Download variability of antioxidant activity among honeybee

VARIABILITY OF ANTIOXIDANT ACTIVITY AMONG
HONEYBEE-COLLECTED POLLEN OF DIFFERENT
BOTANICAL ORIGIN
Norma Almaraz-Abarca, Maria da Graça Campos, J. Antonio Ávila-Reyes,
Néstor Naranjo-Jiménez, Jesús Herrera-Corral and Laura S. González-Valdez
SUMMARY
The antioxidant activities of total extracts of a mixture of
honeybee-collected pollen and its six constituent pollens were determined by lipid peroxidation assay by the thiobarbituric acid
reactive substances (TBARS) test on hepatic microsomal preparations and by free radical scavenging (2,2-diphenyl-1-picrylhydrazyl; DPPH*) method. Activities were compared to the flavonol
and phenolic acid compositions and flavonol contents in pollen.
Introduction
Honeybee-collected pollen is
recognized as a well balanced
food (González-Güerca et al.,
2001). This beehive product
also has several useful pharmacological properties, such as
antibiotic,
antineoplasic,
antidiarrhoeatic and as an antioxidant agent (Campos, 1997).
The antioxidant activity of
honeybee-collected pollen has
been recognized as a free radi-
cal scavenger and as a lipid
peroxidation inhibitor (Campos
et al., 1994; Campos, 1997).
This activity has been associated with the phenolic pollen
content (Campos, 1997). Usually, honeybee-collected pollen
is a mixture of pollen pellets
from different botanical origins, each one being an important source of flavonol glycosides (Wiermann and Vieth,
1983) and, in some species, of
hydroxycinnamic acids (Cam-
All extracts showed antioxidant activities as radical scavenger
substances and as inhibitors of lipid peroxidation. Antioxidant
activities were different for each species and were not clearly
associated to the flavonol content in pollen. Pollen of Amaranthus hybridus was a potent lipid oxidation inhibitor, and that of
Tagetes sp. and the whole mixture were effective antiradical substances.
pos, 1997). These compounds
are found in a species-specific
profile (Campos, 1997), which
suggests that honeybee-collected pollen from different areas or seasons could have different antioxidant activities. In
spite of the relevance of honeybee-collected pollen as an
antioxidant substance, there is
not enough systematic information about the antioxidant
activity levels associated to the
flavonol content and profile of
honeybee-collected pollen
from different botanical origins. The purpose of the
present study was to evaluate
the effectiveness of total extracts of a mixture of honeybee-collected pollen and its
constituent pollens from
Durango, Mexico, as free radical scavengers and as inhibitors of lipid peroxidation, and
correlate the flavonol contents
and profiles with the variability in the observed activities.
KEYWORDS / Antioxidant Activity / Flavonoid Profile / Free Radical Scavenging Activity / Honeybee-collected Pollen /
Received: 04/20/2004. Modified: 08/11/2004. Accepted: 08/13/2004.
Norma Almaraz-Abarca. Biologist,
Universidad Nacional Autónoma
de México (UNAM). Doctor in
Plant Physiology, Instituto Politécnico Nacional (IPN), Mexico.
Researcher, Centro Interdisciplinario de Investigación para
el Desarrollo Integral Regional,
IPN, Durango (CIIDIR-IPNDgo.). Address: Biotechnology
Laboratory, CIIDIR-IPN. Sigma
s/n Frac. 20 de Noviembre II,
574
Durango, Dgo., Mexico. CP
34220. e-mail: [email protected]
Maria da Graça Campos. Doctor in
Phrmacology, Universidade de
Coimbra, Portugal. Professor,
School of Pharmacy, Universidade de Coimbra, Portugal.
José Antonio Ávila-Reyes. Biologist, UNAM. M.Sc. in Science
Methodology, IPN. Doctoral
Candidate, UNAM. Researcher,
CIIDIR-IPN-Dgo., Mexico.
0378-1844/04/10/574-05 $ 3.00/0
Néstor Naranjo-Jiménez. Biologist,
IPN, México. M.Sc. in Ruminal
Nutrition Biotechnology, Universidad Juárez del Estado de Durango (UJED), Mexico. Doctoral
Candidate, Universidad Autónoma de Zacatecas (UAZ), México. Researcher, CIIDIR-IPNDgo., Mexico.
