A comparative study of antioxidant potential of commonly used antidiabetic plants in Bangladesh
Abstract
Various literatures recorded approximately 60 medicinal plants in Bangladesh that have antidiabetic properties. Of these medicinal plants, only 14–16 are found in traditional herbal markets and they are being randomly used to treat diabetes. Since diabetes mellitus increases reactive free radicals along with various complications in the body, antidiabetic plants that can potentially neutralize free radicals, may be of central interest to manage the disease. Present study compares functional bioactive components such as total phenolics, flavonoids, anthocyanins contents and antioxidant potential of methanol extracts of antidiabetic medicinal plants that are common in traditional herbal markets. Among the 14 extracts, Syzygium cumini was very rich in total polyphenol content (294 mg gallic acid equivalent, GAE/g) followed by Swertia chirata (183 mg GAE/g) and Ficus racemosa (bark) (154 mg GAE/g). These three extracts also had elevated amount of flavonoids and anthocyanins. S. cumini showed very high DPPH and NO free radical scavenging activities with IC50 of 6.25 and 48.61 μg/mL respectively followed by S. chirata and F. racemosa (bark). S. cumini also showed very high reducing power and total antioxidant capacity followed by S. chirata and F. racemosa (bark). In addition, the study revealed strong correlation between phenolics and reducing power (r = 0.94). Hence, among the 14 extracts, S. cumini, S. chirata and F. racemosa (bark) are potential sources of antioxidant agents. Therefore, these three medicinal plants have diverse beneficial effects on physiological health and they might be the choice of plants to treat diabetes.
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RESEARCH ARTICLE
A comparative study of antioxidant potential of commonly
used antidiabetic plants in Bangladesh
M. H. Basar &S. J. Hossain &S. K. Sadhu &M. H. Rahman
Received: 3 June 2012 /Accepted: 2 January 2013 / Published online: 17 January 2013
#Institute of Oriental Medicine, Kyung Hee University 2013
Abstract Various literatures recorded approximately 60
medicinal plants in Bangladesh that have antidiabetic prop-
erties. Of these medicinal plants, only 14–16 are found in
traditional herbal markets and they are being randomly used
to treat diabetes. Since diabetes mellitus increases reactive
free radicals along with various complications in the body,
antidiabetic plants that can potentially neutralize free radi-
cals, may be of central interest to manage the disease.
Present study compares functional bioactive components
such as total phenolics, flavonoids, anthocyanins contents
and antioxidant potential of methanol extracts of antidia-
betic medicinal plants that are common in traditional herbal
markets. Among the 14 extracts, Syzygium cumini was very
rich in total polyphenol content (294 mg gallic acid equiv-
alent, GAE/g) followed by Swertia chirata (183 mg GAE/g)
and Ficus racemosa (bark) (154 mg GAE/g). These three
extracts also had elevated amount of flavonoids and antho-
cyanins. S. cumini showed very high DPPH and NO free
radical scavenging activities with IC
50
of 6.25 and
48.61 μg/mL respectively followed by S. chirata and F.
racemosa (bark). S. cumini also showed very high reducing
power and total antioxidant capacity followed by S. chirata
and F. racemosa (bark). In addition, the study revealed
strong correlation between phenolics and reducing power
(r=0.94). Hence, among the 14 extracts, S. cumini,S. chir-
ata and F. racemosa (bark) are potential sources of antiox-
idant agents. Therefore, these three medicinal plants have
diverse beneficial effects on physiological health and they
might be the choice of plants to treat diabetes.
Keywords Antidiabetic .Antioxidant .Flavonoids .Herbs .
Medicinal plants .Polyphenols
Introduction
Polyphenols, flavonoids, anthocyanins are bioactive compo-
nents, which play a vital role in maintaining human health.
Most of them have been reported to exhibit antioxidant
(Trao et al. 1994; Sawa et al. 1999; Kahkonen et al. 1999;
Okawa et al. 2001), anti-hyperglycemic (Hossain et al.
2002; Hanamura et al. 2006; Hossain et al. 2007), anti-
amylase and anti-glucosidase (Kim et al. 2000; Matsui et
al. 2001; Iwai et al. 2006; He et al. 2006); enhance activity
and/or secretion of insulin or act insulin-like (Hyon and Kim
2001; Anderson et al. 2004) and thereby, inhibit the devel-
opment of diabetes (Zunino et al. 2007). Free radicals have
been implicated in the pathophysiology of various diseases
including diabetes, and oxidative stress may be a common
pathway linking diverse mechanisms for diabetes complica-
tions such as vascular dysfunctions, nephropathy, neuropa-
thy and retinopathy (Jones et al. 1988;Baynes1991).
Furthermore, diabetes mellitus results in a reduction of
endogenous antioxidants and an increase in oxidative stress
in the human body. Reportedly, antioxidants have been
shown to reduce the risk of diabetes onset, improve glucose
disposal and improve some of the associated complications.
