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Antiradical activity and amount of phenolic compounds in extracts obtained from some plant raw materials containing methylxanthine alkaloids

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Raw materials containing methylxanthine alkaloids such as yerba mate, guaraná, white and green tea, coffee seeds, chocolate and cacao seed powder and extracts obtained from these raw materials were investigated for their antioxidant features and the amount of phenolic compounds. The level of phenolic compounds was measured with the colorimetric method using Folin-Ciocalteu’s phenol reagent and antioxidant features was determined with the use of DPPH (2,2-diphenyl-1-picrylhydrazyl radical). Amounts of phenolic compounds were presented in percentages per mass of extracts and mass of raw materials. Antiradical potential was shown as the number of
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Vol. 61 No. 3 2015
DOI: 10.1515/hepo-2015-0022
From Botanical to Medical Research
Herba Pol 2015; 61(3): 53-66
Antiradical activity and amount of phenolic compounds in extracts
obtained from some plant raw materials containing methylxanthine
alkaloids
ZBIGNIEW SROKA
1*
, MARIA JANIAK
1
, ANDRZEJ DR
2
1
Department of Pharmacognosy
Faculty of Pharmacy
Wroclaw Medical University
Borowska 211a
50-556 Wroclaw, Poland
2
Department of Physical Chemistry
Faculty of Pharmacy
Wrocław Medical University
Borowska 211a
50-556 Wrocław, Poland
*corresponding author: phone.: +4871 784 0220, fax: +4871 784 0218,
e-mail: zbigniew.sroka@umed.wroc.pl
Summary
Raw materials containing methylxanthine alkaloids such as yerba mate, guaraná, white
and green tea, coffee seeds, chocolate and cacao seed powder and extracts obtained from
these raw materials were investigated for their antioxidant features and the amount of
phenolic compounds. The level of phenolic compounds was measured with the colori-
metric method using Folin-Ciocalteu’s phenol reagent and antioxidant features was deter-
mined with the use of DPPH (2,2-diphenyl-1-picrylhydrazyl radical). Amounts of phenolic
compounds were presented in percentages per mass of extracts and mass of raw materials.
Antiradical potential was shown as the number of TAU
DPPH
units per mg of extracts and g
of raw materials. The highest number of antiradical units TAU
DPPH
as well as the amount of
phenolic compounds was calculated for white tea and its extracts and lowest for choco-
late. The correlation coefficient between the content of phenolics and antiradical features
of raw materials is equal to r=0.994.
Key words: antioxidants, free radical scavengers, plant extracts, plant phenolics, methylxanthine
alkaloid raw materials, antiradical units
EXPERIMENTAL PAPER
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Z. Sroka, M. Janiak, A. Dr

