Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)

Abstract

The study has been aimed to evaluate and compare phytochemical content and the antioxidant activity in peel extracts of nine local varieties of banana, i.e. Musa sapientum species. Ethanolic extract of peels of these varieties were sub-jected to in vitro free radical scavenging assays like DPPH, ABTS and lipid peroxidation inhibition assay. Total anti-oxidant capacity assay to confirm the antioxidant potential and phytochemical content such as total phenols, flavonoids were also determined. The results obtained were analyzed statistically by ANOVA and DMRT analysis. The peel ex-tracts of all the nine varieties of banana exhibited significant antioxidant and phytochemical activities with Musa spp. -Blueggoe (Monthan) -AAB and Musa spp. -Rasthali -AAB showing highest free radical scavenging activity and Musa spp. -Karpooravalli -ABB, Musa spp. -Rasthali -AAB, Musa spp. -Ney Poovan (Kadali) -AB and Musa spp. -My-sore (Poovan) -AAB having highest phytochemical content. The study suggests that peel extracts of these banana varie-ties could be useful to combat free radical mediated diseases.

Full text

Food and Nutrition Sciences, 2011, 2, 1128-1133
doi:10.4236/fns.2011.210151 Published Online December 2011 (http://www.SciRP.org/journal/fns)
Copyright © 2011 SciRes. FNS
Antioxidant Potential of Peel Extracts of Banana
Varieties (Musa sapientum)
Ramakrishnan Baskar, Selvaraj Shrisakthi, Babu Sathyapriya, Radhakrishnan Shyampriya,
Radhakrishnan Nithya, Palanisamy Poongodi
Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, India.
Email: bhubaski@rediffmail.com
Received August 28
th
, 2011; revised October 28
th
, 2011; accepted November 6
th
, 2011.
ABSTRACT
The study has been aimed to evaluate and compare phytochemical content and the antioxidant activity in peel extracts
of nine local varieties of banana, i.e. Musa sapientum species. Ethanolic extract of peels of these varieties were sub-
jected to in vitro free radical scavenging assays like DPPH, ABTS and lipid peroxidation inhibition assay. Total anti-
oxidant capacity assay to confirm the antioxidant potential and phytochemical content such as total phenols, flavonoids
were also determined. The results obtained were analyzed statistically by ANOVA and DMRT analysis. The peel ex-
tracts of all the nine varieties of banana exhibited significant antioxidant and phytochemical activities with Musa spp. -
Blueggoe (Monthan) - AAB and Musa spp. - Rasthali - AAB showing highest free radical scavenging activity and Musa
spp. - Karpooravalli - ABB, Musa spp. - Rasthali - AAB, Musa spp. - Ney Poovan (Kadali) - AB and Musa spp. - My-
sore (Poovan) - AAB having highest phytochemical content. The study suggests that peel extracts of these banana varie-
ties could be useful to combat free radical mediated diseases.
Keywords: Antioxidants, Banana Peel, Lipid Peroxidation, Oxygen Radicals, Phytochemicals
1. Introduction
Free radicals are continuously produced in our body either
naturally or on exposure to environmental stress as well as
other factors and can be implicated in many diseases like
cancer, atherosclerosis, arthritis, Parkinson’s disease,
Alzheimer’s disease, aging and other age related problems
[1]. Mammalian cells possess elaborate defense mecha-
nisms for radical detoxification. Antioxidants are agents,
which scavenge the free radicals and prevent the damage
caused by them. Inspite of these in-built defense mecha-
nisms, it seems more meaningful to utilize extra antioxi-
dants available in diets, especially from fruits, vegetables
and whole grains [2]. Due to their minimal side effects,
there are growing interests in using natural products for
preventive and therapeutic medicine [3].
Musa spp., comprising banana and plantain are among
the world’s leading fruit crops and in terms of economical
value, it is the number five agricultural crop in world trade.
