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Informatics in Medicine Unlocked
journal homepage: www.elsevier.com/locate/imu
Chromatographic analysis of phytochemicals in Costus igneus and
computational studies of flavonoids
John reddy Peasari, Sneha sri Motamarry, Karthikeya Srinivasa Varma, P. Anitha,
Ravindra Babu Potti
∗
Department of Biotechnology, Sreenidhi Institute of Science and Technology, Ghatkesar, Hyderabad, 501 301, Telangana State, India
ARTICLE INFO
Keywords:
Costus igneus
Quercetin
Pioglitazone
Tyrosine kinase
AutoDock
Diabetes
ABSTRACT
Costus igneus, also known as Spiral flag, belongs to the Costaceae family. Recently, studies have emphasized the
anti-diabetic potential of this plant. Literature studies show that it possess hypo-lipidemic, diuretic, anti-oxidant,
anti-microbial, anti-cancerous properties. Phytochemical investigations reveal the presence of carbohydrates,
proteins, triterpenoids, alkaloids, tannins, saponins, flavonoids, and steroids. In the present study, thin layer
chromatography and high performance liquid chromatography profiling was performed for quercetin. The leaf
showed the presence of quercetin with Rf value of 0.56 as compared with the standard Rf value. HPLC chro-
matograph of Standard and Leaf Extract exhibited peaks at 4.263 min and 4.019 min. Further quantitative
analysis was conducted to determine the total flavonoid content of the leaf extract. It is a naturally occurring
bioflavonoid, and an inhibitor of insulin receptor tyrosine kinase-catalyzed phosphorylation of exogenous
substrate. Docking studies were performed to determine the interaction of polyphenols with Insulin Receptor
Tyrosine Kinase, meant to be a target for diabetes. Insulin receptor kinase (PDB Id:1IR3) was selected as the
target molecule. Flavonoids such as quercetin, kaempferol, epicatechin, roseoside, and the standard anti-diabetic
drug pioglitazone were selected as ligand molecules. The docked complex was visualized in the Maestro
Visualizer of the Schrodinger suite. All of the compounds formed hydrogen bonds with the residues of the
receptor. Quercetin showed the best binding energy, with −7.28 kcal/mol indicating improved interactions via
hydrogen bonds with the active site residues. Computational studies revealed that quercetin and kaempferol
have the best binding energies, as compared to the standard drug pioglitazone (−6.26 kcal/mol), which acti-
vates insulin receptor tyrosine kinase. From the present study, we conclude that quercetin can be useful as a
herbal therapeutic agent for diabetes.
1. Introduction
Costus is a genus of perennial tropical herbaceous flowering plants
belongs to the family Costaceae. It is a perennial, upright, spreading
plant reaching about 60 cm in height, with spirally arranged leaves,
solid stem, and attractive flowers [1]. Costus igneus leaves contain
different bioactive compounds which have anti-diabetic, anticancer,
anti-hypertension, antibacterial, and hypolipidemic properties. More
than 400 medicinal plant species show hypoglycemic activity [2].
Phytochemical screening reveals the presence of alkaloids, glycosides,
polysaccharides, tannins, saponins and phenolics such as flavonoids,
terpenoids, carotenoids, and steroids [3] Flavonoids are well-known for
anti-diabetic activity and contain polyphenols, with a common struc-
ture of diphenylpropanes (C6-C3-C6), consisting of two aromatic rings
linked through three carbon atoms. Major subclasses of flavonoids
include flavones (apigenin, luteolin), flavonols (quercetin, myricetin),
flavanones (naringenin, hesperitin), flavanols (catechins - epicatechin
and gallocatechin), anthocyanidins (e.g. cyanidin and pelargonidin)
and isoflavones (genistein, daidezin). Among the flavonoids, quercetin
has gained special attention for its potential therapeutic activities [4].
