Synthesis of Novel Bi-Heterocycles as Valuable Anti-Diabetic Agents: 2-({5-((2-Amino-1,3-Thiazol-4-yl)methyl)-1,3,4-Oxadiazol-2-yl}sulfanyl)-N-(Substituted)acetamides

Article abstract of DOI:10.1134/S1068162020040020

Abstract: The synthesis of a new series of S-substituted acetamides derivatives of 5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-thiol were synthesized and evaluated for enzyme inhibition study along with cytotoxic behavior. Ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate was converted to corresponding acid hydrazide by hydrazine hydrate in ethanol. The reflux of acid hydrazide with carbon disulfide resulted to 5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-thiol. Different electrophiles were synthesized by the reaction of respective anilines (one in each reaction) and 2-bromoacetylbromide in an aqueous medium. The targeted bi-heterocyclic compounds were synthesized by stirring nucleophilic 5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-thiol with different acetamides electrophiles (one after another), in DMF using LiH as base and activator. The proposed structures of newly synthesized compounds were deduced by spectroscopic techniques such as ¹H NMR, ¹³C NMR, EI MS and elemental analysis. These novel bi-heterocycles were tested for their anti-diabetic potential via the in vitro inhibition of α-glucosidase enzyme. The in silico study of these molecules was also coherent with their enzyme inhibition data. Furthermore, these molecules were analyzed for their cytotoxic behavior against brine shrimps. It was inferred from the results that most of them exhibited very potent inhibitory potential against the studied enzyme and can be utilized as valuable anti-diabetic agent.

Full text of DOI:10.1134/S1068162020040020

ISSN 1068-1620, Russian Journal of Bioorganic Chemistry, 2020, Vol. 46, No. 4, pp. 590–598. © Pleiades Publishing, Ltd., 2020.
Synthesis of Novel Bi-Heterocycles as Valuable Anti-Diabetic Agents:
2-({5-((2-Amino-1,3-Thiazol-4-yl)methyl)-1,3,4-Oxadiazol-2-
yl}sulfanyl)-N-(Substituted)acetamides
Muhammad Athar Abbasia, 1, Muhammad Shahid Ramzana, Aziz-ur-Rehmana,
Sabahat Zahra Siddiquia, Syed Adnan Ali Shahb, Muhammad Arif Lodhic,
Farman Ali Khanc, and Bushra Mirzad
aDepartment of Chemistry, Government College University, Lahore, 54000 Pakistan
bFaculty of Pharmacy and Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Level 9, FF3,
Universiti Teknologi MARA, Puncak Alam Campus, Bandar Puncak Alam, Selangor Darul Ehsan, 42300 Malaysia
cDepartment of Biochemistry, Abdul Wali Khan University, Mardan, 23200 Pakistan
dDepartment of Biochemistry, Quaid-i-Azam University, Islamabad, 45320 Pakistan
Received December 2, 2019; revised January 13, 2020; accepted January 16, 2020
Abstract—The synthesis of a new series of S-substituted acetamides derivatives of 5-[(2-amino-1,3-thiazol-
4-yl)methyl]-1,3,4-oxadiazol-2-thiol were synthesized and evaluated for enzyme inhibition study along with
cytotoxic behavior. Ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate was converted to corresponding acid hydra-
zide by hydrazine hydrate in ethanol. The reflux of acid hydrazide with carbon disulfide resulted to 5-[(2-
amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-thiol. Different electrophiles were synthesized by the
reaction of respective anilines (one in each reaction) and 2-bromoacetylbromide in an aqueous medium. The
targeted bi-heterocyclic compounds were synthesized by stirring nucleophilic 5-[(2-amino-1,3-thiazol-4-
yl)methyl]-1,3,4-oxadiazol-2-thiol with different acetamides electrophiles (one after another), in DMF
using LiH as base and activator. The proposed structures of newly synthesized compounds were deduced by
spectroscopic techniques such as 1H NMR, 13C NMR, EI MS and elemental analysis. These novel bi-het-
erocycles were tested for their anti-diabetic potential via the in vitro inhibition of -glucosidase enzyme. The
α
in silico study of these molecules was also coherent with their enzyme inhibition data. Furthermore, these
molecules were analyzed for their cytotoxic behavior against brine shrimps. It was inferred from the results
that most of them exhibited very potent inhibitory potential against the studied enzyme and can be utilized as
valuable anti-diabetic agent.
Keywords: ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate, 1,3,4-oxadiazole, acetamide, enzyme inhibition,
molecular docking, cytotoxicity
DOI: 10.1134/S1068162020040020
INTRODUCTION
activities [8–13]. Oxadiazoles have played an import-
ant role in medicinal chemistry, pesticide chemistry,
polymer and display remarkable biological activities,
such as antimicrobial, anti-HIV, antitubercular, anti-
malarial, analgesic, anti-inflammatory [14–20].
Alpha-glucosidase inhibitors (AGIs) are drugs that
inhibit the absorption of carbohydrates from the gut
and may be used in the treatment of patients with type
2 diabetes or impaired glucose tolerance [21]. AGIs
inhibitors such as acarbose and miglitol, have been
approved for clinical use in the management of type-2
diabetes, as well as in the treatment of diabetic compli-
cations.
