Research Article
Open Access
Substituting tert-butyl group on Murrayanine-
Chalcone Scaffold Produced Tremendously
High Anti-oxidant Activity than the Individual
Components
Debarshi Kar Mahapatra1*, Ruchi S. Shivhare2
1Department of Pharmaceutical Chemistry, Dadasaheb Balpande College of Pharmacy, Nagpur 440037, Maharashtra,
India
2Department of Pharmaceutical Chemistry, Kamla Nehru College of Pharmacy, Nagpur 441108, Maharashtra, India
2Department of Pharmaceutical Chemistry, Kamla Nehru College of Pharmacy, Nagpur 441108, Maharashtra, India
*Corresponding author: Debarshi Kar Mahapatra, PhD. Assistant Professor, Department of Pharmaceutical Chemistry, Dadasaheb Balpande College of
Pharmacy, Nagpur 440037, Maharashtra, India; E-mail: @
Received: November 12, 2018; Accepted: November 13, 2018; Published: December 01, 2018
Citation: Debarshi Kar M, Shivhare RS (2018) Substituting tert-butyl group on Murrayanine-Chalcone Scaffold Produced Tremendously High Anti-oxidant Activity than the Individual Components. Int J Anal Medicinal Chem. 1(1): 1-5.
AbstractTop
Murrayanine is an active carbazole alkaloid having fairly good
anti-oxidant activity. Carbazole scaffold and its hybrid molecules have
been seen to exhibit potentially high radical scavenging activities.
Chalcone successfully scavenges the hydroxyl, superoxide, etc. and
find applications as anti-cancer, anti-inflammatory, anti-diabetic, antiinfective,
and cardiovascular agents. The modern-day synthetically
prepared anti-oxidants such as 2-tert-butyl-4-methoxyphenol (BHA),
tert-butyl hydroquinone (TBHQ), 2, 6-di-tert-butyl-4-methylphenol
(BHT) and 2, 4, 6-tri-tert-butylphenol (TBP) have a prime common
structural phenomenon, i.e. tert-butyl group. Inspiring from the
above facts, a hybrid molecule comprising of Murrayanine (carbazole
moiety), Chalcone, and tert-butyl group was rationally designed, and
it was predicted that the proposed compound will exhibit a better
free-radical scavenging potential. The molecule was synthesized from
Claisen-Schmidt reaction and screened for anti-oxidant activity using
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. The
tested molecule presented a tremendous radical scavenging activity
as evidenced by the IC50 value of 5.94 μM. The higher activity of the
novel compound may be predicted from the synergistic potentials of
the carbazole, Chalcone, and tert-butyl group. The current study will
positively influence, motivate, and incline millions of global researchers
in developing similar therapeutically active low-molecular-weight
ligands and their translated pharmaceutical products for disease
prevention and further utility.
Keywords: Antioxidant; Radical; Scavenging; Murrayanine; Chalcone; tert-butyl.
Keywords: Antioxidant; Radical; Scavenging; Murrayanine; Chalcone; tert-butyl.
IntroductionTop
Free radicals are the chemically reactive species generated
in the human body in a large amount every day under normal
conditions [1]. When ionizing radiations or environmental
toxins (cigarette smoking, high-oxygen atmosphere, etc.) are
encountered by the individuals, an abnormally high concentration
of free radicals is produced in the human body in response. The
free radicals are known to precipitate various diseases such as
neurological complications, cardiac abnormalities, nephritic
diseases, etc [2].
Murrayanine is an active carbazole alkaloid present in the curry tree, Murraya koenigii (Family: Rutaceae). The component is having fairly good anti-oxidant activity ( IC50 value of 7.6 μM) whereas the Schiff’s base based semi-synthetic derivatives of Murrayanine have IC50 values of 6.5-7.3 μM [3-4].
Carbazole is a well-known heterocyclic scaffold having multifarious pharmacological activities. Numerous scientific reports on anti-oxidant activity of this scaffold are available [5]. The hybrid molecules such as carbazole-ferulic acid [6], carbazole-pyrrolidine [7], carbazole-thiazole [8], carbazoletacrine [9], etc. have been seen to exhibit potentially high radical scavenging activities.
Chalcone is a low-molecular-weight natural scaffold with strikingly high anti-oxidant activity. The ligands successfully scavenge the hydroxyl, superoxide, etc. and find applications as anti-cancer [10], anti-inflammatory [11], anti-diabetic [12], anti-infective [13], and cardiovascular [14] agents, owing to such attributes.
The modern-day synthetically prepared anti-oxidants have a prime common structural phenomenon, i.e. tert-butyl group. Products such as 2-tert-butyl-4-methoxyphenol (BHA), tert-butyl hydroquinone (TBHQ), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP) bear tert-butyl groups which are believed to play an imperative role in scavenging the free-radicals [15] (Figure 1).
Inspiring from the above facts, a hybrid molecule comprising of Murrayanine (carbazole moiety), Chalcone, and tert-butyl group was rationally designed, with a prediction that the produced compound will exhibit a tremendous free-radical scavenging potential and play an essential role in several diseased conditions. The molecule was synthesized from Claisen- Schmidt reaction and screened for anti-oxidant activity using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay (Figure 2).
