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International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
e-ISSN: 2583-066X
1
Anticancerous Properties of Tetragonula
travancorica (stingless bee) Honey on
Reproductive Cancer Cells
Namboorimadathil M. Nahala1*, Chennattu M. Pareeth2, K. P. Safna Hussan3,
Thekkekara D Babu4, K. B. Soni5, V. S. Amritha6*
1, 5 Department of Agricultural Biotechnology, College of Agriculture, Thiruvananthapuram, Kerala, India
2, 3, 4 Department of Biochemistry, Amala Cancer Research Centre, Thrissur, Kerala, India
6 Department of Entomology, College of Agriculture, Thiruvananthapuram, Kerala, India
*Corresponding Author’s Email: 1 nahala7nm@gmail.com, 6 amritvs@gmail.com
Abstract
Honey from stingless bee is highly regarded as a medicine in many global communities due to its nutritional and therapeutic value. There
is a comparatively restricted amount of research on the biological characteristics of stingless bee honey (SBH) in contrast to Indian bee
honey (IBH). Therefore, the objective of this research is to explore the anti-cancer properties of Tetragonula travancorica honey. In the
present investigation, antioxidant activity of honey was evaluated using ABTS, DPPH and SOD radical scavenging assays. Anti-proliferative
effects was examined on various cell lines using the MTT assay. Liquid chromatography-mass spectrometry (LCMS) analysis was employed
to characterize the honey. Binding capabilities of compounds identified in SBH on estrogen receptors (ER) α and ER β were explored through
Schrödinger Maestro software. Results indicated that SBH effectively scavenged ABTS, DPPH and SOD free radicals with IC50 values of
22, 36.15, and 79.85 v/v, respectively. SBH exhibited anti-proliferative activity against MCF-7 and HeLa cell lines, with IC50 values of
58.11 and 66.68 v/v, respectively. LCMS analysis, shows the presence of methyl syringate, 2-hydroxycinnamic acid, and fumaric acid in
SBH which were not present in IBH. Docking experiments determined that these compounds, with the exception of fumaric acid, interacted
stronger with the binding sites of ER β than ER α. The comprehensive findings from antioxidant, anti-proliferative, and docking studies
underscore the potential anti-cancer properties of Tetragonula travancorica honey, particularly its heightened cytotoxicity against
reproductive system cancer cell lines, such as of the breast and cervix.
Keywords
Anti-proliferative, estrogen receptor, stingless bee, cytotoxicity.
INTRODUCTION
Cancer is a devastating illness, claiming the lives of ten
million people annually across the globe. It is currently the
second most common cause of death globally, after
cardiovascular disorders. According to recent estimates from
the International Agency for Research on Cancer (IARC) and
the World Health Organization (WHO), there were
approximately 10.0 million deaths from cancer globally in
2020, along with 19.3 million new cancer diagnoses. Most
frequent cancers to be diagnosed were non-melanoma skin
cancer with 1.20 million cases, stomach cancer with 1.09
million cases, colon and rectum cancer with 1.93 million
cases, lung cancer with 2.21 million cases and female breast
cancer with 2.26 million cases. [1].
Honey made from collected and modified plant exudates
served as a prized natural dietary supplement since ancient
times, renowned for its myriad medicinal and nutritional
properties [2]. Natural honey's composition varies according
to variables such as geographic regions, the sources of
honeybee feeding, weather conditions, climate, and any
treatments it may undergo [3] [4]. A variety of biological and
chemical characteristics are present in honey, including its
antioxidant [5], anti-inflammatory [6], anti-tumour [7]
antimicrobial [8], bacteriostatic, wound and sunburn healing
[9], anti-ulcer [10] and antiviral [11] activities.
