Online - 2455-3891
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Vol 12, Issue 5, 2019
Research Article
PHARMACOGNOSTIC STUDIES ON FLOWERS OF DREGEA VOLUBILIS: EVALUATION FOR
AUTHENTICATION AND STANDARDIZATION
BHASKAR DAS1, ARNAB DE1, PIU DAS1, AMALESH NANDA2, AMALESH SAMANTA1*
1
Department of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India. 2Department of Biotechnology, National
Institute of Technology, Arunachal Pradesh, India. Email: asamanta61@yahoo.co.in
Received: 01 February 2019, Revised and Accepted: 19 March 2019
ABSTRACT
Objective: The various parts of Dregea volubilis (Family: Apocynaceae), locally known as Jukti (Bengali), are commonly used in Indian system of
medicine to treat various ailments such as inflammation, piles, leukoderma, asthma, and tumors. Literature review suggested that there has been
no detailed work on systemic pharmacognostic and phytochemical studies done on the flowers of the plant. The present study is aimed to lay down
quality control parameters for D. volubilis flowers to confirm its identity, quality, and purity.
Methods: The present work was designed to study detailed organoleptic, histological, quantitative standards, physicochemical, spectroscopic, and
chromatographic characteristics of the flowers of D. volubilis.
Results: The total ash, acid insoluble ash, water soluble ash, loss on drying, water, and alcohol soluble extractive values were found to be 11.767±0.130%
(w/w), 1.287±0.106% (w/w), 9.140±0.344% (w/w), 14.110±0.061% (w/w), 21.600±0.133% (w/v), and 9.603±0.104% (w/v), respectively.
Phytochemical screening of different extracts showed the presence of carbohydrates, proteins, amino acids, steroids, glycosides, alkaloids, flavonoids,
tannins, and phenolics. The chromatographic study revealed the presence of rhamnose (103.229±4.994 µg/g), fructose (738.670±25.714 µg/g),
glucose (285.532±24.465 µg/g), and maltose (49.082±5.206 µg/g).
Conclusion: The characterization parameters of the present study may serve as a reference standard for proper authentication, identification and for
distinguishing the plant from its adulterants.
Keywords: Dregea volubilis, Organoleptic, Phytochemistry, High-performance liquid chromatography, Fourier transform infrared.
© 2019 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.
org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2019.v12i5.32257
INTRODUCTION
Herbal medicines play an important role in the health-care system
to alleviate and treat diseases. There is a great demand for medicinal
plants in the herbal industry due to its health beneficiary properties
with multi-dimensional chemical structures. Standardization of the
medicinal plants is essential to confirm the authenticity and quality to
avoid deliberate adulteration and substitution [1].
Dregea, a genus of vines, is a rich source of steroidal pregnanes with
potential biological activities [2]. Dregea volubilis (L.f.) Benth. ex Hook.f.
(Synonym: Wattakaka volubilis (L.f.) Stapf., Marsdenia volubilis (L.f.)
Cooke) belongs to the kingdom of Plantae, subfamily of Apocynoideae,
family of Apocynaceae, order of Gentianales, series of Bicarpellatae,
subclass of Gamopetalae, class of Dicotyledons and are distributed
widely in the tropical zone and South East Asia [3]. D. volubilis, a large
twining perennial shrub, grows as a woody climber having woody vines
and is scattered throughout the India and Car-Nicobar ascending to
an altitude of 1500 m [4]. The plant blooms between March and April.
The young branches of the plant are green, slender, and smooth; the
older branches are gray, very long, and glabrous, often with lenticels
or small black dots. Leaves are broadly ovate or somewhat rounded,
sub-orbicular, acuminate, 7.5–15 cm long, 5–10 cm wide. Flowers are
green or pale green, about 1 cm in a radius, bisexual and sweet-scented
in a drooping umbel. Follicles are usually two, slightly tapering to a
very blunt point, glabrous, and striated. The seeds are elliptic, concave,
flattened, smooth, and shining. Different parts of the plant have been
traditionally used in Ayurveda in India for the treatment of various
ailments such as asthma, inflammation, tumors, piles, leukoderma,
application to boils, rat bite, and urinary discharge [5]. The vernacular
names of the medicinally important plant are Jukti (Bengali), Akadbel
(Hindi), Harandodi (Marathi), Velipparuthi (Malayalam), Dudhipaala
(Telugu), Koti-p-palai (Tamil), Dugdhive (Kannada), Dudghika (Oriya),
Khamal lata (Assamese), Kadvo kharkhodo (Gujarati), and Hemajivanti
(Sanskrit). The flowers of D. volubilis are eaten as a seasonal vegetable
in early summer with bitter esthetic principles. Flowers of the plant
are a rich source of biologically active phytochemicals and were
reported to contain volubiloside A, volubiloside B, volubiloside C,
dregealol, volubilogenone, volubilol, drevogenin D, iso-drevogenin P,
17α-marsdenin, dregeanin, vicenin-2, vitexin, isovitexin, isoorientin,
rutin, quercetin, luteolin, apigenin, gallic acid, ferulic acid, ellagic acid,
and cinnamic acid [6-9]. Antioxidant and antidiabetic activities of
hydroalcoholic extract of the flowers of the plant were reported earlier
by the present authors [9].
In spite of a lot of attention to health beneficiary effects, flowers of
D. volubilis have been less explored pharmacognostically. A detailed
study on the structural morphology and other physicochemical
parameters of the flowers of D. volubilis are required. The present
study is aimed to evaluate the flowers to fix the pharmacognostical
parameters for proper identification, authentication, and quality
standardization of the plant.
METHODS
Plant material
The fresh flowers of D. volubilis were collected in the month of April
2017 from Jaynagar Mazilpur, South 24 Parganas, West Bengal, India.
It was taxonomically identified and authenticated by Dr. V.P. Prasad,
Central National Herbarium, Botanical Survey of India, Botanical
Garden, Howrah, West Bengal, India. A voucher specimen of the plant
was kept at Division of Microbiology and Biotechnology, Department
Das et al.
Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
of Pharmaceutical Technology, Jadavpur University, Kolkata, India. The
flowers were dried under shade, powdered using a mechanical grinder
and preserved at 25±2°C in airtight container at a dry place.
and weighed. Acid-insoluble ash content (% w/w) of the material was
calculated with reference to the crude drug according to the following
equation:
Chemicals and instruments
Rhamnose, xylose, fructose, glucose, trehalose, and maltose were
purchased from Sigma-Aldrich, St Louis, MO, USA. Ethanol was
purchased from EMD Millipore, Bedford, MA, USA. Chloroform,
acetone, 2-propanol, ethyl acetate, diethyl ether, petroleum benzine
(40–60°C), methanol for liquid chromatography, acetonitrile for liquid
chromatography, sodium carbonate, anthrone, glacial acetic acid,
hydrochloric acid, nitric acid, acetic acid, sulfuric acid, phosphoric
acid, ammonia solution 25%, Coomassie Brilliant Blue G250, sodium
hydroxide, potassium hydroxide, chloral hydrate, and glycerin were
procured from Merck Life Sciences Private Limited, Mumbai, India.
The water was purified by a Milli-Q water purification system (EMD
Millipore, Bedford, MA, USA) and used for all experiments. All other
reagents used were of analytical grade.
Acid-insoluble ash (% w/w)=(weight of ash/weight of sample)×100
Macroscopic evaluation
The macroscopic study of the crude drug includes evaluation of its
morphological characteristics which are examined by the naked eye
and magnifying lens. The method is the simplest and quickest mean to
check the authenticity of a crude drug [10].
Microscopic evaluation
Fresh flowers were collected and washed with water for carrying out
the microscopical study. Different parts of the flower were cut into very
thin transverse sections (T. S) and boiled in 10% potassium hydroxide
solution to remove fatty materials and coloring substances. The sections
were stained and observed under Magnus microscope (Olympus [India]
Pvt. Ltd., Noida, India). Photomicrographs were captured with Magnus
photomicrography units (MIPS USB 2.0Capture and Display Software)
at ×40 [11].
Powder characteristics
The mechanically grinded dried powdered material was sieved through
mesh number 80 to get uniform powder. It was cleared with chloral
hydrate, stained, and mounted in glycerin to observe under Magnus
microscope (Olympus [India] Pvt. Ltd., Noida, India) [12].
Quantitative standards
The shade dried powdered material of flowers of D. volubilis was
evaluated for the determination of ash values, extractive values, and
loss on drying (LOD).
Ash values
The total ash, water-soluble ash, and acid insoluble ash of the plant
material were performed [13].
Total ash
About 1 g of the material was taken in a previously ignited and tarred
silica crucible. The material was spread in even layer and ignited at 450°C
by gradually increasing the temperature until it was white indicating
the absence of carbon. It was then allowed to cool in a desiccator. The
total ash content (% w/w) of the material was calculated according to
the following equation:
Total ash (% w/w)=(weight of ash/weight of sample)×100
Acid insoluble ash
The acid insoluble ash was determined by boiling the total ash
with 25 ml of 2 (N) hydrochloric acid (HCl) into a China dish. It was
covered with a watch glass and gently boiled for 5 min. The watch
glass was rinsed with 5 ml of boiled water and the rinsed contents
were transferred to the contents of China dish. The insoluble matter of
the contents of the china dish was collected on tarred gooch crucible,
washed with boiled acidulated water, ignited, cooled in a desiccator
Water-soluble ash
About 25 ml of water was added to the total ash in a China dish and was
gently boiled for 5 min. The water-insoluble ash was collected on tarred
gooch crucible, washed with boiled acidulated water, ignited, cooled
in a desiccator, and weighed. The water-soluble ash was calculated by
subtracting the weight of insoluble matter from the weight of total ash.
The water-soluble ash content (% w/w) was determined with respect
to the air-dried material using the following equation:
Water-soluble ash (% w/w)=(weight of water-soluble ash/weight of
sample)×100
Extractive values
The extractive values are indicative weights of the extractable chemical
constituents of crude drugs in different solvents. The extractive values
of crude drugs were determined in water and alcohol [14]. 5 g each of
the crude drugs was taken in a 250 ml stoppered conical flask. 100 ml
of the respective solvent was added to the 250 ml stoppered conical
flask and was allowed to macerate for 24 h with the aid of mechanical
shaker for 6 h. It was then filtered and 25 ml of the filtrate was taken
in a tarred Petri dish. It was evaporated to dryness in an oven at 105°C
and weighed it again. The extractive value (% w/w) was calculated with
respect to the air dried material using the following equation:
Extractive value (% w/w)=(weight of extracted residue/weight of
sample)×100
LOD
The LOD was performed [15] by taking 1 g of the crude drug in
previously weighed LOD weighing bottle. It was dried in an oven for 1 h,
cooled in a desiccator and weighed. The LOD (% w/w) was calculated
with respect to the crude drug using the following equation:
LOD (% w/w)=(weight loss/weight of sample)×100
Fluorescence analysis
The fluorescence analysis was performed by treating the dried
powdered material with different chemicals and was observed in
daylight and ultraviolet (UV) light [16]. Some of the phytochemicals
present in plant material show fluorescence in the visible range in
daylight. The UV ray produces fluorescence in many crude drugs which
do not fluorescence in daylight. A more powerful source of ultraviolet
ray is often needed to produce fluorescence in crude drugs. Different
types of reagents are often applied to the crude drugs which do not
fluoresce to convert them into fluorescent derivatives. The fluorescence
analysis is an important parameter for pharmacognostic evaluation for
assessing crude drugs qualitatively. The behavior of powdered drugs
after treatment with different chemical reagents and their fluorescent
characteristics were observed under UV (254 and 366 nm) and visible
light using CAMAG UV CABINET 4.
