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Antioxidant activity of oregano (Origanum vulgare L.) leaves


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Oregano leaves (Origanum vulgare L.) were extracted with ethanol, diethyl ether, n-hexane:2-propanol 4:1 (v/v) and n-pentane. The highest yield was obtained with ethanol and the ethanol-ic extract showed the strongest inhibi-tory effect on lipid oxidation when add-ed (amounts from 0.02 to 5% w/w) to a model lipid system (made up of refined bleached peanut oil), subjected to forced dynamic oxidation, using the Oxidative Stability Instrument (OSI). The hydro-lyzed ethanolic extract showed a more powerful antioxidant activity than the untreated extract. Total polyphenols in RIASSUNTO Le foglie di origano (Origanum vulga-re L.) sono state estratte con etanolo, etere dietilico, n-esano:isopropanolo 4:1 (v/v) e n-pentano. La resa più elevata è stata ottenuta utilizzando l'etanolo e l'estratto etanolico ha mostrato anche il più forte effetto inibitorio nei confronti dell'ossidazione lipidica, quando addi-zionato (in quantità variabili dallo 0,02 al 5% p/p) ad un sistema lipidico mo-dello (costituito da olio di arachide raf-finato e decolorato), sottoposto ad os-sidazione dinamica forzata, mediante l'Oxidative Stability Instrument (OSI). L'estratto etanolico idrolizzato ha mo--Key words: Antioxidant activity, lipid model system, oregano extracts, oxidative stability instrument, polyphenols -18 Ital. J. Food Sci. n. 1, vol. 14 -2002 this extract, expressed as gallic acid, were quantified by spectrophotometric analysis at 280 nm. The ethanolic ex-tract was also analyzed by TLC (thin layer chromatography) and showed the presence of flavones, flavanones and di-hydroflavonols, whether glycosilated or not. strato una maggiore attività antiossi-dante rispetto all'estratto non trattato. I polifenoli totali di questo estratto, espressi come acido gallico, sono stati quantificati attraverso analisi spettro-fotometrica, a 280 nm. L'estratto eta-nolico è stato anche analizzato in TLC (cromatografia su strato sottile) e ha mostrato la presenza di flavoni, flava-noni e diidroflavonoli, sia liberi che gli-cosilati.
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Ital. J. Food Sci. n. 1, vol. 14 - 2002
Dipartimento di Scienze degli Alimenti, Università di Bologna,
Via Ravennate 1020, 47023 Cesena (FC), Italy
*Corresponding author: Tel. +39 0547 636121, Fax +39 0547 382348,
Oregano leaves (Origanum vulgare L.)
were extracted with ethanol, diethyl
ether, n-hexane:2-propanol 4:1 (v/v)
and n-pentane. The highest yield was
obtained with ethanol and the ethanol-
ic extract showed the strongest inhibi-
tory effect on lipid oxidation when add-
ed (amounts from 0.02 to 5% w/w) to a
model lipid system (made up of refined
bleached peanut oil), subjected to forced
dynamic oxidation, using the Oxidative
Stability Instrument (OSI). The hydro-
lyzed ethanolic extract showed a more
powerful antioxidant activity than the
untreated extract. Total polyphenols in
Le foglie di origano (Origanum vulga-
re L.) sono state estratte con etanolo,
etere dietilico, n-esano:isopropanolo 4:1
(v/v) e n-pentano. La resa più elevata è
stata ottenuta utilizzando l’etanolo e
l’estratto etanolico ha mostrato anche
il più forte effetto inibitorio nei confronti
dell’ossidazione lipidica, quando addi-
zionato (in quantità variabili dallo 0,02
al 5% p/p) ad un sistema lipidico mo-
dello (costituito da olio di arachide raf-
finato e decolorato), sottoposto ad os-
sidazione dinamica forzata, mediante
l’Oxidative Stability Instrument (OSI).
L’estratto etanolico idrolizzato ha mo-
- Key words: Antioxidant activity, lipid model system, oregano extracts, oxidative stability instrument,
polyphenols -
Ital. J. Food Sci. n. 1, vol. 14 - 2002
this extract, expressed as gallic acid,
were quantified by spectrophotometric
analysis at 280 nm. The ethanolic ex-
tract was also analyzed by TLC (thin
layer chromatography) and showed the
presence of flavones, flavanones and di-
hydroflavonols, whether glycosilated or
strato una maggiore attività antiossi-
dante rispetto all’estratto non trattato.
