In vitro Antioxidant activity of Methanolic
Aerial Part Extract of Mimosa pudica.
Md.
Omar Faruk1*, Dibyajyoti Saha2,
Srikanta Chowdhury1, Swati
Paul2, Md. Golam Kabir1
1Department of Biochemistry
and Molecular Biology, University of Chittagong, Bangladesh.
2Department of
Pharmacy, BGC Trust University Bangladesh, Chittagong.
ABSTRACT:
The methanol
crude extracts of the plant parts of Mimosa
pudica (Mimosaceae) was
screened was screened in vitro for antioxidant activity using the 1,
1-diphenyl-2-picrylhydrazyl-hydrate (DPPH) free radical scavenging assay. On
the other hand, the methanol crude extract of the aerial part showed moderate
antioxidant activity (IC50 20.512 μg/ml)
compared to ascorbic acid (IC50 1.143 μg/ml).
The overall experimental results suggest the biologically active constituents
present in the methanolic extract of Mimosa pudica and
justify its use in folkloric remedies.
KEYWORDS: Mimosa pudica; Mimosaceae;
DPPH; antioxidant activity.
INTRODUCTION:
Plants have been the traditional source of raw materials for medicine.
A rich heritage of knowledge to preventive and curative medicines was available
in ancient scholastic works included in the Atharva veda, Charaka, Sushruta, etc. An estimate suggests that about 13,000 plant
species worldwide are known to have use as drugs. The trend of using natural
products has increased and the active plant extracts are frequently for new
drug discoveries and for the presence of antimicrobials1. In recent
years one of the areas which attracted a great deal of attention is the
possible therapeutic potential of antioxidants in controlling degenerative
diseases associated with marked oxidative
damage. Several plant extracts and different classes of phytochemicals
have been found to have quite prominent antioxidant activity2-4.
Mimosa pudica (Bengali name – Lajjabati Lata, Lajanti; English name – Sensitive plant; Family- Mimosaceae). Mimosa plant is a short lived evergeeen shrub which can be treated as an annual or
perennial herb. This is an interesting plant due to peculiar movement of its
leaflets that are sensitive to touch. Its fem like leaves close up and droop
down whenever touched either by hand or by any object, living or non-living. It
is due to the specific characteristics of its leaves that mimosa is regarded as
a plant or high ornamental value. These leaves open in a very short time after
the stimulus is withdrawn. Leaves and stems of the
plant have been reported to contain an alkaloid, mimosine;
leaves also contain mucilage and root, tannins5.
The plants also contain turgorins. M. pudica is regarded as diuretic, astringent and
antispasmodic. Leaves and roots are used in the treatment of piles and fistula.
Paste of leaves is applied to hydrocele. Cotton impregnated with juice of leaves is used
for dressing sinus. Plant is also useful in the treatment of sore gum and is
used as a blood purifier. Itis also used for treating
convulsions of children. Few chemical and biological studies have been carried
out on this plant6-11.
Material and Methods:
Chemicals and Reagents
0.004% DPPH solution (2, 2-diphenyh-1-picrylhydrazyl, MW= 394.32):
5.5mg DPPH (Purchased from Sigma chemicals, Germany) was dissolved with 100 ml
methanol. Various concentrations (20, 40, 60, 80, 100, 200, 400, 800 μg/ml) of ascorbic acid [Merck Chemicals] prepared
with methanol.
Various concentrations (20, 40, 60, 80, 100, 200, 400, 800 μg/ml) of Mimosa pudica extract prepared with methanol.
Plant material
The whole plants of Mimosa pudica were collected from Chittagong district
of Bangladesh. After selection of plants suitable herbarium sheet for plant
with some general information were prepared and the plant was taxonomically
identified by Department of Botany, University of
Chittagong.
Extraction
The fresh plants of Mimosa pudica were washed with water immediately after
collection. The collected plants were chopped into small pieces, air dried at
room temperature for about 10 days and ground into powder form and stored in an
airtight container. 750 gm powder was macerated in 2.5 L pure ethanol for 5
days at room temperature with occasional stirring. 5 days later, ethanol
extract was filtered off through a cotton plug and finally with a Whatman No. 1
filter paper. The extract was concentrated under reduced pressure below 50 şC
through rotatory vacuum evaporator. The concentrated
extracts were collected in a Petri dish and allow to air dry for complete
evaporation of ethanol. The whole process was repeated three times and finally,
48 gm blackish-green colored, concentrated plant extract was obtained (yield
6.4 % w/w) which was kept in refrigerator at 4 şC.
