Evaluation of anti-inflammatory effects of green tea and black tea: A comparative in vitro study

Abstract

The present study was conducted to evaluate and compare the anti-inflammatory effects of aqueous extracts of green tea and black tea leaves (Camellia sinensis) against the denaturation of protein in vitro. The test extracts at different concentrations were incubated with egg albumin under controlled experimental conditions and subjected to determination of absorbance to assess the anti-inflammatory property. Diclofenac sodium was used as the reference drug. The present results exhibited a concentration-dependent inhibition of protein (albumin) denaturation by both the tea extracts. From the present findings it can be concluded that both green and black tea leaves possessed a marked anti-inflammatory effect against the denaturation of protein, in vitro. Green tea was found to be more active than black tea, plausibly due to the higher flavonoid contents of green tea.

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136 Journal of Advanced Pharmaceutical Technology & Research | Apr-Jun 2012 | Vol 3 | Issue 2
Evaluation of anti-inammatory effects of green tea
and black tea: A comparative in vitro study
Abstract
The present study was conducted to evaluate and compare the anti-inflammatory
effects of aqueous extracts of green tea and black tea leaves (Camellia sinensis) against
the denaturation of protein in vitro. The test extracts at different concentrations were
incubated with egg albumin under controlled experimental conditions and subjected
to determination of absorbance to assess the anti-inflammatory property. Diclofenac
sodium was used as the reference drug. The present results exhibited a concentration-
dependent inhibition of protein (albumin) denaturation by both the tea extracts. From
the present findings it can be concluded that both green and black tea leaves possessed
a marked anti-inflammatory effect against the denaturation of protein, in vitro. Green
tea was found to be more active than black tea, plausibly due to the higher flavonoid
contents of green tea.
Key words: Anti-inflammatory, green tea, polyphenols, protein denaturation
Priyanka Chatterjee,
Sangita Chandra, Protapaditya Dey,
Sanjib Bhattacharya
Pharmacognosy Division, Bengal School
of Technology (A College of Pharmacy),
Sugandha, Hooghly, West Bengal, India
J. Adv. Pharm. Tech. Res.
short communication
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DOI:
10.4103/2231-4040.97298
INTRODUCTION
The inammatory process is the response to an injurious
stimulus evoked by a wide variety of noxious agents,
for example, infections, antibodies or physical injuries.
Inammation is a bodily response to injury, infection or
destruction, characterized by heat, redness, pain, swelling
and disturbed physiological functions. Inammation is
a normal protective response to tissue injury caused by
physical trauma, noxious chemical or microbial agents. It
is the body response to inactivate or destroy the invading
organisms, to remove the irritants, and set the stage for tissue
repair. It is triggered by the release of chemical mediators
from injured tissue and migrating cells.[1] The commonly
used drug for the management of inammatory conditions
are non-steroidal anti-inammatory drugs (NSAIDs), which
have several adverse eects especially gastric irritation
leading to the formation of gastric ulcers.[2,3] Natural products
have contributed signicantly towards the development of
modern medicine. Of late, traditional medicine is being
re-evaluated worldwide, by extensive research on dierent
plant species and their active therapeutic principles. The rich
wealth of the plant kingdom can represent a novel source
of newer compounds with signicant anti-inammatory
activities. The major merits of herbal medicine seem to be
their perceived ecacy, low incidence of serious adverse
eects, and low cost.
Tea, a product made from the leaf and bud of the plant,
Camellia sinensis, is the second most consumed beverage
in the world.[4] Camellia sinensis is a large evergreen
shrub indigenous to Eastern Asia, where it is cultivated
extensively. The dried, cured leaves of C. sinensis have
been used to prepare beverages for more than 4000 years.
The method of curing determines the nature of the tea to
be used for infusion. Green tea is a type of cured tea that is
‘non fermented’ and produced by drying and steaming the
fresh leaves; whereas, black tea leaves are withered, rolled,
fermented, and then dried.[5] Tea has been used medicinally
for centuries in the Traditional Chinese Medicine (TCM). In
recent times, there has been renewed interest in green tea, for
the prevention of several disease risks and other important
health benefits.[6] Previous researchers have reported
the eects of several pharmacological and toxicological
properties of green tea and black tea on animals and
Address for correspondence:
Mr. Sanjib Bhattacharya,
Pharmacognosy Division, Bengal School of Technology
(A College of Pharmacy), Sugandha, Hooghly 712102,
West Bengal, India.
E-mail: sakkwai@yahoo.com
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Chatterjee, et al.: Anti-inammatory effects of green and black tea
137
Journal of Advanced Pharmaceutical Technology & Research | Apr-Jun 2012 | Vol 3 | Issue 2
humans, including anti-inammatory activities.[7-12] In the
present study it has been found worthwhile to evaluate and
compare the possible anti-inammatory eect of green tea
and black tea against the denaturation of protein, in vitro,
as their anti-inammatory eects have not been studied in
this model so far.
MATERIALS AND METHODS
Plant Materials
Packaged green tea and black tea leaves were procured in
the month of July, 2011, from Desai and Sons, Ezra Street,
Kolkata 700001, India. Just after procurement, both type of
tea leaves were ground mechanically into ne powder and
kept into an air-tight container for use in the study.
Preparation of Extracts
The powdered plant materials (50g) were extracted
with distilled water (350 mL) by boiling under reux for
30minutes. The extracts were filtered and evaporated
to dryness to yield the dry extracts of green tea (AQGT,