Preliminary phytochemical studies
The shade dried powdered material of flowers of D. volubilis weighing
about 200 g was soaked with sufficient amount of light petroleum
benzine (40–60°C) in a glass beaker for 24 h and then the flowers were
extracted with petroleum benzine (40–60°C), chloroform, methanol
successively using Soxhlet apparatus and the exhausted material
was boiled with water. The petroleum benzine (40–60°C) fraction
obtained after extraction using Soxhlet apparatus was combined
with the initial fraction of petroleum benzine (40–60°C) obtained
after soaking. The extracts of organic solvents were concentrated
using rotary evaporator under reduced pressure and evaporated to
dryness. The aqueous extract was concentrated using a water bath
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and lyophilized. The extracts were preserved in well-closed container
and kept in the dark at a temperature of 10°C for future use. The
different extracts obtained were tested individually for the presence
of different phytoconstituents [17]. Thin-layer chromatography (TLC)
fingerprinting of the extracts was performed using Silica Gel G as an
adsorbent. TLC plates (Millipore Corporation, USA) were activated in a
hot air oven at 110°C for 30 min. The plates were kept in a desiccator
for future use. Different combinations of solvents were used for the
preparation of the mobile phases.
High-performance liquid chromatography (HPLC) fingerprinting
The chromatographic fingerprinting was performed by ultra HPLC
(UHPLC) using a UHPLC+ focused system consisting of a Dionex
Ultimate 3000 Pump, a Dionex Ultimate 3000 autosampler column
compartment, and a Dionex Ultimate 3000 variable wavelength
detector [18]. 1 g of dried and finely powdered (mesh size 85) sample
was taken in 10 ml volumetric flask and sufficient Milli-Q water was
added and heated in boiling water bath for 20 min and cooled and made
up to the volume with Milli-Q water. The solution was filtered through a
0.45 μm syringe filter (Millex, Merck, Germany) which was injected as a
test solution and Milli-Q water was injected as blank. Chromatographic
separations of phytochemicals of the extract were performed using a
C18 column (250 mm×4.6 mm i.d.) with a particle size of 5 μm, Hypersil
GOLD (Thermo Fisher Scientific, U.S.A.) and column oven temperature
were maintained at 25°C. The chromatographic separation was
performed using gradient elution (Table 1) with a flow rate of using 0.2
(% v/v) phosphoric acid as mobile phase A and HPLC grade methanol as
mobile phase B, respectively. The UV detector was set at 280 nm and the
injection volume was 20 μl. The chromatograms were processed with
Chromeleon 7, version 7.2.0.3765 software (Thermo Scientific, U.S.A.).
Fourier transform infrared (FTIR)
FTIR spectra of the different extracts of D. volubilis were performed
in attenuated total reflection (ATR) mode using Nicolet iS10 FT-IR
Spectrometer (Thermo Fisher Scientific, USA) with a total of 30 scans at
a resolution of 4 cm−1 in the wave number range between 4000 cm−1 and
525 cm−1. Background spectrum of a clean ATR crystal was collected
immediately before collecting the spectrum of the plant extracts.
The extracts were then placed in the ATR accessory and pressed for
acquiring the FTIR spectra of the samples. The spectral acquisitions
were processed with OMNIC software supplied by the manufacturer.
FTIR study provided qualitative information on the types of functional
groups and chemical bonds present in the phytochemicals of the
extracts by analyzing the peak values (cm−1) of the spectra [9].
Determination of UV-VIS spectra
The different extracts of D. volubilis were diluted with respective solvents
at a concentration of 0.05% (w/v) in respective solvents and scanned
between 200 nm and 800 nm using a microplate reader (Multiskan GO
Microplate Spectrophotometer, Thermo Fisher Scientific, USA), and the
spectra were recorded [19].
Determination of pH
The shade dried powdered material of flowers of D. volubilis was
mixed with water at a concentration of 1% (w/v), 2% (w/v), and
10% (w/v) and kept in a water bath for 20 min. It was then filtered
through Whatman filter paper No. 1 and the pH of the filtrate was
measured using a pH meter (Model: 3200P, Agilent Technologies, USA)
at 25°C [20].
Determination of protein content
The protein content of the sample was determined according to
Bradford method with some modifications [21]. 0.5 g powder of
D. volubilis flower was mixed with 10 ml of water and the mixture was
shaken for 10 min followed by filtration using Whatman filter paper
No. 1. 0.2 ml of the sample solution was mixed with 5 ml of Bradford’s
reagent (0.1 g of Coomassie Brilliant Blue G250 was dissolved in 50 ml
of ethanol followed by addition of 100 ml 85% (v/v) phosphoric acid
and volume was made up to 1 L). The reaction mixture was kept for
10 min for the development of color completely. The absorbance of
the reaction mixtures was measured at 595 nm against a blank using
a microplate reader (Multiskan GO Microplate Spectrophotometer,
Thermo Fisher Scientific, USA). The protein present in the sample was
quantified from calibration curves of absorbance versus concentration
in µg/ml of bovine serum albumin which was used as a standard.
Determination of carbohydrate content
The total carbohydrate content of the dried powdered material
of flowers of D. volubilis was determined by the anthrone
method with slight modifications [22]. A standard stock solution
(10 mg/ml) containing glucose was prepared in Milli-Q water and
different concentrations (20, 40, 60, 80, 90, and 100 µg/ml) of
standard solutions were prepared by diluting the stock solution for
the calibration curve. 100 mg of dried sample was hydrolyzed by
keeping it in a boiling water bath for 3 h with 5 ml of 2.5 (N) HCl
and cooled down to room temperature. It was then neutralized
with solid sodium carbonate until effervescence ceased and volume
of the solution made up to 100 ml with Milli-Q water. It was then
centrifuged at 2000 rpm and the supernatant was collected. 1 ml
each of standard solutions and sample solution was added to 4 ml
of anthrone reagent (0.2% [w/v] anthrone in ice cold concentrated
sulfuric acid) and heated for 8 min in boiling water bath and cooled
to room temperature. A blank solution was prepared by adding 1 ml
Milli-Q water to 4 ml of anthrone reagent. The absorbance of the
reaction mixtures was measured at 630 nm against the blank using
a microplate reader (Multiskan GO Microplate Spectrophotometer,
Thermo Fisher Scientific, USA).
