Materials and methods
Plant materials:
The bark of S. asoca (Fabaceae) and rhizome of
C. longa (Zingiberaceae) were obtained from the
Ayurvedic Research Centre (ARI), Poojappura,
Kerala and roots of G. glabra (Fabaceae) from
Foundation for Revitalisation of Local Health
Traditions (FRLHT), Bangalore respectively.
All the plant materials were washed thoroughly
with distilled water for removing dust particles.
All these plant materials were oven dried at 40°
for 1 w and then powdered using a mixer grinder
and stored in the dark at room temperature for
experiments.
Preparation of plant extract:
Powdered plant materials of 24 g were used for
extraction by the Soxhlet method in 250 ml of
ethanol and concentrated under reduced pressure
with rotavapor (Buchi Labor Technik AG, Flawil,
Switzerland) R-210 set at 40°. All crude extracts
obtained were stored at 4° until use.
Total phenol:
Folin-Ciocalteu (FC) method with minor
modifications was used to determine the Total
Phenolic Content (TPC) of different extracts using
gallic acid as standard [15] . The FC reagent was mixed
with test extracts, mixed thoroughly and incubated
in the dark for 5 min. 20 % sodium carbonate
solution was added to the solution and incubated
for 30 min at room temperature. The absorbance
was measured at 760 nm using a 1700 Shimadzu
Ultraviolet (UV)-visible spectrophotometer. The
calibration curve was prepared by employing
gallic acid at a concentration of 10-60 µg/ml. The
TPC was determined by using a linear regression
equation from the standard gallic acid graph plot
and was expressed as Gallic Acid Equivalent
(GAE) per gram of the sample. The average of the
triplicates was analyzed.
Total flavonoid:
Aluminum chloride (AlCl 3) method was used to
determine the Total Flavonoid Content (TFC) using
quercetin as standard [16,17] . Briefly, the test extract
was mixed with 0.1 ml AlCl 3 and 0.1 ml Potassium
acetate (CH 3CO2K), incubate at 30° for 10 min.
The absorbance was measured at 415 nm and TFC
was expressed as quercetin per gram (Quality
Assurance Evaluator (QAE)) of the sample. The
average of triplicates was analyzed.
Chorio-Allantoic Membrane (CAM) assay:
The chicken CAM is a highly vascularized
embryonic membrane that offers clear advantages
to studying vascular functions. The anti-
angiogenic activity was evaluated using the
CAM model according to the previously reported
Method
with minor modifications [18] . Fertilized
eggs were purchased from Kerala State Poultry
Development Corporation (KEPCO), Kerala. The
development of the embryo was ensured with the
help of an egg candler. Eggs were carefully surface
sterilized with 70 % isopropanol and incubated
at 37° with 80 % relative humidity. After then
the eggs were randomly divided to carry out the
experiment. Positive and negative controls used
were Dienogest (50 µg) and Phosphate-Buffered
Saline (PBS) respectively. S. asoca , G. glabra , and
C. longa ethanolic extracts (250 µg) were the test
groups.
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Indian Journal of Pharmaceutical Sciences
478
March-April 2024
Drug administration:
On the 5 th d of incubation, control and test extracts
of 20 µl were inoculated into the CAM of fertilized
eggs and sealed with parafilm. Tilted the egg gently
and all eggs were kept in a vertical position with
air sack upwards and were incubated not touching
the eggshell.
Drabkin’s reagent test:
Determination of Hemoglobin (Hb) in the CAM
was performed as explained by Drabkin and
Austin with slight modification [19] . On the 12 th d
of incubation, the eggs were broken gently from
the side of the air sac and the inner content was
removed without disturbing the membrane. The
CAM was scrapped and dispersed carefully into
a tube and centrifuged at 3000 rpm for 5 min. 20
µl of supernatant was added to 5 ml of Drabkin’s
reagent. The reaction was incubated at room
temperature (37°) for 5 min. Hb level was measured
at 546 nm in a spectrophotometer. The level of Hb
in the sample is compared to a standard and results
are expressed as anti-angiogenesis percentage. All
the tests were performed in triplicates to ensure
the reproducibility of the result.
The percentage of inhibition of angiogenesis was
calculated by the following equation:
% Anti-angiogenisis=Optical Density (OD)/OD
sample×100
Results
AND DISCUSSION
Being common ingredients in many Ayurvedic
medicines, S. asoca , G. glabra , and C. longa
have already demonstrated potent health benefits
to humans. All the extracts were rich in total
phenolic and flavonoid compounds. TPC and TFC
Methods
are simple, inexpensive and quick in
estimation. The content of phenol was expressed
in terms of GAE (standard curve equation:
Y=0.0083X–0.0027, R 2= 0.9999) (fig. 1). It was
observed from the analysis that the bark of S. asoca
showed the highest phenolic content mg GAE/g
of 483.5+0.001, G. glabra has 336+0.016 and C.
longa has 164.14+0.002 in the sample (Table 1).