Phytochemical screening and identification of quercetin by thin layer
chromatography (TLC) and High Performance Liquid chromatography
(HPLC) is used simultaneously for determination of quercetin com-
pound. Furthermore, the effect of mobile phase composition on reten-
tion and selectivity and as an aid in partial identification of quercetin
compound has been studied [5]. Quantification of the methanolic ex-
tract of Costus igneus leaves was performed by spectrophotometer assay
for quercetin.
Diabetes mellitus is a metabolic disorder affecting a large percent of
the world population. It is mainly characterized by chronic
https://doi.org/10.1016/j.imu.2018.10.004
Received 9 July 2018; Received in revised form 28 September 2018; Accepted 4 October 2018
∗
Corresponding author.
E-mail address: ravindrap@sreenidhi.edu.in (R.B. Potti).
hyperglycemia, resulting from defects in insulin secretion or insulin
action. Type 1 Diabetes results as Beta cells of the pancreas do not se-
crete insulin. Type 2 Diabetes is a condition of insulin resistance; all of
the cells fail to respond appropriately to insulin, and the absorption of
glucose from the bloodstream by these cells becomes difficult. It is in-
volved in several disorders, including atherosclerosis, neuropathy, ne-
phropathy, retinopathy, increased thirst, increased urinary output, ke-
tonemia, and ketonuria. Currently, it has been reported that
approximately 387 million people live with diabetes globally, and the
number is projected to double by 2030. India had 69.2 million people
living with diabetes (8.7%) as per the 2015 data [6]. Despite the pre-
sence of antidiabetic medicines on the market, diabetes and related
complications continued to be a major problem. The prevalence of the
disease is increasing. Insulin and oral hypoglycemic drugs such as sul-
fonylurea, biguanides, α-glucosidase inhibitors and glinides, as pro-
ducts in developing countries are expensive and not easily accessible.
The use of leaves of Costus igneus as an alternative therapy have shown
a significant decrease in glucose levels in comparison with the standard
sulphonyl urea drug Glibenclamide [7].
The insulin receptor is expressed in almost all mammalian tissues.
The receptor targets for Type II Diabetes Mellitus reported by many
scholars to date are glycogen phosphorylase, protein tyrosine phos-
phatase 1-beta (PTP-1??), dipeptidyl peptidase-IV (DPPIV), glucoki-
nase, peroxisome proliferator activated receptor (PPAR), aldose re-
ductase (AR), and insulin receptor (IR) among others [8]. An in-silico
approach has been used to generate more effective and potential insulin
receptor tyrosine kinase activators through ligand based drug designing
approaches. Insulin signaling, including activation of IR tyrosine kinase
activity, is impaired in most patients with diabetes mellitus. This re-
sistance to insulin then leads to hyperglycemia and other metabolic
abnormalities of the disease. Hence, compounds that augment insulin
receptor tyrosine kinase activity would be useful in the treatment of
diabetes mellitus.
Quercetin exhibits impressive hypoglycemic effects, with significant
improvement, stabilization of long sustaining insulin secretion and re-
generation of human islets in the pancreas without producing serious
health hazards [9]. The insulin receptor (IR) is a transmembrane re-
ceptor that is activated by insulin, Insulin-like growth factor I (IGF-I),
Insulin-like growth factor II (IGF-II), and belongs to the large class of
tyrosine kinase receptors [10]. Its function is regulation of glucose
homeostasis and its metabolic dysfunction results in diabetes and
cancer. [11,12]. Binding of insulin leads to phosphorylation of several
intracellular substrates, including insulin receptor substrates (IRS1, 2,
3, 4), Casitas B-lineage (CBL), and other signaling intermediates [13].
The resulting phosphorylated tyrosines serve as docking sites for var-
ious proteins involved in receptor tyrosine kinase-mediated signaling
transduction pathways.
2. Material and methods
2.1. Cultivation of Costus igneus
The plant was grown with a potting mix of 1:1:0.5 (red soil: sand:
vermicompost) in the Plant biotechnology laboratory, Sreenidhi
Institute of Science and Technology, Hyderabad, India. Sufficient wa-
tering was done in regular intervals for the plant to grow under 50%
shade.