I polifenoli totali di questo estratto,
espressi come acido gallico, sono stati
quantificati attraverso analisi spettro-
fotometrica, a 280 nm. L’estratto eta-
nolico è stato anche analizzato in TLC
(cromatografia su strato sottile) e ha
mostrato la presenza di flavoni, flava-
noni e diidroflavonoli, sia liberi che gli-
In recent years, there has been in-
creasing interest in the possibility of
using vegetable extracts as antioxidants.
The food and cosmetic industries have
attempted to select vegetable extracts to
replace synthetic phenolic antioxidants,
such as BHA and BHT (CERUTTI, 1999;
GIESE, 1996; HAMAMA and NAWAR, 1991).
Furthermore, the possible use of natu-
ral antioxidants for the prevention of
some human diseases has stimulated
increasing interest in this field. In fact,
it is well known that arteriosclerosis, is-
chaemia events, human cancer and in-
flammatory diseases are related to sig-
nificant exposure of cells to oxidative
stress (NAMIKI, 1990; PENG et al., 1992;
VINSON et al., 1995; PORRINI and TESTO-
LIN, 1997).
Many vegetable extracts have been
studied in relation to their antioxidant
activity (LINDBERG and BERTELSEN, 1995;
GALLINA TOSCHI et al., 2000). Notably the
Labiatae family is well-known for its anti-
oxidative properties, and especially rose-
mary and sage have been reported to
have strong effectiveness (CUVELIER et al.,
1990, 1994, 1996; SCHWARZ and TERNES,
1992a, b; SCHWARZ, et al., 1992; CHEN et
al., 1992; PIZZOCARO et al., 1994; RICHHE-
IMER et al., 1996; VARELTZIS et al., 1997).
Oregano, thyme and marjoram extracts
have also shown a pronounced effect in
stabilizing lipids against autoxidation
MOU et al., 1991; CHEVOLLEAU et al., 1992;
VEKIARI et al., 1993a, b).
This study was carried out with the
aim of selecting the best extraction con-
ditions for oregano leaves, often used in
foods for its organoleptic properties, to
obtain greater antioxidant power.
Solvents and reagents were analytical
or HPLC grade, from Carlo Erba (Milan,
Italy) and Prolabo (Paris, France). Flavo-
noid standards (99% pure), gallic acid
and BHT (99% pure) were purchased
from Sigma Chemical Co. (St. Louis, MO,
USA). Oregano leaves (Origanum vulgare
L.) were obtained from the region of Ca-
labria (Italy).
Preparation of oregano extracts
Oregano leaves (50 g) were extracted
separately with 300 mL of four different
solvents: ethanol, diethyl ether (not sta-
bilized with BHT), n-hexane:2-propanol
4:1 (v/v) and n-pentane. Extractions
were conducted at the boiling tempera-
ture of each single solvent, in a Soxhlet
apparatus, for four hours. After each
Ital. J. Food Sci. n. 1, vol. 14 - 2002
extraction, the solvent was dried under
vacuum with a Rotavapor (60°, 30°, 50°
and 30°C, respectively); the solid was
weighed and brought to a final volume
of 25 mL with the same solvent.
Acid hydrolysis of oregano extracts
A certain volume of the solutions ob-
tained from the extraction with four dif-
ferent solvents, containing amounts from
1 to 50 mg of oregano extract (calculat-
ed on the basis of the extraction yield)
were dried under gentle nitrogen flow and
then hydrolyzed using 1.5 mL of 1M HCl
and kept in a boiling water bath for 1 h
(HOLLMAN et al., 1996; LU and FOO, 1997).
The hydrolysis products were extracted
four times with 0.5 mL of diethyl ether
(not stabilized with BHT); the solvent was
then dried, and the solid dissolved in
0.15 mL of the same solvent.
Preparation of the lipid model system
A refined peanut oil, from the market,
was used as the model lipid system. Ten
percent of bleaching earth (previously
activated at 110°C for 18 h) was added
and the oil was kept for 15 min at 80°C
in a Rotavapor, under weak vacuum
(BENDINI et al. 2001).
Antioxidant activity measurement
The antioxidant activity of the differ-
ent oregano extracts was tested on the
refined bleached peanut oil by subject-
ing it to forced dynamic oxidation. An
eight-channel Oxidative Stability Instru-
ment (OSI) (Omnion Inc., Decatur, Illi-
nois) was used. Five grams (±0.1 g) of
peanut oil were weighed in each glass
tube, the temperature was set at 98°C
and the stream of air bubbled through
the oil was 120 mL/min. The OSI meas-
ures the changes in conductivity due to
the formation of ionic volatile organic
acids (mainly formic acid) which are col-
lected in a polycarbonate tube contain-
ing deionized water. The OSI time, ob-
tained under standard conditions of tem-
perature and air bubbling (JEBE et al.,
1993), corresponds to the change in slope
of the volatile organic acid production,
which is considered to be the end of the
induction period of an oil.