Thiazole derivatives are used as drugs in treatment
of cancer, lowering blood pressure and treatment of
infection [1]. The in vitro potency of some thiazole
derivatives has been proven to inhibit the bacterial
pathogens [2]. A large number of thiazole derivatives
have been incorporated into a wide variety of biologi-
cal activities such as antibacterial, antifungal, antitu-
bercular, anti-mycobacterial, anticancer, antiviral
ones [3–7]. 1,3,4-Oxadiazole is an important hetero-
cycle and its different derivatives possess an extensive
spectrum of pharmacological activities such as antivi-
ral, antibacterial, antitumor, antituberculosis, anti-
inflammatory, anticonvulsant and anti-Alzheimer
One of the key objectives of organic and medicinal
chemists is to design and synthesize the molecules
having potent therapeutic values. The rapid develop-
ment of resistance to existing drugs generated a serious
1 Corresponding author: phone: (+92)-42-111000010; e-mail:
atrabbasi@yahoo.com; abbasi@gcu.edu.pk
590

SYNTHESIS OF NOVEL BI-HETEROCYCLES
Table 1. Different substituents (–R) in Scheme 1
591
O
C
5'
O
2'
1'
S
6
R
N3 4
1
S
N4'3'
1"
N
H
2"
2
5
N
H2N
VIIa−m
Compound
–R
Compound
–R
CH3
3"'
5"'
7"'
1"'
IVa, VIa, VIIa
H2C
7"'
IVg, VIg, VIIg
3"'
1"'
5"'
CH3
7"'
3"'
5"'
IVb, VIb, VIIb
IVc, VIc, VIIc
IVh, VIh, VIIh
IVi, VIi, VIIi
1"'
CH3
3"'
5"'
7"'
1"'
CH3
8"'
CH3
8"'
H3C 7"'
H2C7"'
3"'
5"'
1"'
3"'
5"'
1"'
8"'
CH3
9"'
H3C
7"' 8"'
H3C
CH3
3"'
IVd, VId, VIId
IVe, VIe, VIIe
IVj, VIj, VIIj
1"'
CH2 CH3
3"'
1"'
5"'
8"'
7"'
5"'
CH3
CH3
7"'
8"'
H2C 7"'
3"'
1"'
IVk, VIk, VIIk
5"'
3"'
5"'
8"'
CH3
1"'
CH2 CH3
7"'
8"'
O
3"'
IVf, VIf, VIIf
IVl, VIl, VIIl
1"'
5"'
3"'
1"'
5"'
O
7"'
CH3
8"'
O C
IVm, VIm, VIIm
3"'
5"'
1"'
challenge to the scientific community. Consequently, tial. The synthesis was initiated with ethyl 2-(2-
there is a vital need for the development of new thera-
peutic agents having potent activity. So, it prompted us
to synthesize some new bi-heterocycles by the amalga-
mation of thiazole and 1,3,4-oxadiazole heterocyclic
cores to serve as possible lead compounds.
amino-1,3-thiazol-4-yl)acetate (I) which was refluxed
with hydrazine hydrate in methanol to acquire corre-
sponding acid hydrazide, II. This nucleophilic substi-
tution reaction was completed in two hours. The acid
hydrazide, II, was made to react with carbon disulfide
in the presence of KOH, an activator for cyclization, to
yield
5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-
RESULTS AND DISCUSSION
oxadiazol-2-thiol (III). The different acetamides,
VIa–m, were synthesized as electrophiles by stirring
substituted amines, IVa–m, with 2-bromoacetylbro-
mide (V) in a weak basic aqueous medium. Finally, the
Chemistry
Different thiazole derivatives bearing 1,3,4-oxadi-
azole were synthesized (Scheme 1 and Table 1) in a
series of steps and evaluated for their biological poten- target compounds, VIIa–m, were synthesized by stir-
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 46 No. 4 2020

592
MUHAMMAD ATHAR ABBASI et al.
(C=N stretching) cm–1. The 3,4-dimethylphenyl moi-
ety of the molecule was ascribed in its 1H NMR spec-
trum by three signals in aromatic region at δ 7.34 (br.s,
1H, H-2'''), 7.26 (br.d, J = 8.1 Hz, 1H, H-6'''), and
7.06 (br.d, J = 8.1, H-5''') along with two methyl singlets
in aliphatic region at δ 2.18 (s, 3H, CH3-8''') and 2.16 (s,
3H, CH3-7'''). The 2-amino-1,3-thiazol-4-yl heterocy-
cle was characterized by two signals at δ 6.99 (br.s, 2H,
–NH2), and 6.38 (s, 1H, H-5). A signal at δ 4.03 (br.s,
2H, CH2-6) was assignable to a methylene group con-
necting the two heterocycles in the molecule [22]. The
remaining two signals δ 10.21 (s, 1H, –CONH), and
4.23 (br.s, 2H, CH2-2'') were characteristic of the C-
and N-substituted acetamidic moiety in the molecule
[23]. All these assignments are also substantiated by its
13C NMR spectrum which exhibited overall sixteen
carbon resonances. The 2-amino-1,3-thiazol-4-yl
heterocycle was clearly indicated by two quaternary
signals at δ 163.03 (C-2), and 143.90 (C-4), along with
a methine signal at δ 103.12 (C-5) [24]. Similarly, the
other heterocycle i.e. (5-substituted-1,3,4-oxadiazol-
2-yl)sulfanyl was also signified by two quaternary sig-
nals at δ 168.74 (C-2') and 165.66 (C-5') while a meth-
ylene connecting the two heterocycle was obvious at δ
27.52 (C-6) [22]. The 3,4-dimethylphenyl moiety was
also apparent with three quaternary signals at δ 138.34
(C-1'''), 136.41 (C-3'''), and 131.41 (C-4'''), along with
three methine signals at δ 129.62 (C-5'''), 120.35 (C-
2'''), and 116.68 (C-6''') while the two methyl carbon
resonances appeared at δ 19.57 (C-7''') and 18.74 (C-
8'''). The C- and N-substituted acetamidic moiety in
the molecule was corroborated by a quaternary signal
at δ 164.34 (C-1'') and a methylene signal at δ 36.64
(C-2'') [24]. These structural units of the molecule
were also fully coherent with various fragment ion
peaks observed in its EI-MS spectrum. On the basis of
whole consolidated discussion, the structure of VIIb
was confirmed and it was named as 2-({5-[(2-amino-
1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-yl}sulfa-
Table 2. Percent inhibition at 0.5 mM and IC50 values
against α-glucosidase enzyme
α-Glucosidase inhibition
Compd.
IC50, μM
inhibition, %
VIIa
VIIb
VIIc
VIId
VIIe
VIIf
VIIg
VIIh
VIIi
VIIj
VIIk
VIIl
VIIm
Acarbose
89.34 0.17
91.56 0.18
26.25 0.14
91.78 0.16
92.57 0.17
51.48 0.14
91.23 0.15
71.42 0.21
87.82 0.17
75.36 0.24
76.25 0.22
87.42 0.17
77.67 0.13
92.23 0.16
28.52 0.11
14.38 0.12
–
15.47 0.11
18.29 0.13
>500
16.29 0.12
57.45 0.16
35.62 0.12
37.67 0.18
45.42 0.17
23.25 0.12
26.52 0.21
37.38 0.12
All compounds were dissolved in methanol and experiments were
performed in triplicate (mean sem, n = 3).
ring III with different electrophiles, VIa–m, in DMF
using LiH as base and activator. The molecular struc-
tures of these derivatives were well corroborated by IR,
1
13
EI MS, H NMR and C NMR data. The structural
analysis of one of the compounds is discussed hereby
in detail for the benefit of the reader. The molecular
formula, C16H17N5O2S2, of VIIb was established
through EI MS spectrum showing molecular ion peak
at m/z 375, and by counting the number of protons in
1
its H NMR spectrum. The number of the carbon
atoms resonating in its 13C NMR spectrum was also in
agreement with the deduced molecular formula. The
prominent absorption bands in IR spectrum appeared
at ν 3360 (N–H stretching), 3045 (C–H of aromatic
ring), 2920 (‒CH2– stretching), 1660 (C=O stretch-
nyl)-N-(3,4-dimethylphenyl)acetamide.
