Vol.4, No.5B, 141-147 (2013) Agricultural Sciences
Chemical characterization and antioxidative
properties of Polish variety of Morus alba L. leaf
aqueous extracts from the laboratory and pilot-scale
Ewa Flaczyk1*, Joanna Kobus-Cisowska1, Monica Przeor1, Jozef Korczak1,
Marian Remiszewski2, Eugeniusz Korbas2, Maciej Buchowski3
1Department of Food Service and Catering, Poznan University of Life Sciences, Wojska Polskiego, Poznan, Poland; *Corresponding
Author: ewafla@up.poznan.pl
2Institute of Agricultural and Food Biotechnology Department of Food Concentrates and Starch Product, Starolecka, Poznan, Poland
3Vanderbilt University, Department of Medicine, Nashville, Tennessee, USA
Received 2013
White mulberry tree (Morus alba L) is cultivated
throughout Asia and Europe, including Poland.
The leaves and root bark preparations from
Morus alba have been used in traditional phy-
tomedicine. The objective of the present study
was to compare chemical composition and an-
tioxidative activity of aqueous extracts prepared
from Polish variety of Morus alba leaves at the
laboratory (L) and pilot plant scale (PP) condi-
tions. Proximate composition, phenolic acids
profile (HPLC/MS), flavonol glicosides (HPLC/
MS), polyphenols (Folin-Ciocalteu assay), and
the antioxidant activity (ABTS and DPPH assay)
of the extracts were determined. The main phe-
nolic compounds were identified as gallic, pro-
tocatechuic, p-hydroxybenzoic, vanillic, chloro-
genic, caffeic, p-coumaric, ferulic, and sinapic
acids. Chlorogenic acid was the main phenolic
constituent of both extracts. The flavonols frac-
tion contained rutin, quercetin 3-β-D-glucoside,
and kaempferol 3-β-D- glucopyranoside. Total
concentration of phenolic compounds were 7.9
g and 14.4 g gallic acid equivalent/100 g extract,
and antioxidant activity was 137.1 and 214.1
μMol Trolox equivalent/g dry weight for the PP
and L extracts, respectively. We concluded that
current pilot plant process is less efficient than
laboratory process at the aqueous extraction of
bioactive components from Morus alba dried
leaves. Potential improvements may include in-
creasing efficacy of the extraction, decreasing
losses of bioactive components during the
process, or both.
Keywords: Morus Alba Leaves; Pilot Plant Scale;
Antioxidant Activity; Phenolic Acid; Flavonols; HPLC
White mulberry tree (Morus alba L.) is a deciduous
tree originating from Asia but currently cultivated in
subtropical, tropical, and moderate environments [1].
Morus alba is valued for its foliage traditionally used as
feed for silk worms and have been shown to improve
milk yield when fed to dairy cows [2,3]. Morus alba
leaves contain proteins, carbohydrates, calcium, iron,
ascorbic acid, β -carotene, thiamine, folic acid and vita-
min D [4]. Morus alba tree bark, fruits, and leaves have
been used also in both conventional and natural medicine
and beneficial in the treatment of diabetes, atherosclero-
sis, hyperlipidemia, hypertension, and more recently,
some cancer and neurogenerative diseases.
In Poland, a major cultivated variety is Morus alba L
var. wielkolista zolwinska since it is the best adapted
variety to local climate conditions. Typically, it is grown
as a shrub from which leaves are harvested annually in
July, dried, packaged, and sold as herbal teas. Previously,
we have described the laboratory process of aqueous
extraction of Morus alba leaves and young shoots dried
at 30 - 60 and recommended specific technical and
technological requirements for the pilot plant scale proc-
ess [5]. The objective of this study was to compare chemical
composition and antioxidant properties of extracts obtained
at both laboratory and pilot scale processes.
2.1. Preparation of the Morus Al ba Leaves
and Extracts
Morus alba L. var. wielkolistna zolwinska) leaves
Copyright © 2013 SciRes. Openly accessible at http://www.scirp.org/journal/as/
E. Flaczyk et al. / Agricultural Sciences 4 (2013) 141-147
were collected in July 2011 from the experimental farm
Petkowo (Institute of Natural Fibres and Medicinal
Plants, Poznan, Poland). The leaves (50 kg) were dried at
The laboratory (L) extract samples were prepared by
two-level extraction of 10 g of crude dried leaf powder
(0.8 - 0.08 mm) mixed with 100 ml of bidistilled water
(100) in a round-bottom flask for 5 min. and centri-
fuged at 4,400 rpm and 20 for 3 min (Eppendorf
Centrifuges 5702 R). The precipitate was transferred to a
round bottom flask and extracted with 40 ml of bide-
stilled water (100) and centrifuged under the same
conditions. The supernatant was filtered through Whatman
1 filter paper and freeze-dried (Christ Alpha 1-4, LSC,
Germany). The yield of the extraction was 25.55%.