Total polyphenol determination
The quantity of total polyphenols in
the oregano ethanolic extract, expressed
as weight percent (w/w), was determined
by spectrophotometric analysis at 280
nm; the calibration curve was built with
standard solutions of gallic acid, as re-
ported by the official method (MARGH-
ERI and FALCIERI, 1972).
Thin-layer chromatographic analysis
(TLC) of oregano extracts
TLC plates, precoated with silica gel
(20x20 cm, Merck, Darmstadt, Germa-
ny) were used to separate the compo-
nents of the ethanolic oregano extract.
The developing system used was tolu-
ene/acetone/formic acid (30:60:10,
The following spray reagents were
used to identify the chemical com-
pounds: (a) atomization with 5% alumi-
num chloride in water (w/v) (a yellow
color indicates the presence of flavo-
noids) (VEKIARI et al., 1993a), (b) exposure
to ammonia fumes (observation under
UV light shows a dark color that per-
sists after exposure to ammonia fumes,
if the compounds are flavones, dihydro-
flavonols or flavanones) (VEKIARI et al.,
1993a), (c) vaporization with sulphochro-
mic mixture and carbonization at 140°C
(organic compounds appear as brown
color), (d) atomization with Folin-Ciacol-
teau reagent (phosphotungstic and phos-
phomolybdic acids) and, after three min-
utes, with 20% sodium carbonate in
water (w/v) (polyphenol compounds ap-
peared as blue color) (MARGHERI and
FALCIERI, 1972).
Ital. J. Food Sci. n. 1, vol. 14 - 2002
The oregano extraction using four dif-
ferent solvents gave yields of: ethanol
8.3% (w/w), n-hexane:2-propanol 4:1
6.6% (w/w), diethyl ether 5% (w/w:) and
n-pentane 3.9% (w/w). The highest yield
was obtained with ethanol. Methanol was
not used, even if it has been reported to
be the best solvent for phenols (MØLLER
et al., 1999) because it is toxic and should
be completely removed before the extract
can be used as a food additive. The use
of water, which is certainly suitable for
the food industry and considered effec-
tive for the extraction of water-soluble
phenolic compounds (MILO˘
S et al., 2000),
was not considered because it requires a
high temperature and a long time to be
removed, during which time the antioxi-
dant components could easily decompose.
The repeatability of the OSI time of the
peanut oil, used as a model lipid sys-
tem, was checked by analyzing sixteen
samples of oil, freshly bleached each
time. The mean value of the OSI time
was 14.40 h, the standard deviation was
±0.77 h (coefficient of variation was
5.36%). Before analyzing each single ex-
tract, some tests were carried out to
check if small amounts (up to 3% v/w)
of solvents used for the extractions could
modify the OSI time of the model lipid
system. Ethanol caused a small signifi-
cant decrease in OSI time (-2.4%), very
close to the coefficient of variation of the
analysis; no significant effect was record-
ed for diethyl ether but n-pentane or n-
hexane:2-propanol 4:1 caused a slight
increase in the OSI time.
As shown in Fig. 1, the ethanolic ex-
tract gave a higher antioxidant activity
than the other extracts, obtained with
less polar solvents, in increasing
amounts, from 0.1 to 0.6% w/w. It is also
evident that the hydrolyzed ethanolic
extract gave the highest antioxidant ac-
tivity and this effect increased with in-
crease in the concentration of the extract
added to the oil, up to 0.4%.
The effect of the ethanolic extract was
tested under a wider range of concen-
trations, from 0.02 to 5% w/w (Fig. 2).
The OSI time of the model lipid system
(14.40 h) doubled when the ethanolic
extract was added at 0.5% (29.7 h) and
it became almost four times as much at
5% (56.9 h). Due to the organoleptic
modifications induced by adding high
amounts of the extract, percentages
higher than 5% were not tested. As re-
ported in Figs. 1 and 2, the addition of
0.1% (25.70 h) hydrolysed ethanolic ex-
tract exhibited a protective effect corre-
sponding to 97% of that shown by the
addition of 0.04% (26.50 h) BHT, which
is a pure standard product. The total
polyphenol content of the ethanolic oreg-
ano extract was 10.17% ±0.47 (expressed
as weight % as gallic acid), calculated
on four determinations by UV analysis
at 280 nm, near the maximum absorp-
tion of most phenols.