The result of the present investigation indicates
that flavonoid content was abundantly seen in
C. longa when compared to G. glabra , and S.
asoca . The content of flavonoid was expressed in
terms of standard quercetin (Y=0.0237X–0.2081,
R2=0.9895) (fig. 2). Rhizome of C. longa exhibited
the highest flavonoid content of (873+0.0186) mg
GAE/g than roots of G. glabra 106.56+0.0267 and
bark of S. asoca 49.81+0.028 equivalence (Table
1). All data are presented as mean+Standard
Deviation (SD).
Fig. 1: Standard graph of gallic acid
TPC (mg GAE/g) TFC (mg QE/g)
S. asoca 483.5±0.001 873±0.0186
G. glabra 36±0.016 106.56±0.0267
C. longa 164.14±0.002 49.81±0.028
TABLE 1: ESTIMATION OF PHENOL AND FLAVONOID
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479
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the impact of these plant extracts with reported
Selective Estrogen Receptor Modulator (SERM)
activity on the treatment of endometriosis can also
be thoroughly investigated.
The chick embryo CAM model was used to
assess anti-angiogenesis activity. In this study,
we have employed the same reliable method to
study the anti-angiogenic effect of the selected
plant extracts. The fertilized eggs were treated
with ethanolic extract of S. asoca , G. glabra ,
and C. longa . The anti-angiogenic potentials
of the extract were evaluated on the 12 th d of
treatment. The in vitro quantitative determination
of Hb in blood was expressed based on the
cyanmethemoglobin method. The intensity of the
color is proportional to the Hb concentration and is
compared to known cyanmethemoglobin standard
equivalence at 546 nm (standard curve equation:
Y=0.0225X–0.0024, R 2=0.9995) (fig. 3). From
the graph, the g per decilitre (dl) concentration of
control and test extracts was calculated. It is clear
and evident that all the extracts show effective
anti-angiogenic activity in CAM assay with values
(Hb/dl) of 2 for S. asoca , 3.07 for G. glabra , 2.49
for C. longa and extract combination shows 2.7
with respect to control of 7.92. The standard drug
Dienogest shows an effect of 2.91 in the assay.
The inhibitory potential of extracts was expressed
as a percentage anti-angiogenesis. The study
reveals that S. asoca showed the highest inhibition
percentage of 73.65+0.021 followed by C. longa
with 67.65+0.024 and G. glabra with 60.43+0.04
in the sample (Table 2 and fig. 4). The ethanolic
extracts inhibited the growth of blood vessels on
CAM were photographed and can be seen in fig.
5A-fig. 5E.
The rich number of natural flavonoids and
phenol contents in plants have positive effects
on human health as antibacterial, antiviral and
anti-inflammatory agents [20] . They may differ in
concentration during their growth stages and are
considered to have a very vital role in disease
management. The potential benefits of these
secondary metabolites derived from medicinal
plants may act through multiple cell signaling
pathways and may exert their potential effects
by healing diseased cells without affecting
normal cells [21] . S. asoca bark extract is a rich
source of many polyphenols such as catechin
groups and the estimation of total phenol and
flavonoids are also in agreement with the previous
reports demonstrating the plant with a variety
of pharmacological properties [22] . Epicatechin
is one of the primary components of this plant.
Since-epicatechin strongly inhibits the Na +/H+
exchanger, it has been hypothesized that this can
alter the fluidity of the cytosolic plasma membrane
and inhibits the proliferation of cancer cells [23] . It
was also reported that licorice also exhibits anti-
inflammatory, antiviral, gastro protective and
strong estrogen-like activities due to its wide range
of flavonoid and phenolic content in the plant [24] .
Significant flavonoid and phenolic content in C.
longa also result in different medicinal properties
like anti-bacterial, anti-inflammatory, anti-
carcinogenic and anti-proliferative properties [25] .