Plant raw materials containing methylxanthine alkaloids are rich in phenolic
compounds [1-4]. Also extracts obtained from these sources contain large quan-
tities of phenols with strong antioxidative activity. Tea leaves and extracts from
tea are among the most effective. Among them white and green tea exhibit the
strongest antioxidant or antiradical properties [5].
Guaran
á, Paullinia cupana Kunth, is a member of the climbing plant family of
Sapindaceae. The plant is native to the Amazon basin including Brazil. Guaran
á
seeds are rich in caffeine and other methylxanthine derivatives, also contains
tannins and saponins. This raw material contains about 12% tannins, mainly pro-
anthocyanidins, about 6% (+)-catechin and 3.8% (-)-epicatechin [6]. Guaran
á was
consumed for centuries by Indians, who added it to drinks and foods in order to
decrease fatigue and to increase vigor [4, 7]. Nowadays, guaran
á is used for the
production of soft drinks. Guaran
á powder is used as a nutritional supplement to
enhance vigor, to inhibit the platelet aggregation, protect against gastric injury
caused by ethanol, and for antimicrobial and antioxidant activity [4].
White tea (Camellia sinensis (L.) Kuntze is a less processed kind of tea (steamed,
then dried without withering) and exhibit slightly higher antiradical properties
than green teas [5, 8]. It acts advantageously in the prevention of many diseases,
such as heart and neurodegenerative diseases as well as cancers [8]. White tea is
produced from buds and leaves of Camellia sinensis. The white color comes from
the hair of unopened buds. White tea contains similar amount of catechin deriva-
tive as epigallocatechin gallate as green tea but the amount of epigallocatechin
is higher than in green teas. Main catechins in white tea are catechin, epigallo-
catechin gallate, epigallocatechin, and epicatechin [5, 8].
Yerba mate beverage origins from the leaves of Ilex paraguariensis A. St.-Hil. It
is consumed in South America countries such as Brazil (South part), Argentina,
Uruguay and Paraguay. The raw material to be infused consist of dry leaves of Ilex
paraguariensis belonging to the botanical family Aquifoliaceae. According to the
literature, yerba mate has hypocholesterolemic and hepatoprotective activity, and
also exhibits a stimulating effect on the central nervous system [1, 9]. There was
also observed diuretic and antioxidant activity [1, 10, 11], an advantageous effect
on the cardiovascular system [12, 13], and protection of DNA and LDL against
oxidation [14]. Leaves of Ilex paraguariensis contain polyphenols such as phenolic
acids (chlorogenic, caffeic, dicaffeoylquinic acids), flavonoids (quercetin, kaemp-
ferol, rutin), methylxanthines such as caffeine and smaller quantity of theobro-
mine [9]. The leaves of yerba mate also contain amino acids, some vitamins such
as C, B
1
, B
2
, and mineral components (Fe, P, Ca) [9]. In some cases during use of
yerba mate serious adverse effects have been observed, such as oral, oropharyn-
geal and esophageal cancers [15].
Coffee is the most frequently consumed drink in the world, along with tea. Seeds
of coffee contain numerous compounds with antiradical activity such as chlorogen-
ic, 5-caffeoylquinic, feruloylquinic and caffeic acids, melanoidins and caffeine [16].
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Cocoa beans originate from plants of Theobroma cacao L. The amount of total
phenols in cocoa powder is about 6%. There are mainly flavan-3-ols, such as mo-
nomeric catechin or epicatechin, their oligomers (procyanidins) and flavonoids
among other derivatives of quercetin [16, 17].
Chocolate is obtained from cacao. Over many years the use of cacao (Theobroma
cacao) evolved into the product called chocolate. Chocolate is rich in lipids with
high amounts of saturated fatty acids such as stearic (30–33%) and palmitic (28-30%)
[18]. Besides, some amounts of sterols were identified as well as minerals, flavo-
noids, catechin, epicatechin, and procyanidins (in cocoa beans 12
48%). Chocolate
has a concentration of flavan-3-ol higher than most plant-based foods [19, 20]. The
polyphenols present in chocolate and cacao beans might exert advantageous vascu-
lar effects [21]. These compounds might reduce cardiovascular morbidity [22], and
diseases with chronic character [23]. According to scientific opinion demonstrated
in EFSA (European Food Safety Authority) monomeric catechins (mainly epicatechin)
and oligomers (procyanidins) maintain ”endothelium-dependent vasodilation which
contributes to healthy blood flow” at a daily dose of 200 mg [24, 25].
It is necessary to mention that chocolate are high processed products and the
amount of phenols and the antioxidant activity varies widely. The strongest anti-
oxidant activity exhibit dark chocolate but weakest milk chocolate [26].
All above described raw materials are known to have high amounts of phenolic
compounds such as tannins, mainly condensed [4, 27], catechins and gallic acid
derivatives (epigallocatechin gallate, EGCG) [28], and other coupling of catechins
such as procyanidins [29], and simple phenolic acids (gallic, caffeic) [30-32]. Other
phenols belong to the very wide group of flavonoids such as, the most common,
derivatives of quercetin, or kaempferol [31, 33].
The demonstration of methylxanthine raw materials’ strong antiradical or anti-
oxidant activity might expand their therapeutic use as a weapon to fight diseases
caused by free radicals and reactive oxygen species.
Free radicals and reactive oxygen species (ROS) are formed in normal physio-
logical processes and in some diseases, especially chronic [34]. The physiological
level of free radicals and ROS is maintained with an enzymatic system (superoxide
dismutase, catalase), and natural antioxidants such as glutathione, or NADPH, and
vitamins E and C can decrease the amount of ROS [35-37]. During chronic inflam-
mation, in diseases such as diabetes, free radicals are formed in excess and cannot
be effectively eliminated from the organism. Then, providing strong antioxidants
or free radical scavengers in diet or as a medicine could be advantageous.
As it was stated above, raw materials containing methylxanthines (caffeine,
theobromine, theophylline) are rich in polyphenols with strong antioxidant prop-
erties. Thanks to the content of phenolic compounds, these raw materials could
have many beneficial effects to health such as antiatherosclerotic effect.
Although methylxanthines exhibit some antioxidant properties, the main
components responsible for antioxidant activity are polyphenols. There were de-
scribed studies [26] that antioxidant activity of different types of chocolate posi-
tively correlated with the content of phenolic compounds.
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The aim of this work was to measure the antioxidant activity of these raw ma-
terials and study the correlation between antioxidant activity and the amount of
phenolic compounds in extracts.