The ethanolic oregano extract was
then analyzed by TLC (Fig. 3) and nine
bands were isolated as black spots, af-
ter carbonization with a sulphochromic
mixture, and were numbered starting
from the top of the plate (column A). The
reactions to the solution of 5% alumi-
num chloride in water, to ammonia
fumes and to the Folin-Ciocalteau rea-
gent were positive for bands 3-9 (Rf from
0.86 to 0.05); this response is charac-
teristic of polyphenols, particularly of fla-
vones, flavanones and dihydroflavonols.
Bands 1 and 2 with Rf = 0.93 and Rf =
0.89, respectively, were not flavonoids
(probably chlorophylls); the spot with Rf
= 0.84 (band 4 columns A, B) could con-
tain, as reported in the literature (VEKI-
ARI et al., 1993a), apigenin (flavone, col-
umn C), eriodictyol (flavanone, column
D), kaempferol (flavonol, column E),
quercetin (flavonol, column G and I) or
rosmarinic acid (phenolic acid, column
M). Bands 6-9 corresponded to polyphe-
nol glycosides because they disappeared
when the oregano extract was hydrolyzed
(column B) such as: rutin (quercetin-3-
Ital. J. Food Sci. n. 1, vol. 14 - 2002
Fig. 1 - OSI time values (hours)a of refined bleached peanut oil, with the addition of increasing amounts
(from 0.1 to 0.6% w/w) of untreated and hydrolysed oregano leaf extracts, obtained using different
solvents (ethanol, diethyl ether, n-hexane: 2-propanol 4:1, n-pentane). Control group was refined bleached
peanut oil, with the addition of 3% (v/w) of each extraction solvent.
a Calculated from two determinations.
Fig. 2 - OSI time values (hours)a of the refined bleached peanut oil, with the addition of increasing
amounts (from 0.02 to 5% w/w) of untreated ethanolic oregano leaf extracts and BHT (from 0.02 to
0.04% w/w). Control group was refined bleached peanut oil, with the addition of 3% (v/w) ethanol and
diethyl ether (the solvent used to dissolve BHT).
aCalculated from two determinations.
Ital. J. Food Sci. n. 1, vol. 14 - 2002
Fig. 3 - Thin layer chromatography of: A = Untreated ethanolic extract of oregano leaves; B = Hydrolysed
ethanolic extract of oregano leaves; C = Apigenin; D = Eriodictyol; E = Kaempferol; F = Taxifolin (dihy-
droquercetin); G = Quercetin; H = Rutin (quercetin-3-rutinoside); I = Hydrolysed rutin; L = Hesperidin
(hesperetin-7-rhamnoglucoside); M = Rosmarinic acid.
The bands visualized as black spots after carbonisation with sulphochromic mixture, are numbered
from 1 to 9, starting from the top of the plate. The Rf (retention factor) of the bands are:
A1,B1 Rf = 0.93; A2,B2 Rf = 0.89; A3,B3 Rf = 0.86; A,B,C,D,E,G,I,M-4 Rf = 0.84;
A5,B5 Rf = 0.64; A6 Rf = 0.45; A7 Rf = 0.39; A8 Rf = 0.13; A9 Rf = 0.05;
F10 Rf = 0.82; L11 Rf = 0.33; H12 Rf = 0.19.
Mobile phase: toluene/acetone/formic acid 30:60:10 v/v/v.
rutinoside, Rf 0.19, spot number 12, col-
umn H) which, once hydrolyzed (column
I), released its corresponding aglycone
(quercetin, Rf = 0.84, column G).
To evaluate the use of vegetable ex-
tracts to protect food lipids from oxida-
tion, the antioxidant power of the dried
oregano leaf extracts, obtained using
different solvents, was measured by OSI
time. The dried ethanolic extract had the
highest antioxidant activity and, when
added to a model lipid system at a per-
centage of 0.20% w/w (26.40 h of OSI
time), showed the same antioxidant
power as BHT added at 0.04% w/w
(26.50 h of OSI time). Hydrolyzed eth-
anolic oregano extracts had stronger
antioxidant properties, with respect to
Ital. J. Food Sci. n. 1, vol. 14 - 2002
the non-hydrolyzed ones. In fact 0.20%
(42.30 h of OSI time) of the hydrolyzed
extract showed an antioxidant power
1.6 times higher than the untreated
extract. TLC analysis of the untreated
and hydrolyzed extracts showed the
presence of polyphenolic compounds in
both types of extracts and the lack of
phenolic glycosides (spots with low Rf)
in the hydrolyzed ones. This evidence
suggests that free phenolic aglycones
have a higher antioxidant power, as con-
firmed by the structure activity relation-
ship studies of HERRMANN (1976) and
DAS and PEREIRA (1990) and as
showed for oregano volatile aglicone,
tested by measuring peroxide values of
lard, stored at 60°C (MILO˘
S et al., 2000).