Determination of free sugar composition
The free sugars were determined by ultra-fast liquid chromatography
(UFLC) using a prominence UFLC system (Shimadzu, Japan)
equipped with a LC-20AT Solvent Delivery Unit, SIL-20A UFLC
version autosampler, and RID-10A refractive index detector [23].
A mixed standard stock solution (10 mg/ml) containing rhamnose,
xylose, fructose, glucose, trehalose, and maltose was prepared in
Milli-Q water and different concentrations (0.625, 1.25, 2.5, 5, and
7.5 mg/ml) of standard solutions were prepared by diluting the
mixed standard stock solution for calibration curves to quantify
the sugars present in the sample. 1 g of dried sample was extracted
with 40 ml of 80% (v/v) aqueous ethanol at 80°C for 30 min. It was
then centrifuged at 15,000 g for 10 min and the supernatant was
concentrated at 60°C under reduced pressure. The concentrated
sample was defatted 3 times with 10 ml of diethyl ether. The defatted
material was concentrated at 40°C and dried. The dried sample was
dissolved in Milli-Q water to a final volume of 5 ml. The solution was
filtered through a 0.45 μm syringe filter (Millex, Merck, Germany)
which was injected as a test solution and Milli-Q water was injected
as blank. Chromatographic separations of the sugars were performed
using a NH2 column (250 mm × 4.6 mm i.d.) with a particle size of
5 μm and pore size of 100 Ǻ, Luna NH2 (Phenomenex, U.S.A.) and
column oven temperature was maintained at 40°C. A solvent mixture
consisting of seven volumes of acetonitrile and three volumes of
Milli-Q water was used as mobile phase. The chromatographic
separation was performed with a flow rate of 1.0 ml/min with a run
time of 15 min and the injection volume was 10 μl.
Statistical analysis
All experiments were performed in triplicate and the results of the
quantitative studies are presented as mean±standard error of mean.
The statistical analyses were performed with GraphPad PRISM6
software, USA.
RESULTS AND DISCUSSION
Macroscopic evaluation
The flowers were numerous, green or pale green in color, sweetscented, and bitter in taste. Inflorescences were in lateral drooping
umbellate cymes. 2.5–5 cm long slender peduncles were arising from
between the petioles. 1–2.5 cm long slender calyx dividing nearly to
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the base was ovate to oblong, obtuse, and ciliolate. Corolla was deeply
divided and glabrous outside. Lobes were broadly ovate, obtuse and
veined overlapping to the right. Stamina column aroused from the base
of the corolla and anther tips were membranous, broadly ovate, oblong,
and obtuse. Pollen masses were attached to the pollen carriers by very
short caudicles (Fig. 1). The macroscopic evaluation of a crude drug is
used for its authentication by comparing the diagnostic characters with
the prescribed standards of the standard drug. The macroscopic feature
helps to evaluate the basic differentiating characteristics between
the various species within a single genus [10]. The parameters of the
macroscopic evaluation are mostly subjective and there is a chance of
existence of adulterants which are closely resembles the genuine drug.
The microscopic and physicochemical analyses are more authentic
studies to check whether the parameters of the crude drugs conform
to the standard or not. The parameters of the macroscopic evaluation
for the flowers of D. volubilis can be served as reference diagnostic
characters for the authentication of the drug.
Microscopic evaluation
The T. S of the different floral parts of flower (Fig. 2) showed the
following observations under the microscope.
as hypodermis. Several layers of thin-walled parenchyma cells, known
as parenchymatous zone, were present next to the hypodermis in the
cortex. The vascular bundles were collateral and open and each bundle
was composed of external phloem and internal xylem. Pith was made of
parenchyma cells. Trichomes were uniseriate, multicellular with blunt
tip. Cluster crystals of calcium oxalate were present.
Stalk
The T. S of stalk showed that the epidermis was single-layered
outermost zone consisting of compactly set tabular living cells, outer
walls of which were cuticularized. Cortex was distinctive consisting
of hypodermis which was composed of 2–3 layers of collenchyma
cells. General cortex was present next to the hypodermis which was
composed of several layers of thin-walled parenchyma cells. Vascular
bundles were collateral and open consisting of external phloem
and internal xylem. Pith was very distinct and large, situated in the
center consisting of thin-walled, oval, or polygonal parenchyma cells
with abundant intercellular spaces between them. Cluster crystals of
calcium oxalate were found to be present. Trichomes were uniseriate,
multicellular with blunt tip.
Calyx
Thalamus
The T. S of thalamus showed that epidermal layer was composed of a
single layer of compactly arranged tabular cells with cuticularized outer
walls. The cortex was composed of 2–3 layers of collenchyma, known
The T. S of sepal showed that there were two epidermal layers, for
example, upper and lower epidermis. Both the epidermal layers
were uniseriate and composed of compactly arranged tabular cells,
the outer walls of which were cuticled. The mesophyll was made of
parenchyma cells lying between two epidermal layers. The mesophyll
was differentiated into (a) upper closely packed, tubular chloroplast
containing cells, known as palisade parenchyma, and (b) lower loosely
arranged, more or less rounded cells, called spongy parenchyma. Oil
globules and cluster crystals of calcium oxalate were also present.
Trichomes were uniseriate, multicellular with blunt tip. Stomata were
anomocytic.
B
Corolla
C
D
The T. S of petal showed that the epidermal layer was uniseriate and
composed of compactly arranged tabular cells, the outer walls of which
were cuticled. Trichomes were uniseriate, multicellular with blunt tip.
Anomocytic stomata and oil globules were found to be present.
Androecium
A
E
F
Fig. 1: (A) Dregea volubilis in its natural habitat. (B) Pale
green flower in dense drooping umbels. (C) Individual flower
of D. volubilis showing pedicel (a). (D) D. volubilis flower
part showing sepal (calyx) (a). (E) D. volubilis flower part
showing petal (corolla) (a). (F) D. volubilis flower part showing
androecium (a) and gynoecium (b)
Table 1: UHPLC gradient program for the HPLC fingerprinting
study
Time (min)
Flow
rate (mL/min)
Mobile
phase A (%)
Mobile phase
B (%)
0
10
20
30
40
50
60
70
1
1
1
1
1
1
1
1
100
100
90
70
50
30
10
0
0
0
10
30
50
70
90
100
UHPLC: Ultra-high-performance liquid chromatography,
HPLC: High-performance liquid chromatography
The T. S showed that the epidermal layer was uniseriate and composed
of compactly arranged tabular cells, the outer walls of which were
cuticled. The cluster crystals of calcium oxalate were found to be
present.