M. H. Basar :S. J. Hossain (*)
Biotechnology and Genetic Engineering Discipline, Khulna
University, Khulna 9208, Bangladesh
e-mail: sjhossain_ku@yahoo.com
S. K. Sadhu
Pharmacy Discipline, Khulna University, Khulna 9208,
Bangladesh
M. H. Rahman
Department of Microbiology, Jahangirnagar University, Savar
1342, Bangladesh
Orient Pharm Exp Med (2013) 13:21–28
DOI 10.1007/s13596-013-0102-x
Therefore, antidiabetic medicinal plants with high antioxi-
dant potential could be used effectively to manage diabetes,
especially in developing countries. Many plant extracts have
been shown potential antioxidant activity and they are could
be the potential source of antidiabetic agents (Pokorny
1991; Hossain et al. 2008,2009a,b,c; Mubassara et al.
2011).
Medicinal plants constitute an important natural wealth of
Bangladesh and there are approximately 1,000 plant species
possess diverse medicinal properties (Miah 1990). These me-
dicinal plants play a vital role in providing primary health care
services to rural people. Ethno-botanical studies (Ghani 2003;
Uddin 2006) reported that more than 60 medicinal plants are
used traditionally to treat diabetes in Bangladesh. Our survey
on herbal market status showed that only 14–16 antidiabetic
medicinal plants are available and people randomly using
these plants to treat diabetes since they don’t know which
one is the most beneficial to physiological health. No com-
parative study is available in the literature providing compar-
ison of the antioxidant components such as polyphenols,
flavonoids and anthocyanins contents as well as antioxidant
activity of these antidiabetic medicinal plants. However, these
14–16 medicinal plants are predominantly used by traditional
herbal practitioners in Bangladesh and also in Ayurveda,
Unani and Herbal systems of medicine to treat diabetes.
Various reports showed their hypoglycaemic or antidiabetic
effect in normal and drug-induced diabetic animals such as
Achyranthes aspera (Akhtar and Iqbal 1991), Adhatoda zey-
lanica (Ilango et al. 2009), Alpinia nigra (Ghani 2003),
Asparagus racemosus (Hannan et al. 2007), Bacopa monniera
(Ghani 2003), Coccinia indica (Venkateswaran and Pari
2002), Ficus racemosa (Rao et al. 2002), Gymnema sylvestre
(Leach 2007), Momordica chinensis (Krawinkel and Keding
2006), Swertia chirata (Grover et al. 2002), Swietenia maha-
goni (Panda et al. 2010), Syzygium cumini (Prince et al. 2004)
and Trigonella foenum-graecum (Grover et al. 2002).
Reportedly, they are also used to treat asthma, bronchitis,
cough, dyspepsia, epilepsy, hemorrhoids, inflammation, jaun-
dice, leprosy, rheumatism and/or ulcer etc. diseases (Ghani
2003;Uddin2006). These antidiabetic medicinal plants
are rich in alkaloids, essential oils, flavonoids, glyco-
sides, phenolic compounds, saponins, sterols, tannins
etc. (Ghani 2003). This report compares antioxidant
potential of commonly used antidiabetic plants in
Bangladesh.
Materials and methods
Materials
Chemicals Ascorbic acid, (+)-Catechin, Folin-Ciocalteu’s
phenol reagent and Gallic acid were purchased from
Sigma-Aldrich Co (St. Louis, MO). DPPH was purchased
from Wako Pure Chemical Industry, Ltd., Osaka, Japan. All
of these chemicals and reagents were of analytical grade.
Sample collection Depending on our market survey results
and various literature, 14 commonly used antidiabetic me-
dicinal plant samples (fruits, leaves, roots, seeds and/or
stems) namely Achyranthes aspera (leaf), Adhatoda zeylan-
ica (leaf), Alpinia nigra (rhizome), Asparagus racemosus
(root), Bacopa monniera (leaf), Coccinia indica (leaf),
Ficus racemosa (bark), Ficus racemosa (fruit), Gymnema
sylvestre (leaf), Momordica chinensis (fruit), Swertia chir-
ata (whole plant), Swietenia mahagoni (seed), Syzygium
cumini (seed) and Trigonella foenum-graecum (seed), were
collected and cut into small pieces and shed-dried. The dried
parts were ground into powder with the help of a grinder.
The powders were stored separately in an air tight container
and kept in a cool, dark, and dry place.
Methods
Extraction The powder of each type of medicinal plant was
placed separately in a clean, flat-bottomed glass container
and soaked with methanol. Each container was sealed and
kept for a period of 07 days with regular shaking and stirring
of the contents followed by their filtration and evaporation.
The % yield of the final methanol extracts for A. aspera
(leaf), A. zeylanica (leaf), A. nigra (rhizome), A. racemosus
(root), B. monniera (leaf), C. indica (leaf), F. racemosa
(bark), F. racemosa (fruit), G. sylvestre (leaf), M. chinensis
(fruit), S. chirata (whole plant), S. mahagoni (seed), S.
cumini (seed), and T. foenum-graecum (seed) were found
to be 3.45, 7.52, 4.36, 20.00, 6.00, 3.24, 8.52, 6.00, 4.17,
5.84, 7.65, 15.56, 9.36 and 8.08 % of dry weight of the
powder respectively. Ten milligram (10 mg) of each extract
was dissolved in 1 mL of methanol to prepare stock-
concentration for experiments.