The edible fruit cultivars are a man-made complex based
on two wild diploid species originating from South-East
Asia: Musa acuminata Colla (AA), which is highly
polymorphous, with spindly plants that grow in clumps,
and Musa balbisiana Colla (BB), a homogeneous hardy
plant with a massive pseudo-trunk. There are diploid,
triploid or tetraploid genome groups. The main genome
groups are AA, AB, AAA, AAB and ABB [4].
The peels of a variety of fruits have gained attention as
a natural source of antioxidants and phytochemical con-
tent which are rich in compounds with free radical scav-
enging activity. Banana and Plantain peels are major ag-
ricultural wastes which have been used as medicine,
animal feeds, blacking of leathers, soap making, fillers in
rubber and so on [5]. Fruit wastes are highly perishable
and seasonal and are a problem to the processing indus-
tries and pollution monitoring agencies. This problem can
be recovered by utilizing its high value compounds, in-
cluding the dietary fibre fraction that has a great potential
in the preparation of functional foods [6]. Banana peel, an
underutilized source of phenolic compounds is considered
as a good source of antioxidants for foods and functional
foods against cancer and heart disease [7]. The peel of the
fruit contains various antioxidant compounds such as
gallocatechin [7] and dopamine [6].
Recent trends focus on the isolation, characterization
and utilization of natural antioxidants, especially growing
interest in polyphenols as potential disease preventing

Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)
1129
agents. As these compounds are predom
inantly found in
most of fruit tissues, it would be worthwhile investigating
the nature of polyphenols that are present in banana peel, a
potential source of antioxidant and antimicrobial activities.
Hence, the present study has been aimed to evaluate and
compare the phytochemical contents and their in vitro
antioxidant activities in peel extracts of nine local varie-
ties of banana to assess its protective role against free
radical induced cell damage.
2. Materials and Methods
2.1. Materials, Chemicals and Reagents
The banana varieties belonging to Musa balbisiana viz.,
Monthan (Musa spp. - Blueggoe - AAB), Karpooravalli
(Musa spp. - Karpooravalli - ABB) Nendran (Musa spp. -
French Plantain - AAB), Kadali (Musa spp. - Ney Poovan -
AB), and those belonging to Musa acuminata viz., Pach-
ainadan (Musa spp. - Pachanadan - AABS), Poovan
(Musa spp. - Mysore - AAB), Rasthali (Musa spp. - Rast-
hali - AAB), Robusta - Cavendish sub group (Musa spp.
- Robusta - AAB) and Sevvazhai (Musa spp. - Red
banana - AAA) were collected locally from different
farms in the same locality in Coimbatore (Tamil Nadu,
India) and authenticated by Dr. T. S. Balamohan, Pro-
fessor and Head, Faculty of Horticulture, Tamil Nadu
Agricultural University, Coimbatore. A voucher speci-
men of the samples has been deposited in the herbarium
of the department.
1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2-azobis-3-
ethylbenzthiazoline-6-sulphonic acid (ABTS), sodium
nitroprusside, sulphanilamide, naphthyl ethylenediamine
dihydrochloride, 2-deoxyribose, thiobarbituric acid (TBA),
trichloroacetic acid (TCA), sodium dodecyl sulphate
(SDS) and ammonium molybdate were all of analytical
grade.
2.2. Preparation of Peel Extracts
The peel of fresh naturally ripened yellow un-pigmented
bananas were shade-dried for about a week and then
crushed to make a coarse powder. The dried powder (10
g) was weighed and solvent extraction using ethanol was
performed at a 10% concentration. Exhaustive extraction
was carried out in triplicates for about 36 h in a shaker at
37˚C with a gentle shaking. The extracts were then
evaporated at room temperature. The residues obtained
were re-evaporated to remove impurities and stored at
4˚C to carry out radical scavenging assays. The remain-
ing residue was stored in desiccators for further use.
2.3. Free Radical Scavenging Assays
2.3.1. Total Antioxidant Capacity Assay
Aliquots of suitable working solutions (1 - 10 mg/ml) of
the samples were mixed with 1 ml of the reagent solution
(0.6 M sulphuric acid, 28 mM sodium phosphate and 4
mM ammonium molybdate) and incubated at 95˚C for 90
min [8]. The tubes were cooled to room temperature and
the absorbance was measured at 695 nm against a blank.