In vitro antioxidant activities
DPPH Assay
The antioxidant activity of Mimosa pudica extract and the standard antioxidant ascorbic acid was assessed on the basis
of the radical scavenging effect of the stable 2, 2- diphenyl-1 picrylhydrazyl (DPPH)-free radical activity according to
the method described by Brand-William 12 with slight modifications.
Procedure of DPPH free radical scavenging method
Mimosa pudica extract with
different concentrations (10, 15, 25, 30, 40 and 50 µg/ml) were prepared in
methanol. Ascorbic acid was used as standard in 1-50 μg/ml
solution. 0.004 % DPPH solution was prepared in methanol and 3 ml of this
solution was mixed with diluted 5 ml of extract solution and standard solution
separately. These solution mixtures were kept in dark for 30 min. The degree of
DPPH purple decolorization to DPPH yellow indicated
the scavenging efficiency of the extract. The absorbance of the mixture was
determined at 517 nm using UV-Visible Spectrophotometer (Cintra,
Australia) and ascorbic acid was served as a positive control. Lower absorbance
of the reaction mixture indicated higher free radical-scavenging activity. The
scavenging activity against DPPH was calculated using the following equation:
Scavenging activity (%) = [(A - B) / A] x 100
Where A was the absorbance of control (DPPH solution without
the sample), B was the absorbance of DPPH solution in the presence of
the sample (extract/ ascorbic acid) .Then % scavenging activity or % inhibition
was plotted against log concentration and from the graph IC50 (Inhibition
concentration 50) value was calculated by linear regression analysis.
Results and
Discussion:
Antioxidative activity of Mimosa pudica extract was measured by DPPH free radical scavenging method and their
scavenging activity was compared with the standard antioxidant ascorbic acid.
The DPPH free radical scavenging activity of the Mimosa pudica extract and ascorbic acid is shown in Table: 1
and 2 . Both ascorbic acid and extract showed dose dependent activity.
However, extract showed very strong amount of
DPPH free radical scavenging effect compared with ascorbic acid. Among eight
different concentrations used in the study (20, 40, 60, 80, 100, 200, 400 and
800 μg/ml ) extract showed highest scavenging activity at 800 μg/ml which
was 95.85%.
On the other hand, ascorbic acid showed 73.06%, 73.58%, 77.72%,
83.94%, 94.30%, 95.34%, 96.89% and 97.92% activity at 20, 40, 60, 80, 100, 200,
400 and 800 μg/ml respectively (Table- 2 and Fig
-2).
% scavenging activity or %
inhibition was plotted against log concentration and from the graph IC50
(Inhibition concentration 50) value was calculated by linear regression
analysis. IC50 value of ascorbic acid and extract was found
1.143μg/ml and 20.512 μg/ml respectively.
Table 1. DPPH free radical
scavenging activity of Mimosa pudica extract
|
Concentration
(μg/ml) |
log
concentration |
Absorbance |
%
Scavenging activity |
IC50 |
|
Control |
- |
0.193 |
- |
20.512 μg/ml |
|
20 |
1.30 |
0.091 |
52.85 |
|
|
40 |
1.60 |
0.082 |
57.52 |
|
|
60 |
1.77 |
0.081 |
58.03 |
|
|
80 |
1.90 |
0.071 |
63.21 |
|
|
100 |
2.00 |
0.041 |
78.76 |
|
|
200 |
2.30 |
0.032 |
83.42 |
|
|
400 |
2.60 |
0.011 |
94.30 |
|
|
800 |
2.90 |
0.008 |
95.85 |
|
Table 2. DPPH free radical
scavenging activity of ascorbic acid
|
Concentration
(μg/ml) |
log
concentration |
Optical
density |
%
scavenging activity |
IC50 |
|
Control |
- |
0.193 |
- |
1.143 μg/ml |
|
20 |
1.30 |
0.052 |
73.06 |
|
|
40 |
1.60 |
0.051 |
73.58 |
|
|
60 |
1.77 |
0.043 |
77.72 |
|
|
80 |
1.90 |
0.031 |
83.94 |
|
|
100 |
2.00 |
0.011 |
94.30 |
|
|
200 |
2.30 |
0.009 |
95.34 |
|
|
400 |
2.60 |
0.006 |
96.89 |
|
|
800 |
2.90 |
0.004 |
97.92 |
|
Figure 1. IC50 value
of Mimosa pudica aerial part extract was calculated from above plot linear
regression analysis
Figure 2. IC50 value
of Ascorbic acid was calculated from above plot by linear regression analysis
Figure 3. Comparative %
scavenging activity or % inhabitation of standard antioxidant ascorbic acid and
Mimosa pudica aerial part extract
In the present study the free radical scavenging activities of the
medicinal plant was evaluated. Free radicals are involved in many disorders like
neurodegenerative diseases, cancer and AIDS. Antioxidants due to their
scavenging activity are useful for the management of those diseases. DPPH
stable free radical method is a sensitive way to determine the antioxidant
activity of plant extracts13. Ascorbic acid was used as a standard
in this experiment. Among eight different concentrations (20, 40, 60, 80, 100,
200, 400 and 800 μg/ml) used in this study.