Gynoecium
The T. S showed the presence of cluster crystals of calcium oxalate.
The detailed microscopic examination of the flowers of D. volubilis
can be used as a reference to identify the crude drug by comparing
the known histological characters. The microscopic examination is
an easiest and finest way to set standard parameters depending on
the internal anatomy of the plant [15]. The microscopic study alone
cannot provide complete evaluation profile for the herbal drugs.
The histological characters of the drug along with other analytical
parameters can be utilized to set the standardization specifications for
the evaluation of the herbal drug.
Powder characteristics
The powder microscopy showed the presence of fibers, cluster crystals
of calcium oxalate, and epidermal trichomes. Some fragments consisted
of groups and parts of parenchyma cells and epidermal cells. The
observations of the study on the powder of D. volubilis flowers can
serve as useful parameters for the proper identification of the drug. The
dried sample in the powdered form gives characteristic features of the
drug under a microscope after proper treatments. The microscopical
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A
B
C
D
E
F
G
H
I
J
K
O
L
N
M
P
Q
R
Fig. 2: Transverse section (T. S) of different parts of Dregea volubilis flower. (A). T. S of thalamus showing hypodermis (a),
parenchymatous zone (b), xylem (c), phloem (d), and pith (e). (B) Epidermis (a) and trichome (b) in thalamus. (C) Cluster crystals of
calcium oxalate (a) in thalamus. (D) T. S of androecium showing epidermis (a). (E) Cluster crystals of calcium oxalate (a) in androecium.
(F) T. S of stalk showing hypodermis (a) and general cortex (b). (G) Phloem (a), xylem (b), and pith (c) in stalk. (H) Cluster crystals of
calcium oxalate (a) in stalk. (I) Epidermis (a) and trichome (b) in stalk. (J) T. S of gynoecium showing cluster crystals of calcium oxalate.
(K) T. S of sepal showing upper epidermis (a), lower epidermis (b). (L) Stomata in sepal (a). (M) Trichome in sepal (a). (N) Cluster
crystals of calcium oxalate (a) in sepal. (O) T. S of petal showing epidermis (a). (P) Stomata in petal (a). (Q) Trichome in petal (a). (R) Oil
globules in petal (a)
examination of epidermal trichomes and calcium oxalate crystals is
extremely valuable for authentication of crude drugs [17].
Quantitative standards
The total ash, acid-insoluble ash, and water-soluble ash were found to
be 11.767±0.130% (w/w), 1.287±0.106% (w/w), and 9.140±0.344%
(w/w), respectively. The water and alcohol soluble extractive values
were found to be 21.600±0.133% (w/v) and 9.603±0.104% (w/v),
respectively. LOD was 14.110±0.061% (w/w). Therapeutic efficacy
of herbal drugs can be ensured by determining the quantitative
standards. The ash of crude drugs is consisted of nonvolatile inorganic
materials which can be used to set quality control parameter to check
the contamination of crude drugs. A high content of ash value beyond
the standard limit gives an indication of contamination, substitution,
or adulteration [24]. The content of active constituents in a given
amount of crude drug is estimated by extractive value in a particular
solvent. The extractive values give valuable information regarding
the quality of the crude drug whether it is exhausted or not. The high
extractive value is an indicative parameter of better extraction of
phytoconstituents from crude drugs and it is also helpful for proper
selection of solvent that will provide maximum yield [25]. The physical
and physicochemical state of the interior of the cell depends on the loss
of water. The enzymes present in the cell are responsible for different
chemical reactions such as oxidation, hydrolysis, and polymerization
of the phytoconstituents present in the plant material when the
enzymes come in contact with the active substances during the
process of drying. Most of the enzymes present in plant material need
sufficient water to act leading to decomposition reactions of the crude
drugs. Moisture present in the crude drugs helps in microbial growth
leading to degradation of it. It is desirable to keep the water content of
the crude drugs at low level to deactivate the enzyme activity as well
as to retard microbial degradation to such an extent that the storage
stability of the crude drugs is guaranteed [26]. These standardization
parameters are essential to ensure the quality of herbal drugs.
Quantitative standards can be applied for the evaluation of crude
drugs. These parameters can be utilized for maintaining the identity,
purity, and quality of crude drugs. Purity depends on the absence of
foreign matter in crude drugs. Quality depends on the concentration
of the active constituents present in the crude drugs that exert health
beneficiary properties.
Fluorescence analysis
The fluorescence analysis of the powdered drug showed various colors
after treatment with different chemical reagents and observed visually
under daylight, short wavelength ultraviolet light (254 nm), and long
wavelength ultraviolet light (366 nm). The results are shown in Table 2.
The fluorescence analysis of the D. volubilis flower showed various
colors under ordinary light, short wavelength UV light (254 nm),
and long wavelength UV light (366 nm) indicating the presence of
fluorescent compounds. The analysis is a very important and useful tool
for the identification of various phytoconstituents present in the crude
drugs which give fluorescence either itself or after derivatization with
proper chemical treatment under UV light [16]. The method is very
easy and direct method for the identification of fluorescent compounds
present in the test sample and the observations can be used as a quality
control parameter for the identification of the crude drug.
Preliminary phytochemical studies
The results of preliminary qualitative phytochemical studies of the
different extracts of flowers of D. volubilis are presented in Table 3.
The TLC studies of the different extracts were performed in
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Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
Table 2: Fluorescence analysis of powdered flowers of D. volubilis
Sl. No.