Ascorbic acid was used as a standard. Total antioxidant
capacity was expressed as equivalents of ascorbic acid
[9].
2.3.2. DPPH Radical-Scavenging Assay
DPPH scavenging activity was measured by the slightly
modified spectrophotometric method of Brand-Williams
et al. [10]. The absorbance of DPPH diluted in methanol
was considered as control. The decrease in absorbance
was measured at 517 nm. The antioxidant capacity to
scavenge the DPPH radical was calculated by the fol-
lowing equation: Scavenging effect (%): [(1-absorbance
of sample/absorbance of control) × 100]. Results were
expressed as Mean ± SD of three experiments made by
triplicate.
2.3.3. ABTS Radical Cation-Scavenging Assay
The assay was performed by a slightly modified protocol
of Re et al. [11]. ABTS solution (7 mM) was reacted
with ammonium persulphate (2.45 mM) solution to pro-
duce a dark coloured solution containing ABTS radical
cations. The initial absorbance was measured at 745 nm.
This stock solution was diluted with methanol to give a
final absorbance value and equilibrated at 30˚C. The de-
crease in absorbance was measured exactly one minute
after mixing the solution, up to six minutes. The final
absorbance was noted. The percentage inhibition was
calculated according to the formula:
% inhibition = [(A
control
– A
sample
)/A
control
] × 100%
2.3.4. Lipid Peroxidation Inhibition Assay
The lipid peroxidation assay was carried out by a modi-
fied procedure of Ohkawa et al. [12]. Different concen-
tration of the sample (1 - 10 mg/ml) in water was added
to 0.5 ml of the 10% goat liver homogenate. Lipid per-
oxidation was initiated by adding 0.05 ml of 0.07 mol/m
3
ferrous sulphate to the reaction mixture. After 30 min,
1.5 ml of 20% acetic acid (pH 3.5), 1.5 ml of 0.8% TBA
(in 1.1% SDS) and 0.05 ml of 20 × 10
–2
TCA was added
to the incubation solution, vortexed and boiled at 100˚C
for 1 h, cooled to room temperature and read the absorb-
ance at 532 nm. The percentage inhibition was then cal-
culated.
% inhibition = [(A
control
– A
sample
)/A
control
] × 100%
2.4. Determination of Phytochemicals
2.4.1. Determination of Total Polyphenol Content
Total phenolic contents were determined according to the
Copyright © 2011 SciRes. FNS

Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)
1130
spectrophotometric methods of Tanner and Brunner [13]
and Kaur and Kapoor [14]. To 0.5 ml of a methanolic
solution of the extracts, 7 ml of distilled water and 0.5 ml
of Folin-Ciocalteau reagent were added and mixed well.
After 3 min, 2 ml of 20% sodium carbonate was added
and mixed well again. Absorbance of the resultant solu-
tion was read at 720 nm, after 1 h in a water bath at 25˚C
[15]. The total polyphenol content was calculated from
the standard calibration curve obtained from catechol.
2.4.2. Determination of Flavonoids
A slightly modified version of the spectrophotometric
method was used to determine the flavonoid contents of
samples [15]. A 0.5 ml aliquot of the sample in aqueous
methanol was diluted with 3 ml of distilled water to
which 0.3 ml of 5% sodium nitrite was added and mixed
well. After 5 min at room temperature, 0.6 ml of 10%
aluminium chloride was added. After 6 min, 2 ml of 1 M
sodium hydroxide was added and the absorbance was
read at 510 nm. Flavonoid contents were then calculated
using a standard calibration curve, prepared from rutin.
2.5. Statistical Analysis
The experimental results were expressed as mean ± SD
of three replicates. The data were subjected to two-way
ANOVA (Analysis of Variance) and significance of dif-
ference between sample means were calculated by DMRT
analysis using IRRISTAT software version 3.1. Differ-
ence in mean values were considered significant when P
< 0.05.