A large number of bees known as stingless honey bees are
members of the tribe Meliponini. They are members of the
Apidae family, which includes other common bees. They are
found throughout the majority of tropical and subtropical
parts of the world, including Australia, Southeast Asia,
Africa, and tropical America [12]. Surprisingly, although
having better nutritional and therapeutic characteristics than
other honey bee products, SBH is used less frequently as a
dietary and medical supplement [13]. Stingless bee products
are thought to be more promising sources of biologically
active substances than honey bee products, because of the
availability of plants in stingless bee habitats in the tropics
and subtropics. In several populations in South America and
Africa, stingless bee honey is utilized as medicine. SBH has
been demonstrated to have therapeutic potential in
hyperglycemia, the healing process, vision problems, blood
pressure, reproductive problems, malignancies, chronic
infections and disrupted lipid levels, which could be due to
the different compounds present in the honey [14]. The bee
of interest Tetragonula travancorica is a new species
distinguished from other Indian species of the subgenus. This
species has morphological changes from Tetragonula
iridipennis, which is predominantly found in India but was
originally discovered on the island of Sri Lanka [15]. It can
International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
e-ISSN: 2583-066X
2
be distinguished from Tetragonula iridipennis by a change in
its hind wings, longer antenna and other features [16]. But
these species are poorly characterized and have not been
directly compared with molecular studies. Hence, there is
uncertainty about whether they are separate species [17].
OBJECTIVE
The purpose of this study was to evaluate the potential
anticancer properties of stingless bee honey, recognizing its
significance. A comparative evaluation was conducted with
Indian bee (Apis indica) honey. The study involved assessing
its cytotoxic potential on murine tumour cells such as DLA
and EAC and examining the antiproliferative effects on
various cancer cell lines of human origin, including breast
and cervix. Using assays for ABTS, DPPH and SOD radical
scavenging, its antioxidant properties were evaluated.
Compounds of the honeys were qualitatively analyzed
through the LCMS method and the compounds identified
were docked using in silico methods.
MATERIAL AND METHODS
Collection and preparation of honey samples
Stingless bee honey (SBH) and Indian bee honey (IBH)
were sourced from College of Agriculture,
Thiruvananthapuram, affiliated with Kerala Agricultural
University. The samples were kept under sunlight and filtered
using a muslin cloth. The honey was prepared in an aqueous
solution as volume/volume.
Cell lines
Cervical cancer cells, HeLa; breast cancer cells MCF-7;
Intestinal epithelial cells, IEC-6 and kidney epithelial cells,
Vero were sourced from the National Centre for Cell Science,
Pune. The cell lines were maintained at 37°C, 5% CO2, 100%
humidity, 95% air and were cultivated in DMEM medium
supplemented with 10% v/v FBS, 100 μg/mL antibiotic and
100 U/mL penicillin. The Ehrlich Ascites Carcinoma (EAC)
and Daltons Lymphoma Ascites (DLA) cell lines were
acquired from the Amala Cancer Research Centre, Kerala.
Total phenolic content
The Folin-Ciocalteu colorimetric technique was utilized to
evaluate the phenolic content [18]. In this analysis, a 50 µL
aliquot of the extract was combined with 1 mL Folin-
Ciocalteu phenol reagent and 0.8 mL 7.5% sodium carbonate.
Following a 60-minute incubation at room temperature, the
absorbance of mixture at 765 nm was measured using a
Systronics UV-VIS Spectrophotometer Type 119. Gallic acid
equivalents (GAE), measured in milligrams per gram of
extract, were used to express the results.
Total flavonoid content
Aluminium chloride colorimetric technique was employed
to evaluate the flavonoid concentration. [19]. 0.1 mL of plant
extracts were combined with 1 mL 2% aluminium chloride.
A separate test tube containing a blank was prepared. These
tubes were incubated at room temperature for 30 minutes, and
the absorbance at 415 nm was recorded. Quercetin
equivalents (QTE) measured in milligrams per gram of
extract were used to express the total flavonoid concentration.