Determination of total phenolics (TPH), flavonoids (TF),
and anthocyanins The total concentration of phenolics
(TPH) in the extracts was determined according to the
Folin-Ciocalteu method (Ough and Amerine 1988)with
gallic acid (GA) as the standard and expressed (mg) as gallic
acid equivalents (GAE)/g of extract.
Total flavonoids content was determined by using a col-
orimetric method according to the Zhishen et al. (1999).
Briefly, test tube containing 50 μg extract or different con-
centrations of (+)-catechin standard solution (20–80 μg/mL)
mixed with 75 μL of 5 % (w/v) NaNO
2
solution. After
6 min, 150 μl of a 10 % (w/v) AlCl
3
.6H
2
O solution was
added and the mixture was allowed to stand for a further
5 min before 0.5 mL of 1 M NaOH was added. The mixture
was brought to 2.5 mL with distilled water and mixed well.
22 M.H. Basar et al.
The absorbance was measured immediately at 510 nm using
a spectrophotometer. The results were expressed as the
mean±SD mg of (+)-catechin equivalents (CE) per gram
of extract.
The anthocyanins content of the plant extract was deter-
mined according to the modified method of Padmavati et al.
(1997). Four mL of acidifed methanol (1 % v/v,
HCl/methanol) containing extract stored in dark at 4 °C
for 24 h in screw caped test tube, and then centrifuged at
800 rpm for 15 min. The anthocyanin concentration in the
supernatant was measured spectrophotometrically at 530
and 657 nm. And the absorbance values were indicated as
A
530
and A
657
. The concentration was calculated using the
following equation: anthocyanin concentration μmol g
=
ðÞ¼
A530 0:33 A657
½31:6
=
ðÞvolume mL½weight g½
=
ðÞ.
DPPH radical scavenging activity The reaction mixture
(3 mL), consisting of 0.5 mL of a 0.5 M acetic acid buffer
solution of pH 5.5, 1 mL of 0.2 mM DPPH in ethanol, and
1.5 mL of a 50 % (v/v) ethanol aqueous solution, was
shaken vigorously with the extracts (Blois 1958). After
incubation at room temperature for 30 min, the amount of
DPPH remaining was determined by measuring absorbance
at 517 nm. Mean values were obtained from triplicate
experiments.
NO radical scavenging activity The scavenging effect of
extracts on nitric oxide was measured according to the
slightly modified method of Marcocci et al. (1994). Four
mL of methanolic extract solutions of different concentra-
tions were then added in the test tubes to 1 mL sodium
nitroprusside solution (10 mM), and the test tubes were
incubated at 37 °C for 3 h. The same reaction mixture,
without the extracts but with an equivalent amount of
methanol, served as control. An aliquot (0.5 mL) of the
incubation solution was removed, diluted with 0.5 mL
Griess reagent (1 % sulfanilamide in 5 % H
3
PO
4
and
0.1 % naphthylethylenediamine dihydrochloride) and the
absorbance of the chromophore was immediately read at
570 nm.
Determination of reducing power The reducing power of
the extracts was determined according to the method of
(Oyaizu 1986). Briefly, different concentrations of the
extracts were mixed with 2.5 mL of 0.2 M phosphate buffer,
pH 6.6 and 2.5 mL of 1 % potassioum ferricyanide solution.
After incubation at 50 °C for 20 min, the mixtures were
mixed with 2.5 mL of 10 % trichloroacetic acid followed by
centrifugation at 650 g for 10 min. The supernatant (2.5 mL)
was mixed with 2.5 mL of distilled water and 0.5 mL of
0.1 % ferric chloride. The absorbance of this solution was
measured at 700 nm. Ascorbic acid served as positive
control.
Determination of total antioxidant capacity The assay was
done according to Prieto et al. (1999). The tubes containing
extract and reagent solution (0.6 M sulfuric acid, 28 mM
sodium phosphate and 4 mM ammonium molybdate) were
incubated at 90 °C for 90 min. The antioxidant capacity was
expressed as ascorbic acid equivalent (AAE) and gallic acid
equivalent (GAE).
Statistical analysis Results were expressed as mean ± SD
for a given number of observations (n= 3 or 5). The level of
significance was set at 0.05 by Student’st-test.
Results
Polyphenols, flavonoids and anthocyanins contents
Total phenolic contents (TPH) of 14 methanol extracts of
common antidiabetic plants were measured by the Folin-
Ciocalteu method and the results were shown in Table 1.
The TPH content was expressed as gallic acid equivalent
(GAE) per gram of extract. The TPH content ranged from
294.5 to 17.9 mg GAE/g of extract. Seeds of S. cumini had
highest amount of polyphenols (294.5 mg GAE/g extract)
followed by S. chirata (183.1 mg GAE/g extract), F race-
mosa (bark) (154.2 mg GAE/g extract) and B. monniera
(63.2 mg GAE/g extract). Total flavonoids (TF) content was
expressed as (+)-catechin equivalent (CE). Flavonoid(s)
content in B. monniera,S. chirata and S. cumini was 60,
77.9and31.7mgCE/gextract,respectively(Table1).