3. Results and Discussion
3.1. Total Antioxidant Activity
The total antioxidant activities of various banana peel
extracts are depicted in Table 1. The values represent the
total antioxidant capacity of banana peel extracts ex-
pressed in terms of equivalents of ascorbic acid. This
assay gives an estimate of the overall antioxidant poten-
tial of the banana peel [16]. In the presence of the ex-
tracts, Mo(VI) is reduced to Mo(V) and forms a green-
coloured phosphomolybdenum V complex, which shows
maximum absorbance at 700 nm. According to the re-
sults, the ethanolic extract of Pachainadan showed higher
activity in the range of 5.85 mM·g
–1
in comparison to
other varieties of banana peel, whereas the ethanolic ex-
tract of Nendran showed least activity. Similar studies by
Gonzalez-Montelongo et al. [17] showed the total anti-
oxidant activity of banana peel extract under different
solvent and incubation conditions.
3.2. DPPH Radical Scavenging Activity
The line chart shown in Figures 1(a)-(b) for DPPH radi-
cal scavenging potential of the ethanolic extracts of
Table 1. Total Antioxidant activity in peels of banana varie-
ties.
Total Antioxidant Activity
Banana Varieties
mM AAE g
–1
Kadali 4.89
d
± 0.33
Karpooravalli 3.49
b
± 0.02
Monthan 4.73
d
± 0.06
Nendran 2.64
a
± 0.06
Poovan 3.59
b
± 0.03
Pachainadan 5.85
e
± 0.11
Rasthali 3.39
b
± 0.09
Robusta 4.79
d
± 0.11
Sevvazhai 4.04
c
± 0.09
Values represent mean ± SD of 3 replicates; Total antioxidant activity was
expressed as mM ascorbic acid equivalents g
–1
peel extract; Mean followed
by a common letter are not significantly different at the 5% level by DMRT.
(a)
(b)
Figure 1. Scavenging activity (%) on DPPH radical by
ethanolic extracts of (a) balbisiana (b) acuminate type of
banana varieties.
Cop
yright © 2011 SciRes. FNS

Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)
1131
balbisiana and acu
minata type of local varieties of ba-
nana peel respectively, elucidating the mean values
across the concentration range, clearly indicates the po-
tential of Mondhan peel extract in scavenging free radi-
cals as high percentage inhibition (98.19%) was noticed
at 10 mg·ml
–1
in comparison to the peels of other varie-
ties from both groups. DPPH radicals react with suitable
reducing agents, during which the electrons become
paired off and the solution loses colour stoichiometrically
depending on the number of electrons taken up [18]. In
the experiment, the solution progressively reduced to a
yellow coloured product, diphenylpicryl hydrazine, with
the addition of the extracts in a concentration-dependent
manner.
3.3. ABTS Radical Scavenging Activity
The line charts 2(a) and 2(b) of Figure 2 indicates the
ABTS radical scavenging potential of the ethanolic ex-
tracts of the various peel extracts of both groups of ba-
nanas at various concentrations.
(a)
(b)
Figure 2. Scavenging activity (%) on ABTS radical by
ethanolic extracts of (a) balbisiana (b) acuminate type of
banana varieties.
From the results, it may be postulated that ethanolic
extract of Rasthali, among all species, inhibit the radical
or scavenge the radical in a concentration dependent
manner with highest percentage inhibition (97.66%) no-
ticed at 10 mg·ml
–1
. Studies by Okonogi et al. [19] de-
termined the scavenging activity of banana peel extract
on ABTS radical.
3.4. Lipid Peroxidation Inhibition Activity
Inhibition of lipid peroxidation by the ethanolic extracts
of various banana peels is represented in Figures
3(a)-(b). Lipid peroxides are unstable and decompose to
form reactive carbonyl compounds responsible for DNA
damage, generation of cancer and age related diseases
[20]. Most abundant among them is malondialdehyde
(MDA), which reacts with thiobarbituric acid (TBA) to
form a pink chromogen [21]. The decrease in the MDA
levels in the presence of increased concentration of each
extract indicates the role of extracts as antioxidants.