Pilot plant (PP) extract samples were prepared from
dried and crushed Morus alba leaves mixed with water
(80 - 90) by the counter-flow process (1:10 w/w)
using continuous twin-screw extractor (IBPRS, Poznan,
Poland). The extract was concentrated using a vacuum
periodic spherical evaporator (WWA20, Spomasz, Pleszew,
Poland), at 70 - 80 and pressure 0.6 - 0.8 atm (14.7
psi). The concentrated extract was air-dried in a spray
dryer (SR16, Niro Atomizer, Denmark). Drying inlet and
outlet temperatures were 180 - 90 and 90 - 95,
respectively. The yield of the process was 21.61%.
2.2. Chemical Standards
All chemicals were purchased from Sigma-Aldrich
(Poznań, Poland). Chemical used were gallic acid (3,
4,5-tri-hydroxy benzoic acid), p-hydroxy-benzoic acid
(4-hydroxy-benzoic acid), protocatechuic acid (3,4-di-
hydroxy benzoic acid), vanillic acid (4-hydroxy-3-meth-
oxybenzoic acid), caffeic acid (acid 3,4- dihydroxycin-
namon acid) chlorogenic acid (5- O-caffeoylquinic acid),
ferulic acid (4-hydroxy-3-methoxycinnamic acid), p-cou-
maric acid (4-hydroxycinnamic acid), sinapic acid (acid,
4-hydroxy-3,5-dimetoxy cinnamon), quercetin (3,3',4',
5,7-pentahydroxyflavone), kaempferol (3,4',5,7-tetrahy-
droxyflavone), myricetin (3,3' 4', 5,5',7-heksahy- droxsy-
flavon), isoquercetin (3-O-glucoside, quercetin) hipero-
side (3-O-galactoside quercetin), rutin (quercetin-3-O-
rutinoside), astragalin (3-O-gluco pyranoside kaempferol),
L-ascorbic acid (γ-lactoneendiol acid, 2-oxo-L- gulonic
acid), 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2'-
azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS+),
6-hydroxy 2,5,7,8-tetramethylchroman-2-carboxylic acid
(Trolox). All chemicals were of HPLC-grade or analytic-
cal grade purity.
3.1. Proximate Composition
The moisture, protein, lipids and ash of extracts were
determined according to the AOAC methods [6].
3.2. Reducing Sugars
Qualitative and quantitative content of reducing sugars
and sucrose was determined using a Waters Alliance
HPLC® System 2695 (USA) with a refractometer detector
(RI) Waters 2414 (Waters, USA) and an ion column
(Rezex RPM-Monosaccharide Pb+2 [8%]; 300 × 7.80 mm;
Phenomenex, Torrance, CA, USA). The separation and
detection (an objective measurement of RI) temperature
was 65 and 50, respectively. The separation of sam-
ples (5 ml) was isocratic and deionized water (0.6 ml/
min) was used as an eluent.
3.3. Phenolic Acids
Qualitative and quantitative analysis of phenolic acids
were made by HPLC with Bin Pump Infinity DAD 1290
detector, at λ = 260 nm and 310 nm. The dry extract was
dissolved in phase. A non-linear concentration gradient
was used. The mobile phase utilized a gradient composed
of H3PO4 buffer (solvent A) pH = 2.7 and was adjusted
with 1:1 v/v acetonitrile-water (solvent B)).The gradient
profile was decreasing smoothly from 95% of solvent A
at 1 min to 50% of B at 52 min. Run time was 58 min.
The volume of injected sample after filtration (PTFE
filter; 0.45 μm) was 10 µl. The identification of phenolic
acids was based on the analysis of standards dissolved in
methanol (gallic, p-hydroxybenzoic, protocatechuic, va-
nillic, caffeic, chlorogenic, ferulic acid, p-coumaric, and
sinapic acid) as described by Kobus et al. [7]. Concen-
tration of phenolic acids in samples were calculated us-
ing internal standard. Results were expressed in micro-
grams per gram of dry matter of extract.