Among the extracts, A. aspera,C. indica,F racemosa
(bark), S. chirata and S. cumini had considerable amount
of anthocyanins (Table 1).
Antioxidant activity
Antioxidant potential of 14 methanol extracts of antidiabetic
plants was determined by the tests of DPPH free radical
scavenging, NO scavenging, reducing power and total anti-
oxidant capacity. F. r a c e m o s a (bark), S. chirata and S.
cumini showed very high activity in DPPH & NO free
radical scavenging, reducing power, and total antioxidant
capacity compare to other extracts. The DPPH free radical
scavenging activity of 14 extracts at 100 μg/mL was shown
in Table 1. At this concentration, B. monniera,F. racemosa
(bark), F. racemosa (fruit), S. chirata and S. cumini showed
very high (> 90 %) activity in DPPH scavenging. Figure 1
(a) showed dose-dependent scavenging of DPPH free radi-
cal by these extracts. Extract of S. cumini showed nearly
same result as shown by vitamin C. The IC
50
values for
DPPH free radical scavenging for B. monniera,F. racemosa
(bark), F. racemosa (fruit), S. chirata,S. cumini and vitamin
C were 42.57, 10.28, 25.69, 12.61, 6.25 and 4.3 μg/mL
Antioxidant potential of antidiabetic plants 23
respectively (Table 2). The NO-scavenging effect of the
extracts at 400 μg/mL was shown in Table 1. Among the
extracts, B. monniera,F. racemosa (bark), F. racemosa
(fruit), S. chirata and S. cumini were the most potential to
scavenge NO free radical and their dose-dependent inhibi-
tion of nitrite production was shown in Fig. 1(b) with IC
50
values of 337.98, 161.76, 213.4, 110.55 and 48.61 μg/mL
respectively (Table 2).
Table 1showed the reducing power of the extracts deter-
mined using the potassium ferricyanide reduction method.
At the concentration of 200 μg/mL extract in phosphate
buffer, the reducing activity of F. racemosa (bark), S. chir-
ata and S. cumini was 1.5, 1.5 and 1.7 respectively. Since, F.
racemosa (bark), S. chirata and S. cumini had high content
of polyphenols, they displayed high reducing power and
their dose-dependent increase of reducing power was shown
in Fig. 1(c). Furthermore, total antioxidant capacities, which
were expressed as the ascorbic acid (AAE), and gallic acid
equivalents (GAE) of the extract were shown in Fig. 1(d).
The capacity was highest in S. cumini followed by S.
chirata.
Relationship between total polyphenols content (TPH)
and DPPH, NO, reducing power or total antioxidant capacity
Generally, extracts with a higher phenolic content show
more DPPH radical scavenging activity and vis-à-vis.
When considered TPH content versus DPPH scavenging
activity (%) of all extracts, the correlation coefficient (r)
was 0.71 and that for NO was 0.82 (Table 3). Since reducing
power develops concomitant with antioxidant activity (Duh
et al. 1999), we examined the correlation between TPH
content and the reducing power of all extracts, and obtained
a strong correlation of 0.94 (Table 3). On the other hand, the
results showed a good correlation between TPH content and
total antioxidant capacity (Table 3) of the extracts (r=0.84
for GAE; r=0.87 for AAE).
Discussion
Diabetes is a chronic metabolic disorder characterized by
hyperglycemia resulting from malfunction in insulin secre-
tion and/or insulin action. However, generation of free rad-
icals is one of the major factors in the onset and
development of diabetes. Hyperglycemia increases the pro-
duction of reactive oxygen species (ROS), which are asso-
ciated with diabetes related complications in human body.
Thus, effective control of blood glucose and ROS with
traditional antidiabetic medicinal plants that possess sub-
stantial quantity of antioxidant components could play a
key role for preventing or reversing diabetic complications.
Therefore, it is essential to explore potentiality of traditional
antidiabetic medicinal plants to develop hypoglycemic
agents coupled with antioxidant activity. Polyphenols, fla-
vonoids, and anthocyanins are bioactive components of
plants and reportedly, they show various beneficial
health promoting activities such as antioxidant, anti-
cardiovascular disorders, antidiabetic, antiallergy, anti-
inflammation, antimicrobial, anticancer, antiaging etc.
Table 1 Phenolics, flavonoids, anthocyanins contents, DPPH and NO radical scavenging activities & reducing power of the methanol extracts of
antidiabetic plants
Sample name Polyphenols
mg GAE/g extract
Flavonoids
mg CE/g extract
Anthocyanins
μmol/g extract
% DPPH scavenging
at 100 μg/mL
%NO
scavenging
at 400 μg/mL
Reducing
power (O.D.)