2.2. Extraction
Fresh leaves of Costus igneus were collected, cleaned and shade-
dried and made into powder using a mechanical grinder, and passed
through a 20-mesh sieve to have homogenous size, and were weighed
separately. The powdered samples (10 g) were separated and extracted
with methanol using a Soxhlet apparatus as illustrated in Fig. 1. The
extraction was carried out for 8 h at a room temperature of 30 °C. The
extracts were filtered and concentrated using a rotary evaporator at
70 °C and then used for further analysis.
2.3. Qualitative analysis of phytochemicals in leaf of Costus igneus
Phytochemical tests were carried out on the methanol extract using
standard procedures to identify the constituents, as described by Refs.
[14], [15].
2.3.1. Test for tannins
About 0.5 g of the powdered sample was boiled in 20ml of water in
a test tube and then filtered. A few drops of 0.1% ferric chloride was
added and observed for brownish green or a blue-black color.
2.3.2. Test for flavonoids
Methanolic extract of 1 ml was taken in a test tube with 0.5 ml of
alcohol, a pinch of Magnesium, and a few drops of a concentrated HCl
was added. The appearance of red color indicates the presence of fla-
vonoids.
2.3.3. Terpenoids (Salkowski test)
5.0 ml extract was shaken with 2.0 ml chloroform (CHCl
3
) and
concentrated H
2
SO
4
(aq) (2.0 ml) was added along the sides of the test
tube. A reddish-brown coloration of the interface can be considered as
the presence of terpenoid.
2.3.4. Alkaloids
1.0 mg of extract was dissolved in 10.0 ml of dilute hydrochloric
acid (HCl) and filtered. The filtrate was separately treated with
Dragendorff's, Mayer's, and Wagner's reagents to test for the presence of
alkaloids.
Fig. 1. Methanolic Extraction of Phytochemicals from Costus igneus leaves by
Soxhlet Apparatus.
J.r. Peasari et al.
2.3.5. Mayer's test
To one portion of the filtrate, 1.0 ml of Mayer‘s reagent (potassium
mercuric iodide solution) was added. Cream colored precipitate for-
mation indicates the presence of alkaloids.
2.3.6. Saponins (Froth test)
The Extract was shaken with distilled water (10.0 ml) in a test tube.
The formation of frothing, which persists in warming in a water bath for
5 min, showed the presence of saponins.
2.3.7. Anthocyanosides
1 ml of extract was taken in a test tube and treated with 5 ml diluted
HCl(aq). Pale pink color solution confirms the presence of anthocya-
nosides.
2.3.8. Reducing sugars
1.0 ml of plant extract was acidified with dilute HCl and neutralized
with dilute NaOH. Then the solution was heated with Fehling‘s A and B
solutions. The appearance of the red precipitate can be considered as
the indication for positive results.
2.3.9. Test for steroids
Two ml of acetic anhydride was added to a 0.5 g methanolic extract
of each sample with 2 ml sulphuric acid. The change of color from violet
to blue or green in samples indicates the presence of steroids.
2.4. Chromatographic studies
2.4.1. Qualitative analysis of quercetin by thin layer chromatography
Thin Layer Chromatographic (TLC) analysis of Costus igneus in
methanol extracts of a leaf was separated using a stationary phase
containing a plate with aluminum silica gel 60F254(Merck) with a size
of 10 ×10 cm. Mobile phases with different concentrations were em-
ployed for screening of flavonoids and selected the one in which se-
paration of flavonoid was clear using standard methods. Quercetin was
clear in the mobile phase [16] Butanol: Acetic acid: Water (6:6:18 v/v/
v) for all the samples [17]. Quercetin (1 mg) standard was dissolved in
methanol. All plates were visualized directly after drying by subjecting
to iodine vapors in an iodine chamber for visualization of colored spots.