Jesús Herrera-Corral. M.Sc. in Ruminal Nutrition Biotechnology,
Universidad Juárez del Estado de
Durango (UJED), México. Doctoral Candidate, Universidad
Autónoma de Zacatecas (UAZ),
Mexico. Researcher, CIIDIRIPN-Dgo., Mexico.
Laura Silvia González-Valdez. Biochemical Engineer and M.Sc. in
Biochemistry, Instituto Tecnológico de Durango (ITD), Mexico.
Researcher, CIIDIR-IPN-Dgo.,
Mexico.
OCT 2004, VOL. 29 Nº 10
RESUMEN
Se determinaron las actividades antioxidantes de los extractos
crudos de una mezcla de polen apícola y de cada uno de los seis
polen constituyentes que formaban esa mezcla. Las determinaciones
se hicieron por el método de sustancias reactivas al ácido
tiobarbitúrico (TBARS) en preparaciones microsomales de hígado y
por el método del bloqueo del radical libre 2,2-difenil-1picrilhidracilo (DPPH*). Las actividades se compararon con la
composición de flavonoles y ácidos fenólicos y con los contenidos
de flavonoles en el polen. Todos los extractos mostraron actividades
antioxidantes. Éstas fueron diferentes para cada especie y no
estuvieron claramente asociadas al contenido de flavonoles en el
polen. El polen de Amarathus hybridus mostró una alta capacidad
inhibidora de la oxidación lipídica. El de la mezcla entera y el de
Tagetes sp. fueron efectivos bloqueadores de radicales libres.
RESUMO
Determinaram-se as atividades antioxidantes dos extratos
crus de uma mescla de pólen apícola e de cada um dos seis
polens constituintes que formavam essa mescla. As determinações
se fizeram pelo método de substâncias reativas ao ácido
tiobarbitúrico (TBARS) em preparações microssomais de fígado e
pelo método do bloqueio do radical livre 2,2-difenil-1picrilhidracilo (DPPH*). As atividades se compararam com a
Materials and Methods
Microscopic examination
Chemicals
Honeybee-collected pollen
was manually sorted by pellet
color into different types, as
previously described (Campos,
1997). Fifteen pollen pellets
from each type and five
samples of anther pollen were
individually submitted to microscopic examination to define
the botanical origin and homogeneity of the constituent
pollens of the mixture of honeybee-collected pollen. Pollen
samples were previously acetolyzed (Erdtman, 1966). An
Olympus BX 40 microscope
was used.
Standards for ascorbic acid,
caffeic acid, quercetin, quercitrin and p-coumaric acid; 2,2diphenyl-1-picrylhydrazyl
(DPPH*); analytical grade absolute ethanol, n-butanol and
aluminum chloride, and HPLC
grade methanol, and acetonitrile
were purchased from Sigma,
USA.
Pollen samples
The mixture of honeybeecollected pollen was provided
by local beekeepers expressly
for this research. This sample
represents the collection from
La Parrilla, Durango, Mexico,
harvested in September 1999.
Pollen from the anthers of
flowers of Zea mays L. (Poaceae), Tagetes sp. (Compositae), Amaranthus hybridus L.
(Amaranthaceae), Solanum
rostratum Dun. (Solanaceae),
Bidens odorata Cav. (Compositae) and Ranunculus petiolaris HBK. (Ranunculaceae),
among others, was collected
from plants growing in the
surroundings of the beehives.
The voucher specimens were
placed in the Herbarium of the
Centro Interdisciplinario de
Investigación para el Desarrollo Integral Regional (CIIDIR)
and all the species were identified by Socorro González, herbarium botanist.
Preparation of extracts
Twenty grams of the mixture of honeybee-collected pollen and of each of the constituent pollens were individually extracted five times in
200ml ethanol-water solution
(50% v/v) with a 60min maceration. The extracts were
separated by centrifugation
(15269g) for 10min. All the
supernatants of each type were
brought together and formed
the total extracts. These total
extracts were evaporated to
dryness at low-pressure.