3.4. Flavonols
Qualitative and quantitative analysis of phenolic acids
were made by HPLC with Bin Pump Infinity DAD 1290
detector, at λ = 370 nm. Flavonols were determined, after
dissolving the dry extract in-phase column Zorbax SB
C18 (3.9 × 150 mm, 5 um) (Agilent, USA). A non-linear
concentration gradient was used. Solvent A was H3PO4
buffer (pH = 2.7), whereas solvent B was acetonitrile-
water (1:1) using a flow rate of 1 ml / min. The gradient
profile was decreasing smoothly from 95% of solvent A
at 1 min to 20% of solvent B at 30 min. Run time was 37
min. The volume of injected sample was 10 µl. The
identification of separated compounds was carried out by
retention time mapping with a set of standards dissolved
in methanol (rutin, quercetin-3-D-galactoside, quercetin
galactoside, kaempferol 3-β-D-glucopyranoside, myricetin,
kaempferol, and quercetin). Identification of individual
flavonols was performed by comparing UV-VIS spectra
and the retention time of flavonols in samples with the
Copyright © 2013 SciRes. Openly accessible at http://www.scirp.org/journal/as/
E. Flaczyk et al. / Agricultural Sciences 4 (2013) 141-147 143
standard as described by Kobus et al. [7].
3.5. Total Phenolics
The total polyphenols content was determined by
Folin-Ciocalteu’s reagent. The absorbance of samples
was measured at a wavelength of 765nm with UV-VIS
spectrophotometer (Jena). Gallic acid was the standard,
and results were expressed in mg / g dry weight of the
extract according to Cheung et al. [6].
3.6. Ascorbic Acid
HPLC technique was used for the separation and
identification of ascorbic acid in the extracts (HPLC with
Bin Pump Infinity DAD 1290 detector, Agilent, Germany).
Separation was performed using Luna Phenomenex col-
umn (4.6 × 250 mm; 5 µm; Phenomenex, Torrance, CA,
USA. The mobile phase was a KH2PO4 (pH 5.0)
dissolved in methanol. The gradient profile was decreas-
ing smoothly from 95% of KH2PO4 solution at 1 min to
78% at 6 min. Run time was 10 min. The volume of
injected sample was 20 µl. Ascorbic acid was identified
using retention time mapping with ascorbic acid as
internal standard. Ascorbic acid content was determined
colorimetrically (λ = 245 mm) based on the calibration
curve [8].
3.7. Chelating Activity
Chelating activity of the extracts was measured as de-
scribed by Tang et al. [9]. The colorimetric assay in-
volves determining the quantity of Fe2+ , which does not
chelate with the extract and 3-(2-pyridyl)-5,6-bis (4-
phenylsulfonic acid)-1,2,4-triazine mono sodium salt (i.e.,
ferrozine). A sample (1 mL) was mixed with 0.1 mL of 2
mM FeCl2 and 0.2 mL of ferrozine reagent in a test tube.
The mixture was vortexed for ~60 s and incubated at
room temperature for 20 min followed by measurements
of absorbance at λ = 562 nm ( SPECORD® 40 (Analytik,
Jena, Germany). Deionized water was used as a control
and ferrozine as a reference standard. The chelating ac-
tivity was calculated using the following equation: Che-
lating activity = 1 - [(Abs. of sample – Abs. of refer-
ence)/Abs. of control)] × 100.
3.8. Radical Scavenging Capacity Against
The free-radical scavenging potentials of crude ex-
tracts were tested in a methanolic solution of DPPH as
described by Amarowicz et al. [10]. The extent of dis-
coloration of the solution indicates the scavenging effi-
cacy of the added substance. A 1-mL aliquot of extract
solution was combined with 2 mL of CH3OH and then
0.25 mL of a 1 mM ethanolic solution of DPPH. The
mixture was vortexed for ~60 s and incubated at room
temperature for 20 min followed by measurements of
absorbance at λ = 517 nm (SPECORD® 40, Analytik
Jena, Germany). A reference sample was prepared with
methanol instead of DPPH and the control instead of the
extract sample. To construct a calibration curve, absorb-
ance of samples containing 0.5, 1.0, 1.5, and 2.0 mg/mL
Trolox were measured simultaneously. Results were ex-
pressed as µMol Trolox equivalents/g extract dry weight.