In vitro antioxidant assays
DPPH radical scavenging assay
To evaluate the extract's ability to scavenge free radicals,
the DPPH technique was employed [20]. Various extract
concentrations were introduced into 187 μL of newly made
DPPH solution. Methanol was added to the volume to get it
up to 1000 μL. The absorbance at 517 nm of the reaction
mixture was measured after 20 minutes of dark incubation.
The following formula was used to get the radical scavenging
percentage: % scavenging of DPPH = Abs. of blank - Abs. of
sample / Abs. of blank x 100.
ABTS radical scavenging assay
The ABTS assay was used to evaluate the samples' ability
to scavenge free radicals [21]. A 1:1 reaction between ABTS
in water (7 mM) and potassium persulfate (2.45 mM) yielded
the ABTS radical. An equal quantity of methanol was mixed,
and it was let to stand at room temperature for 12 to 16 hours
in dark before being utilized. After that, methanol was added
to the ABTS•+ solution to dilute it until the absorbance at 734
nm was between 0.700 and 0.800. Thirty minutes after the
first mixing, the absorbance was measured after adding one
to five microliters of samples and making up the reaction
volume to four milliliters with diluted ABTS•+ solution. For
every assay, a suitable solvent blank was run. A minimum of
three measurements were made for each. The calculation of
percentage inhibition of absorbance at 734 nm was
determined using the following formula: % scavenging of
ABTS = Abs. of blank - Abs. of sample / Abs. of blank x 100.
Superoxide scavenging assay
The procedure of nitro blue tetrazolium (NBT) reduction
was utilized to ascertain the extracts' ability to scavenge
superoxide radical [22]. It is dependent upon riboflavin's
production of superoxide when exposed to light and NBT's
subsequent decrease. The reaction mixture (3 mL) contained
EDTA (0.1 M), NaCN (0.3 mM), riboflavin (0.12 mM), NBT
(1.5 mM) and phosphate buffer (0.067 M), supplemented
with different quantities of the plant extracts. An
incandescent light was used to illuminate the tubes uniformly
for 15 minutes. The optical density was determined at 560 nm
both prior to and following the light exposure. The
absorbance values of the control and experimental tubes were
compared in order to determine the percentage reduction of
superoxide production.
Trypan blue dye exclusion method
Using the trypan blue dye exclusion method, the short-term
cytotoxicity of SBH and IBH was assessed using murine
tumor cells, DLA and EAC cells [23]. Trypsin was used to
treat the cells, and after being washed with PBS, they were
centrifuged for five minutes at 1000 rpm. Upon resuspending
International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
e-ISSN: 2583-066X
3
the cell pellets in PBS, 1x106 cells/mL was used as the
corrected cell count. After pipetting out the cells, they were
transferred into separate PBS tubes containing various doses
of samples. After that, the tubes were incubated at 37 oC for
three hours. Trypan blue dye was added after the incubation
period, and there was a three-minute waiting interval. Lastly,
a hemocytometer was used to examine the cells under a
microscope. By calculating the ratio of all dead cells to all
living cells and entering these numbers into the calculation,
the percentage of cytotoxicity was determined:
% of cytotoxicity = No. of dead cells x 100
Total no of cells
The Hill equation was employed to fit the dose-response
curve of SBH and IBH [24].
MTT assay
In 24 well plates with medium, the MCF-7, HeLa, Vero,
and IEC-6 cell lines were added (0.5 x 105 cells) and
incubated at 37 oC for 24 hours. Following that, cells were
cultured for 48 hours at 37 oC with various doses of SBH and
IBH. Additionally, a blank containing a full culture media
devoid of cells was included in the test. Following incubation,
well plates were transferred to the new medium and rinsed
with phosphate buffer saline (PBS). Each well received 50 µL
of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium
bromide (MTT), which was then incubated at 37 ºC for four
hours. One mL of DMSO was used to dissolve the dark blue
formazan crystals through repeated mixing and re-
suspension. The absorbance of the resulting colored product
was recorded at 570 nm. Cytotoxicity was assessed by
comparing the proportion of dead cells in the treated
population of cells to untreated cells as shown by their
relative absorbance levels determined using the MTT test
(Mosmann, 1983). The Hill equation was used to fit SBH and
IBH's dose-response curves [24].