HPLC analysis
Single pellets of each type
were extracted with ethanolwater (50% v/v; 1ml) and sonicated for 60min. The resultant
OCT 2004, VOL. 29 Nº 10
composição de flavonóis e ácidos fenólicos e com os conteúdos de
flavonóis no pólen. Todos os extratos mostraram atividades antioxidantes. Estas foram diferentes para cada espécie e não estiveram claramente associadas ao conteúdo de flavonóis no pólen. O
pólen de Amarathus hybridus mostrou uma alta capacidade
inibidora da oxidação lipídica. O da mescla inteira e o de Tagetes
sp. foram efetivos bloqueadores de radicais livres.
mixtures were centrifuged
(15269g) for 10min and the supernatants used for high pressure liquid chromatographic
(HPLC) analysis, as previously
described (Campos, 1997). Extracts (20µl) were analyzed on
a Gylson 305 HPLC system,
UV detector Gilson 170 and
Waters Spherisorb S50D52
(5µm) column (4.6x250mm) by
an acidified acetonitrile-water
gradient (Campos, 1997). Standard chromatograms were plotted at 340nm. Spectral data for
all peaks were accumulated in
the range 220-400nm using diode-array detection. Samples of
pollen collected directly from
anthers were analyzed in the
same manner.
Determination of flavonol
content
Flavonol contents were determined by linear regression
analysis from the standard
curve of quercetin (1 to 50µg/
ml vs. absorbance): Abs425nm= 0.00221 + 0.054899 [Quercetin], correlation coefficient r=
0.9973 and from calibration
curves of each total extract (1
to 400µl vs. absorbance). Curves were registered after the
addition of aluminum chloride.
Absorbances were registered at
425nm. Flavonol contents were
expressed in µg of quercetin/g
of polen dry matter, according
to the flavonol predominance in
this reproductive structure
(Campos, 1997).
Free radical scavenging activity
Modifications to DPPH*
method reported elsewhere
(Campos, 1997) were used to
evaluate the free radical scavenging activity. Four concentrations (0 to 400µl, respective
concentrations of flavonols calculated from calibration curves
and standard curve of quercetin) of each sample were individually added to a DPPH* solution (3.422µg/ml in ethanolwater, 50% v/v) in such a way
as to maintain a final volume
of 2ml. The decrease in absorbance was determined at
523nm after 10min. The
DPPH* concentrations in the
reaction medium against the
flavonol concentrations of
samples were plotted to determine, by linear regression, the
efficient concentration at 50%,
defined as the amount of antioxidant needed to decrease by
50% the initial DPPH* concentration (EC50). The standards
for ascorbic acid, caffeic acid,
quercetin, quercitrin and pcoumaric acid, were also evaluated. The following calibration
curve, made with DPPH* between 1.0 and 6.6µg/ml, was
used to calculate the DPPH*
concentration (µg/ml) in the reaction medium: A 523nm=
0.00021 + 0.02916 [DPPH*],
correlation coefficient r=
0.9999. Antiradical activities
were expressed in relation to a
comparable constant dry weight
in terms of EC50 in µg/ml.
575
Lipid peroxidation assay
Determination of inhibition
of lipid peroxidation was made
by quantification of thiobarbituric acid reactive substances
(TBARS) by a modification of
the methods used by Ohkawa
et al. (1979) and Uchiyama
and Mihara (1978) on mouse
liver microsomal preparations.
The amounts of thiobarbituric
acid reactants were expressed
in terms of the malondialdehyde (MDA) concentrations (µg/
ml). The livers of decapitated
CF1 mice (Instituto Nacional
de Virología, Mexico) were
washed with ice-cold 0.9%
NaCl and homogenated in
chilled 1.15% KCl in a ratio of
1g of wet tissue to 9ml of KCl
solution. Microsomal fractions
were prepared according to
Diczfalusy et al. (1996). Protein assay was performed on
microsomal fractions by the
method of Lowry (García and
Vázquez, 1998). The reaction
mixtures composed of 100µl
microsomal suspension (86µg
of protein/ml), 0-100µl of assay
substance (respective concentrations of flavonols calculated
from calibration curves and
standard curve of quercetin),
50µl of an aqueous solution of
6.95mg of FeSO4 and 17.62mg
of ascorbic acid, and a variable
volume of Tris-HCl buffer
(10mM, pH 7.4) in such a way
as to maintain a constant final
volume of 500µl (Campos,
1997), were incubated at 37ºC
for 30min in capped tubes. After cooling in tap water, 3ml of
an aqueous solution of phosphoric acid (1%) and 1ml of
an aqueous solution of thiobarbituric acid (0.6%) were added
to each tube. The mixtures
were heated to boiling for
60min in sealed tubes. After
cooling in tap water, 4ml of nbutanol was added, and the
mixture was shaken vigorously.