TBARS assay was used to determine the anti-lipid per-
(a)
(b)
Figure 3. Scavenging activity (%) on lipid peroxidation by
ethanolic extracts of (a) balbisiana (b) acuminate type of
banana varieties.
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Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)
1132
oxidation properties of the banana peel extracts. The re-
sult values obtained indicate a moderate percentage inhi-
bition with Poovan peel extract exhibiting highest inhibi-
tion among other varieties at 10 mg·ml
–1
.
3.5. Total Phenol and Flavonoid Content
The total phenol and flavonoid content of the different
banana peel extracts is shown in Table 2.
The antioxidant activity of the plant products is asso-
ciated to their bioactive compounds, mainly antioxidant
phenolics, because of their ability to scavenge free radi-
cals [22,23]. Phenols are secondary metabolites in plants
and are known to possess a wide range of therapeutic
uses, such as antioxidant, antimutagenic, anticarcinogenic,
free radical-scavenging activities and also decrease car-
diovascular complications [24]. From the results, it is
inferred that Rasthali extract showed higher phenol con-
tent compared to other varieties, which could be related
to its antioxidant potential.
Many flavonoids are found to be strong antioxidants
capable of effectively scavenging the reactive oxygen
species because of their phenolic hydroxyl groups [25].
In our study, from the table values, Poovan peel extract
exhibited higher flavonoid content which might be cor-
related with its anti-lipid peroxidation activity.
Several mechanisms have been proposed to be in-
volved in the antioxidant activity such as hydrogen dona-
tion, termination of free radical mediated chain reaction,
prevention of hydrogen abstraction, chelation of catalytic
ions, and elimination of peroxides [26].
Antioxidant activity is a dependent system and the
characteristic of a particular system can influence the
outcome of the analysis. Hence, a single assay would not
be representative of the antioxidant potential of plant
extracts. In the present study, we employed different
models of antioxidant assays which could provide a more
reliable approach to assess the antioxidant and radical
scavenging potential of peel extracts of various banana
varieties.
4. Conclusions
The investigation of the antioxidant potential and phyto-
chemical content of banana peel of nine different local
varieties showed that the content of total phenols were
higher in Rasthali compared to other species which might
be correlated with its high ABTS scavenging activity. In
contrast, the content of flavonoids was higher in Poovan
banana and is highly correlated with its lipid peroxida-
tion inhibition activity. Hence the relationship between
phytochemical content and free radical scavenging activ-
ity of banana peel indicates that peel extracts from these
varieties may be useful to combat free radical mediated
diseases. These observations may be used to substantiate
Table 2. Phytochemical contents in peels of banana varie-
ties.
Total Phenols Flavanoids
Banana varieties
mg CE g
–1
mg rutin g
–1
Kadali 0.15
a
± 0.01 13.80
b
± 0.50
Karpooravalli 0.19
a
± 0.01 16.91
c
± 0.23
Monthan 0.32
b
± 0.03 11.91
a
± 0.23
Nendran 0.49
d
± 0.06 21.72
e
± 0.71
Poovan 0.39
e
± 0.09 22.83
e
± 1.54
Pachainadan 0.30
b
± 0.02 18.79
d
± 1.35
Rasthali 0.60
c
± 0.01 21.33
e
± 1.44
Robusta 0.20
a
±0.02 17.93
cd
± 0.52
Sevvazhai 0.46
cd
± 0.07 12.96
ab
± 1.04
Values represent mean ± SD of 3 replicates; Total phenols was expressed as
mg catechol equivalents g
–1
fresh tissue; Flavonoids was expressed as mg
rutin equivalents g
–1
fresh tissue; Mean followed by a common letter are not
significantly different at the 5% level by DMRT.
the scientific reasoning that free radical-scavenging is
indeed the mode of operation of these peel varieties in
the treatment or prevention of the onset of diseases that
evidence free radical activity.
5. Acknowledgements
The authors gratefully acknowledge the Management of
Kumaraguru College of Technology, Coimbatore for
financial assistance to carry out this work.