This evidence merits further investiga-
tion on the use of phenolic hydrolyzed
oregano extracts as a source of natural
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... Constituents and mechanism(s) of action of some selected natural antidotes Chelation and scavengingCarolina et al. 2003;Amutha et al. 2017 Garlic Thiosulfur constituents, allicin ChelationChowdhury et al. 2008;Amagase et al. 2001;Lawson et al. 1992;Okada et al. 2005 Oregano Rosmarinic acid; phenolic carboxylic acids, and glycosides Scavenging Kim and Cho 2001;Bending et al. 2002;Nakatani 2003;Hernandez-Hernandez et al. 2009 Basil Eugenol, rosmarinic acid, carnosic acid, carnosol, caffein acid, Linalool, epi-α-cadinol, and α-bergamotene (7.4% to 9.2%) and γ-cadinene Chelation and scavengingLee and Scagel 2009;Padurar et al. 2008;Juliani and Simon 2002 Thyme Thyme oil, thymol, carvacrol, γ-terpinene, myrcene, linalool, p-cymene, limonene, 1,8-cineole, α-pinene ChelationYoudim et al. 2002;Lee et al. 2005 Black pepper Piperine, caffeic acid, p-Coumaric acid, piperolein B, piperamide, guineensine, β-caryophyllene, limonene, sabinene, β-bisabolene, and α-coapene ScavengingMittal and Gupta 2000; Kapoor et al. 2009 ...
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The global burden of heavy metal especially mercury, arsenic, lead, and cadmium toxicities remains a significant public health challenge. Developing nations are particularly at high risk and carry the highest burden of this hazard. Chelation therapy has been the mainstay for treatment of heavy metal poisoning where the chelating agent binds metal ions to form complex ring–like structures called “chelates” to enhance their elimination from the body. Metal chelators have some drawbacks such as redistribution of some heavy metals from other tissues to the brain thereby increasing its neurotoxicity, causing loss of essential metals such as copper and zinc as well as some serious adverse effects, e.g., hepatotoxicity. The use of natural antidotes, which are easily available, affordable, and with little or no side effects compared to the classic metal chelators, is the focus of this review and suggested as cheaper options for developing nations in the treatment of heavy metal poisoning.
... Several studies have reported that OEO possesses antimicrobial [8,9] and antioxidant properties [10,11]. Feed efficiency was improved when feeding OEO via stimulating the beneficial gut microbes [12] while inhibiting pathogenic microorganism growth, i.e. Escherichia coli and Staphylococcus aureus [13]. ...
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Oregano essential oil (OEO), which has antimicrobial properties, may be used for altering the ruminal pH and microbial populations of sheep, as observed by the altered volatile fatty acid patterns. To further elucidate the effects of OEO on ruminal pH and microbial populations of sheep, 3 German merino sheep × local sheep crossbred rams with permanent ruminal fistulas were randomly assigned to a 3 × 3 Latin square design with 12-d periods. The treatments were as follows: control (CON); OEO4: OEO supplied at 4 g•d⁻¹; and OEO7: OEO supplied at 7 g•d⁻¹. Starting on day 11, rumen fluid was collected at 0 h, and at 4, 8, 12, 24 and 48 h after supplying OEO, and then pH values of rumen fluid were immediately measured. The abundance of microbial populations was determined by using qPCR. The ruminal pH values were similar among the sheep from all treatments. The abundance of ruminal fungi was higher for the sheep supplied OEO7 compared with the sheep supplied CON and OEO4, especially at 4 and 12 h. The abundance of ruminal protozoa decreased with supplied OEO, indicating that OEO could inhibit the protozoa. The abundance of the total ruminal bacteria was similar for the sheep from all treatments, but R. flavefaciens, R. albus and F. succinogenes increased in the sheep supplied OEO4 compared with those in the sheep supplied CON, however, the sheep supplied OEO7 had higher abundances of R. flavefaciens than the sheep supplied CON. These results demonstrated that supplying OEO to sheep did not affect the ruminal pH but could shift the rumen microbial population to one with less protozoa. Supplying OEO can preferentially enhance the growth of certain rumen microbial populations, but the shifts were influenced by the supply rate. Therefore, supplying low amount (i.e. 4 g•d⁻¹) of OEO could have positive effects on ruminal microbial populations, whereas supplying elevated doses of OEO could be detrimental to those same ruminal microbial populations.