Similar
approach was exercised for the structural analysis of all
ing), 1570 (C=C stretching of aromatic ring) and 1545 the synthesized bi-heterocycles.
Table 3. Brine shrimp activity
LD50, mM
LD50, mM
LD50, mM
Compd.
Compd.
Compd.
VIIa
VIIb
VIIc
VIId
VIIe
350.9
443.2
213.5
398.4
155.4
VIIf
VIIg
VIIh
VIIi
VIIj
458.1
498.8
344.1
199.1
21.8
VIIk
VIIl
151.7
245.7
287.4
5.21
VIIm
Doxorubicin
Doxorubicin was used as standard.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY
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SYNTHESIS OF NOVEL BI-HETEROCYCLES
593
NH NH2
O
CH3
C
O
C
O
(a)
N
N
I
II
H2N
H2N
S
S
Ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate
2-(2-Amino-1,3-thiazol-4-yl)acetohydrazide
(b)
O
5'
O
3'
N
O
2'
6
1'
R
S
C
SH
N3 4
1
N
N4'
N
(d)
1''
N
H
2''
5
2
N
H2N
H2N
S
S
III
VIIa−m
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-
1,3,4-oxadiazol-2-yl}sulfanyl)-
N-(substituted)acetamides
5-[(2-Amino-1,3-thiazol-4-yl)methyl]-
1,3,4-oxadiazole-2-thiol
O
C
(c)
R
Br
R
NH2
IVa−m
Amines
N
H
V
VIa−m
2-Bromo-N-(substituted)acetamides
Scheme 1. Outline for the synthesis of 2-({5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-yl}sulfanyl)-
N-(substituted)acetamides (VIIa–m). Reagents and conditions: (a) MeOH/N2H4 ⋅ H2O/refluxing for 2 hours.
(b) EtOH/CS2/KOH/refluxing for 3 hours. (c) Aq. 5% Na2CO3 soln./stirring for 1–2 hours after addition
of 2-bromoacetylbromide (V). (d) DMF/LiH/stirring for 3–5 hours.
α-Glucosidase Inhibition and Structure–Activity
IC50 value of 37.38
0.12 μM. The most excellent
Relationship
inhibitory potential of this compound might be
attributed to the presence of 3,4-dimethylphenyl
group at the acetamidic nitrogen atom in the mole-
cule. Similarly, very comparable inhibitory potentials
were revealed by VIId and VIIg, bearing IC50 values of
Thesynthesizedmoleculeswerescreenedforα-glu-
cosidase inhibition. The results of percentage inhibi-
tion and IC50 values are presented in Table 2, as mean
SEM. From the results, it was obvious that eight mol-
ecules in the series exhibited IC50 values lower than the
15.47
0.11 and 16.29
0.12 μM, respectively.
Acarbose, a reference standard against this enzyme. Hereby, their valuable potential can be an outcome of
The most potent compound was VIIb, with IC50 value
the presence of 2,3-dimethylphenyl and 3-methylphe-
of 14.38 0.12 μM, relative to Acarbose, having an nyl groups in these molecules. The inhibition order of
Arg
312
His
279
Leu218
Asn241
Arg
439
His245
1.82
His279
Thr215
N
Arg212
N
S
N
NH
NH2
His348
O
O
Pro309
Phe31
His
245
S
Asp
349
Arg312
His
348
Asp349
Glu
304
Phe
300
Ser308
Ala
278
Phe311
Phe
157
Arg439
Glu
276
Fig. 1. The 2D and 3D interaction analysis of compound (VIIb) against α-glucosidase enzyme.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 46 No. 4 2020

594
MUHAMMAD ATHAR ABBASI et al.
synthesized compounds was found to be VIIb > VIIg > Procedure for the Synthesis of 5-[(2-Amino-1,3-thiazol-
4-yl)acetohydrazide (II)
VIIe >VIIl > VIIm > VIIa >VIIi > VIIj >VIIh. So, in
general, it was lucid to infer that most of the com-
pounds exhibited very excellent activities against the
α-glucosidase enzyme and might serve as valuable
anti-diabetic agents.
Ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate (I; 10 g,
0.050 mol) and methanol (200 mL) were taken in a
500 mL RB flask. Hydrazine hydrate (2.5 mL,
0.050 mol) was added drop wise and the mixture was
allowed to reflux for 2 hours. The reaction progress
was observed by TLC using n-hexane and ethyl acetate
solvent system (40 : 60). After complete reaction, the
reaction mixture was allowed to cool at room tempera-
ture to attain white colored precipitates of hydrazide (II).
Molecular Docking (in silico) Study
All these bi-heterocycles, VIIa–m, were docked
into the active pocket of this enzyme. Whereby, the Product was filtered and washed with methanol [22].
most potent compound, VIIb, inhibited alpha-gluco-
sidase by making three interactions From the Fig. 1
Procedure for the Synthesis of 5-[(2-Amino-1,3-thiazol-
(2D and 3D), it was clear that His245 has made a
4-yl)methyl]-1,3,4-oxadiazol-2-thiol (III)
strong acidic interaction with acetamoyl mioety of the
5-[(2-Amino-1,3-thiazol-4-yl)acetohydrazide (II;
4 g, 0.024 mol) was dissolved in C2H5OH (70 mL) in a
250 mL RB flask at 28°C and then solid KOH (1.34 g,
0.024 mol) was dissolved on reflux. Carbon disulfide
(3.70 mL, 0.048 mol) was poured drop-wise at 28°C
and then the reaction mixture was allowed to reflux
again for 3 hours. The completion of reaction was
observed by TLC using n-hexane and ethyl acetate sol-
vent system (70 : 30). The excess of ethanol was dis-
tilled off. Excess of ice cold distilled water was added
followed by addition of dilute HCl till constant pH of
4–5. Light peach colored precipitates of III were fil-
tered and washed with distilled water [22].
compound showing bond length of 1.82 Å. The
Arg439 and His279 have also made somewhat weak
arene-cation and a couple of π-π interactions with ter-
minal thiazol-2-amine ring and with phenyl ring of the
compound, respectively. Similarly, the in silico results
of other molecules were also coherent with their
in vitro enzyme inhibition data.