White tea leaf from Camellia sinensis (L.) Kuntze (wt) – 44.5 g
Guaraná seeds from Paullinia cupana Kunth (gs) – 48.6 g
Yerba mate leaf from Ilex paraguariensis A. St.-Hil. (ym) – 39.8 g
Green tea leaf (gunpowder) from Camellia sinensis (L.) Kuntze (gt) – 50.0 g
Costa Rica coffee seeds from Coffea arabica L. (cc) – 48.0 g
Arabica coffee seeds from Coffea arabica L. (ca) – 46.0 g
Chocolate (Ristora) (cr) – 48.1 g
Chocolate (van Heuten) (ch) – 50.0 g
Chocolate (Tazza) (ct) – 48.1 g
Cacao (van Heuten) seed powder from Theobroma cacao L. (c) – 50.0 g
All raw materials were of commercial origin, edible quality.

Raw materials were extracted according to the modified method described by
Kasprzyk et al., [38] with methanol (900 ml) at a temperature of 50°C for 48 h.
Twenty percent of methanol extract (180 ml) was separated and concentrated
to dryness under reduced pressure to obtain the WA residue. The remaining
part of methanol extract (720 ml) was concentrated to dryness under reduced
pressure and then dissolved in 600 ml of water at 45°C. Water solution of ex-
tract was stored at 4°C for 48 h. The precipitate was separated with filter paper
(Filtrak, 388, 80 g/m
2
) and then dried under reduced pressure to obtain the WD
residue.
After precipitate separation, aqueous solution was exhaustively extracted with
ethyl acetate. Aqueous remaining and ethyl acetate solution were concentrated
to dryness under reduced pressure to obtain WB and WC residues, respectively.
Extracts from white tea were marked additionally with wt”, extracts from
guaraná seeds with “gs”, extracts from yerba mate ym”, extracts from green tea
with “gt”, extracts from Costa Rica coffee “cc”, extracts from Arabica coffee “ca”,
extracts from chocolate (Ristora) with “cr”, extracts from chocolate (van Heuten)
with “ch”, extracts from chocolate Tazza” with “ct”, and extracts from cacao
(van Heuten) with “c”. For example, extracts obtained from white tea leaves are
marked with WAwt, WBwt, WCwt and WDwt.
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During extraction to the ethyl acetate, in most cases the emulsion was formed,
which was individually separated and then condensed to dryness under reduced
pressure to obtain WE extract.