The retention factor (Rf) value of standard and sample was calculated
by using the following formula: Rf = Distance travelled by solute/Dis-
tance travelled by solvent ×100. The spots were scratched and sus-
pended in the mobile phase for further identification of quercetin by
HPLC analysis.
2.4.2. HPLC analysis
2.4.2.1. Preparation of standard quercetin. Quercetin was purchased
from Hi-Media and HPLC grade of methanol and orthophosphoric
acid from Merck. Standard quercetin of 1 mg (HiMedia) was dissolved
into 1 ml of Methanol [18]. The standard was maintained at a room
temperature of 28 °C. Methanolic leaf extracts of Costus igneus was
weighed for 0.1 mg of each test sample, and dissolved in the diluent.
The TLC separated Costus igneus extracts of quercetin were subjected to
High Performance Liquid Chromatography.
2.4.2.2. Preparation of mobile phase. 1.0 ml of orthophosphoric acid
was pipetted into a 2000 ml volumetric flask, and three times the
pipette was rinsed with water, and made up to volume with water.
Mobile phase B: Methanol Gradient programme Chromatographic
conditions.
2.4.2.3. Method specification. The standard and the isolated fraction of
quercetin were analyzed by the HPLC technique using the following
conditions are presented in Table 1. HPLC studies were carried out
using Empower 2 software.
2.5. Quantitative assay of flavonoids using spectrophotometer
Flavonoids are widely distributed in nature. They consist of a
Benzene–gamma –pyrone structure. They have the ability to complex
with metal ions and act as an antioxidants, and bind to proteins such as
structural proteins and enzymes. The different classes within the groups
are distinguished by additional oxygen containing heterocyclic rings
and hydroxyl groups, which includes Flavones, Flavanones, Flavonols,
Isoflavones, Catechin, Anthocyanidins, Leuco anthocynadins,
Chalcones and Aurones.
The Aluminum chloride colorimetric technique was used for esti-
mation of total flavonoid content [19]. The intensity of the color is
proportional to the amount of flavonoids and can be estimated as
quercetin equivalent at wavelength of 415 nm. Aliquots of standard
quercetin (10–100 μg/ml) were obtained in the test tubes, followed by
1.5 ml of 95% of methanol, then 0.1 ml AlCl3(10%), 0.1 ml potassium
acetate of 1M and 2.8 ml distilled water was added sequentially. The
test solution was vigorously shaken. The amount of aluminum chloride
(10%) was substituted by the same amount of distilled water in blank.
All prepared solutions were filtered through Whatman filter paper prior
to measurement. The absorbance at 415 nm was recorded by using a
UV1800 (Shimadzu) spectrophotometer after 30 min of incubation.
Results were expressed as quercetin equivalent (mg/g). 50–200 μg/ml
of leaf extract was taken as a test sample. The amount of flavonoids
present was determined by linear regression analysis. The total flavo-
noid content was expressed as mg of quercetin equivalents per gm of
extract.
2.6. In silico approach
2.6.1. Preparation of macromolecule & active site analysis
The X-ray crystal structure of Insulin Receptor of Homo sapiens with
a resolution of 1.9 A° used in the present study was obtained from
Protein Database (PDB: ID 1IR3) [20]. The list of compounds present in
the leaf of insulin plant was identified from the literature. Energy
minimization of the protein molecule was done using AutoDock tools.
All the HETERO atoms in the PDB file were removed prior to docking,
and the protein was used further in computational studies. Residues
present in the active site of receptor tyrosine kinase molecule were
identified using SPDBV [21].
2.6.2. Preparation of ligand molecules and ADMET properties
The 3D structures of the ligand molecules are retrieved from the
NCBI PubChem database [22]. Epicatechin, quercetin, roseoside,
kaempferol and the standard drug pioglitazone were retrieved in SDF
format and converted into PDB files using SPDBV 4.10 (Swiss PDB
Viewer). 2D structures of the ligands were sketched using ChemSpider.