Where the maximum percentage of inhibition is Emax, the
half-maximal effective concentration is EC50, the Hill
coefficient is n and the drug concentration is A. The hill
equation was calculated with data analysis and graphing
software, OriginPro 9.
UV-VIS spectrum analysis
The UV-VIS spectrum analysis of honey samples was done
by diluting with water and scanned at a wavelength ranging
from 200 to 500 nm using UV-VIS Spectrophotometer Type
T80+ (PG Instruments Ltd). The characteristic peaks were
detected (White Jr, 1979). Using the following formula, the
hydroxymethylfurfural (HMF) amount in honey was
determined:
Where W is the weight of the sample (g), A284, A336=
absorbance reading at 284 and 336 nm.
LCMS analysis
Honey chromatographic separation was conducted at
CARe Keralam, KINFRA Park, Thrissur, using the Agilent
Technologies 1260 Infinity MS-6120 Quadrupole instrument
with an Agilent Eclipse Plus C-18 column (4.6 x 250 mm).
The mobile phase was composed of a 60:40 ratio of
acetonitrile to 0.1% acetic acid in water and 10 μL injection
volume was utilized, employing a 0.6 mL/min flow rate,
leading to a total run time of 42 minutes.
Molecular docking
To investigate the possible interactions between specific
compounds identified in stingless bee honey (methyl
syringate, 2-hydroxycinnamic acid, fumaric acid) with the
targeted estrogen receptor (ER) α and estrogen receptor (ER)
β, molecular docking was done using Schrodinger Maestro
software.
RESULTS
Collection and preparation of honey
The stingless bee honey appeared darker than Indian bee
honey and the viscosity of SBH was observed less compared
to IBH. The microscopic evaluation of SBH showed pollen
grains of various shapes and IBH did not show any presence
of pollen grains.
Total phenol and flavonoid content estimation
The total phenol content of stingless bee and Indian bee
honey were 1.591 and 1.22 mg GAE/g extract and 0.266 and
0.242 mg QE/g extract respectively.
In vitro antioxidant assays
The DPPH and ABTS free radical were scavenged by SBH
and IBH with an IC50 value of 36.15, 72.75 v/v and 22, 57.89
v/v respectively. The superoxide radical was scavenged by
SBH with an IC50 of 79.85 v/v. For IBH there was 44 %
inhibition observed at a concentration of 100 v/v (Figure 1).
Trypan blue dye method
With IC50 values of 37.41 and 48.02 v/v, respectively, the
stingless bee honey revealed considerable cytotoxic activity
towards EAC and DLA cell lines in a concentration-
dependent way. The Indian honey has shown barely 2.56 and
3.45 % cytotoxicity for EAC and DLA cell lines,
respectively, at the highest dosage of 100 v/v.
MTT assay
It was discovered that the stingless bee honey was
cytotoxic to HeLa and MCF-7 cell lines with IC50 values of
66.68 and 58.11 v/v, respectively (Figure 1 and 2). Different
concentrations of IBH were tested for cytotoxicity and found
to have 24.79 and 37.35 % inhibition at a concentration of
100 v/v for HeLa and MCF-7 respectively. The in vitro safety
evaluation done in Vero and IEC-6 did not show any
cytotoxicity up to the concentration of 100 v/v (Figure 1and
2).
International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
e-ISSN: 2583-066X
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Figure 1 (A) Inhibition percentage (%) of free radicals by SBH and IBH (B) Inhibition percentage (%) of different cell lines
after honey treatment
Figure 2. Morphology of different cell lines after honey treatment
International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
e-ISSN: 2583-066X
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UV-VIS spectrum analysis
The UV-VIS spectrum profile of SBH and IBH showed
peaks between 200-500 nm. In the spectra of SBH,
excitations were observed at 220, 284, and 384, whereas IBH
exhibited peaks at 280 and 344, accompanied by a few minor
peaks (Figure 3). The peaks obtained at 284 nm are of
hydroxymethylfurfural (HMF). Its weight ratio was
calculated and found to be 14.30 and 8.19 mg/kg. The HMF
amount was seen more in SBH compared to IBH.