Brine Shrimps Activity
The cytotoxicity of the synthesized compounds was
evaluated through brine shrimp lethality. The higher
LD50 values of brine shrimp lethality analysis demon-
strated the lowest toxicity of these compounds (Table 3).
It was rational from the results that the synthesized
derivatives were not highly toxic and hence can be uti-
lized as safe therapeutic agents.
General Procedure for the Preparation of 2-Bromo-
N-(substituted)acetamides (VIa–m)
Substituted amines (IVa–m; 0.038 mol; one in
each reaction) were suspended in 30 mL distilled water
in an iodine flask (100 mL). Aqueous Na2CO3 solu-
tion (10%, 2–3 mL) was poured to keep the reaction
continued. 2-Bromoacetylbromide (V; 0.038 mol) was
added gradually on vigorous shaking and then stirred
for further 1–2 h. Reaction completion was monitored
by TLC. Excess ice cold distilled water (60 mL) was
added. The resulting precipitates were collected
through filtration, washed with distilled water and
dried [24].
EXPERIMENTAL
General
All the chemical reagents were purchased from Alfa
Aesar, Merck and Sigma Aldrich through local suppli-
ers. The solvents were of analytical grade and used
without further purification. The reaction completion
and purity were confirmed by TLC performed on alu-
minum plates coated with silica gel G-25-UV254, run
by ethyl acetate : n-hexane solvent system and visual-
ized under UV at 254 nm. Melting points were
recorded on Griffin-George melting point apparatus
by using open capillary tubes and were uncorrected.
1H NMR spectra (δ, ppm) were recorded at 600 MHz
(13C NMR spectra, at 150 MHz) in DMSO-d6 using
the Bruker Advance III 600 As- cend spectrometer
using BBO probe. EI-MS spectra were measured on a
JEOL JMS-600H instrument with data processing
system. IR spectra were recorded by KBr pellet
method using on Jasco-320-A spectrometer.
General Procedure for the Synthesis of 2-({5-[(2-Amino-
1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazol-2-
yl}sulfanyl)-N-(substituted)acetamides (VIIa–m)
5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxa-
diazol-2-thiol (3; 0.1 g, 0.47 mmol) was dissolved in
N,N-dimethyl formamide (DMF, 5-10 mL) in a
100 mL RB flask. Solid LiH (0.005 g) was added and
the mixture was stirred for half an hour. Then, differ-
ent electrophiles, N-substituted-2-bromoacetamide
(VIa–m; 0.47 mmol; one in each reaction), were added
and set to stir for 3–5 h. The reaction was monitored
by TLC using n-hexane and ethyl acetate solvent sys-
tem (80 : 20). Excess ice cold distilled water was added
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SYNTHESIS OF NOVEL BI-HETEROCYCLES
595
and the products (VIIa–m) were filtered, washed with 163.05 (C-2), 143.90 (C-4), 138.61 (C-1'''), 128.70
distilled water and dried for further use.
(C-3'' and C-5''), 123.64 (C-4'''), 119.15 (C-2''' and C-6'''),
103.13 (C-5), 36.67 (C-2''), 27.53 (C-6); EI MS: m/z
375 [M]+, 301 [[C15H15N3O2S]+, 262 [C12H12N3O2S]+,
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-benzylacetamide (VIIa).
Light brown solid; Yield: 89%; mp: 229–230°C; Mol.
Formula: C15H15N5O2S2; Mol. Mass.: 361 g mol–1; IR:
3345 (N–H stretching), 3050 (C–H of aromatic ring),
2915 (–CH2– stretching), 1675 (C=O stretching ),
1570 (C=C stretching of aromatic ring), 1515 (C=N
stretching); 1H NMR: 10.37 (s, 1H, N–H), 7.56 (br.d,
J = 8.0, 2H, H-2''' & H-6'''), 7.32 (br.t, J = 7.8, 2H, H-
3''' and H-5'''), 7.07 (br.t, J = 7.2, 1H, H-4'''), 6.99
(2H, –NH2), 6.39 (s, 1H, H-5), 4.26 (s, 2H, CH2-2''),
235 [C11H11N2O2S]+, 195 [C10H13NOS]+, 163
[C10H13NO]+, 141 [C5H5N2OS]+, 121 [C8H11N]+, 114
[C4H6N2S]+.
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2,3-dimethylphenyl)acet-
amide (VIId). Brown solid; Yield: 87%; mp: 241–
242°C; Mol. Formula: C16H17N5O2S2; Mol. Mass:
375 g mol–1; IR: 3352 (N–H stretching), 3050 (C–H
of aromatic ring), 2930 (–CH2 stretching), 1675 (C=O
stretching), 1575 (C=C stretching of aromatic ring),
4.04 (s, 2H, CH2-6); 13C NMR: 168.75 (C-2'), 165.69 (C-
5'), 164.71 (C-1''), 163.05 (C-2), 143.90 (C-4), 138.61 (C-
1'''), 128.70 (C-3''' and C-5'''), 123.64 (C-4'''), 119.15
(C-2''' and C-6'''), 103.13 (C-5), 36.67 (C-2''), 27.53
(C-6); EI MS: m/z 361 [M]+, 287 [C14H13N3O2S]+,
1
1520 (C=N stretching); H NMR: 10.21 (s, 1H, N–
H), 7.26 (br.d, J = 8.1 Hz, 1H, H-4'''), 7.06 (br.d, J =
8.1, 1H, H-5'''), 7.26 (br.d, J = 8.1 Hz, 1H, H-6'''),
6.99 (br.s, 2H, –NH2), 6.38 (s, 1H, H-5), 4.23 (br.s,
2H, CH2-2''), 4.03 (br.s, 2H, CH2-6), 2.18 (s, 3H,
248
[C11H10N3O2S]+, 228 [C7H8N4OS2]+, 221
[C10H9N2O2S]+, 194 [C9H10N2OS]+, 181 [C9H11NOS],
141 [C5H5N2OS]+, 114 [C4H6N2S]+, 91 [C7H7].