Treatment
Daylight
UV light
254 nm
366 nm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Powder as such
Powder+Acetic acid
Powder+Ferric chloride (5% FeCl3)
Powder+Conc. Hydrochloric acid (HCl, 5N)
Powder+Conc. Nitric acid HNO3
Powder+Conc. Sulfuric acid (H2SO4)
Powder+Iodine solution (1%)
Powder+Methanol
Powder+Picric acid
Powder+NaOH Solution (1 N)
Powder+Distilled water
Powder+Liquid ammonia (NH3)
Powder+Conc. HNO3+NH3
Powder+Dilute HNO3
Powder+10% potassium dichromate solution
Powder+Acetone
Light brown
Brown
Greenish brown
Yellowish brown
Reddish brown
Brownish black
Reddish yellow
Light brown
Yellowish brown
Reddish yellow
Yellowish brown
Deep brown
Reddish brown
Yellowish brown
Deep yellow
Brown
Dark green
Dark brown
Brownish black
Brown
Brownish black
Brown
Brown
Dark brown
Brownish yellow
Dark brown
Dark brown
Dark brown
Dark brown
Brown
Dark brown
Yellowish brown
Reddish brown
Brownish black
Black
Bluish-black
Black
Brownish black
Brownish black
Brownish black
Brownish black
Brownish black
Brownish black
Brownish black
Brownish black
Brownish black
Black
Bluish black
D. volubilis: Dregea volubilis, UV: Ultraviolet
Table 3: Preliminary phytochemical analysis of D. volubilis flower extracts
Phytochemicals
Petroleum benzine extract
Chloroform extract
Methanol extract
Aqueous extract
Carbohydrates
Proteins
Amino acids
Steroids
Glycosides
Alkaloids
Tannins and Phenolics
Flavonoids
−
−
−
+
−
−
−
−
−
−
−
+
+
−
−
−
+
+
+
−
+
+
+
+
+
+
+
−
+
+
+
+
D. volubilis: Dregea volubilis
different solvent systems on trial and error method. The retention
factor (Rf) values of the different extracts are presented in Table 4.
The phytochemical studies of the different extracts of D. volubilis
flower showed the presence of different types of plant metabolites
which are responsible for the medicinal values of the plant. The
extraction with different solvents gives rise to the separation of
medicinally active portions of the plant according to the polarity
of the solvents. The purpose of the standardized extracts is to
obtain the therapeutically active compounds and to eliminate
unwanted materials by treatment with a selective solvent known as
menstruum. The extracts of the crude drugs can be considered a good
source of useful drugs [27]. The various types of phytochemicals
present contribute medicinal as well as physiological properties to
the plants. The TLC analysis of the different extracts was carried
out for the development of characteristic fingerprint profile
which may be used as a reference for the quality evaluation and
standardization of the drug. The bands of the different extracts in
the TLC plates were obtained at different R f values which can be
used as identifying markers [11]. The extracts can be utilized as
medicinal agents after standardization in different dosage forms
of pharmaceutical interest. The preliminary phytochemical studies
are of great importance in the field of standardization of crude
drugs.
HPLC fingerprinting
The different phytoconstituents present in the sample were separated
on C18 column using UHPLC (Fig. 3). The different peaks along with
their retention times (min), area (mAU*min), height (mAU), relative
area (%), and relative height (%) are presented in Table 5. HPLC plays
an important role as an important analytical tool for the quality control
of drugs [28]. Natural products have a unique chemical diversity
which results in diversity in their biological activity leading to the
development of lead compounds which will play an important role
in the discovery of drugs for treating various ailments. The modern
analytical technique (HPLC) with high power of separation and
reproducibility can be used to separate multidimensional chemical
structures present in the plant materials. The peak number 7 and 26
with a retention time of 4.912 min and 34.855 min, respectively, are
the two more intense peaks among the others in the chromatogram
generated after HPLC study. The peak number 7 accounts for 27.54%
and the peak number 26 accounts for 23.92% relative area. The
chromatograms generated after HPLC study can be used to establish
reference HPLC fingerprints of the flower of D. volubilis against which
raw materials can be evaluated and finished products containing the
plant material can be analyzed.
FTIR
The FTIR spectra of the different extracts of D. volubilis flowers
are presented in Fig. 4. The petroleum benzine and chloroform
extracts exhibited characteristic bands for the asymmetrical
stretching vibrations of the C–H bonds in CH2 and CH3 groups
between 2980 and 2810 cm−1, C–H bending vibrations between
1480 and 1400 cm−1, C=O stretching vibrations between 1870 and
1540 cm−1, interactions of O–H bending and C–O stretching in the
C–O–H group between 1390 and 1350 cm−1, and the secondary
C–O vibrations in the C–O–H group between 1060 and 1025 cm−1
which are characteristics of phytosterols [29]. The aqueous,
chloroform, and methanol extracts showed characteristic bands
for the O–H stretching vibrations between 3550 and 3200 cm−1,
C–O stretching vibration band between 1060 and 1000 cm−1, and
O–H bending vibration band between 1420 and 1330 cm−1 which
are due to the presence of phenolic compounds. The extracts
also exhibited characteristic O–H stretching vibration band near
3000 cm−1 and C=O stretching vibration band near 1700 cm−1,
C–O stretching vibration band between 1320 and 1210 cm−1, and
O–H bending vibration band between 1440 and 1395 cm−1 which
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Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
Table 4: Thin-layer chromatography of D. volubilis flower extracts
Sl. No.