The amount of total phenolic compounds was measured with use the method
of Singleton and Rossi [39]. Seven ml of water, then 0.5 ml of Folin and Ciocalteu’s
phenol reagent (3H
2
O x P
2
O
5
x 13WO
3
x 5MoO
3
x 10H
2
O) and 0.5 ml of methanol
solution of extract was poured into the test tube. After 3 min, 2 ml of 20% aque-
ous solution of sodium carbonate was added. The mixture was heated at 100°C
for 1 min. After cooling, absorbency was measured at 685 nm. The measurement
was repeated for five times. Maximal error was calculated with total differential
method. Phenolic compounds were expressed as gallic acid and calculated in per-
centage per weight of extract.

Antiradical activity of extracts was measured by the method of Brand-Williams
et al. [40]. The decrease of absorbency of DPPH (2.2-diphenyl-1-picrylhydrazyl
radical) solution in methanol (94 µmol/l) at 515 nm is measured in the presence
of a substance with antiradical activity. The rate of the decrease of absorbance is
proportional to antiradical activity of the substance.
DPPH was dissolved in methanol (gradient grade, Merck). The reagent was prepared
a day before the experiment so that absorbency at 515 nm of solution was stable.
2 ml of DPPH solution (94 µmol/l) was placed in glass cuvette with optical path
of 1 cm. 50 µl of methanol solution of extract was added. The absorbance of the
solution was measured at 0 and 60 s.
The antiradical potential of the extract was demonstrated as a number of
antiradical units TAU
DPPH
per mg of extract (TAU
DPPH/mg
) and per g of raw material
(TAU
DPPH/g
) calculated according to the equations (1) and (2), respectively.
One unit of antiradical activity is the quantity of antioxidant that scavenges 1 µmol
of DPPH radical in 1 ml of reaction mixture during 1 minute of reaction at 25°C.
(1)
7990.0
10
c
AA
TAU
ss
DPPH/mg
=
(1)
The above equation was derived using absorption attenuation coefficient (ε)
equal to: 1.250910
4
L mol
-1
cm
-1
[40], where TAU
DPPH/mg
is the number of antiradical
units per mg of substance, A
s0
is absorbency of DPPH solution at the beginning of
the reaction, A
s1
is absorbency of DPPH solution after 1 min of reaction, c is con-
centration of substance in reaction mixture [mg/ml].
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Z. Sroka, M. Janiak, A. Dr
The number of antiradical units per gram of raw material (TAU
DPPH/g
) was cal-
culated by summing up all TAU
DPPH/mg
units calculated for all extracts multiplied
by the total mass of extracts obtained from given raw material according to the
equation:
/ / / / /
/
( )( )( )( )( )
(2)
DPPH mgWA WA DPPH mgWB WB DPPH mgWC WC DPPH mgWD WD DPPH mgWE WE
DPPH g
R
TAU m TAU m TAU m TAU m TAU m
TAU
W
⋅+ ⋅+ ⋅+ ⋅+
=
(2)
where TAU
DPPH/g
is the number of antiradical units calculated per g of raw material;
TAU
DPPH/mgWA,
TAU
DPPH/mgWB,
TAU
DPPH/mgWC,
TAU
DPPH/mgWD,
TAU
DPPH/mgWE
is the number of anti-
radical units per mg of extract WA, WB, WC, WD and WE respectively; m
WA,
m
WB,
m
WC,
m
WD,
m
WE
is whole mass of WA, WB, WC, WD, WE extracts [mg], respectively;
W
R
is mass of raw material [g] taken for extraction.