at 200 μg/mL
A. aspera 37.1± 0.8 7.6± 0.2 4.7 ± 0.04 39± 0.8 Nil 0.12 ±0.02
A. nigra 53.1± 1.2 1.2 ± 0.3
*
1.1± 0.08 36.7 ± 2.3 Nil 0.12± 0.01
A. racemosus 17.9 ± 0.4 6.11± 0.2 0.1 ± 0.04
*
4.5±0.9 Nil 0.06±0.06
*
A. zeylanica 35.2± 0.8 9.8± 0.1 0.5 ± 0.17 22± 0.9 1.8±0.8
*
0.12± 0.01
B. monniera 63.2±1.4 60± 0.9 0.5± 0.01 93.6±0.2 57.4± 0.9 0.46±0.05
C. indica 25.3± 0.8 2.3± 0.2 1.2 ± 0.2 8.3±1 1.4± 0.7
*
0.09± 0.01
F. racemosa (bark) 154.2±5 8.5±0.3 1.8±0.17 92.1 ±0.2 81.7± 0.1 1.50 ± 0.01
F. racemosa (fruit) 53.9± 1.7 4.6 ± 0.2 0.4± 0.09 92.5 ± 0.1 68.6 ±0.6 0.56±0.06
G. sylvestre 59.5± 1.4 25.2±2.1 0.3 ± 0.03 51±0.5 Nil 0.24 ± 0.03
M. chinensis 27.8±0.6 1.9 ± 0.2 0.4± 0.00 11± 0.8 13.3 ±0.7 0.07±0.01
*
S. chirata 183.1± 4.2 77.9± 3.5 1 ± 0.07 92± 0.3 82.4±0.1 1.50± 0.04
S. mahagoni 33.5 ± 1.1 1±0.2
*
0.2± 0.02
*
20.2± 3.4 Nil 0.31± 0.05
S. cumini 294.5± 9.6 31.7± 3.2 0.8±0.02 92.7±0.8 92.7± 0.1 1.70 ± 0.06
T. foenumgraecum 26.9± 0.6 1 ± 0.2
*
0.3± 0.01 1.6 ± 1.1
*
Nil 0.07± 0.01
*
GAE Gallic Acid Equivalent; CE (+)-Catechin Equivalent; * = Non-significant
24 M.H. Basar et al.
This report describes amount of polyphenols, flavonoids
andanthocyaninsincommonlyusedantidiabeticplants
in Bangladesh (Table 1). Among the antidiabetic plants
used in this study, F. racemosa (bark), S. chirata and S.
cumini were very rich in total polyphenol, flavonoids
and anthocyanins contents. In previous studies, we
reported polyphenols content of various edible fruits
(Hossain et al. 2008,2012;Tsujiyamaetal.2012)and
plants (Hossain et al. 2009b), & mangroves (Hossain et
al. 2009a; Mubassara et al. 2011). Polyphenols content
(294 mg GAE/g extract) of the seeds of S. cumini was
near to that of Phyllanthus emblica (Emblic Myrobalan,
339 mg GAE/g extract) (Hossain et al. 2008)andseeds
of Sonneratia apetala (300.1 mg GAE/g extract)
(Hossain et al. 2012). However, the extraction of phe-
nolic compounds is commonly achieved with methanol
or aqueous methanol (Antolovich et al. 2000).
Reportedly, polyphenols, flavonoids, anthocyanins also
inhibit key digestive enzymes, activate and/or increase
insulin secretion and thus antidiabetic. Reported antidia-
betic activity of S. cumini (Prince et al. 2004), S.
chirata (Grover et al. 2002)andF. racemosa (bark)
0
20
40
60
80
100
1 10 100
(%) DPPH free radical scavenging activity
Concentration (µg/mL)
AA
BN
FR (b)
FR (f)
SCh
SCu
0
20
40
60
80
100
1 10 100 1000
(%) NO scavenging activity
Concentration (µg/mL)
GA
BN
FR (b)
FR (f)
SCh
SCu
(a) (b)
(c) (d)
0
0.5
1
1.5
2
2.5
3
1 10 100 1000
Reducing power (O.D.) at 700 nm
Concentration (µg/mL)
AA
BN
FR (b)
FR (f)
SCh
SCu
0
50
100
150
200
250
GAE and AAE/g extract
Name of extract
GAE
AAE
Fig. 1 Antioxidant activity of commonly used antidiabetic plants in
Bangladesh. Dose-dependency of a: the DPPH and b: NO free radical
scavenging activities of methanol extracts (AA: ascorbic acid, GA:
gallic acid, positive control); c: Dose-dependent increase of reducing
power of the extracts (AA: ascorbic acid, positive control); d: Com-
parison of total antioxidant capacity of the extracts (AAE: ascorbic acid
equivalent, GAE: gallic acid equivalent). Data are presented as mean ±
SD (bar), n=3–5. AAs = A. aspera,AN=A. nigra,AR=A. race-
mosus,AZ=A. zeylanica,BN=B. monniera,CI=C. indica, FR (b) =
F. racemosa (bark), FR (f) = F. racemosa (fruit), GS = G. sylvestre,MC
=M. chinensis, SCh = S. chirata, SCu = S. cumini,SM=S. mahagoni
and TF = T. foenumgraecum
Antioxidant potential of antidiabetic plants 25
(Ahmed and Urooj 2009; Veerapur et al. 2011) probably
come, at least a part, from their high content of poly-
phenols, flavonoids as well as antioxidant agents.