Figure 3. UV-VIS spectra of SBH and IBH
LCMS analysis
The SBH contains sucrose, methyl syringate, syringic acid,
fumaric acid, p- coumaric acid, 5-hydroxy methyl furfural,
cinnamic acid and 2-hydroxy cinnamic acid whereas IBH
contains constituents such as sucrose, syringic acid,
phenylacetic acid, 4-hydroxy benzoic acid, p- coumaric acid
and 5-hydroxy methyl furfural (Figure 4). The stingless bee
honey was found to have specific compounds such as methyl
syringate, fumaric acid and 2-hydroxy cinnamic acid with the
retention time of 3.452, 3.692 and 4.441 respectively.
Figure 4. (a, b). LCMS spectrum of SBH, IBH and its
constituents
Molecular docking
The docking of the inbuilt ligand, estradiol into the 3D
structure estrogen β (3OLS) was done using a glide dock. The
active site of 3OLS comprises the following amino acid
residues: LEU 390, PHE 377, ILE 376, ILE 373, LEU 339,
MET 340, MET 336, ALA 302, ARG 346, LEU 343, GLU
305, PHE 356, LEU 301, LEU 298, THR 299, MET 295,
MET 479, HID 475, LEU 476 and GLY 472. The docking
data gave additional insights into the selective interactions of
estradiol with 3OLS in a 2D picture, as shown in Figure5.
Estradiol, the inbuilt ligand, was bound deep into the active
site area, making weak hydrogen bonding interactions with
HID 475, ARG 346, GLU 305 and π-π stacking interactions
with PHE 356. The inbuilt ligand shows a docking score of -
11.635 and binding energy of -94.07 kcal/mol (Tab.1). After
being docked into the active site region, the 2-hydroxy
cinnamic acid interacted with the residues through hydrogen
bonding with LEU 298 and π-π stacking with PHE 356
(Figure5). The docking score and binding energy were found
to be -6.146 and -35.607 kcal/mol which was more compared
to 5- hydroxy methyl furfural, methyl syringate and fumaric
acid (Tab. 1).
The estradiol was docked into the 3D structure estrogen α
(1A52). PHE 434, LEU 349, MET 528, THR 347, ALA 350,
LEU 346, MET 343, LEU 525, HIE 524, GLY 521, MET
421, ILE 424, LEU 384, TRP 383, LEU 428, LEU 387, MET
388, ARG 394, LEU 391 and GLU 353 are residues of amino
acids that can be found in 1A52's active site. After the
estradiol was docked into the active site region, it interacted
with the residues through π-π stacking with PHE 434,
hydrogen bonding with ARG 394, GLU 353, and HIE 524
(Figure 5 and 6). The inbuilt ligand shows a docking score of
-10.917 and binding energy of -89.185 kcal/mol (Tab. 1). The
other ligand, 2-hydroxy cinnamic acid docked into active
sites, made interactions with the residues by π-π stacking with
PHE 356 and hydrogen bonding with LEU 298 (Figure 5 and
6). The docking score and binding energy were found to be
4.955 and -41.58 kcal/mol which was better compared to 5-
hydroxy methyl furfural, methyl syringate and fumaric acid.
