
3h,6h
4'
H C
3
Br
6'
6'
2'
2'
4'
H C
3
4'
C
Cl
Cl
H C
3
CH
3
6'
CH3
2'
4'
6'
2'
Cl
4'
CH3
H3C
Scheme-I: Synthesis of O- and N-substituted derivatives of planetol
molecules as evident from their IC50 (Table-1) and MIC (Table-
2) values respectively.
get rid of unreacted amine and also to enhance the yield but
excess of it was obviated because of decrement in yield. The
synthesized molecules 3a-i, were further treated with N-(2,3-
dihydro-1,4-benzodioxin-6-yl)-2-bromoacetamide (5) to yield
the final products 6a-i, in a weak basic aprotic polar medium.
The products 6a-i, were collected after basifying the reaction
mixture in order to remove unreacted 3a-i molecules. The
electrophile 5, was prepared by the vigorous reaction of 2,3-
dihydro-1,4-benzodioxin-6-amine (4) with the 2-bromoacetyl
bromide in a basic medium and was also collected after
acidification. The structures of all the synthesized compounds
The presented research work is comprised of three major
steps. First N-(4-hydroxyphenyl)-N-methylarylsulfonamides
(3a-i) were synthesized by the reaction of N-methyl-4-
hydroxyanilinium sulfate (1) and different aryl sulfonyl
chlorides (2a-i) in a weak basic aqueous medium. The reaction
was processed in basic media with pH of 8-10 to avoid the
capturing of lone pair present at nitrogen by the acid produced
which suppresses the nucleophilic character and also the rate
of reaction. The products were separated after acidification to

Vol. 26, No. 4 (2014)
O- and N-Substituted Derivatives of Planetol as Valuable Bioactive Compounds 1157
TABLE-1
PERCENTAGE INHIBITION AND IC50 VALUES FOR ENZYME INHIBITION ACTIVITY OF SYNTHESIZED MOLECULES
AChE
BChE
LOX
Compd
Inhibition (%)
70.75 1.11
93.49 1.22
93.41 0.81
89.92 0.91
79.88 0.86
85.24 0.86
93.53 1.21
87.82 1.16
94.92 0.91
82.58 0.96
83.69 0.98
35.56 0.53
98.10 0.97
96.15 1.12
93.69 0.84
81.94 1.25
77.78 0.95
85.48 1.19
95.63 1.14
91.29 1.17a
IC50 (µM)
Inhibition (%)
51.82 0.52
88.88 0.96
88.41 1.13
81.18 0.89
79.53 0.97
81.53 1.19
90.82 0.93
86.88 1.12
85.18 0.92
84.53 0.89
60.65 1.11
31.47 0.36
96.43 0.87
83.76 0.87
93.43 0.96
86.10 0.98
51.41 0.66
86.71 1.15
89.12 0.81
82.82 1.09a
IC50 (µM)
489.12 0.59
170.10 0.62
66.30 0.89
187.54 0.74
208.33 0.72
239.64 0.84
140.21 0.47
221.42 0.69
48.11 0.59
338.81 0.43
447.42 0.58
>500
Inhibition (%)
37.92 0.17
37.71 0.16
73.29 0.65
44.79 0.45
66.46 0.12
73.02 0.16
93.71 0.82
93.75 0.42
96.25 1.45
14.90 0.25
47.81 0.38
89.48 0.11
86.75 0.85
33.54 0.65
75.61 0.96
79.80 0.38
47.80 0.63
70.15 0.55
99.64 1.85
93.79 1.27b
IC50 (µM)
-
153.83 0.82
21.62 0.53
59.10 0.61
135.22 0.69
135.62 0.32
62.81 0.63
90.52 0.82
132.86 0.75
93.13 0.62
270.81 0.73
231.34 0.45
>500
3a
3b
3c
-
365.5 0.32
>500
3d
3e
308.1 0.75
194.3 0.54
174.7 0.35
169.3 0.86
306.8 0.95
-
3f
3g
3h
3i
5
>500
6a
335.6 0.21
253.7 0.95
-
6b
6c
109.11 0.79
161.83 0.81
87.53 0.49
183.11 0.89
206.77 0.79
145.81 0.93
168.11 0.91