Among the traditionally used antidiabetic plants, F. race-
mosa (bark), S. chirata and S. cumini showed high antiox-
idant activity (Fig. 1). The lowest IC
50
(6.25 μg/mL) was for
S. cumini (Table 2), which means that among all the anti-
diabetic plants tested, it had strongest DPPH radical scav-
enging activity. The IC
50
values for the fruits namely
Dillenia indica,Phyllanthus acidus,P. emblica,Spondias
dulcis,S. cumini, and Sonneratia apetala were 57, 93, 2.1,
81, 8.6, and 4.3 μg/mL respectively (Hossain et al. 2008,
2012). It was also reported that leaves and bark of man-
groves scavenge DPPH radical (Masuda et al. 1999;
Hossain et al. 2009a; Mubassara et al. 2011). It has been
found that cysteine, glutathione, ascorbic acid, tocopherol,
polyhydroxy aromatic compounds, and aromatic amines
reduce and decolorize DPPH by their hydrogen donating
ability (Blois 1958). Therefore, these three plants potentially
possess hydrogen donating capabilities to act as antioxidant.
However, nitric oxide (NO) is synthesized in many different
mammalian cells types such as endothelial cells, vascular
smooth muscular cells, neurons, platelets, macrophages and
neutrophils. NO or some related reactive nitrogen species
act as neurotransmitter, prevent platelet aggregation and
they are one of the defense molecules of immune system
against tumor cells, parasites and bacteria. Though, large
amounts of NO, peroxynitrite and other reactive nitrogen
oxide species are considered to be potentially cytotoxic and
capable of injuring the surrounding cells (Peksel et al.
2010). F. racemosa (bark), S. chirata and S. cumini poten-
tially scavenged NO free radicals. Similar reports were
found for lotus seed extract (Yen et al. 2006) and leaves of
Pistacia atlantica (Peksel et al. 2010). Reportedly, the ac-
tivity of antioxidants is concomitant with the development
of reducing power (Duh et al. 1999). Extracts with high
content of polyphenols showed high reducing power (r=
0.94). Therefore S. cumini showed highest reducing power
followed by S. chirata and F. racemosa (bark). In a previous
study on Egyptian plants, we reported that correlation be-
tween total polyphenol and DPPH radical scavenging activ-
ity, reducing power or total antioxidant capacity was 0.73,
0.65 or 0.79 respectively (Hossain et al. 2009b). For
Bangladeshi fruits, correlation between total polyphenol
and DPPH radical scavenging activity or reducing power
was 0.54 or 0.97 (Hossain et al. 2008).
Reportedly, the activities of the endogenous antioxidant
enzymes catalase, superoxide dismutase and glutathione
peroxidase are reduced in diabetic patients. Due to the
reduced activity of antioxidant enzymes, pancreatic islets
and insulinoma cells are vulnerable to serious damage by
cytotoxic NO and/or oxidative stress. However, high levels
of free radicals cause damage to cellular proteins, mem-
brane lipids and nucleic acids. Hence, lipid peroxidation
is one of the characteristics features of chronic diabetes.
Natural antioxidants boost up the content of plasma
antioxidants, which in turn, reinforce the endogenous
antioxidant defenses from ROS. Medicinal plants con-
tain alkaloids, anthocyanins, carotenoids, flavonoids,
glycosides, polyphenols, terpenoids etc. that are fre-
quently implicated as having antidiabetic, antioxidant,
antiallergic, antihyperlipidemic etc. effects. In this study,
extracts with the high content of polyphenols and fla-
vonoids, displayed very high antioxidant activity.
Among these 14 extracts, F. racemosa (bark), S. chirata
and S. cumini are most potential in promoting physio-
logical health since they consist of high polyphenols
and flavonoids as well as antioxidants. Therefore, they
could potentially prevent physiological stresses generat-
ed by free radicals when used in treating diabetes.
Owing to the complexity of the oxidation-antioxidation
process, multi-method approach is necessary to assess
antioxidative activity. However, attention should be paid
to potential cytotoxic effects when they are used for the
preparation of dietary supplements, and in the enrich-
ment of beverages or foods, since some polyphenols
perturb the membrane structure (Hossain et al. 2002;
Aoshima et al. 2005).
Table 3 Correlation coefficient (r) between antioxidant activities and
total polyphenols
Activities Correlation coefficient (r)
DPPH radical scavenging activity 0.71
NO radical scavenging activity 0.82
Reducing power (O.D.) 0.94
Total antioxidant capacity 0.84
#
or 0.87
*
When considered for GAE
#
or AAE
*
Table 2 IC
50
values of methanol extracts of antidiabetic plants poten-
tial as antioxidant
Sample name Inhibitory concentration (IC
50
,μg/mL)
DPPH NO
AA 4.29 ND
GA ND 20.76
B. monniera 42.57 337.98
F. racemosa (bark) 10.28 161.76
F. racemosa (fruit) 25.69 213.4
S. chirata 12.61 110.55
S. cumini 6.25 48.61
AA Ascorbic acid; GA Gallic acid; ND Not done
26 M.H. Basar et al.
Acknowledgments This research work was supported by the grant
from the Ministry of Science and Technology, Govt. of Bangladesh in
2009, which is gratefully acknowledged.
