Biology Reference
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species (RNS), are extremely reactive, and
when there is an over-production of them a
damaging process known as 'oxidative
stress' occurs (Wang
et al
., 2011). There is a
large body of evidence that shows a strong
relationship between ROS and pathological
and physiological disorders such as cancer,
neurodegenerative disorders, hypertension,
diabetes, hyperlipidemia, cardiovascular
diseases, inflammation, autoimmune disor-
ders and so on (Fu
et al
., 2011). The reason
for this is the considerable number of harm-
ful effects generated by ROS species in the
organism's biomolecules, cells, tissues and
organs (Dryden
et al
., 2005; Dimitrios,
2006). To overcome these problems there is
an incessant search for novel antioxidants,
and it is commonly accepted that substances
with antioxidant activity can contribute to
preventing diseases, promoting health and
serve as a template for the development of
potentially novel therapeutic agents (Venkat-
Ratnam
et al
., 2006).
Additionally, at present most of the
antioxidant's arsenal available in pharma-
ceutical, food and cosmetic industries has
been substantially reduced, mainly owing
to three factors: (i) toxicity problems associ-
ated with synthetic molecules used as anti-
oxidants; (ii) a strong tendency of consumers
to buy products based on natural ingredi-
ents; and (iii) an increased move by manu-
facturers from synthetic to natural origin
antioxidants
to be considered safer and healthier than
synthetic products (Shi
et al
., 2001;
Krishnaiah
et al
., 2011), but some problems
related to low bioavailability and delivery
formulation have arisen (Venkat-Ratnam
et al
., 2006). That is why more studies to
find new, secure, healthy and cheap anti-
oxidant compounds must be carried out.
In the Colombian context, although
products based on this resinous material
(propolis) are available on the market, there
is scarce information about their chemistry
and their biological activities. At the
moment, both physicochemical characteri-
zation and evaluation of biological activi-
ties are considered two good parameters for
establishing propolis' quality. Moreover, it
is well known that depending on the geo-
graphic origin of propolis samples, the bio-
logical activities are different (Popova
et al
.,
2011). For these reasons, we are interested
in chemical and biological characterization
of propolis collected in some regions from
Colombia.
One of the most analysed activities for
propolis, together with antimicrobial
activity, is antioxidant capacity. In many
countries several studies have been car-
ried out to analyse this particular activity
(Kumazawa
et al
., 2004; Laskar
et al
., 2010).
These reports have shown a good correla-
tion between polyphenolic content and
antioxidant activity (Russo
et al
., 2004;
Choi
et al
., 2006; Ahn
et al
., 2007), and
that is the reason why this class of com-
pound is usually associated with this
activity. Owing to the number of factors
that can affect the antioxidant capacity
(species and reaction systems), and the
diverse number of mechanisms through
which antioxidant substances exert their
action, numerous methods to test the
antioxidant properties of biological origin
samples are currently available (Badarinath
et al
., 2010; Cíz
et al
., 2010). The methods
that we used to evaluate antioxidant activ-
ity on propolis were (to see more detailed
information about each method please
refer to Huang
et al
. (2005)):
to
comply
with
people's
demands (Pokorny, 2001).
In the search for novel antioxidant mol-
ecules from nature, many compounds have
been tested and have shown potential as
antioxidant agents (Ng
et al
., 2000; Wootton-
Beard and Ryan, 2011). The most common
natural compounds associated with antioxi-
dant capacity are polyphenols that include
hydroxycinnamic acids, flavonoids, hydroxy-
benzoic acids, dihydrochalcones, isoflavo-
noids and tannins. Furthermore, some other
types of metabolites have also demonstrated
good activity (quinines, betalains, organo-
sulfides, steroids, saponins, etc.) (Uttara
et al
., 2009; Aiyegoro and Okoh, 2010).
These natural compounds are highly appre-
ciated because their traditional uses as food
and medicinal products has allowed them
1.
2,2-Diphenyl-1-picrylhydrazyl (DPPH), a
stable radical that is used to evaluate the
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