Antioxidant activity was calculated as a percentage of
DPPH change in absorbance using the following equa-
Radical scavenging activity = 100 - [(Abs. of sample –
Abs. of reference)/Abs. of control)] × 100
3.9. Total Antioxidant Capacity with ABTS+•
The method of assessing the ability of inhibiting
ABTS+• (2,2'-azinobis-3-ethylbenzo thiazoline-6-sul-
fonate) is based on the spectrophotometric measurement
of change in absorbance at λ = 734 nm. The ABTS+•
solution was prepared 24 h earlier and incubated with the
sample at 35 for 6 min. The extent of decolorization,
expressed as percentage of absorbance inhibition of
ABTS+• was calculated according to Re et al. [11].
% Inhibition = (Abs. of control – Abs. of sample) /Abs.
of control * 100
Antioxidative status of the extracts is expressed in
percentages and in Trolox equivalents (mM) Trolox/100
g dry extract.
3.10. Statistical Analysis
All measurements were performed in six or more rep-
lications. All results are means and standard deviations.
The significance of differences between the means was
determined at P 0.05, after applying a one-way analy-
sis of variance (ANOVA) followed by Tukey’s multiple
range test. All statistical analysis analyses were per-
formed using SPPS v 17. SPSS, Chicago, IL, USA).
4.1. Proximate Composition
The total amount of protein, fat, sugars, and ash in the
Morus alba leaf water extracts are shown in Table 1. The
extract from pilot plant (PP) had lower concentration of
protein, glucose and galactose than laboratory (L) extract.
The PP extract had significantly higher than L extract
concentration of saccharose (24.4 vs. 18.6 g/100g), but
lower concentration of protein (12.7 vs. 14.7 g/100g).
Both extracts have higher concentration of protein and
ash than those in the Morus alba leaf ethanol extract
reported by Nakamura et al [12].
The differences in protein, fat, ash, and sugar content
Copyright © 2013 SciRes. Openly accessi ble at http://www.scirp.org/journal/as/
E. Flaczyk et al. / Agricultural Sciences 4 (2013) 141-147
between the PP and L extracts were most likely due to
different conditions during the extraction and concentra-
tion processes. Thus, it seems necessary to perform further
tests and determine qualitative indicators necessary for
optimization of extraction and/or concentration in the PP
4.2. Bioactive Compounds - Phenolic Acids
Morus alba leaves are used in medicine mainly be-
cause of high concentration of constituents with antioxi-
dative activity such as phenolic compounds. Among
phenolics, the highest antioxidative activity exhibit phe-
nolic acids and flavonoids [13,14]. In our extracts,
chlorogenic acid had the highest concentration among
active compounds detected. The L extract contained ap-
proximately double the amount of chlorogenic acid
found in the PP extract (Table 2). A plausible explanation
is that during the PP process, chlorogenic acid was con-
verted to caffeic and/or chinoic acids. However, we did
not find an increased concentration of caffeic acid in the
final PP extract. This suggests a possibility of intermit-
tent losses occurring during one or more stages of the PP
process, which requires further investigation.
Our results are similar to those reported by Memon et
al. [15], who analyzed phenolics in fruits and leaves
from Morus Alba species grown in Pakistan and found
that chlorogenic acid was a prominent phenolic acid.
Other identified phenolic acids were caffeic, vanillic, p-
hydroxybenzoic, p-coumaric, sinapic, proto catechuic,
syringic, ferulic, and m-coumaric acids. Gallic, proto-
catechuic, p-coumaric and ferulic acids were found in
fruits and extracts but not leaves, suggesting a possibility
that the acids were present in leaves in an inactive/
bound form(s) and released during the extraction process
Table 1. Basic compounds in Morus alba leaf water extracts
from pilot plant (PP) and laboratory (L) process a,b.
Pilot plant (PP) Laboratory (L)
Water 5.40b ± 0.07 5.12a ± 0.10
Protein 12.70a ± 1.73 14.70b ± 0.03
Ash 22.70b ± 0.13 22.37a ± 1.21
Fat 0.15b ± 0.02 0.11a ± 0.01
Saccharose 24.35b ± 1.03 18.62a ± 0.92
Glucose 3.00a ± 0.02 4.90b ± 0.02
Fructose 3.02b ± 0.01 1.61a± 0.01
Xylose 0.64a ± 0.00 0.85b ± 0.01
Galactose 1.14b ± 0.02 0.27a ± 0.01
Other carbohydratesc 18.50b 17.04a
aValues are means ± SD of 5 measurements. bValues in columns with dif-
ferent superscript letters are significantly different (P 0.05). Calculated
from the difference (100 g).