The canonical SMILES of these molecules were obtained from PubChem
(www.ncbi.nlm.nih.gov/pubchem). Drug-likeness of all ligand mole-
cules were predicted using the molinspiration property prediction tool
(www.molinspiration.com)[23]. This tool analyzes the molecular
properties based on Lipinski's rule of five, and addresses the violation of
particular properties.
Table 1
Method Description for HPLC analysis.
Parameters Description
Column Symmetry C18
Column size 4.6 mm*160 mm*5μm
Mobile Phase Methanol:0.1%Orthophosphoric acid (65:35%)
Flow Rate 1 ml/min
Detector and Wavelength PDA photodiode array,375 nm
Injection loop capacity 20
Retention time 4.2min
Run time 8min
J.r. Peasari et al.
2.6.3. Docking analysis
Docking was performed by an offline molecular modeling software
AutoDock 4.2. [24] Protein and ligands were converted into PDBQT
format. Hydrogen atoms and Kollmann charges are added to the protein
molecule. Torsion and rotatable bonds for ligands are identified in
AutoDock tools. Energy minimization of ligands was performed. A grid
was set in such a way that it covers all the residues in the active site of
protein residue. The grid was centered in the active site region which
involves all functional amino acid residues. Cartesian coordinates of a
residue (SER 1006) present in the active site were set at X = −26.596,
Y = 23.409, Z = 11.416. Grid box dimensions were set at 60*60*60 Å.
GPF was generated after running AutoGrid. AutoDock 4.2 makes use of
Monte Carlo simulated annealing as well as the Lamarckian Genetic
algorithm for the generation of possible orientations of ligand. The
results were displayed in the DLG file format (Docking Log File).
Docking was performed by taking the initial population size as 150. Ten
runs or conformations were generated. The pose with least binding
energy was selected as the best pose. The docked complexes were vi-
sualized in Maestro of Schrodinger Suite 2017-3 [25]. Both 2D and 3D
overlays were used to study the covalent and non-covalent interactions.
3. Results and discussion
3.1. Qualitative phytochemical analysis
The Phytochemical screening of leaf extract showed the presence of
flavonoids, triterpenoids, tannins, alkaloids, steroids, and reducing su-
gars except for saponin, which was negative. Light orange colored spots
were observed when sprayed with iodine vapors. The spot visualized
coincides with that of standard quercetin, as illustrated in Fig. 2. The
calculated retention factor for leaf extract was 0.58, compared with that
for standard quercetin of 0.6 as indicated in the literature [26].
3.2. High performance liquid chromatography (HPLC)
Quercetin presence in the leaf extract was confirmed by HPLC. The
melting point of standard quercetin was found to be 316 °C (Literature
value: 316 °C). The HPLC chromatogram for both standard quercetin
and leaf extract indicated a single peak, and retention time was found at
approximately 4.0 min, as is illustrated in Fig. 3 &Fig. 4.
3.3. Quantitative assay of flavonoids using spectrophotometer
Concentration values of extracts were obtained from the quercetin
standard curve as illustrated in Fig. 5, by interpolating to the X-axis. In
Costus igneus, methanolic leaf extract of the total flavonoid content was
found to have a maximum value of 3.02 ± 0.04 mg/gm quercetin
equivalent.
3.4. Docking studies
3.4.1. Active site analysis of 1IR3
The active site of the tyrosine kinase receptor consists of amino acid
residues: SER 1006, LYS 1030, GLU 1077, ASP 1083, ASN 1137, and
ASP 1150, MET 1079; these are eventually bound to phospho-amino
phosphonicacid –adenylate ester substrate as illustrated in Fig. 6.
3.4.2. Prediction of ADMET properties
All four ligands including standard drug showed 0 violations (Fig. 7)
from Lipinski rule of five. These compounds were used for docking
analysis that activates the Insulin Tyrosine receptor. The best lead
compound was identified by RO5. The Molinspiration prediction values
of the compounds are depicted in Table 2.
3.5. Molecular docking
Docking was performed between insulin receptor and ligands that
satisfied Lipinski's rule. Maximum energy evaluations were 250000.