The number of antiradical units calculated per mg of extracts (TAU
DPPH/mg
) and
amount of phenolic compounds in extracts and raw materials (Ph%) is demonstrat-
ed in table 1, figure 1, and figure 2. The general observation is that the highest
values of TAU
DPPH/mg
were obtained for extracts WC for all investigated raw materi-
als; also the amount of phenolic compounds for this extract was the highest. The
strongest antiradical properties exhibited extracts from white tea, among them
WCwt was the strongest (6.86±0.55) among all investigated extracts. Similar,
in terms of antiradical activity, were extracts obtained from leaves of green tea.
Among them the strongest was WCgt extract (6.73±0.21).
WBc
1670.0 0.061±0.007 3.72±0.17
WCc
349.8 0.37±0.03 9.88±0.52
WDc
580.7 0.082±0.012 1.26±0.18
WEc
4.3 0.078±0.012 2.56±0.19
Figure. 1.
Number of antiradical units (TAU
DPPH/mg
) per mg of extracts obtained from white tea (wt), extracts
from guarana seeds (gs), extracts from yerba mate (ym), extracts from green tea (gt). As a positive
control trolox was used, in figure marked with light gray colour
Figure 1.
Number of antiradical units (TAU
DPPH/mg
) per mg of extracts obtained from white tea (wt), extracts
from guaraná seeds (gs), extracts from yerba mate (ym), extracts from green tea (gt).
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Figure 2.
Number of antiradical units (TAU
DPPH/mg
) per mg of extracts obtained from coffee Costa Rica (cc),
coffee Arabica (ca), chocolate Ristora (cr), chocolate van Heuten (ch), chocolate Tazza (ct) and cacao
(c). As a positive control trolox was used, in figure marked with light grey colour
Figure 2.
Number of antiradical units (TAU
DPPH/mg
) per mg of extracts obtained from coffee Costa Rica (cc), coffee
Arabica (ca), chocolate Ristora (cr), chocolate van Heuten (ch), chocolate Tazza (ct) and cacao (c).
 
The weight of extracts [mg], number of antiradical units per mg of extract (TAU
DPPH/mg
), amount of
phenolic compounds in extracts expressed in percentage, number of antiradical units per g of raw
material (TAU
DPPH/g
), amount of phenolic compounds in raw materials (Ph%) expressed in percentage.
Raw
material
Extract
Weight of
extract [mg]
TAU
DPPH/mg
The amount
of phenolic
compounds in
extracts [w/w]
TAU
DPPH/g
The amount of
phenolic compounds
in raw materials Ph%
[w/w]

 2523.9 6.16±0.78 43.2±3.22
1268.6±133.5 12.26±10.57
 4606.8 2.55±0.10 21.1±2.25
 3160.6 6.86±0.55 65.6±3.24
 2616.6 2.66±0.17 49.2±2.23
 213.8 2.45±0.11 15.8±0.89

 1654.5 3.10±0.31 30.5±2.01
474.8±44.6 4.42±3.93
 1899.6 1.98±0.21 18.1±1.29
 1518.7 4.12±0.35 37.1±2.55
 2226.3 3.55±0.16 33.2±2.25

 1701.8 1.17±0.45 23.5±1.46
445.8±62.4 4.21±4.26
 4095.4 1.98±0.16 17.6±1.37
 1220.8 4.98±0.25 41.3±3.16
 555.7 2.76±0.17 9.3±1.42

 2984.7 4.45±0.15 30.4±5.07
1184.4±64.4 9.79±0.56
 4808.4 1.71±0.12 15.84±2.64
 2831.4 6.73±0.21 59.2±9.87
 3474.2 5.32±0.11 42.09±7.01
 420.5 0.39±0.08 20.17±3.36
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Z. Sroka, M. Janiak, A. Dr
Raw
material
Extract
Weight of
extract [mg]
TAU
DPPH/mg
The amount
of phenolic
compounds in
extracts [w/w]
TAU
DPPH/g
The amount of
phenolic compounds
in raw materials Ph%
[w/w]

 1168.9 0.57±0.10 10.98±3.85
60.9±6.5 1.36±0.19
 1168.3 0.73±0.005 11.79±1.39
 831.2 0.71±0.075 24.06±0.83
 1245.2 0.32±0.05 9.39±1.25
 76.7 0.52±0.04 13.43±0.46

 998.0 0.34±0.02 6.14±1.88
41.8±4.2 0.94±0.15
 1237.9 0.57±0.02 13.63±0.94
 644.8 0.76±0.075 20.11±2.60
 1530.4 0.24±0.034 4.63±1.56
 36.5 0.44±0.038 12.53±1.0