CH3-8'''), 2.16 (s, 3H, CH3-7'''); 13C NMR: 168.74 (C-2'),
165.66 (C-5'), 164.37 (C-1''), 163.03 (C-2), 143.90
(C-4), 138.34 (C-1'''), 136.41 (C-3'''), 131.41(C-4'''),
129.62 (C-5'''), 120.35 (C-2'''), 116.68 (C-6'''), 103.12
(C-5), 36.64 (C-2''), 27.52 (C-6), 19.57 (C-7'''), 18.74
(C-8'''); EI MS: m/z 375 [M]+, 301 [C15H15N3O2S]+,
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(3,4-dimethylphenyl)acet-
amide (VIIb). Dark brown gummy solid; Yield: 84%;
mp: 278–279°C; Mol. Formula: C16H17N5O2S2; Mol.
262 [C12H12N3O2S]+, 235 [C11H11N2O2S]+, 195
[C10H13NOS]+, 163 [C10H13NO]+, 141 [C5H5N2OS]+,
121 [C8H11N]+, 114 [C4H6N2S]+.
Mass: 375 g mol–1; IR: 3360 (N–H stretching), 3045
(C–H of aromatic ring), 2920 (–CH2 stretching),
1660 (C=O stretching), 1570 (C=C stretching of aro-
1
matic ring), 1545 (C=N stretching); H NMR: 10.21
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(3,5-dimethylphenyl)acet-
amide (VIIe). Light brown amorphous solid; Yield:
82%; mp: 297–298°C; Mol. Formula: C16H17N5O2S2;
(s, 1H, N–H), 7.34 (br.s, 1H, H-2'''), 7.26 (br.d, J =
8.1 Hz, 1H, H-6'''), 7.06 (br.d, J = 8.1, H-5'''), 6.99
(br.s, 2H, –NH2), 6.38 (s, 1H, H-5), 4.23 (br.s, 2H,
CH2-2''), 4.03 (br.s, 2H, CH2-6), 2.18 (s, 3H, CH3-
Mol. Mass: 375 g mol–1; IR: 3367 (N–H stretching),
3040 (C–H of aromatic ring), 2940 (‒CH2 stretch-
ing), 1665 (C=O stretching), 1570 (C=C stretching of
13
8'''), 2.16 (s, 3H, CH3-7'''); C NMR: 168.74 (C-2'),
165.66 (C-5'), 164.37 (C-1''), 163.03 (C-2), 143.90
(C-4), 138.34 (C-1'''), 136.41 (C-3'''), 131.41 (C-4'''),
129.62 (C-5'''), 120.35 (C-2'''), 116.68 (C-6'''), 103.12
(C-5), 36.64 (C-2''), 27.52 (C-6), 19.57 (C-7'''), 18.74
(C-8'''); EI MS: m/z 375 [M]+, 301 [[C15H15N3O2S]+,
1
aromatic ring), 1530 (C=N stretching); H NMR:
10.21 (s, 1H, N–H), 7.34 (br.s, 1H, H-2'''), 7.26 (br.d,
J = 8.1 Hz, 1H, H-6'''), 7.06 (d, J = 8.1, H-4'''), 6.99
(br.s, 2H, –NH2), 6.38 (s, 1H, H-5), 4.23 (br.s, 2H,
CH2-2''), 4.03 (br.s, 2H, CH2-6), 2.18 (s, 3H, CH3-8'''),
262 [C12H12N3O2S]+, 235 [C11H11N2O2S]+, 195
[C10H13NOS]+, 163 [C10H13NO]+, 141 [C5H5N2OS]+,
121 [C8H11N]+, 114 [C4H6N2S]+.
2.16 (s, 3H, CH3-7'''); 13C NMR: 168.75 (C-2'), 165.67
(C-5'), 164.39 (C-1''), 163.05 (C-2), 143.90 (C-4),
138.34 (C-1'''), 136.41 (C-3'''), 131.41 (C-4'''), 129.62
(C-5'''), 120.35 (C-2'''), 116.68 (C-6'''), 103.12 (C-5),
36.64 (C-2''), 27.52 (C-6), 19.57 (C-7'''), 18.74 (C-
8'''); EI MS: m/z 375 [M]+, 301 [[C15H15N3O2S]+, 262
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2,5-dimethylphenyl)acet-
amide (VIIc). Dull white amorphous solid; Yield:
83%; mp: 207–208°C; Mol. Formula: C16H17N5O2S2;
[C12H12N3O2S]+,
235
[C11H11N2O2S]+,
195
Mol. Mass: 375 g mol–1; IR: 3340 (N–H stretching),
3060 (C–H of aromatic ring), 2915 (‒CH2 stretch-
ing), 1570 (C=C stretching of aromatic ring), 1520
[C10H13NOS]+, 163 [C10H13NO]+, 141 [C5H5N2OS]+,
121 [C8H11N]+, 114 [C4H6N2S]+.
1
(C=N stretching); H NMR: 10.37 (s, 1H, N–H),
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
7.56 (br.d, J = 8.0 Hz, 2H, H-2''' and H-6'''), 7.32 oxadiazol-2-yl}sulfanyl)-N-phenylacetamide
(VIIf).
(br.t, J = 7.8 Hz, 2H, H-3''' and H-5'''), 7.07 (br.t, J = Brick brown amorphous solid; Yield: 87%; mp: 190–
7.2 Hz, 1H, H-4'''), 6.99 (s, 2H, –NH2), 6.39 (s, 1H, 191°C; Mol. Formula: C14H13N5O2S2; Mol. Mass:
H-5), 4.26 (s, 2H, CH2-2''), 4.04 (s, 2H, CH2-6); 13C 347 g mol–1; IR: 3350 (N–H stretching), 3052 (C–H
of aromatic ring), 2923 (–CH2 stretching), 1576 (C=C
NMR: 168.75 (C-2'), 165.69 (C-5'), 164.71 (C-1''),
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 46 No. 4 2020

596
MUHAMMAD ATHAR ABBASI et al.