4.3. Bioactive Compounds –Flavonols
Flavonols are major contributors to antioxidant active-
ity of Morus alba leaves. High antioxidative properties
of flavonols are attributed to their structure and in par-
ticular, to the presence and configuration of hydroxyl and
metoxyl groups and glycosidic bonds [16]. Qualitative
and quantitative analyses of flavonol glicosides yielded
similar results in both, PP and L extracts (Ta b le 3 ). We
identified rutin (3-O-rutinoside quercetin), izoquercitrin
(quercetin 3-β-D-glucoside) and astragalin (kaempferol
3-β-D-glucopyranoside) in the glycoside but not in the
free form.
The same compounds were identified by Kim et al in
Korean Morus alba leaf extract [17]. In addition, we
found two other compounds, most likely quercetin 3-(6-
malonyl)-glucoside and kaempferol 3-(6-malonyl)-glu-
coside, first identified in Morus alba by Katsube et al.
[18]. The authors found that quercetin 3-(6-malonyl glu-
coside) and rutin (quercetin 3-rutinoside) were two pre-
dominant flavonol glycosides in the 60% ethanol leaf
extract from Japanese variety of Morus Alba. Other an-
tioxidant flavonols identified by Katsube et al were iso-
quercitrin and astragalin. In our extracts we identified all
Table 2. Phenolic acids concentration in Morus alba leaf
aqueous extracts from pilot plant (PP) and laboratory (L) proc-
esses (g/100g of extract dry weight)a,b.
Acid Pilot plant (PP) Laboratory (L)
Gallic 0.28b ± 0.15 0.02a ± 0.02
Protocatechuic 0.08a ± 0.03 0.16b ± 0.03
p-hydroxybenzoic 0.11b ± 0.02 0.11a ± 0.02
Vanillic 0.42a ± 0.12 0.71b ± 0.01
Chlorogenic 2.33a ± 0.10 4.64b ± 0.01
Caffeic 0.66a ± 0.04 2.54b ± 0.01
p-coumaric 0.12a ± 0.02 0.27b ± 0.04
Ferulic 0.09a ± 0.01 0.39b ± 0.01
Sinapic 0.11a ± 0.02 0.21b ± 0.04
Total phenolic acids4.27a ± 0.02 9.09b± 0.02
aValues are means ± SD of 5 measurements. bValues in columns with differ-
ent superscript letters are significantly different (P 0.05).
Table 3. Flavonols concentration in Morus alba leaf aqueous
extracts from pilot plant (PP) and laboratory (L) processes
(g/100g of extract dry weight) a,b.
Compound Pilot plant (PP) Laboratory (L)
Rutin 0.90a ± 0.01 0.91a ± 0.01
Quercetin 3-β-D-glucoside 0.47a ± 0.01 0.54b ± 0.01
Kaempferol 3-β-D- glu-
copyranoside 0.19a ± 0.02 0.32b ± 0.01
Total Flavonols 1.56a± 0.02 1.76b ± 0.02
aValues are means ± SD of 5 measurements. bValues in columns with differ-
ent superscript letters are significantly different (P 0.05).
Copyright © 2013 SciRes. Openly accessible at http://www.scirp.org/journal/as/
E. Flaczyk et al. / Agricultural Sciences 4 (2013) 141-147 145
these compounds except quercetin 3-(6-malonylgluco-
side). Concentrations of isoquercitrin and astragalin were
similar, but the concentration of rutin was two times
lower than those reported by Katsube and colleagues
[13]. However, similar to the concentration of rutin in
our study was found by Song et al in the leaf extract
from Chinese Morus alba varieties [19].
4.4. Bioactive Compounds- Phenolics and
Ascorbic Acid
Total phenolics and ascorbic acid content in the
extracts was significantly higher in the L than PP extracts
(Table 4).
4.5. Antioxidant Activity
Bioactive compounds present in the Morus alba leaf
extract have been showed to affect antioxidant properties
in both model and biological systems. It has been
suggested that antioxidants extinguish the free radicals
chelating complexes of transition metals (e.g., iron and
copper), thereby reducing the metal-support action of
antioxidant enzymes and inhibit the formation of pro-
oxidative enzymes such as cyclooxygenase, particularly
in biological systems [20]. In this study we utilized three
commonly used the ABTS cation, scavenging activity
against DPPH, and the iron chelating activity assays. To
confirm the antioxidant activity of the extracts we used
the ATBS method [20]. Both extracts had a relatively
high capacity to reduce the ABTS cation, but the L ex-
tract had higher than PP extract s suggesting that the
higher content of flavonols and chlorogenic acid was
associated with the increased antioxidant activity of the
Morus alba leaf extracts. Our results (Ta bl e 5 ) confirm
findings by Heo et al. [21] that the increase of polyphenols
in the mixture influences the total antioxidant ABTS
cation activity. They also showed that antioxidant activity
of chlorogenic acid, quercetin, and rutinoside cyanidyn
mixture influenced the result of the additive activity of
the components.