Solvent
system
Extracts
No. of spots
(254 nm)
Rf values (254 nm)
No. of spots (366 nm)
Rf values (366 nm)
1
Chloroform:
ethyl
acetate (6:4)
Aqueous
Methanol
Chloroform
1
4
16
0.48
0.04, 0.09, 0.13, 0.47
0.04, 0.06, 0.10, 0.12, 0.19, 0.30, 0.35, 0.41,
0.48, 0.56, 0.61, 0.72, 0.79, 0.95, 0.96, 0.98
1
9
7
0.07, 0.23, 0.48, 0.56, 0.72, 0.91, 0.96
3
Chloroform:
ethyl
acetate (8:2)
Petroleum
benzine
Aqueous
Methanol
Chloroform
0.25
0.08, 0.16, 0.30,
0.35, 0.41, 0.93,
0.95, 0.97, 0.98
0.84, 0.92, 0.96
2
4
9
3
4
1
7
0.04, 0.15
0.02, 0.06, 0.10, 0.16
0.02, 0.05, 0.08, 0.10, 0.15, 0.16, 0.88, 0.91,
0.96
0.10, 0.20, 0.24, 0.29, 0.52, 0.64, 0.67, 0.79,
0.86, 0.89, 0.91, 0.97
0.69
0.13, 0.17, 0.24, 0.53, 0.66, 0.76, 0.90
2
5
2
3
4
5
6
7
Chloroform:
methanol:
glacial acetic
acid
(4:5:1)
Chloroform:
ethylacetate:
glacial acetic
acid
(4:5:1)
Chloroform:
2propanol:
glacial acetic
acid
(5:4:1)
Chloroform:
ethanol:
triethylamine
(6:3:1)
Chloroform:
methanol:
glacial acetic
acid
(5:4:1)
Petroleum
benzine
Aqueous
Methanol
12
3
0.01, 0.05, 0.14
0.06, 0.09, 0.90,
0.96
0.66, 0.89, 0.96
0.10, 0.73
0.24, 0.69, 0.78,
0.90, 0.97
0.74, 0.87
0.46, 0.72, 0.78,
0.90
0.88
0.04, 0.13, 0.16,
0.70, 0.96
0.04, 0.85, 0.94,
0.96
0.94
Chloroform
Petroleum
benzine
Aqueous
Methanol
2
3
0.84, 0.93
0.46, 0.48, 0.72
2
4
3
8
0.06, 0.17, 0.88
0.03, 0.04, 0.07, 0.12, 0.19, 0.33, 0.71, 0.87
1
5
Chloroform
8
0.02, 0.04, 0.42, 0.55, 0.86, 0.90, 0.94, 0.95
4
Petroleum
benzine
Aqueous
Methanol
1
0.94
1
1
9
0.05
0.03, 0.12, 0.19, 0.48, 0.57, 0.62, 0.72, 0.92,
0.96
1
7
4
1
0.12, 0.72, 0.88, 0.94
0.94
1
1
3
12
5
2
3
0.06, 0.89, 0.92,
0.95, 0.97
0.91, 0.96
0.82, 0.89, 0.96
Chloroform
Petroleum
benzine
Aqueous
Methanol
0.05
0.05, 0.13, 0.21,
0.48, 0.62, 0.69,
0.92
0.97
0.97
Chloroform
Petroleum
benzine
Aqueous
3
2
0.06, 0.08, 0.11
0.05, 0.13, 0.16, 0.19, 0.31, 0.37, 0.41, 0.47,
0.61, 0.65, 0.90, 0.96
0.44, 0.84, 0.95
0.81, 0.90
6
0.08, 0.12, 0.38, 0.50, 0.69, 0.88
2
0.52, 0.69
Methanol
11
0.04, 0.09, 0.16, 0.34, 0.44, 0.62, 0.68, 0.78,
0.87, 0.95, 0.98
7
Chloroform
Petroleum
benzine
2
2
0.80, 0.92
0.80, 0.96
3
2
0.16, 0.40, 0.65,
0.79, 0.83, 0.95,
0.98
0.79, 0.87, 0.93
0.87, 0.96
D. volubilis: Dregea volubilis, Rf: Retention factor
are due to presence of phenolic acids. All the extracts showed
characteristic absorption bands for the out-of-plane bending of
ring C–H bonds between 900 and 675 cm−1, in-plane bending bands
between 1300 and 1000 cm−1, and C–C stretching band within the
ring between 1600 and 1585 cm−1 and 1500 and 1400 cm−1 which
are due to the presence of mononuclear and polynuclear aromatic
hydrocarbons [30]. The characteristic absorption bands of the
different extracts of the plant material confirm the presence of
different types of phytoconstituents in D. volubilis flowers. FTIR is
a useful analytical tool in the field of standardization of drugs. FTIR
spectrum is useful in the identification of drugs by comparing the
spectrum of the test material with that of the reference material.
The FTIR spectra of the different extracts can be served as reference
FTIR fingerprints of D. volubilis flowers for the quality control of
raw materials and finished products containing it [9]. The study
also provides qualitative information on the types of chemicals
present in the different extracts of the flowers of D. volubilis.
Determination of UV-VIS spectra
The UV-VIS spectrum of different extracts of D. volubilis flowers
is presented in Fig. 5. The aqueous extract showed the peaks at
250 nm, 290 nm (λmax); the methanol extract showed the peaks at
230 nm and 300 nm (λmax); the chloroform extract showed the peaks
at 250 nm, 300 nm (λmax), 410 nm, 510 nm, 540 nm, and 670 nm;
and the petroleum benzine extract showed the peaks at 300 nm
(λmax), 400 nm, 500 nm, 530 nm, and 670 nm. UV-VIS spectrum
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Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
A
B
Fig. 3: Ultra-high-performance liquid chromatograms of a sample solution of the flower of Dregea volubilis (A) and an overlapped chromatogram
(black colored chromatogram represents blank solution and blue colored chromatogram represents sample solution) (B) as detected at 280 nm.