 857.8 0.065±0.008 1.51±0.13
6.3±1.1 0.088±0.004
 3238.5 0.055±0.009 0.59±0.10
 75.3 0.56±0.067 9.85±1.72
 212.3 0.11±0.024 2.25±0.20
 67.8 0.06±0.01 1.54±0.19

 2033.4 0.068±0.01 1.81±0.20
10.4±3.2 0.260±0.052
 7757.0 0.031±0.01 0.77±0.20
 131.6 0.56±0.065 16.52±0.68
 348.6 0.10±0.007 1.23±0.38
 194.4 0.17±0.03 3.77±1.13

 671.4 0.05±0.006 1.37±0.30
3.0±0.44 0.067±0.02
 2405.9 0.029±0.003 0.51±0.29
 86.2 0.29±0.025 8.54±0.58
 207.1 0.05±0.015 1.0±0.17
 92.4 0.04±0.006 0.82±0.08
 646.2 0.28±0.008 5.73±0.55
9.2±0.87 0.282±0.019
 1670.0 0.061±0.007 3.72±0.17
 349.8 0.37±0.03 9.88±0.52
 580.7 0.082±0.012 1.26±0.18
 4.3 0.078±0.012 2.56±0.19
WA - methanol extract, WB - water remaining extract, WC - ethyl acetate extract, WD - precipitate,
WE - emulsion (layer formed between the water and ethyl acetate), wt” white tea, “gs” guaraná
seeds, ym” yerba mate, “gt” green tea, “cc” coffee seeds (Costa Rica), “ca” coffee seeds (Arabica),
“crchocolate Ristora, “ch” chocolate van Heuten, “ct” chocolate Tazza, “c” cacao. Value TAU
DPPH/mg
for trolox is 3.22 ± 0.06.
  