0.04 0.0001a
172.23 0.57
302.31 0.78
133.93 0.77
62.10 0.52
494.23 0.41
217.41 0.92
135.92 0.72
0.85 0.0001a
6d
6e
351.9 0.12
323.8 0.45
>500
6f
6g
385.1 0.54
73.12 1.99
22.4 1.3b
6h
6i
Control
Note: IC50 values (concentration at which there is 50% enzyme inhibition) of compounds were calculated using EZ–Fit Enzyme kinetics software
(Perella Scientific Inc. Amherst, USA). AChE = Acetyl cholinesterase BChE = Butyrylcholinesterase LOX = Lipoxygenase a = Eserine b =
Baicalein
TABLE-2
PERCENTAGE INHIBITION AND MIC VALUES OF ANTIBACTERIAL ACTIVITY OF SYNTHESIZED MOLECULES
S. typhi (-)
% age
E. coli (-)
P. aeroginosa (-)
% age
inhibition
11.66 3.22 56.63 2.50 16.96 5.00 47.67 3.40
B. subtili (+)
S. aureus (+)
% age
% age
inhibition
% age
MIC
MIC
MIC
MIC
MIC
inhibition
71.16 0.18
53.96 1.52
64.82 1.40
55.98 3.05
53.05 2.93
44.82 3.60
29.57 4.23
61.40 2.26
60.67 1.52
85.67 0.18
44.76 4.98
75.30 0.06
69.33 1.40
53.84 0.06
43.96 3.43
70.43 4.72
64.15 1.34
82.01 1.16
73.54 0.85
90.98 1.43
inhibition
47.64 2.21
46.57 0.57
inhibition
68.07 1.13
53.27 2.47
69.67 1.53
61.33 1.20
63.47 1.33
50.20 1.27
49.33 2.93
67.47 0.00
67.47 3.60
85.47 0.00
54.40 3.47
63.87 0.40
67.73 0.13
59.87 0.93
58.40 1.33
78.33 1.13
66.93 0.40
81.80 0.87
80.80 0.40
91.65 1.04
11.03 2.00
16.08 3.64
10.64 3.55
11.55 1.82
11.82 2.76
19.70 4.18
-
-
-
-
-
-
-
-
-
-
-
-
3a
3b
3c
3d
3e
3f
18.32 2.76 49.63 4.50
13.56 3.89 48.31 4.31
-
-
41.07 0.67
44.60 1.67
52.29 4.14 18.44 4.64
59.43 4.71 13.83 1.98
14.49 4.05 51.50 1.25 19.33 4.17 46.80 1.73
16.62 4.17 60.00 0.38 17.30 5.00 35.07 0.40
47.36 0.36
38.07 0.93
40.93 2.93
-
-
-
-
-
43.94 1.94
44.06 0.06
-
-
32.33 2.60
24.73 1.80
3g
3h
3i
10.85 4.73
11.02 1.54
10.79 1.73
11.98 2.09
11.26 3.13
10.24 2.52
13.36 1.87
14.76 3.73
10.98 1.76
11.94 3.00
10.43 2.64
10.88 4.09
9.22 1.36
14.83 2.33 58.94 0.19 16.99 5.00 38.53 0.40
15.91 1.67 44.88 2.75 49.00 1.40
55.43 4.71 16.01 2.73
49.43 0.14
-
-
11.32 3.89 77.13 0.00 10.64 2.43 84.00 0.93 10.64 1.40 86.14 0.86 10.46 1.77
5
-
48.00 1.00
-
30.73 0.33
-
-
37.50 3.93
-
6a
6b
6c
6d
6e
6f
15.43 3.56 57.19 1.06 17.83 3.83 30.93 0.00
55.14 2.71 18.14 1.44
10.69 3.72 54.06 1.44 16.58 3.33 61.87 4.27 12.87 1.28 59.14 0.57 14.80 2.31
17.43 2.44 37.63 0.25
-
35.60 4.13
-
-
42.57 4.57
-
-
57.31 1.81 17.41 5.00 41.73 4.27
56.93 2.36 17.52 2.00
12.19 2.39 65.13 1.38 13.05 4.50 60.00 1.20 12.52 2.36 62.86 4.00 12.11 3.91
10.82 1.06 58.13 0.63 18.47 4.08 42.53 1.87 51.00 1.57 17.44 3.27
-
6g
6h
6i
10.83 1.41 67.13 0.25 10.46 2.67 69.20 2.27 11.65 1.42 60.93 1.36 14.22 2.42
11.90 4.22 65.88 1.00 12.39 1.17 73.27 1.40 11.41 1.47 69.93 2.79 11.25 2.12
8.79 2.00
90.46 1.99
8.93 2.42
89.90 0.79
9.43 1.87
92.04 1.44
9.04 1.50
Ci
Note: Minimum inhibitory concentration (MIC) was measured with suitable dilutions (5-30 µg/ well) and results were calculated using EZ-
FitPerrella Scientific Inc. Amherst USA software; Ci = Ciprofloxacin.