... However, some other studies indicate that plant extracts (capsaicin and polyphenols) can have beneficial effects on the daily weight gain and feed conversion ratio (FCR) of broiler chickens (Kamel 2001). Some other studies focused on other functions of phytogenic feed additives, such as their antioxidant function (Cervato et al. 2000;Abdalla and Roozen 2001;Damechki et al. 2001;Martinez-Tomé et al. 2001;Vichi et al. 2001;Bendini et al. 2002). It has been reported that carvacrol and thymol, the two main phenols which constitute about 78-82% of the essential oil of oregano, are mainly responsible for this antioxidant function (Yanishlieva and Marinova 1995;Yanishlieva et al. 1999). ...
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A total of 160 1-d-old ducklings (mixed gender) were used to evaluate the effects of dietary phytogenic supplementation on growth performance, carcass characteristics, and nutrient digestibility. Each treatment consisted of eight replications and five birds/replication. Treatments were: (T1) high nutrient diet; (T2) T1+phytobiotics; (T3) low nutrient diet; (T4) T3+phytobiotics. The results indicated that inclusion of phytobiotics and nutrients’ density of diets influenced body weight gain and feed conversion ratio (P < .05). Feeding low nutrient diets had a negative effect on drip loss percentage. Cooking loss percentage increased (P < .05) by reducing nutrient density. Relative weights of breast muscle, abdominal fat and body organs, pH value, and colour of breast muscle were not affected by treatment diets. Supplementing the diets reduced TBARS value on d 14 post-slaughter (P < .05). Density of nutrients and phytogenic blend (P < .05) improved the digestibility of dry matter and energy, but the digestibility of calcium and phosphorous were not affected by treatments.
... It affects the quality of the product due to loss of desirable colour, odour and flavour and a reduced shelf life (BOTSOGLOU et al., 2003;KAYNAKCI and KILIC, 2009). Moreover, atherosclerosis, ischemic events, human cancer and inflammatory diseases are related to tissue exposure to oxidative stress (BENTINI et al., 2002). The quality of poultry meat may be affected by numerous factors associated with either the animal or its environment, such as age, sex, breed, species, rearing and feeding system, handling and slaughtering condition (BERRI, 2004;MCKEE, 2007). ...
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The effects of thyme oil on meat quality in Japanese quails were investigated. A total of 192 mixed sexes Japanese quail chicks were used in the feeding trial, which lasted until the birds reached 35 d of age. Birds were randomly allocated to 4 dietary treatments comprising three experimental groups and one control group (basal diet). Each group was divided into 4 subgroups, with each containing twelve quails. Basal diet was formulated according to NRC recommendations. Thyme oil was added daily to the basal diet at 200 (T1), 400 (T2) and 600 mg/kg (T3) levels, respectively. After slaughtering and evisceration, the carcasses were stored at 3 ± 0.5°C for 10–12 h and then the breast fillets were removed from carcass.
... During the last decades scientists have expressed a steadily growing interest in the antioxidant potential of culinary aromatic plants and their impact on health. The antioxidant capacity of these plants is mostly attributed to the phytochemicals, mainly flavonoids, contained in their essential oils (Bendini et al., 2002; Goliaris et al., 2003; Papageorgiou et al., 2008; Bozin et al., 2007). The antioxidant properties of flavonoids are ascribed not only to their free radical scavenging activities (Costa et al., 2007), but also to the iron-chelating activity of the 3-OH group in their aromatic ring (Morel et al., 1993). ...
... For example, thyme and oregano extracts were reported to inhibit hexanal generation and the formation of conjugated dienes in sunflower oil and its 20% oil-in-water emulsion at 607C [28]. The extract of oregano stabilized the oxidation of lard [8] and demonstrated antioxidant activity when added to refined bleached peanut oil [29] and sunflower oil [30]. Zandi and Ahmadi [31] reported the antioxidant activity of marjoram and thyme extracts using the active oxygen method (AOM), Rancimat method and Schaal oven test methods in soybean oil. ...