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Vol. 61 No. 3 2015
White and green tea extracts appeared to be the strongest antiradicals, and
white tea was even more active than green tea. Our previous research exhibited
strong antiradical features of green tea leaves [41]. Green and white teas do not
undergo a fermentation process. These two kinds of teas contain phenolic com-
pounds such as gallocatechin and gallocatechin gallate [5], which appeared to be
very effective antiradical scavengers.
The raw materials such as yerba mate (ym) and guaraná seeds (gs) appeared to
have lower antiradical properties than those of white and green teas (tab. 1, fig. 3).
Yerba mate contains many classes of caffeoyl derivatives (caffeic, chlorogenic and
5-caffeoylquinic acids and flavonoids, such as rutin [9]. Phenolic compounds present
in yerba mate leaves exhibit the antioxidant activity in vitro and in vivo, and have the
ability to scavenge free radicals and reactive oxygen species [10, 11].
Figure. 3.
Number of antiradical units per g of raw material (TAU
DPPH/g
) for white tea (wt), guarana seeds (gs),
yerba mate (ym), green tea (gt)
Figure 3.
Number of antiradical units per g of raw material (TAU
DPPH/g
) for white tea (wt), guaraná seeds (gs),
yerba mate (ym), green tea (gt)
Guaraná seeds is a raw material rich in methylxanthine derivatives, and contain
more caffeine than other raw materials [42]. This raw material contains polyphe-
nols with strong antioxidant activity such as tannins, especially condensed tannins
[4]. It is believed that condensed and hydrolysable tannins apart from antioxidant
activity have other therapeutic properties [43, 44].
Our investigation showed that extracts obtained from coffee seeds (cc, ca) have
average antioxidative activity (tab. 1, fig. 2). The antioxidant features are posi-
tively correlated with amount of phenolic compounds in these extracts (tab. 1).
Correlation coefficient (r) between amount of phenolic compounds in extracts
and number of antiradical activity TAU
DPPH/mg
was equal to 0.91 (fig. 4). Correlation
coefficient (r) between amount of phenols and number of activity units in raw
materials (TAU
DPPH/g
) was equal to 0.99.
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Z. Sroka, M. Janiak, A. Dr
Figure 4.
Correlation coefficient (r) between number of antiradical units per mg of extract (TAU
515/mg
) and
amount of phenolic compounds in extracts (% w/w)
Seeds of coffee are known to contain effective antiradical phenolic compounds
such as caffeic and chlorogenic acids [45]. The chlorogenic acid, apart from an-
tioxidant activity, also exhibits some astringency and bitterness. Other phenolic
compounds present in coffee seeds are ferulic, p-coumaric, vanillic, and syringic
acids [46], which are rather weak antioxidants. Phenolic compounds play an im-
portant role in the quality and flavor of coffee seeds. Other compounds present
in coffee seeds with antioxidant activity are melanoidins [47] and caffeine [48].
Our investigation showed that chocolates (cr, ch, ct) appeared to be the weak-
est antioxidants among all raw materials investigated in this work (tab. 1, fig. 5),
which correlated positively with small amount of phenolic compounds. Choco-
late has variable amounts of phenolic compounds. White chocolate contains
low amounts of phenols, dark chocolate is rich in phenols [45]. The amount of
phenolic compounds correlated positively with antioxidant activity in dark, milk
and white chocolate [49]. According to Miller et al. [19] the antiradical activity
varies from 66.7±8.7 (µmol TE/g) for chocolate syrup to 499±35.5 (µmol TE/g)
for baking chocolate and even to 816±37.6 (µmol TE/g) for cacao powder. The
main phenolic compounds present in chocolate are epicatechin, catechin, pro-
cyanidin B2, procyanidin C1, and procyanidin B5 which are antioxidants, valu-
able for health [50].
In our research, cacao powder and extracts from this raw material were found
to be weak antioxidants (tab. 1, fig. 5). The literature describes rather strong an-
tiradical activity of cocoa [19, 51] due to presence of high amounts of phenolic
compounds.
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Antiradical activity and amount of phenolic compounds in extracts obtained from some plant raw materials containing...
Vol. 61 No. 3 2015
Figure. 5.
Number of antiradical units per g of raw material (TAU
DPPH/g
) for (Costa Rica) coffee (cc), (Arabica)
coffee (ca), (Ristora) chocolate (cr), (van Heuten) chocolate (ch), (Tazza) chocolate (ct), cacao (c)
Figure 5.
Number of antiradical units per g of raw material (TAU
DPPH/g
) for Costa Rica coffee (cc), Arabica coffee
(ca), Ristora chocolate (cr), van Heuten chocolate (ch), Tazza chocolate (ct), cacao (c)

1. It can be concluded that the extracts of non-fermented, white and green teas
exhibited very high antioxidant features. Much lower activity was observed for
guaraná seeds and yerba mate leaves, and chocolates and cocoa powder ap-
peared to be the weakest antioxidants.
2. The antioxidant properties highly positively correlated with the amount of
phenolic compounds.

The authors would like to thank the technical staff of the Department of Phar-
macognosy, Wrocław Medical University for the help in the research.
The study was financially supported by the Wroclaw Medical University, grant
No. ST-527.