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- CitationsCitations9
- ReferencesReferences66
- The chloroform extract of leaves of Acacia salicina was found to possess significant antimutagenic and antioxidant activities against superoxide radicals. The antioxidant property of medicinal plants is associated with the presence of several phytoconstituents such as flavonoids (Hamouz et al., 2011), anthocyanins and phenolics (Basar et al., 2013). A flavonol 3-O-glycosides (Isorhamnetin 3-O-neohesperidoside) isolated from A. salicina leaves protected the cells against oxidative stress by inhibiting xanthine oxidase and superoxide anion scavengers (Bouhlel et al., 2010 ).
[Show abstract] [Hide abstract] ABSTRACT: The present study assessed the comparative antioxidant potential of the ethanol extract (EE) of leaves of four Acacia species (A. salicina, AS; A. laeta, AL; A. hamulosa AH; and A. tortilis, AT) grown in Saudi Arabia, including RP-HPTLC quantification of antioxidant biomarker rutin. In vitro DPPH radical scavenging and β-carotene-linoleic acid bleaching assays showed the promising antioxidant activities of Acacia extracts: ASEE (IC50: 60.39 and 324.65 μg/ml) >ALEE (IC50: 217.06 and 423.36 μg/ml) >ATEE (IC50: 250.13 and 747.50 μg/ml) >AHEE (IC50: 255.83 and 417.28 μg/ml). This was comparable to rutin tested at 500μg/ml. Further, a RP- HPTLC densitometric method was developed (acetonitrile: water; 6:4; v/v) using glass-backed RP-18 silica gel F254 plate, and scanned at UVmax 254 nm. The method was validated as per the ICH guidelines. Analysis of the validated RP-HPTLC displayed an intense peak (Rf = 0.65±0.004) of rutin that was estimated (μg/mg dry weight) to be highest in ASEE (10.42), followed by ALEE (2.67), AHEE (1.36) and ATEE (0.31). Taken together, presence of rutin strongly supported the high antioxidant property of the tested Acacia species, especially A. salicina. The developed RP-HPTLC method therefore, affirms its application in the quality control of commercialized herbal drugs or formulation containing rutin.- Correlation of TAC was with flavonoids is in accordance with many previous studies [11, 27] as similar to the previous reports to have correlation between total antioxidant capacity saponins [30][31][32]. This correlation between total phenolics and TAC and DPPH radical scavenging activity is also in accordance with the results of some researches [29, 33]. Furthermore, in our present study positive correlation between TAC and anthocyanins content was observed which is in line with other previous reports.
[Show abstract] [Hide abstract] ABSTRACT: Metabolomic profiling of different parts (shoot, fruits and seeds) of Opophytum forsskalii was evaluated by spectrophotometric data analysis combined with multivariate data analysis including principal component analysis (PCA) and hierarchal clustering analysis (HCA). Score scatter plot of principal component analysis discriminated different parts into three separate groups. Furthermore, score loading plot of PCA showed that shoots and fruits of O. forsskalii are discriminated from seeds by higher content of important secondary metabolites i.e. saponins, flavonoids, flavonols, phenolics, tannins and anthocyanins, however seeds had a higher content of proteins. A comparison among shoots and fruits proved higher contents of saponins, anthocyanins, flavonoids and flavonols in shoots, while fruits had higher content of phenolics, tannins and total antioxidant capacity (TAC). Furthermore , the DPPH radical scavenging activity of different fractions (methanol, hexane and butanol) of each part was assessed. Overall, butanol fraction of each part was more potent than methanol fraction, among these seeds had the highest radical scavenging activity (23.7 %) than shoot and fruits (15.8 and 14.5 %), respectively. Moreover, the methanol fraction of shoot had the highest radical scavenging activity at 400 µg/mL followed by seeds and fruits (14.3 %, 9.6 % and 1.9 %), respectively.- Correlation of TAC was with flavonoids is in accordance with many previous studies [11, 27] as similar to the previous reports to have correlation between total antioxidant capacity saponins [30][31][32]. This correlation between total phenolics and TAC and DPPH radical scavenging activity is also in accordance with the results of some researches [29, 33]. Furthermore, in our present study positive correlation between TAC and anthocyanins content was observed which is in line with other previous reports.
[Show abstract] [Hide abstract] ABSTRACT: Metabolomic profiling of different parts (shoot, fruits and seeds) of Opophytum forsskalii was evaluated by spectrophotometric data analysis combined with multivariate data analysis including principal component analysis (PCA) and hierarchal clustering analysis (HCA). Score scatter plot of principal component analysis discriminated different parts into three separate groups. Furthermore, score loading plot of PCA showed that shoots and fruits of O. forsskalii are discriminated from seeds by higher content of important secondary metabolites i.e. saponins, flavonoids, flavonols, phenolics, tannins and anthocyanins, however seeds had a higher content of proteins. A comparison among shoots and fruits proved higher contents of saponins, anthocyanins, flavonoids and flavonols in shoots, while fruits had higher content of phenolics, tannins and total antioxidant capacity (TAC). Furthermore , the DPPH radical scavenging activity of different fractions (methanol, hexane and butanol) of each part was assessed. Overall, butanol fraction of each part was more potent than methanol fraction, among these seeds had the highest radical scavenging activity (23.7 %) than shoot and fruits (15.8 and 14.5 %), respectively. Moreover, the methanol fraction of shoot had the highest radical scavenging activity at 400 µg/mL followed by seeds and fruits (14.3 %, 9.6 % and 1.9 %), respectively.- In this study, was found the extracts which have the highest secondary metabolites content such as those of A. sieberi, P. incisa and R. eppaposum which also showed the highest TAC and DPPH radical scavenging activity. This finding is in agreement with previous reports such as Basar et al. (2013) and Abdel-Farid et al. (2014), which showed that there is a significant positive correlation between various secondary metabolites content such as phenolics, flavonoids, saponins and anthocyanins with the total antioxidant capacity. AbdelFarid et al. (2014) reported TAC was found to be positively correlated with saponins and flavonoids content.