Murrayanine is an active carbazole alkaloid present in the curry tree, Murraya koenigii (Family: Rutaceae). The component is having fairly good anti-oxidant activity ( IC50 value of 7.6 μM) whereas the Schiff’s base based semi-synthetic derivatives of Murrayanine have IC50 values of 6.5-7.3 μM [3-4].
Carbazole is a well-known heterocyclic scaffold having multifarious pharmacological activities. Numerous scientific reports on anti-oxidant activity of this scaffold are available [5]. The hybrid molecules such as carbazole-ferulic acid [6], carbazole-pyrrolidine [7], carbazole-thiazole [8], carbazoletacrine [9], etc. have been seen to exhibit potentially high radical scavenging activities.
Chalcone is a low-molecular-weight natural scaffold with strikingly high anti-oxidant activity. The ligands successfully scavenge the hydroxyl, superoxide, etc. and find applications as anti-cancer [10], anti-inflammatory [11], anti-diabetic [12], anti-infective [13], and cardiovascular [14] agents, owing to such attributes.
The modern-day synthetically prepared anti-oxidants have a prime common structural phenomenon, i.e. tert-butyl group. Products such as 2-tert-butyl-4-methoxyphenol (BHA), tert-butyl hydroquinone (TBHQ), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP) bear tert-butyl groups which are believed to play an imperative role in scavenging the free-radicals [15] (Figure 1).
Inspiring from the above facts, a hybrid molecule comprising of Murrayanine (carbazole moiety), Chalcone, and tert-butyl group was rationally designed, with a prediction that the produced compound will exhibit a tremendous free-radical scavenging potential and play an essential role in several diseased conditions. The molecule was synthesized from Claisen- Schmidt reaction and screened for anti-oxidant activity using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay (Figure 2).
Figure 1: Examples of some common marketed synthetic anti-oxidant products with an active tert-butyl group.
Figure 2: The rational for the designing of the novel tert-butyl containing murrayanine-chalcone compound
Materials and MethodsTop
Chemicals and Instrumentation
The substrate was obtained by extraction from the M. koenigii
powdered stem bark by n-hexane based silica gel-based column
chromatography as per our previously developed method [16].
The reactant 1-(4-(tert-butyl) phenyl) ethanone (CAS Number
943-27-1) was acquired from Sigma Aldrich, Germany through
a local vendor at Nagpur. The compound was characterized
by Fourier-transformed Infrared Spectroscopy recorded on
a Shimadzu® IR-Affinity-1 instrument, 1H (proton)-NMR
Spectroscopy was performed on a Bruker Avance-II instrument,
Mass Spectroscopy was carried out on a MICROMASS Q-TOF
instrument, and Elemental Analysis on a PerkinElmer 2400
Analyzer. The progress of the chemical reaction was monitored
on Merck® pre-coated Silica gel-G TLC plates. The double-beam
Shimadzu® Ultraviolet-Visible Spectrophotometer (UV-1800,
Japan) with spectral characteristics (1 nm bandwidth, 10 mm
path length, and 0.3 nm wavelength accuracy), connected with a
computer was employed for anti-oxidant characterization.
Synthesis of Target Compounds
The Chalcone scaffold (3) was synthesized from Claisen-
Schmidt reaction where a β-hydroxyketone function was formed
through an aldol condensation mechanism. The Murrayanine (1),
the starting substrate having aldehydes portion was made to react
with the acetyl part of the acetophenone containing reactant (2)
in the presence of ethanolic NAOH solution (Scheme 1) [17].
Scheme 1: Synthesis of tert-butyl containing murrayanine-chalcone molecule.
Synthetic Protocol for (E)-3-(4-(Tert-Butyl) Phenyl)-1-
(1-Methoxy-9H-Carbazol-3-Yl) Prop-2-En-1-One
0.01 M concentration of both starting substrate, Murrayanine
(1) and 1-(4-(tert-butyl)phenyl)ethanone (2) were refluxed in
the presence of 20 mL sodium hydroxide aqueous solution and
25 mL 90% ethanol solution. The reaction mixture was allowed
to stand for the whole night and the next day, the content was
poured over crushed ice containing a few drops of dilute HCl
with vigorous stirring by a glass rod. The acquired product (3)
was filtered completely, washed thoroughly with cold water, and
recrystallized properly [18]. 62% yield; FTIR (KBr) υ (cm-1): 3287
(-NH, stretching), 3073 (C-H, aromatic), 1743 (C=O), 1670 (C=C,
alkene), 1592 (C=C, aromatic), 1566 (-NH, bending), 1346 (C-N),
1177 (C-O); 1H NMR (δ, ppm, CDCl3): 10.19 (9, 1H), 8.17 (12, 1H),
6.7-8.3 (Aromatic, 10H), 3.88 (1, 3H), 1.31 (17, 3H). MS: M+ 383.
Anal. Calcd. For C26H25NO2: C, 81.43; H, 6.57; N, 3.65. Found: C,
80.91; H, 6.14; N, 3.51.