REFERENCES
[1] B. Halliwell and J. M. C. Gutteridge, “Free Radicals in
Biology and Medicine,” 2nd Edition, Oxford Science
Publications, Clarendon, 1989.
[2] B. A. Silva, F. Ferreres, J. O. Malva and A. C. P. Dias,
“Phytochemical and Antioxidant Characterization of Hy-
pericum perforatum Alcoholic Extracts,” Food Chemistry,
Vol. 90, No. 1-2, 2005, pp. 157-167.
doi:10.1016/j.foodchem.2004.03.049
[3] K. J. Jo, M. R. Cha, M. R. Lee, M. Y. Yoon and H. R.
Park, “Methanolic Extracts of Uncaria rhynchophylla
Induce Cytotoxicity and Apoptosis in HT-29 Human Co-
lon Carcinoma Cells,” Plant Foods for Human Nutrition,
Vol. 63, No. 2, 2008, pp. 77-82.
doi:10.1007/s11130-008-0074-z
[4] A. Guyle`ne, P. Berthe and F. Louis, “Bananas, Raw
Materials for Making Processed Food Products,” Trends
in Food Science and Technology, Vol. 20, No. 2, 2008,
pp. 1-3.
[5] J. O. Arawande and E. A. Komolafe, “Antioxidative Po-
tentials of Banana and Plantain Peel Extracts on Crude
Cop
yright © 2011 SciRes. FNS

Antioxidant Potential of Peel Extracts of Banana Varieties (Musa sapientum)
Copyright © 2011 SciRes. FNS
1133
Palm Oil,” Ethnobotanical Leaflets, Vol. 14, 2010, pp.
559-569.
[6] K. Kanazawa and H. Sakakibara, “High Content of Do-
pamine, a Strong Antioxidant in Cavendish Banana,”
Journal of Agricultural Food Chemistry, Vol. 48, No. 3,
2000, pp. 844-848. doi:10.1021/jf9909860
[7] S. Someya, Y. Yoshiki and K. Okubo, “Antioxidant Com-
pounds from Bananas (Musa cavendish),” Food Chemistry,
Vol. 79, No. 3, 2002, pp. 351-354.
doi:10.1016/S0308-8146(02)00186-3
[8] M. Umamaheswari and T. K. Chatterjee, “In Vitro Anti-
oxidant Activities of the Fractions of Coccinia grandis L.
Leaf Extract,” African Journal of Traditional, Comple-
mentary and Alterrnative Medicine, Vol. 5, No. 1, 2008,
pp. 61-73. doi:10.4314/ajtcam.v5i1.31258
[9] G. Raghavan, M. Vijayakumar and S. Mehrotra, “Free
Radical Scavenging Potential of Chlorophytum tubero-
sum Baker,” Journal of Ethnopharmacology, Vol. 104,
No. 3, 2003, pp. 423-425.
[10] W. Brand-Williams, M. E. Cuvelier and C. Berset, “Use
of Free Radical Method to Evaluate Antioxidant Activ-
ity,” Lebensmittel Wissenschaft und Technologie, Vol. 28,
No. 1, 1995, pp. 25-30.
doi:10.1016/S0023-6438(95)80008-5
[11] R. Re, N. Pellegrini, A. Proteggente, A. Pannala, M.
Yang and C. Rice-Evans, “Antioxidant Activity Applying
Improved ABTS Radical Cation Decolorization Assay,”
Free Radical Biology and Medicine, Vol. 26, No. 9-10,
1999, pp. 1231-1237.
doi:10.1016/S0891-5849(98)00315-3
[12] H. Ohkawa, N. Ohishi and K. Yagi, “Assay for Lipid
Peroxidation in Animal Tissues by Thiobarbituric Acid
Reaction,” Annals in Biochemistry, Vol. 95, No. 2, 1979,
pp. 351-358. doi:10.1016/0003-2697(79)90738-3
[13] H. Tanner and H. R. Brunner, “Gentranke-Analytik,”
Verlag Heller Chemie und Verwaltunsgesellschaft mbH,
Germany, 1979.