One best will be preserved for each genetic algorithm. Binding energies
are shown in Table 3. The genetic algorithm is run for at most 27000
generations. Mutation and crossover rate were found to be 0.020000 &
is 0.800000. The docked complex was visualized in the Maestro
Schrodinger Suite 2017-3. All of the ligands indicated negative energy.
Quercetin is the compound having the least binding energy. The stan-
dard antidiabetic drug pioglitazone that activates insulin tyrosine re-
ceptor, has found to have a binding energy less than that of quercetin
and kaempferol. Interactions between ligand molecules and insulin
receptor tyrosine kinase were analyzed and it was observed that these
compounds can activate the kinase domain, since the phosphorylated
tyrosines were bound to the residues located in the activated loop of the
protein, and it was hydrogen bonded to the ligand molecule. Ligand
interaction diagrams and 3D overlays were obtained from Maestro Vi-
sualizer.
3.5.1. Binding mode analysis of compounds against receptor tyrosine kinase
The Post-docking analysis was analyzed using Maestro Schrodinger
2017-3. Ligand interactions with the active site residues of the protein
molecule were studied as represented in Fig. 7 &Table 4. Active site
residues formed both covalent and non-covalent interactions with re-
spective ligand molecules. Hydrogen bond length was measured in A°.
Quercetin had the least binding energy of −7.28 kcal/mol in Table 3,
indicating it could be the compound that can activate the insulin re-
ceptor. It formed three hydrogen bonds with binding site residues,
namely ASP 1047 (2.03 A°), MET 1079 (1.93 A°), MET 1079 (1.68 A°).
A total of six non-covalent interactions were formed against 1IR3. The
Kaempferol binding energy is almost equal to that of quercetin, which is
−7.27 kcal/mol from Table 3. A phosphorylated tyrosine residue (PTR
1163) formed a hydrogen bond (1.96 A°) with the ligand along with
ASP 1132 (1.89 A). Three non-covalent interactions were formed.
Fig. 2. Identification of Quercetin from methanolic leaf extract of Costus igneus
by Thin Layer Chromatography.
J.r. Peasari et al.
Pioglitazone is a standard drug available on the market which plays a
significant role in increasing insulin sensitivity by the activation of
insulin tyrosine kinase receptor [27] as illustrated in Fig. 8. It was
shown to increase autophosphorylation of the insulin receptor. The
binding energy (Table 3) was less compared to quercetin and kaemp-
ferol with a value of −6.26 kcal/mol. Epicatechin formed 4 Hydrogen
bonds viz., ASP 1083 (1,73 A°) & GLU 1004 (3 bonds (1.96,2,05, 1.86
A°). It also formed a non-covalent interaction with ASP 1083. As in-
dicated in Table 3, the binding energy was found to be −6.25 kcal/mol.
Roseoside binding energy in Table 3 was −5.36 kcal/mol. Sixteen hy-
drophobic interactions were observed between the protein and the li-
gand. Two hydrogen bonds were formed with the same residue ASP
1132 (2.60 & 1.86 A°) as illustrated in Figs. 9 and 10.
In Ref. [28] the insulin receptor kinase PDB ID 1IR3 was addressed
as a target for diabetes mellitus with docking scoring function of Mol-
Dock which is an extension of the piecewise linear potential (PLP)
Fig. 3. HPLC chromatogram for quercetin standard.
Fig. 4. C-18 HPLC-PDA chromatogram for identification of quercetin shows strong absorbance at 375 nm and retention time around 4 min.
Fig. 5. Standard Curve of Quercetin for quantitative estimation.
J.r. Peasari et al.
including new hydrogen bonding and electrostatic terms. The authors
screened the various ligands with AutoDock, with scoring function of
force field & linear weights that can be used to compute a binding
energy. The understanding of the advantages and limitations of each
docking program is fundamentally important to conduct more reason-
able docking studies and docking-based virtual screening. With in-
hibition of this target, the compounds might be useful as herbal ther-
apeutic agents for diabetes. Zhe Wang et al., [29] illustrates that among
the ten docking programs tested, three of them, including AutoDock
Vina, GOLD and MOE Dock, achieved the best scoring, and no single
docking program has dominative advantages as compared with other
programs.