International Journal of Agro Nutrifood Practices
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e-ISSN: 2583-066X
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Table 1. Binding energy and docking score of estrogen receptors and ligands
Chemical Compounds
Estrogen alpha
Estrogen beta
Docking Score
Binding Energy
Docking Score
Binding Energy
Inbuilt ligand (Estradiol)
-10.917
-89.185
-11.635
-94.07
2-hydroxy cinnamic acid
-4.955
-41.58
-6.146
-35.607
5-Hydroxymethylfurfural
-4.587
-33.614
-5.905
-36.151
Methyl syringate
-4.09
-31.72
-5.950
-44.314
fumaric acid
-1.813
-13.106
-3.187
-20.747
Figure 5. (A) Two-dimensional image of the interaction between estrogen receptor β and ligands (B) estrogen receptor α
and ligands
Figure 6. (A) Three-dimensional image of the interaction between estrogen receptor β and ligands (B) estrogen receptor α
and ligands
International Journal of Agro Nutrifood Practices
Vol-3, Issue-4, December 2023
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DISCUSSION
The stingless bee honey showed significant
antiproliferative activity on breast and cervical cancer cell
lines and cytotoxicity towards murine tumour cell lines such
as DLA and EAC than Indian bee honey suggesting its
anticancer potential. Stingless bee honey exhibits an
enhanced ability to scavenge free radicals such DPPH,
ABTS, and superoxide than Indian bee honey, demonstrating
its antioxidant properties. Fumaric acid, methyl syringate,
and 2-hydroxy cinnamic acid were detected in SBH by LCMS
analysis; these compounds were absent from IBH. Also in
molecular docking, compounds identified in SBH bind well
with estrogen receptor β than estrogen receptor α.
Stingless bee honey demonstrated superior scavenging of
DPPH, ABTS, and superoxide free radicals compared to
Indian bee honey. Studies have also documented the
antioxidant capacity of several varieties of honey produced
by stingless bees. For instance, Australian pot-honey from
Tetragonula carbonaria has exhibited DPPH and ABTS free
radical scavenging activity [25]. An additional study
involving Tetragona clavipes and Trigona fuscipennis honey
revealed DPPH and FRAP radical scavenging activity [26].
The ability to scavenge radicals is linked to the capacity of
secondary metabolites to counteract free radicals and other
reactive species within the body [27]. Consequently, it is
presumed that the polyphenols present in stingless bee honey
play a pivotal role in its antioxidant properties. These
compounds have a potent scavenging effect on free radicals.
There is a positive relationship between the presence of
polyphenols and the effectiveness of antioxidants, as phenolic
and flavonoid compounds are closely related to antioxidant
activity [28].
The stingless bee honey revealed significant cytotoxic
activity toward breast cancer and cervical cancer cell lines.
Upon SBH treatment, the morphology of cell lines was
changed from an epithelial-like appearance to a round shape.
The cells were shrunk and some granulation was also found
in the cells. Many cells were detached from the surface and
seen to be floating in the media. In normal cell lines, Vero
and IEC-6 did not show any cytotoxicity up to the
concentration of 100 v/v. Additionally, stingless bee honey's
cytotoxic properties have been documented by other authors.
The cytotoxic activity of T. laeviceps honey, an Indonesian
stingless bee, was examined in vitro on the HepG2 liver
cancer cell line [29]. The anti-cancer potential of sixteen
kinds of pot honey produced by thirteen different stingless
bee species was assessed using human ovarian cancer cells.
The findings indicated significant variations in the ability of
honey samples to induce cancer cell death [30]. Moreover,
using the trypan blue exclusion method, it was observed that
SBH exhibited substantial cytotoxicity towards murine
tumour cells, including the DLA and EAC cell lines, in a
dose-dependent manner. These preliminary studies, taken
together, reveal promising results that suggest SBH could be
used as cancer therapeutics. This unique activity could be
owing to the polyphenols present, and they could do so
through specific mechanisms including gene regulation or
altering metabolic pathways in cancer cells [31]. While there
are reports on the anti-proliferative properties of stingless bee
propolis and cerumen [32, 33], there hasn't been much
research on stingless bee honey's anticancer properties, which
calls for more research.