The effectiveness of plant extracts (0.05% rosemary and 0.08% oregano) to extend shelf life of bison strip loin steaks in terms of color stability and consumer acceptability was studied. Steaks treated with oregano presented lower oxygen consumption, higher metmyoglobin‐reducing activity (MRA), decreased lipid oxidation, and provided a stable red color with less discoloration during the retail display period than the control and rosemary treated steaks (P < 0.05). Results from consumer sensory evaluation indicated that treated steaks under study were not significantly different from the control (P > 0.05) based on palatability attributes and acceptability. However, rosemary treated steaks were more desirable and palatable than their oregano counterparts (P < 0.05). Overall, plant extracts, particularly oregano, can improve color stability of bison steaks due to its antioxidants properties and ability to increase MRA capacity in fresh bison meat without posing any negative impact on its sensory attributes. Practical Application This study will provide valuable information to the bison meat industry on how to offer a more consistent and acceptable product (in terms of palatability and color) to consumers using plant‐based natural antioxidants, without diminishing the palatability of their products. This technology can offer two more days of shelf life in retail overwrap packaging, consequently, opening the possibility for the bison industry to expand its market with a potential to reduce retail losses due to poor color stability and early browning (that is, stock out, markdowns, and waste due to expired display life).
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Peanut oil is widely used in food but is susceptible to oxidation. This study investigated the antioxidant stability of high oleic (HO: 78.85 g/100 g oleic acid) and regular (C: 43.85 g/100 g oleic acid) peanut oils with oregano essential oil (OEO) added as a natural antioxidant. OEO contained γ-terpinene (25.71%), carvacrol (16.73%) and terpinen-4-ol (16.17%) as the principal compounds. Thermal processing (60 °C for 28 days) of OEO increased the carvacrol and o-cymene contents and decreased the terpinen-4-ol, linalool and γ-terpinene levels. Thus, carvacrol was the major compound with high oxidative stability. Thermal processing of the peanut oils showed that HO peanut oil developed less oxidation than C peanut oil. OEO provided antioxidant activity, which increased as its concentration increased (at 0.02 and 0.10% p/p of OEO, the peroxide value decreased by 18 and 46%, respectively). OEO displayed 54.7% free radical scavenging activity and 9.2 mg/g total phenolic content, explaining its antioxidant activity. Sensory analysis showed that OEO was detected in all samples, but consumer acceptance was greater when OEO was present (hedonic values of 7.4 and 6.8 for OEO at 0.02 and 0.10 g/100 g, respectively) compared to the peanut oil only control (hedonic value of 6.0).
Zachodzące podczas ogrzewania olejów zmiany, są nie tylko niekorzystne z punk-tu widzenia walorów smakowych, ale także niebezpieczne dla organizmu ludzkiego. Spożywanie nadmiaru tłuszczów, nawet roślinnych, skutkuje otyłością, a w konse-kwencji jest powodem wzmożonego nasilenia tzw. chorób cywilizacyjnych, w tym cukrzycy i miażdżycy. Poza nadmiernym spożywaniem tłuszczów problemem jest również nieprzestrzeganie właściwego sposobu ich przechowywania i stosowania. Nie wszystkie bowiem tłuszcze, w tym oleje, można dowolnie poddawać zabiegom kulinarnym związanym z ogrzewaniem w wysokiej temperaturze (1, 2). Aby zapobiegać niekorzystnym zmianom zachodzącym w olejach jadalnych do-daje się do nich różnorodnych przeciwutleniaczy. Jedynymi, nie budzącymi zastrze-żeń co do zdrowotnego bezpieczeństwa stosowania przeciwutleniaczami olejów rafi nowanych są: naturalny i syntetyczny tokoferol oraz sól sodowa kwasu cytry-nowego (3, 4, 5). Coraz więcej uwagi poświęca się badaniom surowców roślinnych, których natu-ralne składniki wykazują właściwości przeciwutleniające. Skuteczność tych związ-ków jako antyoksydantów jest porównywalna, a niejednokrotnie nawet wyższa niż przeciwutleniaczy syntetycznych, a dodatkowo są one bezpieczniejsze dla zdrowia człowieka. Związki te wykryto w znacznych ilościach w przyprawach i ziołach, a wśród nich także w oregano (6, 7, 8). W przeprowadzonym w niniejszej pracy eksperymencie oceniono wpływ oregano na proces ogrzewania oleju rzepakowego i słonecznikowego w aspekcie hydrolizy olejów oraz powstawania produktów peroksydacji lipidów.