Table 4. Total phenolics and ascorbic acid concentration in
Morus alba leaf aqueous extracts from pilot plant (PP) and
laboratory (L) processes a, b.
Compound Pilot plant (PP) Laboratory (L)
Total phenolics
(g gallic acid
equivalents/100g DW)
7.94a ± 0.23 14.42b ± 0.36
Ascorbic acid
(mg/100g of DW) 1.32a ± 0.05 1.76b ± 0.23
aValues are means ± SD of 5 measurements. bValues in columns with differ-
ent superscript letters are significantly different (P 0.05). DW- extract dry
Table 5. Antioxidant activity in Morus alba leaf aqueous ex-
tracts from pilot plant (PP) and laboratory (L) processesa,b.
Assay Pilot plant (PP) Laboratory (L)
(µMol Trolox /g DW)
± 0.05
± 0.57
(µMol Trolox /g DW)
± 0.08
± 0.06
Chelating activity (%) 38.04 for 0.003g 29.88 for 0.002g
aValues are means ± SD of 5 measurements. bValues in columns with differ-
ent superscript letters are significantly different (P 0.05). DW- extract dry
Table 3 shows results for antioxidative activity against
DPPH. Both extracts had high activity against DPPH
however, the PP extract had lower activity than the L
extract. This can be explained by a lower polyphenol
content, in particular phenolic acids and flavonols
glycosides in our extract. Support to our findings comes
from the mentioned earlier work by Katsube et al. [14]
who measured antioxidative activity of the 60% ethanol
Morus alba leaf extract and the activity of individual
polyphenols. Among tested polyphenols, the highest activity
against DPPH was demonstrated by chlorogenic acid
(36.2%) followed by 3-(6-malonyloglikozyd) quercetin
(21.4%), rutin (8.4%) and isoquercitrin (3.2%). Kaemp-
ferol glycosides showed a significantly lower ability to
reduce DPPH. The results described by Wang et al. also
showed that the antioxidant activity of kaempferol was
3-fold lower than those of quercetin, which high
antioxidant activity is due to the presence of 3,4-catechol
group in the B ring [22].
Our results show that the L extract, which had a higher
content of polyphenols, phenolic acids, and flavonols
than the PP extract, also exhibited higher antioxidant
activity, as measured by ABTS and DPPH tests. Similar
results were reported by Arabshahi et al. [2].
From our results could be assumed that the main
compounds contributing to the antioxidant activity in
both extracts were flavonols glycosides and chlorogenic,
ferulic, and caffeic acids. The tested L and PP extracts
had the ability to chelate iron (II). We found that the
ability to chelate iron (II) was affected by dilution of the
extract (Figure 1).
The ability of the extracts to chelate iron was most
likely due to the presence of chlorogenic, caffeic, and
ferulic acids. Similar activity of the polyphenolic acids
was reported by Andjelkovic et al. [23]. They ranged the
chelatic ability of several phenolic acids and found that
the highest chelatic ability to chelate iron (II) had chloro-
genic acid, followed by gallic, caffeic, and protocateinuic
Copyright © 2013 SciRes. Openly accessi ble at http://www.scirp.org/journal/as/
E. Flaczyk et al. / Agricultural Sciences 4 (2013) 141-147
Figure 1. Chelating activity of Morus alba leaf aqueous extract
from the pilot plant (PP) process. The same letters above the bars
indicate no significant statistical differences.
Taken together, results of this study show that both,
tested Morus alba leaf extracts exhibited antioxidant
activity measured by scavenging of stable DPPH and
ABTS radicals and the ability to chelate iron (II). The PP
extract obtained at the pilot-scale had lower than the ob-
tained at laboratory L extract content of phenolic com-
pounds, phenolic acids, and flavonols, lower antioxidant
properties as measured by ABTS, DPPH assays, and
lower ability to chelate iron (II). Potential improvements
of the PP process may include increasing efficacy of the
extraction, decreasing losses of bioactive components
during the process, or both.
This research was supported by POIG 01.01.02 -00-061/09 „New
bioactive food with designed functional properties”.
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