yield: 51.28%) and black tea (AQBT, yield: 17.45%). The dry
extracts were kept in a vacuum desiccator until use.
Evaluation of Anti-inammatory Eect in vitro
The reaction mixture (5 mL) consisted of 0.2 mL of egg
albumin (from fresh hen’s egg), 2.8 mL of phosphate-buered
saline (PBS, pH 6.4) and 2 mL of varying concentrations of
AQGT and AQBT so that nal concentrations became 31.25,
62.5, 125, 250, 500, 1000 μg/mL. A similar volume of double-
distilled water served as the control. Next, the mixtures
were incubated at 37 ± 2ºC in a BOD incubator (Labline
Technologies) for 15minutes and then heated at 70ºC for
ve minutes. After cooling, their absorbance was measured
at 660 nm (SHIMADZU, UV 1800) by using the vehicle as
a blank. Diclofenac sodium in the nal concentrations of
(78.125, 156.25, 312.5, 625, 1250, 2500 μg/mL) was used as the
reference drug and treated similarly for the determination
of absorbance.[13] The percentage inhibition of protein
denaturation was calculated by using the following formula:
% inhibition = 100 × [Vt / VC - 1]
Where, Vt = absorbance of the test sample, Vc = absorbance
of control.
The extract concentration for 50% inhibition (IC50) was
determined by the dose-response curve.
RESULTS AND DISCUSSION
There are certain problems associated with the use of
animals in experimental pharmacological research, such as,
ethical issues and the lack of rationale for their use when
other suitable methods are available, or can be investigated.
Hence, in the present study the protein denaturation
bioassay was selected for in vitro assessment of the anti-
inammatory property of the aqueous extracts of green
tea and black tea (AQGT and AQBT). Denaturation of
the tissue proteins is one of the well-documented causes
of inflammatory and arthritic diseases. Production of
auto-antigens in certain arthritic diseases may be due to
denaturation of proteins in vivo.[14,15] Therefore, using agents
that can prevent protein denaturation would be worthwhile
for anti-inammatory drug development.
In the present investigation, the in vitro anti-inammatory
eect of AQGT and AQBT was evaluated against denaturation
of egg albumin. The results are summarized in Table 1.
The present ndings exhibited a concentration-dependent
inhibition of protein (albumin) denaturation by AQGT and
AQBT, throughout the concentration range of 31.25 to 1000
μg/mL. Diclofenac sodium, in the concentration range of
78.125 to 2500 μg/mL, was used as a reference drug which
also exhibited concentration-dependent inhibition of protein
denaturation [Table 2]. The IC50 values are summarized in
Table 3. Here, AQGT was found to be more eective than
AQBT; however, the eect of diclofenac sodium was found to
be quite low when compared with both the test tea extracts.
This was further conrmed by comparing their IC50 values
[Table 3].
The increments in the absorbance of the test samples, with
respect to the control, indicated stabilization of protein,
that is, inhibition of protein (albumin) denaturation or an
anti-denaturation eect by the tea extracts and the reference
drug, diclofenac sodium.[16]
Tea leaves contain varying amounts of polyphenols
Table 1: Effect of AQGT and AQBT against
protein denaturation.
Concentration
(µg/mL)
% Inhibition
(AQGT)
% Inhibition
(AQBT)
Control - -
31.25 220 140
62.5 320 180
125 620 220
250 1100 700
500 2480 1540
1000 4980 2480
AQGT: Aqueous extract of green tea, AQBT: Aqueous extract of black tea
Table 2: Effect of diclofenac sodium against
protein denaturation
Concentration (µg/mL) % Inhibition
Control -
78.125 12.5
156.25 12.5
312.5 25
625 50
1250 212.5
2500 812.5
AQGT: Aqueous extract of green tea, AQBT: Aqueous extract of black tea
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Chatterjee, et al.: Anti-inammatory effects of green and black tea
138 Journal of Advanced Pharmaceutical Technology & Research | Apr-Jun 2012 | Vol 3 | Issue 2
particularly flavonoids. Polyphenols are well-known
natural products known to possess several notable
biological properties.[17] Black tea and green tea both contain
almost a similar amount of flavonoids, however, they
dier in their chemical composition; green tea contains
more catechins (simple avonoids), while the oxidation
undergone by the leaves, in order to make black tea,
polymerizes these simple avonoids into theaavins and
thearubigins (polymerized avonoids).[8,18] In the present
study, the higher anti-inammatory eect of green tea can
be aributed to its higher avonoids (catechin) content.
The eect may be due to the synergistic eect rather than
a single constituent.
It has been reported that one of the features of several
non-steroidal, anti-inammatory drugs, is their ability to
stabilize (prevent denaturation) heat-treated albumin at
the physiological pH (pH: 6.2 – 6.5).[19] Therefore, from
the results of the present preliminary study, it can be
concluded that both green and black tea leaves possess a
marked anti-inammatory eect against the denaturation of
protein in vitro. Previous researchers have reported the anti-
inammatory activity of both green tea and black tea.[9-12] The
present ndings corroborated this property in vitro, against
this protein denaturation model. This correlation is further
strengthened by the fact that the present study was performed
in a dierent model, in which it has not been studied earlier.
It is suggested that the anti-inammatory eect of tea leaves
could be further evaluated in other experimental models.
ACKNOWLEDGEMENT
The authors are thankful to the authority of the Bengal School of
Technology (A College of Pharmacy), Sugandha, Hooghly, 712102,
West Bengal, India, for providing the necessary facilities for the
present study.
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Table 3: IC50 values of AQGT, AQBT and
diclofenac sodium
Treatments IC50 (µg/mL)
AQGT 7.10
AQBT 11.16
Diclofenac sodium 625
AQGT: Aqueous extract of green tea, AQBT: Aqueous extract of black tea
How to cite this article: Chatterjee P, Chandra S, Dey P,
Bhaacharya S. Evaluation of anti-inammatory eects of green
tea and black tea: A comparative in vitro study. J Adv Pharm Tech
Res 2012;3:136-8.
Source of Support: Nil, Conict of Interest: Nil.
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