[14] C. Kaur and H. C. Kapoor, “Antioxidant Activity and
Total Phenolic Content of Some Asian Vegetables,” In-
ternational Journal of Food Science and Technology, Vol.
37, No. 2, 2002, pp. 153-161.
[15] F. Karadeniz, H. S. Burdurlu, N. Koca and Y. Soyer,
“Antioxidant Activity of Selected Fruits and Vegetables
Grown in Turkey,” Turkish Journal of Agricultural Fo-
rum, Vol. 29, 2005, pp. 297-303.
[16] P. Preito, M. Pineda and M. Aguliar, “Spectrophotometric
Quantitation of Antioxidant Capacity through the Forma-
tion of a Phosphomolybdenum Complex: Specific App-
lication to the Determination of Vitamin E,” Annals in
Biochemistry, Vol. 269, No. 2, 1999, pp. 337-341.
doi:10.1006/abio.1999.4019
[17] M. Gonzalez-Montelongo, L. Gloria and G. Monica,
“Antioxidant Activity in Banana Peel Extracts: Testing
Extraction Conditions and Related Bioactive Compounds,”
Food Chemistry, Vol. 119, No. 3, 2010, pp. 1030-1039.
doi:10.1016/j.foodchem.2009.08.012
[18] B. Subhasree, R. Baskar, R. Laxmi Keerthana, R. L.
Susan and P. Rajasekaran, “Evaluation of Antioxidant Poten-
tial in Selected Green Leafy Vegetables,” Food Chemistry,
Vol. 115, No. 4, 2009, pp. 1213-1220.
doi:10.1016/j.foodchem.2009.01.029
[19] C. Okonogi, A. Songyot, T. Suganya and C. Sombat,
“Comparison of Antioxidant Capacities and Cytotox-
icities of Certain Fruit Peels,” Food Chemistry, Vol. 103,
No. 3, 2007, pp. 839-846.
doi:10.1016/j.foodchem.2006.09.034
[20] T. Kulisic, V. Ddagovic-Uzelac and V. Milos, “Antioxi-
dant Activity of Herbal Tea Infusions,” Food Technology
and Biotechnology, Vol. 44, No. 4, 2006, pp. 485-492.
[21] R. Baskar, V. Rajeswari and T. S. Kumar, “In Vitro An-
tioxidant Studies in Leaves of Annona Species,” Indian
Journal of Experimental Biology, Vol. 45, No. 5, 2007,
pp. 480-485.
[22] E. Casanova, J. M. García-Mina and M. I. Calvo, “Anti-
oxidant and Antifungal Activity of Verbena officinalis L.
Leaves,” Plant Foods for Human Nutrition, Vol. 63, No.
3, 2008, pp. 93-145. doi:10.1007/s11130-008-0073-0
[23] K. Saito, M. Kohno, F. Yoshizaki and Y. Niwano, “Ex-
tensive Screening for Edible Herbal Extracts with Potent
Scavenging Activity against Superoxide Anions,” Plant
Foods for Human Nutrition, Vol. 63, No. 2, 2008, pp. 65-
70. doi:10.1007/s11130-008-0071-2
[24] G. C. Yen, P. D. Duh and C. L. Tsai, “Relationship be-
tween Antioxidant Activity and Maturity of Peanut Hulls,”
Journal of Agricultural Food Chemistry, Vol. 41, No. 1,
1993, pp. 67-70. doi:10.1021/jf00025a015
[25] G. Cao, E. Sofic and R. L. Prior, “Antioxidant and Pro-
Oxidant Behaviour of Flavonoids: Structure Activity Re-
lationships,” Free Radical Biology and Medicine, Vol. 22,
No. 5, 1997, pp. 749-60.
doi:10.1016/S0891-5849(96)00351-6
[26] M. F. Gordon, “The Mechanism of Antioxidant Action in
Vitro,” In: B. J. F. Hudson, Ed., Food Antioxidants, El-
sevier Applied Science, London, 1990, pp. 1-18.