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AKTYWNOŚĆ PRZECIWRODNIKOWA ORAZ ZAWARTOŚĆ ZWIĄZKÓW FENOLOWYCH
W WYCIĄGACH OTRZYMANYCH Z SUROWCÓW ROŚLINNYCH ZAWIERAJĄCYCH ALKALOIDY
METYLOKSANTYNOWE
ZBIGNIEW SROKA
1*
, MARIA JANIAK
1
, ANDRZEJ DR
2
1
Katedra i Zakład Farmakognozji
Wydział Farmaceutyczny z Oddz. Analityki Medycznej
Uniwersytet Medyczny we Wrocławiu
ul. Borowska 211a, 50-556 Wrocław
2
Katedra i Zakład Chemii Fizycznej
Wydział Farmaceutyczny z Oddz. Analityki Medycznej
Uniwersytet Medyczny we Wrocławiu
ul. Borowska 211a, 50-556 Wrocław
*autor, do którego należy kierować korespondencję: tel.: +4871 784 0220,
faks: +4871 784 0218, e-mail: zbigniew.sroka@umed.wroc.pl
Streszczenie
Surowce takie jak yerba mate, guaraná , biała i zielona herbata, nasiona kawy, czekolada
i kakao zawierające alkaloidy metyloksantynowe były badane na zawartość związków fe-
nolowych i aktywność przeciwutleniającą. Poziom związków fenolowych określono meto-
dą kolorymetryczną za pomocą odczynnika Folin-Ciocalteu, a właściwości przeciwutlenia-
jące mierzono stosując rodnik DPPH (difenylo-pikrylohydrazylowy). Ilość związków feno-
lowych wyrażono w procentach masy wyciągów i surowców. Potencjał przeciwrodnikowy
określono jako liczbę jednostek TAU
DPPH
na mg wyciągów i g surowców. Największą liczbę
jednostek przeciwrodnikowych TAU
DPPH
oraz najwyższą zawartość związków fenolowych
wykazano dla białej herbaty i wyciągów otrzymanych z tego surowca, a najniższe wartości
uzyskano dla czekolady. Współczynnik korelacji pomiędzy ilością związków fenolowych
i aktywnością przeciwrodnikową surowców wynosił r=0,994.
 przeciwutleniacze, zmiatacze wolnych rodników, wyciągi roślinne, fenole roślin-
ne, surowce zawierające alkaloidy metyloksantynowe, jednostki przeciwrodnikowe
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... Then, there was an indication that a group of methylxanthine compounds such as theobromine and caffeine could be considered as sources of antioxidants. However, the radical scavenging ability of methylxanthine compounds has not been proven in major reports (Sroka et al., 2015;Petrucci et al., 2018). Although Table 2 indicates that there was a possible relationship between total theobromine and antioxidant capacity, previous studies had focused only on the antioxidant capacity of cocoa sourced from polyphenol contents (Cádiz-Gurrea et al., 2014;Todorovic et al., 2015). ...
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Industrial processing modified the polyphenol content, composition and antioxidant activity of the yerba mate extracts. Pre-dried leaves were the most appropriate raw material combining maximum activity with high polyphenol content. Chlorogenic acid and its derivatives were the major components of the phenolic fraction but we also identified caffeic, rutin and quercetin.Yerba mate extracts inhibited malonedialdehyde formation in sunflower oil (20 μmol/kg) and conjugated dienes production in oil/water emulsions (60 μmol/kg). Enhancing the dose to 60 μmol/kg reduced 27.8% the extract’s activity in oil.The relationship between polyphenol composition and antioxidant activity of a mixture of caffeic, chlorogenic, kaempferol, quercetin and rutin was satisfactorily predicted with a polynomial model. Results showed that quercetin was the highest contributor to the linear term followed by kaempferol and caffeic acid while rutin and chlorogenic acid inputs were the lowest. The model detected five synergistic and six antagonistic effects.
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The consumption of high-cacao-content chocolate has been associated with positive health benefits ascribed to flavanol [corrected] antioxidants derived from the ground, fermented cocoa seeds of Theobroma cacao. However, flavanols [corrected] impart a bitter, astringent flavor to foodstuffs, frequently masked in chocolates and confections by aggressive processing and adulteration with other flavors. Recent reports have implied that not all varieties of dark chocolate are created equally, and significant caveats exist regarding its potential health benefits. It is perhaps not surprising that extensive processing, dilution, and the addition of flavor modifiers may improve the palatability of chocolate, but could have negative nutritional and clinical benefits. This article examines the chemical composition of chocolate and the clinical data associated with the consumption of flavonoid-rich cocoa. We review the steps in chocolate manufacturing that directly affect the antioxidant levels in chocolate products, and the caveats associated with claims of health benefits from the consumption of dark chocolate.