4. Conclusion
Qualitative analysis of different plant secondary metabolites was
performed in this study. Presence of Quercetin in leaf extract was
confirmed by TLC and HPLC. The antidiabetic property of the quercetin
was studied by computational methods. Quercetin yielded the best
binding energy compared to other flavonoids present in the plant, along
with the standard drug Pioglitazone. Also shown were both the covalent
and non-covalent interactions. Docked conformations revealed that
most of the active site residues exhibited interaction with the protein
molecule. Phosphorylated tyrosines present in the protein were found
to interact with the ligand molecule. PTR 1163 was hydrogen bonded
Fig. 6. Active site residues interacting with the ligand using SPDBV.
Fig. 7. (a–e): 2D Structures of the Ligands (www.ncbi.nlm.nih.gov/).
Table 2
Molinspiration prediction values of the compounds.
Compound miLogP
a
Natoms
b
M.Wt
c
nON
d
nOHNH
e
nVio
f
Nrotb
g
Volume
h
Quercetin 1.68 22 302.24 7 5 0 1 240.08
Kaempferol 2.17 21 286.24 6 4 0 1 232.07
Epicatechin 1.37 21 290.27 6 5 0 1 244.14
Roseoside −0.19 27 386.44 8 5 0 5 356.65
Pioglitazone 3.07 25 356.45 5 1 0 7 318.53
a) Partition coefficient b) Total number of atoms c) Molecular weight d) Hydrogen bond acceptors e) H bond donors f) Violations g) Number of Rotatable Bonds h)
Molecular volume.
Table 3
Binding energies of Ligands with the target Protein.
Compound Binding energy (kcal/mol)
Quercetin −7.28
Kaempferol −7.27
Pioglitazone −6.26
Epicatechin −6.25
Roseoside −5.36
Table 4
Comparision of Ligand interaction with binding pocket residues.
Compound Number of
Hydrogen
bonds
Hydrogen bond
Interacting
residues
H-Bond
Length
(Aº)
Non Covalent
Interactions
Quercetin 3 ASP 1047
MET 1079
MET 1079
2.03
1.93
1.69
LYS 1030 (2)
VAL 1010 (2)
MET 1079
LEU 1002
Kaempferol 2 PTR 1163
ASP 1132
1.96
1.89
LEU 1170
MET 1153
TYR 10
Epicatechin 4 ASP 1083
GLN 1004
GLN 1004
GLN 1004
1.73
1.96
2.05
1.86
ASP 1083
Roseoside 2 ASP 1132
ASP 1132
2.60
1.86
ASP 1150
VAL 1010
ASP 1132
LYS 1030 (4)
TYR 10 (9)
Pioglitazone 1 GLU 1047 1.98 GLY 1003
MET 1139 (2)
Fig. 8. 2D and 3D overlay of Standard drug Pioglitazone with the Insulin
Receptor active domain residues.
J.r. Peasari et al.
with Kaempferol, having a binding energy almost the same as compared
to quercetin, which is a part of the activation loop. Almost all ligands
showed interaction with functional residues in the binding pocket.
Various structural orientations suggest that the insulin receptor tyrosine
kinase in its active site. The presence of phytochemicals in the Costus
igneus plant holds great potential in the treatment of diabetes.
Acknowledgements
We would like to thank our management Sreenidhi Institute of
Science and Technology and the Department of Biotechnology for
providing the necessary Infrastructure and facilities.
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Fig. 9. (a–d):Ligand Interaction diagrams of a)Quercetin b)Kaempferol c)
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Fig. 10. (a–d): 3D overlays of the docked complexes A)Quercetin B)Kaempferol
C) Epicatechin D)Roseoside.
J.r. Peasari et al.