[Show abstract] [Hide abstract] ABSTRACT: The present study was conducted to evaluate the metabolic profiling, antioxidant capacity and anticancer activities of some common widely grown plants of the family Compositae. The total phenolics, flavonoids, anthocyanins, saponins, total antioxidant capacity (TAC) and 2,2-diphenyl-1picrylhydrazyl (DPPH) assays were determined in the selected plant extracts. In vitro anticancer activity was also assessed using human hepatocellular carcinoma (HepG-2) and breast adenocarcinoma (MCF-7) cell lines. The plant species revealed different metabolomic profiling. Artemisia showed the highest contents of the detected secondary metabolites compared to other plant extracts. Pulcaria crispa showed the highest inhibition concentration 50% (IC50) among the screened extracts against HepG-2 (8.9 μg/ml) and MCF-7 (8.14 μg/ml). The high performance liquid chromatography analysis (HPLC) of P. crispa extract revealed the presence of high content of three phenolic compounds, benzoic, chlorogenic acid and vanillic acid, along with two polyphenolic compounds, hesperidin and quercetrin. In summary, among the screened extracts, P. crispa has the most potent anti-tumor activity in vitro against HepG-2 and MCF-7 cell lines.- Similarly, antioxidants play vital role in the body and protect from many health problems including diabetes by reducing oxidative damages. Again, the use of synthetic antioxidants has been reported to be unsafe to health [4, 5]. To avoid these harmful effects, efforts have been taken throughout the world to develop safe drugs from plants for various ailments including diabetes.
[Show abstract] [Hide abstract] ABSTRACT: Objective: To investigate chemical compositions, α-amylase inhibitory and antioxidant capacity of the essential oils from the unripe fruit pulp and leaves of a traditional medicinal plant Syzygium cumini. Methods: The essential oils of unripe fruit pulp and leaves of S. cumini were obtained by hydro-distillation and analyzed by GC-FID and GC-MS. In vitro α-amylase inhibitory and DPPH radical scavenging assay were carried out to study the antidiabetic and antioxidant activities of the essential oils. Results: Thirty four components representing 99.3% of the unripe fruit pulp oil and 66 components representing 95.3% of the leaf essential oil were identified. α-cadinol (25.8%) and α-pinene (21.5%) were the major component of unripe fruit pulp and leaf oil respectively. The leaf oil showed better α-amylase inhibitory activity than unripe fruit pulp oil, while unripe fruit pulp oil exhibited higher antioxidant activity. Conclusions: The mild α-amylase inhibitory and antioxidant activities of both oils are ideal for designing functional foods and can be used in food applications which aim to control diabetes. © 2015, International Journal of Pharmacy and Pharmaceutical Sciences. All rights reserved.- The highest content of secondary metabolites detected in both A. nilotica and A. seyal such as saponins, phenolics, anthocyanins and flavonoids may be the reason for increasing the potentialities of these extracts as antioxidants. The antioxidant activity of many plant extracts is attributed to the presence of saponins (Vu et al., 2013), flavonoids (Hamouz et al., 2011), anthocyanins (Sutharut and Sudarat, 2012) and phenolics (Basar et al., 2013).
[Show abstract] [Hide abstract] ABSTRACT: Metabolomic profiling of different parts (leaves, flowers and pods) of Acacia species (Acacia nilotica, Acacia seyal and Acacia laeta) was evaluated. The multivariate data analysis such as principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) was used to differentiate the distribution of plant metabolites among different species or different organs of the same species. Acacia nilotica was characterized with high content of saponins and Acacia seyal was characterized with high content of proteins, phenolics, flavonoids and anthocyanins. Acacia laeta had higher content of carbohydrates than A. nilotica and A. seyal. On the basis of these results, total antioxidant capacity, DPPH free radical scavenging activity and reducing power of the methanolic extracts of studied parts were evaluated. Acacia nilotica and Acacia seyal extracts showed less inhibitory concentration 50 (IC50) compared to Acacia laeta extracts which means that these two species have the strongest radical scavenging activity where as A. laeta extracts have the lowest radical scavenging activity. Positive correlation between saponins and flavonoids with total antioxidant capacity and DPPH radical scavenging activity was observed. Based on these results, the potentiality of these plants as antioxidants was discussed.
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