After centrifugation at 10179g
for 10min, the MDA content
was determined by measuring
the absorbance of the organic
layer at 535nm. Reference substances (quercetin and caffeic
acid) were assayed at four concentrations. Lipid inhibition activities were expressed in terms
of the concentration of antioxi-
576
TABLE I
CONSTITUENT POLLENS (% WEIGHT) OF A MIXTURE OF DURANGO, MEXICO,
HONEYBEE-COLLECTED POLLEN AND THEIR MAJOR PHENOLS
Constituent pollen
%
Pollen
color
Retention time
(min)
Major phenols
Zea mays (G1)
24
Yellow
Tagetes sp. (G2)
20
Brown yellow
Amaranthus hybridus (G3)
18
Green
Solanum rostratum (G4)
17
Green yellow
Bidens odorata (G5)
14
Orange
Ranunculus petiolaris (G6)
7
Pale yellow
30.47
33.24
35.01
35.72
36.49
38.87
34.76
36.54
37.88
50.14
53.27
34.02
34.09
34.17
34.69
37.82
36.43
39.58
43.52
45.09
46.03
52.97
38.61
39.60
53.56
44.56
45.18
46.03
47.11
53.06
Quercetin glycoside
Lutheolin derivative ?
Flavonol glycoside
Flavonol glycoside
Quercetin glycoside
Quercetin glycoside
Quercetin glycoside
Kaenferol glycoside
Kaenferol glycoside
Cinnamic acid derivative
Cinnamic acid derivative
Flavonol glycoside
Flavonol glycoside
Flavonol glycoside
Flavonol glycoside
Flavonol glycoside
Kaenferol glycoside
Cinnamic acid derivative
Cinnamic acid derivative
Cinnamic acid derivative
Cinnamic acid derivative
Cinnamic acid derivative
Quercetin glycoside
Quercetin glycoside
Cinnamic acid derivative
Quercetin glycoside
Quercetin glycoside
Kaenferol glycoside
Kaenferol glycoside
Cinnamic acid derivative
dant required to inhibit MDA
formation by 50% values (IC50
in µg/ml), calculated from absorbances against the sample
flavonol concentrations curves
by linear regression, using the
extinction coefficient of MDA
(1.56·105M-1·cm-1).
Statistical analysis
The analyses were carried
out in triplicate. Data were
separated by an analysis of
variance (p≤0.05) and means
separated by Duncan's multiple
range test. The results were
processed by COSTAT computer program (1982).
Results and Discussion
Microscopic examination
On the basis of color, six
types of pollen pellets were
found in the mixture of honeybee-collected pollen (Table I).
Microscopic examination of all
pollen samples showed that
each pellet of the honeybeecollected pollen was largely
homogeneous, confirming the
observation (Campos et al.,
1997) that pollen pellets predominantly consist of pollen
grains from one species. The
direct microscopic comparison
between the different types of
pollen pellets and the pollen
collected from anthers provided
evidence of the botanical origin
of the six constituent pollens.
The botanical identifications are
showed in Table I.
These results reflect the
complexity in terms of number of constituent pollens of
this honeybee-collected pollen, in contrast with other reports (Serra et al., 2001)
where monofloral pollen was
reported as a frequent condition in honeybee-collected
pollen. Regarding species
dominance, in this mixture of
honeybee-collected pollen codominance of practically five
species of plants is found.
These results and others as yet
not reported do not agree with
those of Campos et al. (1997),
who reported that the major
pollen types represented in any
one bee pollen tends to be
rather small. It has been
claimed that bees are selective in their harvesting of pollen of wild over cultivated
species of plants. It is of interest that in the present, as
well as in other studies as yet
not reported, analysis of mixtures of honeybee-collected
pollen from Durango, Mexico,
it is observed that pollen from
Zea mays, a cultivated and
anemophile plant, is found
with the highest percentage.
This implies that pollen collection behavior may be determined by a more complex
combination of factors than it
has been thought.
OCT 2004, VOL. 29 Nº 10
TABLE II
ANTIOXIDANT ACTIVITIES OF REFERENCE SUBSTANCES
Compounds
EC50 (µg/ml)*
Quercetin
Quercitrin
Caffeic acid
Ascorbic acid
p-coumaric acid
0.4
1.1
0.3
0.6
±0.007
±0.01
±0.004
±0.003
NA
IC50 (µg/ml)*
2.2 ±0.1
**
1.7 ±0.3
**
**
* Samples analyzed in triplicate. ** Not evaluated. NA: no activity.
Figure 1. Disappearance of DPPH* in the presence of increasing flavonol concentrations for total extract of whole mixture of honeybeecollected pollen.