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Besides the positive effects, γ-irradiation and heat treatment of foods usually lead to changes in their structure or composition, thus influencing their quality. In view of the fact that herbs and spices are important source of antioxidants in a human diet, any kind of treatment can have an impact on their antioxidant status, as well. In this contribution, we review the effects of γ-radiation and heat treatment on some constituents and antioxidant properties of culinary herbs and spices. Both methods of treatment result in some common qualitative changes in herbs and spices, mostly in the content of polyphenols or volatile components. The results of antioxidant testing assays are sometimes contradictory in observed effect or trends, in dependence on the manner of treatment and character of spice matrix. Based on this review, the effects of γ-radiation or heat processing on antioxidants, or the vitamin content in herbs and spices is still lacking, which makes the direct assessment of the effect of treatment on the antioxidant status of herbs and spices practically impossible. However, the changes in composition that have been observed to date suggest that they have only a small effect on the behavior of herbs and spices in a real food matrix.
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Flavonoids, commonly occurring antioxidants in foods, have been compared in a dose-response manner with vitamins C and E and beta-carotene and found to be powerful antioxidants using an in vitro lipoprotein oxidation model. This model simulates the oxidation of low-density lipoproteins, which results in atherosclerosis. Of the flavonoids and flavonoid-related compounds, flavonols found in tea are the most powerful natural antioxidants. These results provide a mechanism for the beneficial epidemiological effect of dietary flavonoids on heart disease.
Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) have been used widely for many years to retard lipid oxidation. Concern about the safety of synthetic antioxidants together with consumer preference for natural products has resulted in increased research on natural antioxidants. Many spices have been shown to impart an antioxidative effect in foods. This article summarizes the literature on the antioxidative effects of spices. The term spice is defined as dry plant material that is normally added to food to impart flavour.
Afin de mesurer l'efficacité d'antioxygènes, un test d'autooxydation accélérée du linoléate de méthyle a été utilisé, par chromatographie en phase gazeuse. L'efficacité de l'antioxygène est évaluée par l'accroissement du temps de 1/2 réaction par rapport à une oxydation témoin sans antioxygène. L'ensemble des résultats montre que ce test, d'une durée inférieure à 10 heures, permet de comparer le pouvoir antioxydant connu ou potentiel d'extraits végétaux.
Five antioxidative phenolic acids were isolated from the leaves of oregano (Origanum vulgare L.). The structure of a new compound (5a) was determined to be 2-caffeoyloxy-3-[2-(4-hydroxybenzyl)- 4, 5-dihydroxy]phenylpropionic acid on the basis of spectroscopic evidence. Especially, phenyl glucoside (1) and 5a showed an activity comparable to that of BHA.
The effects of several flavonoids and other known antioxidants on the thermal autoxidation of refined, bleached and deodorized (RBD)-palm oil were studied. The lipid peroxidation was indexed by measuring the malonyldialdehyde (MDA) production using the 2-thiobarbituric acid (TBA) test. The antioxidative action decreased in the order of morin > kaempferol > myricetin > quercetin > vitamin A > α-tocopherol > apigenin > (+)-catechin > chrysin > datiscetin > luteolin > naringin > taxifolin > rutin > butylated hydroxytoluene (BHT) > naringenin. The flavonoid aglycones were more potent in their antiperoxidative action than their corresponding glycosides. Structure-activity revealed that the flavonoid molecule with polyhydroxylated substitutions on rings A and B, a 2–3 double bond, a free 3-hydroxyl substitution and a 4-keto moiety, would confer potent antiperoxidative properties upon the compound. The flavonols, namely morin, myricetin, kaempferol and quercetin, would be suitable potential antioxidants for use in the stabilization of RBD-palm oil and its fractions against thermal autoxidation. The structural activity of the flavonoids on the RBD-palm oil was similar to those observed for these compounds in animal tissue or enzyme systems.
The antioxidant compounds of oleoresin of sage (Salvia officinalis) were separated by column chromatography and high-performance liquid chromatography. Six major compounds were purified and identified by IR, MS, and H-1 NMR spectrometry as carnosol, carnosic acid, rosmadial, rosmanol, epirosmanol, and methyl carnosate. Their antioxidative activity was measured with an accelerated test, and their content was quantified in sage and in four commercial rosemary extracts.
The loss of antioxidants at elevated temperatures occurs as a result of both evaporation and decomposition. The stability of four phenolic antioxidants at 185-degrees-C was examined by TLC and gas chromatography and found to be in the order BHT > PG > BHA > TBHQ. Several products arising from thermal oxidation of the antioxidants were separated and identified by gas chromatography/mass spectrometry and mechanisms for their formation suggested.