stretching of aromatic ring), 1518 (C=N stretching);
1H NMR: 10.37 (s, 1H, N–H), 7.56 (br.d, J = 8.0 Hz,
2H, H-2''' and H-6'''), 7.32 (br.t, J = 7.8 Hz, 2H, H-3'''
and H-5'''), 7.07 (br.t, J = 7.2 Hz, 1H, H-4'''), 6.99 (s,
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2-ethyl-6-methylphenyl)-
acetamide (VIIi). Light brown amorphous solid;
Yield: 89%; mp: 237–238°C; Mol. Formula:
2H, –NH2), 6.39 (s, 1H, H-5), 4.26 (s, 2H, CH2-2''), C17H19N5O2S2; Mol. Mass: 389 g mol–1; IR: 3355
4.04 (s, 2H, CH2-6); 13C-NMR: 168.74 (C-2'), 165.69
(C-5'), 164.71 (C-1''), 163.05 (C-2), 143.90 (C-4),
(N‒H stretching), 3050 (C–H of aromatic ring), 2923
(–CH2 stretching), 1570 (C=C stretching of aromatic
1
138.61 (C-1'''), 128.70 (C-3''' and C-5'''), 123.64 ring), 1545 (C=N stretching); H NMR: 7.31 (br.s,
(C-4'''), 119.15 (C-2''' and C-6'''), 103.13 (C-5), 36.67 1H, H-5'''), 7.04 (d, J = 7.68 Hz, 1H, H-3'''), 6.89 (s,
(C-2''), 27.53 (C-6); EI MS: m/z 347 [M]+, 273
2H, –NH2), 6.38 (br.d, J = 7.38 Hz, 1H, H-4'''), 6.27
(s, 1H, H-4), 4.26 (s, 2H, CH2-2''), 4.04 (s, 2H, CH2-6),
2.43 (q, J = 7.5, 2H, CH2-7'''), 2.09 (s, 3H, CH3-9'''),
[C13H11N3O2S]+,
[C9H7N2O2S]+,
234
193
[C13H11N3O2S]+,
[C9H9N2OS]+,
207
141
13
[C5H5N2OS]+, 120 [C7H6NO]+, 92 [C6H6N]+.
1.06 (t, J = 7.5, 3H, CH3-8'''); C NMR: 168.75 (C-
2'), 165.69 (C-5'), 164.71 (C-1''), 163.05 (C-2), 143.91
(C-4), 141.05 (C-1'''), 135.59 (C-6'''), 134.19 (C-2'''),
127.64 (C-4'''), 126.84 (C-3'''), 125.99 (C-5'''), 103.11
(C-5), 36.62 (C-2'') 27.54 (C-6), 24.25 (C-9'''), 17.99
(C-7'''), 14.63 (C-8'''); EI MS: m/z 389 [M]+, 347
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(3-methylphenyl)acetamide
(VIIg). Light brown solid; Yield: 87%; mp: 245–
246°C; Mol. Formula: C15H15N5O2S2; Mol. Mass:
361 g mol–1; IR: 3370 (N–H stretching), 3050 (C–H
of aromatic ring), 2930 (–CH2 stretching), 1680
(C=O stretching), 1550 (C=C stretching of aromatic
ring), 1545 (C=N stretching); 1H NMR: 10.21 (s, 1H,
N–H), 7.34 (br.s, 1H, H-2'''), 7.26 (br.d, J = 8.1 Hz, 1H,
H-6'''), 7.06 (d, J = 8.1, H-5'''), 6.99 (br.s, 2H, –NH2),
6.38 (s, 1H, H-5), 4.23 (br.s, 2H, CH2-2''), 4.03 (br.s,
2H, CH2-6), 2.18 (s, 3H, CH3-8'''), 2.16 (s, 3H, CH3-
[C16H17N3O2S]+,
[C13H11N3O2S]+,
276
209
[C13H14N3O2S]+,
[C11H15NOS]+,
234
176
[C11H14NO]+, 162 [C10H12NO]+, 141 [C5H5N2OS]+,
134 [C9H12N]+.
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(4-ethyl-phenyl)acetamide
(VIIj). Light brown amorphous solid; Yield: 84%; mp:
113–14°C; Mol. Formula: C16H17N5O2S2; Mol. Mass:
13
7'''); C NMR: 168.74 (C-2'), 165.66 (C-5'), 164.77
375 g mol–1; IR: 3345 (N–H stretching), 3050 (C–H
of aromatic ring), 2940 (–CH2 stretching), 1580
(C=C stretching of aromatic ring), 1518 (C=N
(C-1''), 163.03 (C-2), 143.90 (C-4), 138.34 (C-1'''),
136.41 (C-3'''), 131.41 (C-4'''), 129.62 (C-5'''), 120.35
(C-2'''), 116.68 (C-6'''), 103.12 (C-5), 36.64 (C-2''),
27.52 (C-6), 19.57 (C-7'''), 18.74 (C-8'''); EI MS: m/z
361 [M]+, 287 [C14H13N3O2S]+, 248 [C11H10N3O2S]+,
1
stretching); H NMR: 10.30 (s, 1H, HN–CO), 7.32
(d, J = 9.0 Hz, 2H, H-2''' & H-6'''), 6.82 (d, J = 9.0
Hz, 2H, H-3''' & H-5'''), 7.00 (br.s, 2H, –NH2), 6.39
(s, 1H, H-5), 4.24 (s, 2H, CH2-2''), 4.03 (s, 2H, CH2-
6), 2.52 (q, J = 7.1, 2H, CH2-7'''), 1.15 (t, J = 7.1, 3H,
228 [C7H8N4OS2]+, 221 [C10H9N2O2S]+, 194
[C9H10N2OS]+, 181 [C9H11NOS], 141 [C5H5N2OS]+,
114 [C4H6N2S]+, 91 [C7H7].
CH3-8'''); 13C NMR: 168.74 (C-2'), 165.68 (C-5'),
164.44 (C-1''), 163.07 (C-2), 143.89 (C-4), 138.10
(C-1'''), 136.41 (C-4'''), 128.98 (C-3''' & C-5'''), 119.15
(C-2''' & 6'''), 103.12 (C-5), 37.01 (C-7'''), 27.55 (C-6),
27.52 (C-2''), 15.61 (C-8'''); EI MS: m/z 375 [M]+, 301
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(4-methylphenyl)acetamide
(VIIh). Light brown amorphous solid; Yield: 80%; mp:
237–238°C; Mol. Formula: C15H15N5O2S2; Mol.