HPLC analysis
As found by other authors
(Campos et al., 1997) the botanical origin of constituent
pollens could be confirmed by
direct comparison of the respective HPLC phenolic profiles with those of the pollen
collected from anthers. The
phenolic profile of any constituent pollen from the mixture
of honeybee-collected pollen
was identical to that of the species it came from. These results do not agree with those of
Serra et al. (2001), who indicate that the specific plant origin of honeybee pollen can not
be distinguished from its HPLC
profile. Under the experimental
conditions in which HPLC
chromatograms were obtained
(Campos, 1997), patterns comprising flavonoids and cinnamic
acid derivatives were the only
ones found (Table I). All
pollens individually analyzed
contained flavonol glycosides,
specially quercetin and
kaempferol derivatives, compounds with a broad spectrum
of biological activity (Formica
and Regelson, 1995; Campos,
1997). Pollen from Solanum
rostratum was particularly rich
in phenolic acid derivatives and
those from Zea mays and Amaranthus hybridus were characterized by the absence of phenolic acid derivatives.
Free radical scavenging
The reduction of DPPH*
concentration with increasing
flavonol concentration was observed in all total extracts. The
reduction was linear and dependent on the flavonol concentrations in the samples. According with the classification
of kinetic behavior of BrandWilliams et al. (1995), the reaction kinetics was “rapid”,
reaching a steady state in less
than one minute. The spectrometric recording of the DPPH*
disappearance in the presence
of increasing flavonol concentrations of total extract of mixture G is shown in Figure 1.
These results show a clear correlation between the flavonol
concentration and antiradical
activity for the kinetic behavior
of DPPH* disappearance, as
was reported for some phenolic
compounds (Brand-Williams et
al., 1995), vegetable oils (Espín
et al., 2000) and wine and
grape fruits (Sánchez-Moreno
et al., 1999). However, a clear
correlation between the flavonol content in pollen and the
antiradical activity seems to be
more difficult to establish.
Table II contains the EC 50
values of the reference compounds used; caffeic acid has
the highest free radical scavenging capacity (EC50= 0.3µg/
ml) among the tested standards and quercitrin has the
lowest (EC50= 1.1µg/ml). This
property was intermediate for
quercetin and ascorbic acid
(EC50= 0.4 and 0.6µg/ml, respectively). It is known that pcoumaric acid has a slow kinetic behavior, taking more
than an hour to reach a steady
state in the reaction with
DPPH* (Brand-Williams et al.,
1995). The absence of activity
in this case was due to the fact
that the evaluation of its antiradical activity was made after
10 minutes. Other authors have
also reported a higher activity
for caffeic acid than for ascorbic acid by the DPPH* method
(Brand-Williams et al., 1995).
Quercetin, a flavonol aglycon,
is a more potent antiradical
TABLE III
ANTIOXIDANT ACTIVITY AND FLAVONOL CONTENT IN THE MIXTURE
OF HONEYBEE-COLLECTED POLLEN AND CONSTITUENT POLLENS
Total extracts
Total flavonol content
EC50 (µg/ml)*
IC50 (10–1µg/ml)*
(µg/g dry matter of pollen)*
Mixture (G)
G6
G2
G3
G4
G1
G5
3435.1
1648.3
534.1
506.0
448.0
402.8
183.6
±85.0
±42.1
±5.8
±4.4
±2.9
±2.3
±6.9
6.4
9.9
6.8
14.0
8.4
10.3
9.3
±0.3 d
±0.3 b
±0.3 d
±0.9 a
±0.7 c
±0.6 b
±0.3 b
0.7
5.2
2.6
0.7
5.9
16.2
3.6
±0.04 d
±0.4 b
±0.1 c
±0.01 d
±0.5 b
±2.3 a
±0.3 c
* Samples analyzed in triplicate. Different letters in the same column mean significant differences (p≤0.5).
OCT 2004, VOL. 29 Nº 10
substance than quercitrin,
which is a quercetin monosaccharide derivative with a C 3
rhamnosyl substituent. It is
known that only C3 disaccharide derivatives have a drastically reduced antiradical activity (Von Gadow et al., 1997).
The total extracts of honeybee-collected pollen mixture
and the six different constituent pollens were effective antioxidants as free radical scavengers, although with lower
levels of antiradical activities
than all the standards tested.
Antiradical activity (EC50) and
flavonol content in pollen were
calculated in all the cases,
looking for a correlation between the two measurements.