Ascorbic acid showed 73.06%, 73.58%, 77.52%, 83.94%, 94.30%, 95.34%, 96.89% and
97.92% scavenging activity where highest scavenging activity was 97.92% at
concentration 800μg/ml.
On the other hand methanolic aerial part
extract of Mimosa pudica. Showed 52.85%,
57.52%, 58.03%, 63.21%, 78.76%, 83.42%, 94.30% and 95.85% scavenging activity
at eight different concentrations, where highest scavenging activity was 95.85%
at concentrations 800 μg/ml.
IC50 value of ascorbic acid and extract was found 1.143 μg/ml and 20.512 μg/ml
respectively .The free radical scavenging action of methanolic
aerial part extracts of plant Mimosa pudica showed the strongest DPPH radical
scavenging activity. The therapeutic potential of natural medicinal plants as
an antioxidant in reducing such free radical induced tissue injury, suggests
that many plants have antioxidant activities that can be therapeutically useful14.
A simple method utilizing the stable 2,2-diphenyl- 1-picrylhydrazyl
(DPPH) radical has been developed to determine the antioxidant activity of
natural products. The odd electron in the DPPH free radical gives a strong
absorption maximum at 517 nm and is purple in color. The color turns from
purple to yellow (Fig: 3) as the molar absorptivity
of the DPPH radical at 517 nm reduces from 9660 to 1640 when the odd electron
of DPPH radical becomes paired with hydrogen from a free radical scavenging
antioxidant to form the reduced DPPH-H. The resulting decolorization
is stoichiometric with respect to number of electrons
captured.
Ascorbic acid was used as a standard and it is acting as a chain
breaking antioxidant impairs with the formation of free radicals in the process
of formation of intracellular substances throughout the body, including
collagen, bone matrix and tooth dentine15. The quantitative
determination of ascorbic acid in plant extract shows that they are good source
of ascorbic acid. A striking pathological change resulting from ascorbic acid
deficiency is the weakening of the endothelial wall of the capillaries due to a
reduction in the amount of intercellular substance. Therefore, a clinical
manifestation of scurvy hemorrhage from mucous membrane of the mouth and
gastrointestinal tract, anemia, pains in the joints can be related to the
association of ascorbic acid and normal connective tissue metabolism16.
A striking pathological change resulting from ascorbic acid deficiency is the
weakening of the endothelial wall of the capillaries due to a reduction in the
amount of intercellular substance. Therefore, a clinical manifestation of
scurvy hemorrhage from mucous membrane of the mouth and gastrointestinal tract,
anemia, pains in the joints can be related to the association of ascorbic acid
and normal connective tissue metabolism.
It was proved that carotenoids have a
positive role on the epithelisation process and
influence the cell cycle progression of the fibroblasts17. Carotenoids act as photoprotective
agents and may reduce the risk of sunburns, photo-allergy and even some types
of skin cancer18. It was proved that carotenoids
have a positive role on the epithelisation process
and influence the cell cycle progression of the fibroblasts. Carotenoids act as photoprotective
agents and may reduce the risk of sunburns, photo-allergy and even some types
of skin cancer. Mimosa pudica is a strong source of carotenoids and it can be a promising plant for use in pharmacological
products designed for antioxidant activity.
So far as plant phenolics constitute one of
the major groups of compounds acting as primary antioxidants or free radical
terminators. The phenols contain hydroxyls that are responsible for the radical
scavenging effect mainly due to redox properties19.
The high phenolic content in Mimosa pudica can explain its high free radical scavenging
activity.
This study reveals that tested plant material have significant
antioxidant activity and free radical scavenging activity. The result of the
present study suggests that selected plants can be used as a source of
antioxidants for pharmacological preparations which is very well evidenced by
the present work.
Conclusion:
Based on the results of the present study, we conclude that the plant
extract possesses antioxidant potential. However, further studies are necessary
to examine underlying mechanisms of antioxidant effect to isolate the active
compound(s) responsible for these pharmacological activities.
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Received on 23.04.2012
Modified on 28.05.2012
Accepted on 30.05.2012
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reserved
Research J. Pharmacology and
Pharmacodynamics. 4(4): July
–August, 2012, 202-205