[[C15H15N3O2S]+,
[C11H11N2O2S]+,
262
195
[C12H12N3O2S]+,
[C10H13NOS]+,
235
163
Mass.: 361 g mol–1; IR: 3340 (N–H stretching), 3060
(C–H of aromatic ring), 2915 (–CH2– stretching),
1570 (C=C stretching of aromatic ring), 1540 (C=N
[C10H13NO]+, 141 [C5H5N2OS]+, 121 [C8H11N]+, 114
[C4H6N2S]+.
1
stretching); H NMR: 10.21 (s, 1H, N–H), 7.42 (d,
J = 7.0 Hz, 2H, H-2''' and H-6'''), 7.12 (d, J = 7.0 Hz,
2H, H-3''' and H-5'''), 6.99 (br.s, 2H, –NH2), 6.38 (s,
1H, H-5), 4.23 (br.s, 2H, CH2-2''), 4.03 (br.s, 2H,
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2-ethyl-phenyl)acetamide
(VIIk). Light brown amorphous solid; Yield: 81%; mp:
189–190°C; Mol. Formula: C16H17N5O2S2; Mol.
CH2-6), 2.21 (s, 3H, CH3-7'''); 13C NMR: 168.74
(C-2'), 165.66 (C-5'), 164.37 (C-1''), 163.03 (C-2),
143.90 (C-4), 136.39 (C-1'''), 132.10 (C-4'''), 129.05 (C-3'''
and C-5'''), 119.06 (C-2''' and C-6'''), 103.12 (C-5), 36.64
(C-2''), 27.52 (C-6), 20.39 (C-7'''); EI MS: m/z 361 [M]+,
287 [C14H13N3O2S]+, 248 [C11H10N3O2S]+, 228
Mass: 375 g mol–1; IR: 3350 (N–H stretching), 3052
(C–H of aromatic ring), 2923 (–CH2 stretching),
1570 (C=C stretching of aromatic ring), 1540 (C=N
stretching); 1H NMR: 10.21 (s, 1H, N–H), 7.27 (br.d,
J = 7.0 Hz, 1H, H-6'''), 7.18 (br.d, J = 7.5 Hz, 1H,
H-3'''), 7.15–7.13 (m, 1H, H-5'''), 7.12–7.10 (m, 1H,
H-4''') 6.99 (br.s, 2H, –NH2), 6.38 (s, 1H, H-5), 4.23
(br.s, 2H, CH2-2''), 4.03 (br.s, 2H, CH2-6), 2.51 (q,
[C7H8N4OS2]+,
221
[C10H9N2O2S]+,
194
[C9H10N2OS]+, 181 [C9H11NOS], 141 [C5H5N2OS]+,
114 [C4H6N2S]+, 91 [C7H7].
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY
Vol. 46
No. 4
2020

SYNTHESIS OF NOVEL BI-HETEROCYCLES
597
J = 7.3, 2H, CH2-7'''), 1.14 (t, J = 7.3, 3H, CH3-8'''); (50 mM) with pH of 6.8, 10 μL of test compound
13C NMR: 168.74 (C-2'), 165.66 (C-5'), 164.37 (C-1''),
163.03 (C-2), 143.90 (C-4), 137.34 (C-1'''), 135.22
(C-2'''), 128.58 (C-3'''), 126.14 (C-5'''), 125.88 (C-4'''),
125.13 (C-6'''), 103.12 (C-5), 36.64 (C-2''), 27.56
(C-6), 24.68 (C-7'''), 14.96 (C-8'''); EI MS: m/z 375
[M]+, 301 [[C15H15N3O2S]+, 262 [C12H12N3O2S]+, 235
(0.5 mM) and 10 μL enzyme (0.057 units). The con-
tents were mixed, pre-incubated for 10 min at 37°C
and pre-read at 400 nm. The reaction was initiated by
the addition of 10 μL of 0.5 mM substrate (p-nitro-
phenylglucopyranoside). Acarbose was used as posi-
tive control. After 30 minutes of incubation at 37°C,
absorbance was measured at 400 nm using Synergy
HT microplate reader. All experiments were carried
out in triplicates. The percent inhibition was calcu-
lated by the help of following formula:
[C11H11N2O2S]+,
195
[C10H13NOS]+,
163
[C10H13NO]+, 141 [C5H5N2OS]+, 121 [C8H11N]+, 114
[C4H6N2S]+.
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2-ethoxyphenyl)acet-
amide (VIIl). Light brown amorphous solid; Yield:
77%; mp: 181–182°C; Mol. Formula: C16H17N5O3S2;
Control − Test
Inhibition % =
( )
×100.
Control
Control = Total enzyme activity without inhibitor.
Test = Activity in the presence of test compound.
The IC50 values were calculated using EZ–Fit
Enzyme kinetics software (Perrella Scientific Inc.
Amherst, USA).
m.m.: 391 g mol–1; IR: 3350 (N–H stretching), 3052
(C–H of aromatic ring), 2923 (–CH2– stretching),
1576 (C=C stretching of aromatic ring), 1518 (C=N
1
stretching); H NMR: 10.21 (s, 1H, N–H), 7.92 (d,
J = 7.2 Hz, 1H, H-6'''), 7.05-7.03 (m, 2H, H-3''' and
H-5'''), 6.99 (br.s, 2H, –NH2), 6.87 (dt, J = 1.2, 7.4
Hz, 1H, H-4'''), 6.38 (s, 1H, H-5), 4.23 (br.s, 2H,
CH2-2''), 4.08 (q, J = 6.8 Hz, 2H, CH2-7'''), 4.03 (br.s,
Molecular Docking
To predict the bioactive conformations, various
ligands were docked into the binding pockets of the
enzymes by using the default parameters of MOE-
Dock program.