were confirmed through spectral analysis as depicted in
experimental section. The physical data for the final product
6a is given in experimental section. The HR-MS provided a
[M]+ peak at 454.4975 (Calcd. for C23H22N2O6S; 454.5031).
The molecular formula C23H22N2O6S was also supported by
molecular ion peak at m/z 454 in EIMS and the number of
protons in its 1H NMR spectrum. The peaks of EIMS spectrum
which well supported the molecule, were m/z 150, 141 and
121 for the cations of 2,3-dihydro-1,4-benzodioxin-6-amino
group, phenylsulfonyl group and 4-(methylamino)phenoxy
group respectively. The IR spectrum supported the structure
by two characteristics absorption bands at 3462 cm-1 and 1381

1158 Irshad et al.
Asian J. Chem.
cm-1 for N-H (stretching) of amide and S=O (stretching) of
sulfonyl group, respectively. Benzene sulfonyl ring was confir-
med by two signals in the aromatic region of 1H NMR spectrum
appearing at δ 7.64 (dd, J = 7.8, 1.8 Hz, 2H, H-2' & H-6') and
7.51-7.41 (m, 3H, H-3' to H-5'). The benzodioxine ring was
supported by four signals, three in aromatic region and one in
aliphatic region, at δ 7.17 (d, J = 2.4, 1H, H-5'''), 7.02 (dd, J =
8.4, 1.2 Hz, 1H, H-7'''), 6.99 (d, J = 7.5 Hz, 1H, H-8''') and
4.21 (s, 4H, CH2-2''' & CH2-3'''). The two doublets resonating
at δ 6.97 (d, J = 8.1 Hz, 2H, H-2 & H-6) and 6.78 (d, J = 8.7
Hz, 2H, H-3 & H-5) were assigned to the protons of 1,4-
disubstituted phenyl ring. In the aliphatic region of the 1H NMR
spectrum, the two singlets, appearing at δ 3.92 (s, 2H, CH2-
2'''') and 3.14 (s, 3H, CH3-1'') in 2:3 ratio, indicated the presence
of two methylene and three methyl protons in the molecule.
The proposed structure of 6a was corroborated and named, 2-
{4-[methyl(phenylsulfonyl) amino]phenoxy}-N-(2,3-dihydro-
1,4-benzodioxin-6-yl)-acetamide. Likewise, the structures of
other synthesized compounds were characterized. The mass
fragmetation pattern of 6a is given in Fig. 1.
Enzyme inhibition activity: The results of screening
against all the three enzymes are presented in Table-1 in the
O
O
O
S
CH3
N
O
CH2
C
NH
O
O
[M]+ m/z = 454
C10H9NO3
C17H17N2O4
C15H14NO4S
O
S
CH3
N
O
O
S
OH
NH
O
O
O
m/z = 150
m/z = 141
m/ z = 263
NH
SO2
C6H5SO2
O
CH3
N
OH
O
m/z = 122
m/ z = 135
m/z = 77
CH3N
C2H4
C2H2
O
OH
O
m/z = 107
m/z = 51
m/z = 93
Fig. 1. Mass fragmentation pattern of 2-{4-[methyl(phenylsulfonyl)amino]phenoxy}-N-(2,3-dihydro-1,4-benzodioxin-6-yl)acetamide
(6a)

Vol. 26, No. 4 (2014)
O- and N-Substituted Derivatives of Planetol as Valuable Bioactive Compounds 1159
form of % age inhibition and IC50 values. The screening of
synthesized molecules against acetyl cholinesterase enzyme
showed that all the molecules exhibited promising inhibitory
action and 3b was the most prominent with the lowest IC50
value of 21.62 0.53 µM relative to the reference standard,
eserine, with IC50 value of 0.04 0.0001 µM. Only 6b molecule
remained inactive as evident from IC50 value. Butyryl choline-
sterase enzyme was also promisingly inhibited by all the
molecules except 6b. 3i was the most active against this enzyme
by the IC50 value of 48.11 0.59 µM relative to reference
standard, eserine, with IC50 value of 0.85 0.0001 µM. The
most potent molecules against both the cholinesterase enzymes
were 3c and 3i with the structural features of p-substituted
tertiary methyl and naphthyl group interacting at large area
respectively.Against lipoxygenase enzyme, some were inactive
and most of them showed moderate inhibitory action. The most
potent molecule against this enzyme was 6i with IC50 value of
73.12 1.99 µM relative to baicalein with IC50 value of 22.4
1.3 µM.