Although there is little evidence to support the
use of estrogen-progestins for endometriosis,
the European Society of Human Reproduction
and Embryology (ESHRE) guidelines on
endometriosis also noted that combined hormonal
contraception is frequently used as a treatment for
pain associated with endometriosis [26] . Therefore,
Fig. 2: Standard graph of quercetin
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Indian Journal of Pharmaceutical Sciences
480
March-April 2024
Fig. 3: Standard graph of hemoglobin
Fig. 4: Anti-angiogenic activity of selected plant extract
Fig. 5: Inhibitory effect on angiogenesis and captured digital image of the CAM section
Drugs Dose µg/ml Tested eggs % Anti-angiogenesis
PBS (Negative control) - 3 -
S. asoca 250 3 (73.65±0.021) %
G. glabra 250 3 (60.43±0.04) %
C. longa 250 3 (67.65±0.024) %
Dienogest 50 3 (62.42±0.02) %
TABLE 2: ANTI-ANGIOGENIC EFFECT OF EXTRACTS
G. glabra
Dienogest
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481
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emphasize the beneficial use of conventional drugs
in endometriosis therapy. Further research on the
mechanism of action of the extracts has to be
worked out in future studies to substantiate these
findings on the basis of lower concentrations. The
involvement of angiogenesis in preventing the
growth of endometriosis has been indicated by
several researches. However, many of them only
provide circumstantial evidence, frequently based
on the downregulation of anti-inflammatory factors
like VEGF levels or Matrix Metalloproteinase-9
(MMP-9) activity [34] . According to preclinical
investigations, the antiangiogenic treatment may
have the largest initial impact on micro metastases
and in general, smaller dosages of an angiogenesis
inhibitor are needed to prevent neovascularization
of microscopic metastases than to regress a primary
tumour [35] .
Our present study reveals that medicinal plants like
S. asoca , G. glabra and C. longa with their major
phenolic and flavonoid compounds may have a
significant role in suppressing angiogenesis. It
may be presumed that the collective contribution
of phenol and flavonoid compounds in the extract
provides anti-angiogenic properties. The study
highlighted the activity of crude extract through
CAM assay. This technique was well accepted and
does not need so much of financial and technical
support to perform. Although many aspects
are relevant to the pathophysiologic process of
endometriosis, it is clear that angiogenesis is
necessary for the development and maintenance of
ectopic implants in the tissue. We have investigated
the antiangiogenic effect through a simple method
and the analyzed plant extracts seem to be a
promising therapeutic source for endometriosis
treatment. Further, in vivo studies and gene
expression studies are needed to investigate the
role of these phyto metabolites for their molecular
level of action.
Acknowledgement
We are gratefully acknowledging the facilities
provided by JNTBGRI, Palode and CRDC, HLL
Lifecare Limited, Trivandrum for supporting the
study. This work was financially supported by
ICMR for an SRF fellowship to Reshmi Nair.
Conflict of interest:
The authors declared no conflict of interests.
Angiogenesis can be defined as the formation
of new blood vessels from pre-existing vascular
tissue [27] . Onishi et al. [28] have reported that the
pathogenesis of endometriotic lesions includes
major steps like blood vessel breakdown,
membrane degradation, surrounding extracellular
matrix and new blood vessel formation leading
to angiogenesis. In these aspects, the long-term
survival and proliferation of endometriotic lesions
are critically reliant upon adequate blood supply
via angiogenesis [29] . The goal of an anti-angiogenic
therapy strategy for endometriosis illness is
to successfully induce conception in infertile
individuals while simultaneously relieving pelvic
pain. Endometriotic lesions have the ability to
create cytokines and growth factors that regulates
their vascularization and proliferation [30] . It
was also reported that the neovascularization
of endometriotic lesions is significantly aided
by the dominant Interleukin (IL)-1 released by
active peritoneal macrophages, IL-1 [31] . Estradiol
promotes endometrial Vascular Endothelial
Cell Growth Factor (VEGF) production, and its
levels are associated with neovascularization and
increased vascular permeability during the late
proliferative phase [32] . As endometriosis condition
is heavily reliant on estrogen, hormonal therapies
aim to reduce endogenous ovarian estrogen
production
The CAM method provides a simple and rapid
evaluation of the anti-angiogenic effect of the
extracts in well-developed vascular tissue [33] .
Paradkar et al. [21] have described it as an efficient
and widely used model for determining anti or
pro-angiogenic activity in a sample. CAM assay
model is an informative method used to study the
process of endometriotic lesion formation in order
to show that a viable endometrium is necessary
to form an endometriotic lesion and the results
indicate that S. asoca and C. longa extracts have
strong anti-angiogenic activity than positive
control dienogest, a potent drug currently used
in endometriosis treatment. Thus, the studies are
promising and clinically relevant for the therapy.
The relevant amount of flavonoids and phenolic
compounds in all the studied plants may be
responsible for the bioactivity of the crude
extracts and serve as an inhibitory agent for
angiogenesis. Since the results show a proven
anti-angiogenic effect in CAM, these extracts
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Indian Journal of Pharmaceutical Sciences
482
March-April 2024
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