The LCMS analysis of SBH identified some compounds
which were not present in IBH and they include 2-hydroxy
cinnamic acid, methyl syringate and fumaric acid. The first
two are plant phenolic compounds and the latter is an organic
acid naturally present in honey. Polyphenols have been found
in honey produced by the Tetragonula genus, according to
reports by various authors. The LCMS analysis of
Tetragonula carbonaria honey from Australia identified
quercetin, kaempferol and isorhamnetin [34]. The Indonesian
stingless bee, Tetragonula laeviceps honey contains 17 amino
acids detected by LCMS/MS [35]. As reported by another
author, LC-MS analysis has revealed that Tetragonula biroi
honey contains the flavonoid isorhamnetin (3-
methylquercetin) [36]. The primary polyphenolic groups
found in honey are these flavonoids and phenolic acids,
which are derived from benzoic and cinnamic acids. Both
SBH and IBH have the presence of flavonoids and phenols
with SBH having more amounts. Polyphenols present in
honey come through flower nectar, propolis and pollen.
These compounds have various nutritional properties and
have a possible role in treating various diseases [9].
Molecular docking was employed to explore potential
interactions between the specific compounds present in SBH
and targeted receptors, namely estrogen receptor (ER) α and
estrogen receptor (ER) β, within MCF7 and HeLa cell lines.
ERα plays a significant role in differentiation by controlling
target genes, leading to proliferation. In contrast, ERβ serves
as a potent tumour suppressor inhibiting the growth of cells
and mitigating ERα's impact in reproductive tissue across
various cancer types [37]. The results of docking of 2-
hydroxy cinnamic acid with ERβ show interactions by
hydrogen bonding with LEU 298 and π-π stacking with PHE
356. The ligand shows the highest docking score of -6.146
and binding energy of -35.607 kcal/mol compared with other
ligands such as methyl syringate and fumaric acid. Also, all
the ligands bind well with estrogen receptor β than estrogen
receptor α. This could be the cause of stingless bee honey's
anticancer properties, as ligand binding to ERβ leads to
inhibition of cell proliferation. In a study using the
Schrödinger Maestro v10.1 program, molecular docking
performed with six active honeybee products from manuka
honey with SARS-CoV-2 Mpro showed good binding
affinity and the outcomes suggested that it might prevent the
COVID-19 virus from replicating [38]. According to a recent
study, phenylalanine, a constituent of Malaysian stingless bee
honey, has the ability to cause the overexpression of synaptic
genes, such as brain-derived neurotrophic factor and inositol
1,4,5-triphosphate receptor type 1 [39]. According to the
author, in-depth investigations into the docking studies,
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e-ISSN: 2583-066X
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quantum-chemical analysis and antioxidant characteristics of
the main phenolic components found in honey of stingless
bee are still necessary. Hence, several studies are reporting
the potent biological compounds present in stingless bee
honey and computational methods should be done to analyse
its binding to active receptors, as in-silico methods have an
important role in drug designing.
CONCLUSION
Stingless bee honey has higher antioxidant activity and is
shown to have significant antiproliferative activity against
cancers of reproductive system including cervical and breast
cancer, than Indian bee honey. The characterization revealed
some additional compounds in the honey of stingless bees
that were absent from Indian bee honey. Also, the in-silico
studies revealed the effective binding of compounds found in
SBH to ERβ than ERα which might the reason for its
anticancer activity. Given its superior nutritional and
therapeutic attributes compared to other honey bee products,
further research into the biological activities of stingless bee
honey is necessary.
DECLARATIONS
Acknowledgements-The first author extends thanks to
the Department of Entomology and Department of
Agricultural Biotechnology at the College of
Agriculture, Thiruvananthapuram, as well as the
Department of Biochemistry at the Amala Cancer
Research Centre for their assistance and the facilities
they made available for the study.
Ethical statements (and/or Informed Consent in case
of human study)- not applicable
Conflict of competing interest - The authors all agree
that the data should be published, and they all declare
that they have no conflicting interests.
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