Fig. 2. 2D interaction analysis of docked compound 3b against acetyl
cholinesterase
case of butyryl cholinesterase revealed that two important
moieties are contributing in the interactions. Asn 85 interacts
with the phenol moiety whereas; His126 interacts with
sulfonamide group directly as well as through water molecule
(Fig. 3).
Antibacterial activity: All the synthesized molecules
were screened against three Gram-negative and two Gram-
positive bacterial strains and were found to be moderate
inhibitors. The results are tabulated as (%) inhibition and MIC
values in Table-2. Most of the compounds showed activities
against the both Gram-positive bacterial strains except a few.
Almost all the compounds showed the same inhibition potential
against S. typhi and E. coli, as that of the reference standard,
ciprofloxacin used. P. aeroginosa and S. aureus were inhibited
by the majority of the molecules with 50 % inhibitory action
as that of the reference used. The synthesized molecules, 5,
6f, 6h and 6i were active against all the bacterial strains with
much low MIC values, credibly because of the presence of
bromo group at 2nd carbon of acetyl group, bromo group at 4th
position of phenyl group, two chloro groups at 2nd and 5th
position of phenyl group and naphthyl group, respectively.
The aromatic naphthyl rings are responsible for more
interaction and the halogens in better positions are creditworthy
for the antibacterial inhibition potential.
Fig. 3. 2D interaction analysis of compound 3c with butyryl cholinesterase
Computational analysis of a potent compound 6i
against lipoxygenase (LOX):All the compounds were compu-
tationally docked against lipoxygenase as well, a similar sort
of interactions was observed in case of lipoxygenase. Here,
compound 6i is shown in Fig. 4. A total of six interactions
were observed with five residues of the binding site. Val 566
interacts with oxygen of sulfonamide moiety, whereas rest of
other five interactions was observed with acetamide moiety.
His513, His518, Gln514 and Gln716 are other interacting
residues of the active site shown in Fig. 4.
Computational analysis of potent compounds against
acetyl cholinesterase (AchE) and butyryl cholinesterase
(BChE): The synthesized compounds were computationally
docked against the active site of acetyl cholinesterase and
butyryl cholinesterase to find out their binding modes. All the
compounds showed good binding pattern, 3b is discussed for
acetyl cholinesterase and 3c for butyryl cholinesterase as below.
Interaction analysis of compound 3b against acetyl
cholinesterase: One of the potent compound 3b showed very
decent interaction with the active site of the target protein acetyl
cholinesterase. A total of six interactions were observed with
five residues of the active sites. Tyr 70,Asp72, Trp 84 andAsn
85 made interaction with the phenol ring. However, Trp 84
also interacts with the toluene moiety through arene-hydrogen
bonding. Ser 122 interacts with sulfonamide group and makes
the interaction of compound stronger (Fig. 2). So, in this
interaction analysis we observed that three different moieties
of compound are contributing in the interaction between ligand
and protein.
Conclusion
All the compounds were synthesized in good yields by
the depicted methods in experimental section. The proposed
structures were corroborated by the spectroscopic analysis
using IR, 1H NMR and EIMS techniques. All the synthesized
compounds were evaluated for the enzyme inhibition and
antibacterial activities. The IC50 values of these molecules
rendered them better inhibitors of cholinesterase enzymes and
moderately less inhibitors of lipoxygenase enzyme. The MIC
values of taken into account molecules against the different
Interaction analysis of compound 3c against butyryl
cholinesterase: The interaction analysis of compound 3c in

1160 Irshad et al.
Asian J. Chem.
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ACKNOWLEDGEMENTS
The authors are thankful to the Higher Education Comm-
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acknowledgements are also due to Dr.AbdulWadood, Chairman
Department of Biochemistry, Abdul Wali Khan University
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