13
2H, CH2-6), 1.38 (t, J = 6.8 Hz, 3H, CH3-8'''); C
NMR: 168.77 (C-2'), 165.65 (C-5'), 164.35 (C-1''),
163.04 (C-2), 148.52 (C-2'''), 143.90 (C-4), 127.07
(C-1'''), 124.68 (C-4'''), 121.39 (C-6'''), 120.35 (C-5'''),
112.31 (C-3'''), 103.12 (C-5), 63.98 (C-7'''), 36.64
(C-2''), 27.52 (C-6), 14.49 (C-8'''); EI MS: m/z 391
[M]+, 317 [C15H15N3O3S], 278 [C12H12N3O3S], 211
Ligands preparation. The three dimensional (3D)
structures of synthesized compounds were made by
using ChemDraw Ultra 12.0 (Cambridge Soft, 2001)
and saved in MDL Mol file format which were then
opened in Molecular Operating Environment (MOE
2009–2010). The energies of the compounds were
minimized by using the default parameter of MOE
energy minimization algorithm (gradients: 0.05, force
field: MMFF94X). Database was created in which all
the compounds were saved in the mdb file format for
the next step of docking.
Receptor protein preparation. The 3D structures of
receptor protein molecules of yeast α-glucosidase
(PDB Code: 3NO4) were retrieved from Protein Data
Bank. All water molecules were released from the
receptor proteins and 3D protonation was carried out
by using Protonate 3D Option [26]. Protein molecules
were energy minimized by using the default parame-
ters of MOE 2009–2010 energy minimization algo-
rithm (gradient: 0.05, Force Field: MMFF94X). By
using default parameters of MOE-Dock Program, all
the compounds were docked into binding pockets of
the above proteins. Re-docking procedure was also
used to increase the validity of docking protocol [27].
[C10H12NO2S], 114 [C4H6N2S]+.
2-({5-[(2-Amino-1,3-thiazol-4-yl)methyl]-1,3,4-
oxadiazol-2-yl}sulfanyl)-N-(2-methoxycarbonylphe-
nyl)acetamide (VIIm). Light brown amorphous solid;
Yield: 85%; mp: 243–244°C; Mol. Formula:
C16H15N5O4S2; Mol. Mass: 405 g mol–1; IR: 3380 (N–
H stretching), 3065 (C–H of aromatic ring), 2950
(‒CH2 stretching), 1570 (C=C stretching of aromatic
ring), 1540 (C=N stretching); 1H NMR: 11.04 (s, 1H,
N–H), 8.23 (br.d, J = 8.2, 1H, H-3'''), 7.92 (dist. d,
J = 7.1, 1H, H-4'''), 7.62 (br.t, J = 7.9, 1H, H-5'''), 7.23
(br.d, J = 7.7, 1H, H-6'''), 6.98 (2H, –NH2), 6.38 (s,
1H, H-5), 4.27 (s, 2H, CH2-2''), 4.05 (s, 2H, CH2-6),
3.83 (s, 3H, CH3O-8'''); 13C NMR: 168.74 (C-2'),
167.25 (C-7'''), 165.85 (C-5'), 165.30 (C-1''), 162.70
(C-2), 143.85 (C-4), 138.83 (C-1'''), 133.84 (C-5'''),
130.57 (C-3'''), 123.80 (C-4'''), 121.31 (C-6'''), 118.17
(C-2'''), 52.43 (C-8'''), 36.48 (C-2'') 27.53 (C-6); EI
MS: m/z 405 [M]+, 265 [C11H9N2O4S], 228
[C7H8N4OS2], 193 [C10H11NO3], 114 [C4H6N2S]+.
Cytotoxicity Assay
α-Glucosidase Inhibition Assay
The α-glucosidase inhibition activity was per-
The cytotoxicity was studied by the brine-shrimp
cytotoxic assay method [28]. Artificial sea water was
formed according to the slightly modified method prepared using sea salt 34 g L–1. Brine shrimp (Artemia
[25]. Total volume of the reaction mixture was made salina) eggs (Sera, Heidelberg, Germany) were
100 μL containing 70 μL phosphate buffer saline hatched in shallow rectangular dish (22 × 32 cm)
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 46 No. 4 2020

598
MUHAMMAD ATHAR ABBASI et al.
5. Cihan-ustundag, G., Simsek, B., Ilhan, E., and Capan, G.,
under constant aeration for 48 hours at room tempera-
ture. After hatching, active shrimps free from eggs
were collected from brighter portion of the hatching
chamber and used for the assay. Ten shrimps were
transferred to each vial using Pasteur pipette vial con-
taining 5 mL of artificial sea water with 200, 20, 2 and
0.2 μg mL–1 final concentration of test compound
from their stock solution. The vials were maintained
under illumination at room temperature 25 to 28°C.
After 24 hours, the number of surviving shrimp was
counted. Experiment was performed in triplicate.
Data was analyzed with Finney computer program to
determine LD50 (Lethal Dose that killed 50% of
shrimps) values.
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The targeted series of bi-heterocyclic compounds
was synthesized in good yields by a convergent strategy
and most of the compounds exhibited potent enzyme
inhibitory potential against α-glucosidase and also
possessed very mild cytotoxicity. Therefore, these
molecules can be utilized as safe anti-diabetic agents
in drug discovery and designing program.
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FUNDING
The Higher Education Commission (HEC) of Pakistan
is highly acknowledged by the authors for financial support
regarding purchasing of chemicals and spectral study.
20. Kitchen, D.B., Decornez, H., Furr, J.R., and Bajorath, J.,
Nat. Rev. Drug Discov., 2004, vol. 3, pp. 935–949.
21. Sama, K., Murugesan, K., and Sivaraj, R., Asian J.
Plant Sci. Res., 2012, vol. 2, pp. 550–553.
COMPLIANCE WITH ETHICAL STANDARDS
22. Abbasi, M.A., Ramzan, M.S., Aziz-ur-Rehman, Sid-
diqui, S.Z., Hassan, M., Raza, H., Shah, S.A.A., Mir-
za, B., and Seo, S.-Y., J. Serb. Chem. Soc., 2019,
vol. 84, pp. 649–661.
This article does not contain any studies involving ani-
mals or human participants performed by any of the
authors.
23. Abbasi, M.A., Ramzan, M.S., Aziz-ur-Rehman, Sid-
diqui, S.Z., Shah, S.A.A., Hassan, M., Seo, S.-Y.,
Ashraf, M., Mirza, B., and Ismail, H., Russ. J. Bioorg.
Chem., 2018, 44, pp. 801–811.
Conflict of Interests
The authors declare that they have no conflict of interests.
24. Butt, A.R.S., Abbasi, M.A., Aziz-ur-Rehman, Sid-
diqui, S.Z., Hassan, M., Raza, H., Shah, S.A.A., and
Seo, S.-Y., Bioorg. Chem. 2019, vol. 86, pp. 197–209.
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2020