Table 1: Summary statistics from 30 runs
Compounds |
IC50 value (μM) |
3 |
5.94 ± 0.81** |
1 |
7.79 ± 0.94* |
Ascorbic acid |
4.32 ± 0.27 |
n = 3; **p< 0.01 with respect to standard drug
Ant-Oxidant Screening
The ability of the compound in scavenging the DPPH radical
was investigated according to the given protocol. A stock solution
of 1 mg/mL of the test compound was prepared initially and then
100 μg/mL of the compound was added to the methanolic DPPH
solution (0.1 μM) at equal concentration. The above mixture was
incubated at room temperature for half an hour and at 517 nm
wavelength, the absorbance was recorded. The IC50 values of the
molecules were calculated accordingly. Ascorbic acid was utilized
as the positive control [19].
Statistical Treatment
The obtained anti-inflammatory data were analyzed initially
by one-way ANOVA method followed by treating with Dunnett’s
multiple comparison tests. The P value of < 0.01 was regarded as
statistically considerable.
Results and DiscussionTop
Chemistry
The spectroscopic and elemental analysis strongly supported
the formation of the tert-butyl Chalcone. The transformation of
the Murrayanine into murrayanine-chalcone was ascertained
from the FT-IR spectra. The formation of ketonic carbonyl moiety
(at 1743 cm-1) from the aldehydic carbonyl moiety, which earlier
appeared at 1753 cm-1 in the spectra confirmed the formation
of the Chalcone scaffold. Moreover, the prop-2-ene-1-one
component was corroborated from 1670 cm-1 peak in vibrational
spectroscopy and 8.17 ppm in rotational spectroscopy. The
presence of carbazole portion in the compound was substantiated
from the FT-IR and NMR spectra. The NH stretching and bending
of the carbazole were noticed at 3287 cm-1 and 1566 cm-1,
respectively. The 1H-NMR spectra represented amide part from
the peak at 10.19 ppm. In addition to it, C-N part of the carbazole
was authenticated by FT-IR spectra at 1346 cm-1. Additionally, the
verification of methoxy group at carbazole moiety was performed
from both FT-IR and NMR spectra. The C-O component was
located from FT-IR spectra at 1177 cm-1 whereas the NMR spectra
showed proton peak at 3.88 ppm. The tert-butyl part at B-ring
was made sure from the NMR spectra at 1.31 ppm.
The appearance of beak peak corresponding to the molecular mass of the proposed structure (M+ 383) confirmed the formation of the benzylidene acetophenone scaffold. In the mass spectra, the fragment peaks in the range between 100-150 of m/z was observed. However, no such degradation of the Chalcone into low molecular weight products was seen from the mass spectra. Furthermore, the practically estimated ratio of carbon, hydrogen, and nitrogen and its close resemblance with the theoretical values proved the formation of tert-butyl bearing murrayaninechalcone.
The appearance of beak peak corresponding to the molecular mass of the proposed structure (M+ 383) confirmed the formation of the benzylidene acetophenone scaffold. In the mass spectra, the fragment peaks in the range between 100-150 of m/z was observed. However, no such degradation of the Chalcone into low molecular weight products was seen from the mass spectra. Furthermore, the practically estimated ratio of carbon, hydrogen, and nitrogen and its close resemblance with the theoretical values proved the formation of tert-butyl bearing murrayaninechalcone.
Anti-oxidant activity
The anti-oxidant potential of the Chalcone is based on the
ability of the compound to reduce the ferric form into ferrous
form. The tested molecule presented a tremendous radical
scavenging activity as evidenced by the IC50 value of 5.94 μM.
The higher activity of the novel compound may be predicted
from the synergistic potentials of the carbazole, Chalcone, and
tert-butyl group. The study represented a better scavenging
reduction activity than that of the parent molecule Murrayanine,
which showed IC50 value of 7.79 μM. Therefore, the existing study
rejuvenated the approach of hybridization of multiple dynamic
scaffolds of similar biological activity and potency.
ConclusionTop
This innovative research presented a very rational approach to
the successful development of potential anti-oxidant compounds,
which will have a remarkable clinical perspective. The Chalcone
based product obtained by hybridization of multiple dynamic
scaffolds of similar biological activity and potency will positively
open new avenues of applied research. From the results, it can
surely be concluded that the molecule can be used for reducing
the oxidative stress imposed by the reactive free radicals,
thereby preventing the cancer, nephritic disorders, neurological
disorders, cardiac complications, Alzheimer’s disease, metabolic
syndromes, etc. In addition, due to the presence of tert-butyl
function which marketed anti-oxidant products do have, it
may be predicted that the synthesized compound will also find
application in the preservation of formulations, food products,
and neutraceuticals. The current study will positively influence,
motivate, and incline millions of global researchers in developing
similar therapeutically active low-molecular-weight ligands and
their translated pharmaceutical products for disease prevention
and further utility.
AcknowledgmentTop
Authors are highly thankful to Savitribai Phule Pune
University, Pune, Maharashtra, India for providing research
grants (Grant No. 13PHM000126).
Conflict Of InterestTop
No conflict of interest declared.
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