Table 5: HPLC peaks present in the sample solution of the flower of D. volubilis as detected at 280 nm
Sl. No. of HPLC Peaks
Retention time (min)
Are(mAU*min)
Height (mAU)
Relative area (%)
Relative height (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Total
3.007
3.460
3.688
3.942
4.343
4.708
4.912
6.023
6.822
7.610
8.445
9.688
10.460
12.578
14.140
17.290
18.342
22.708
23.800
27.108
27.740
28.632
32.073
32.538
33.720
34.855
35.565
36.180
36.352
36.855
37.582
38.357
40.072
41.305
41.578
56.565
3.639
2.992
2.887
1.443
3.521
1.774
39.758
2.299
1.329
1.339
2.820
0.501
5.894
0.595
1.131
1.123
0.735
0.772
0.936
0.644
6.010
3.555
1.885
0.623
0.911
34.533
2.167
2.312
3.113
1.667
1.252
0.592
4.243
1.173
3.454
0.749
144.370
26.758
29.535
22.366
13.231
22.164
19.838
236.210
9.147
5.662
4.054
10.939
1.924
17.178
2.365
4.393
2.568
3.604
3.080
3.735
3.177
21.011
17.369
8.404
4.004
4.209
210.94
14.434
14.081
17.537
8.962
8.645
4.046
21.997
6.969
18.030
3.239
825.81
2.52
2.07
2.00
1.00
2.44
1.23
27.54
1.59
0.92
0.93
1.95
0.35
4.08
0.41
0.78
0.78
0.51
0.53
0.65
0.45
4.16
2.46
1.31
0.43
0.63
23.92
1.50
1.60
2.16
1.15
0.87
0.41
2.94
0.81
2.39
0.52
100
3.24
3.58
2.71
1.60
2.68
2.40
28.60
1.11
0.69
0.49
1.32
0.23
2.08
0.29
0.53
0.31
0.44
0.37
0.45
0.38
2.54
2.10
1.02
0.48
0.51
25.54
1.75
1.71
2.12
1.09
1.05
0.49
2.66
0.84
2.18
0.39
100
HPLC: High-performance liquid chromatography, D. volubilis: Dregea volubilis
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Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
plays an important role in the identification and quantification of
many drugs. This analytical tool is very useful for the quality control
of drugs [31]. The UV-VIS spectrum of the different extracts of
D. volubilis flowers can be served as a reference spectrum for quality
control of drugs.
helpful in the development of suitable extraction procedure for the
phytoconstituents from the plant [15].
Determination of protein content
Proteins are important biomolecules with multiple functions within
organ and the molecules are differing from one another primarily in
their sequence of amino acids. The protein content of the sample was
found to be 2.112±0.058 mg/g of the sample. The protein content of the
powder of D. volubilis flower can be served as a quantitative parameter
for standardization of the plant material. Any deviation from the
standard value of protein content reflects the changes in the quality of
the crude drug. Estimation of protein of herbal drugs plays a crucial
role in assessing the nutritional significance and health effects [32]. The
parameter can be used as a reference for the quality control of crude
drugs.
Determination of pH
The pH of the 1% (w/v), 2% (w/v), and 10% (w/v) aqueous solutions
of the dried powdered material was found to be 5.02±0.02, 4.89±0.02,
and 4.74±0.02, respectively. pH can also serve as a quality control tool
for the identification of the drugs. A change in the value of pH from the
standard value indicates the deterioration of the quality of the product.
The aqueous solution of D. volubilis flower was found to be acidic in
nature. The pH value is of great importance in product development to
estimate stability and dissolution of the product. The pH value is also
Determination of carbohydrate content
The carbohydrate content of the dried powdered material of
D. volubilis flowers was found to be 124.243±3.573 mg/g of the sample.
Carbohydrate is one of the most widely used substances in nature and is
the main ingredient of food. The quantitative analysis for the estimation
of the carbohydrate content of crude drugs can be considered as a
quality control parameter for assessing the crude drugs [33].
Determination of free sugar composition
The UFLC analysis (Fig. 6) was performed to identify and quantify the
free sugars present in the D. volubilis flowers. The retention times of
rhamnose, xylose, fructose, glucose, trehalose, and maltose were found
to be 4.982, 5.456, 5.734, 6.198, 7.351, and 8.032 min, respectively.
The sugars present in the sample were identified by comparing the
retention times of the standards with that of the sample. Xylose and
trehalose were not detected in the crude drug. The study showed
that the flower contained rhamnose (103.229±4.994 µg/g), fructose
(738.670±25.714 µg/g), glucose (285.532±24.465 µg/g), and maltose
(49.082±5.206 µg/g). Characterization of sugars present in crude drugs
is very important for their quality control [33]. The sugars present in
the flower can be considered as markers for the standardization of the
crude drug.
Fig. 4: Fourier transform infrared spectra of the petroleum
benzine extract (A), aqueous extract (B), chloroform extract (C),
and methanol extract (D) of the flower of Dregea volubilis
A
C
B
D
Fig. 5: Ultraviolet-visible spectra of the aqueous extract (A), methanol extract (B), chloroform extract (C), and petroleum benzine extract
(D) of the flower of Dregea volubilis
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Asian J Pharm Clin Res, Vol 12, Issue 5, 2019, 79-89
A
B
Fig. 6: High-performance liquid chromatography chromatograms of the mixed standard of sugars (A) and the sample solution of the
flower of Dregea volubilis (B) as detected with refractive index detector (1: Rhamnose, 2: Xylose, 3: Fructose, 4: Glucose, 5: Trehalose,
6: Maltose)
CONCLUSION
2.
Herbal drugs are subjected to variability in quality as they derived
from heterogeneous sources. The main concerned area is that the
activity of the plant material may vary and even inferior quality
material may be produced which may impart a quality impact on
the products of the pharmaceutical industry. Standardization of
herbal drugs is an important topic of great concern. The present
study of pharmacognostical evaluation on the flowers of D. volubilis
has laid down standard parameters for proper identification,
authentication, and for distinguishing the material from its adulterants
and substitutes. The detailed study also set the parameters which
can be utilized as a pharmacopeial reference for recognition of its
distinctiveness, genuineness, and quality. The study also contributes
to the documentation of the nutritional composition on the flowers of
D. volubilis which are consumed as a vegetable.
3.
4.
5.
6.
7.
ACKNOWLEDGMENT
The authors gratefully acknowledge the University Grants Commission,
New Delhi, for providing the instrumental facilities under UGC-UPE
Phase–II program at the Department of Pharmaceutical Technology,
Jadavpur University, Kolkata.
8.
9.
AUTHOR’S CONTRIBUTIONS
10.
Bhaskar Das was involved in performing all the experiments and
preparing the manuscript. Arnab De, Piu Das, and Amalesh Nanda were
involved in the plant identification, methodology, and interpretation of
data. Dr. Amalesh Samanta had revised and finalized the manuscript.
11.
12.
CONFLICTS OF INTEREST
The authors declare that they have no potential conflicts of interest.
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