The antiradical activities and
the flavonol contents in the
mixture and in the individual
pollens appear in Table III,
where samples are listed in
decreasing flavonol content.
Contrary to reports for the extracts from reproductive organs
of Crataegus monogyna
(Bahorun et al., 1994), a correlation between the flavonol
content in pollen and antiradical activity is not apparent for
the total extracts.
Significant differences were
found among the EC50 values
of pollen of species of plants
analyzed. The mean separation
by Duncan's multiple range
test is shown in Table III. Pollen from Amaranthus hybridus
(G3) had the lowest antiradical
activity (EC50= 14.0µg/ml, labelled a). Those from Zea
mays (G1), Ranunculus petiolaris (G6) and Bidens odorata
(G5) had intermediate levels
of activity (EC 50= 10.3, 9.9
and 9.3µg/ml, respectively)
without significant differences
among them despite large differences in flavonol content.
Pollen from Solanum rostra-
577
Figure 2 Reduction of MDA concentration with the increase of flavonol concentration in the total extract of constituent pollen G3.
tum (G4) was grouped individually and showed a high
level of antiradical activity
(EC50= 8.4µg/ml), while that
from Tagetes sp. (G2) and the
whole mixture had the highest
antiradical activity (EC50= 6.8
and 6.4µg/ml, respectively),
without significant differences
between them.
Comparing the antiradical
scavenging activity of the total
extract of the mixture of honeybee-collected pollen and
those of its six constituent
pollens individually, no correlation seems to exist between
the flavonol content and the
antiradical activity for pollen
from different botanical origins. The results suggest that
the flavonol and phenolic acid
composition, rather than the
concentration, could be the determinant factor. The particular
combination of flavonol glycosides and phenolic acids could
define the level of antioxidant
capability of pollen of different origin.
Lipid peroxidation
Extracts were evaluated for
their capability of inhibition of
lipid peroxidation. In all cases,
the reduction of MDA concentration with increasing flavonol
concentration was linear. An
example, obtained with the total extract of pollen from
Amaranthus hybridus (G2), is
shown in Figure 2.
The corresponding IC50 values are shown in Table III,
while those of the standards
quercetin and caffeic acid are
shown in Table II. Under the
present experimental condi-
578
tions, all the total extracts
were effective inhibitors of
lipid peroxidation although, as
in the case of antiradical activity, a correlation between flavonol content in pollen and
lipid inhibition activity is not
clear. Significant differences
were found among the IC 50
values from pollen of the plant
species analyzed, and the
mean separation by Duncan’s
multiple range test is included
in Table III. Pollen from Amaranthus hybridus (G3) and the
mixture of honeybee-collected
pollen had the highest activities as lipid oxidation inhibitors (IC 50= 0.7×10 -1µg/ml in
both), even higher than those
of the caffeic acid (IC 50 =
1.7×10 -1µg/ml) and quercetin
(IC 50 = 2.2×10 -1µg/ml) standards, this last one considered
as a powerful antioxidant
against lipid peroxidation
(Terao, 1999). As with antioxidant activity, the results suggest that the diverse levels of
lipid peroxidation activity
could be mainly associated to
the species-specific phenolic
profile.
Conclusion
Honeybee-collected pollen
can be a complex mixture of
pollen from different botanical
origins. Pollen from a cultivated and anemophile plant like
Zea mays is found in a high
proportion in mixtures of honeybee-collected pollen from
Durango, Mexico.
Honeybee-collected pollen
can be an effective antioxidant substance. Its antioxidant
capacity is based on free radi-
cal scavenging and on lipid
peroxidation inhibition activities. Pollen from different botanical origin had different
antioxidant capacity. Individually, pollen from Amaranthus
hybridus is among the ones
with the highest lipid oxidation inhibition capacity, and
that from Tagetes sp. is
among the ones with the
highest level of antiradical capacity. The species-specific
flavonol and phenolic acid
profiles may be more important than flavonol content to
determine the particular antioxidant capacity of pollen of
different botanical origin. This
beehive product can be considered as an important
source of natural flavonol antioxidants.
To reach a better understanding and to take advantage of
the antioxidant properties of
this apicultural product it is
necessary to carry out in vivo
assays and systematic analyses
with standard methods so as to
create databases that will make
it possible to compare the antioxidant activities of honeybeecollected pollen from different
botanical origins.
ACKNOWLEDGMENTS
The authors wish to thank
Antonio Rivas Orozco for providing the honeybee-collected
pollen samples.
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