The genus Phoenix is one of the most widely cultivated groups of palms around the world. The aim of this study was to determine the antioxidant activity and total phenolic compounds of 14 different varieties of date palm (Phoenix dactylifera L., Arecaceae) seed extracts with 5 solvents [water, methanol, methanol (50%), DMSO, and water: methanol: acetone: formic acid (20:40:40:0.1)]. Ferric reducing antioxidant power assay and Folin-Ciocalteu reagent was used for determination of the antioxidant effect and phenolic content of date seeds. DMSO extract of the “Zahedi” variety had the highest antioxidant effect (37.42 mmol/100 g dry plant) and total phenolic content (3541 mg /100 g dry plant) among these 14 varieties and 5 solvents. There was a significant correlation between the total phenolic content and antioxidant activity (R2 = 0.791, P < 0.001) of the “Zahedi” variety DMSO extract, which can indicates that polyphenols are the main antioxidants. Iranian date palm seed has a relatively high antioxidant activity due to contribution of phenolic compounds. The present study showed that the Iranian date seeds are strong radical scavengers and can be considered as a good source of natural antioxidants for medicinal and commercial uses.
Acute and Subchronic Toxicity?of Teucrium polium Total Extract in Rats
Iranian Journal of Pharmaceutical Research
(2010), 9 (2): 141-146
Received: March 2009
Accepted: September 2009
Copyright ? 2010 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services
Comparison of Antioxidant Activity and Total Phenol
Contents of some Date Seed Varieties from Iran
Mohammad Reza Shams Ardekania,b, Mahnaz Khanavia,b*, Mannan Hajimahmoodib,c,
Maryam Jahangiria and Abbas Hadjiakhoondia,b
aDepartment of Pharmacognosy and Medicinal Plants Research Center, Faculty of
Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. bDepartment of
Traditional Pharmacy, School of Traditional Medicine, Tehran University of
Medical Sciences, Tehran, Iran. cDepartment of Drug and Food Control, Faculty of
Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
The genus Phoenix is one of the most widely cultivated groups of palms around
the world. The aim of this study was to determine the antioxidant activity and
total phenolic compounds of 14 different varieties of date palm (Phoenix dactylifera L., Arecaceae) seed extracts with 5 solvents [water, methanol,
methanol (50%), DMSO, and water: methanol: acetone: formic acid (20:40:40:0.1)].
Ferric reducing antioxidant power assay and Folin-Ciocalteu reagent was used for
determination of the antioxidant effect and phenolic content of date seeds. DMSO
extract of the ?Zahedi? variety had the highest antioxidant effect (37.42 mmol/100
g dry plant) and total phenolic content (3541 mg /100 g dry plant) among these
14 varieties and 5 solvents. There was a significant correlation between the
total phenolic content and antioxidant activity (R2 = 0.791, P < 0.001) of the
?Zahedi? variety DMSO extract, which can indicates that polyphenols are the main
Iranian date palm seed has a relatively high antioxidant activity due to
contribution of phenolic compounds. The present study showed that the Iranian
date seeds are strong radical scavengers and can be considered as a good source
of natural antioxidants for medicinal and commercial uses.
Keywords: Antioxidant; Total phenol; Phoenix dactyliferea L.; Seed; Date.
The date palm (Phoenix dactylifera L., Arecaceae) is one of mankind?s oldest
cultivated plants (1). It is highly popular worldwide, particularly in the
Middle East and North Africa (2). Iran produced 918000 metric tons of dates in
2006, contributing about 21% to the total global production (3).
Date has been used as food for 6000 years (1). It could be used for generations
to come due to its remarkable nutritional, health and economic value in addition
to its aesthetic and environmental benefits (4). The fruit of the date palm is
well known as a staple food which is composed of a fleshy pericarp and seed (5).
The date seeds (pits) constitue approximately 10% of the fruits (6). A date is a
high-energy food being high in carbohydrates (70-80%) and low fats and proteins,
and a good source of vitamin, calcium, magnesium, phosphorous, zink, iron,
potassium and iodine (7-10). Most of the carbohydrates in dates are in the form
of fructose and glucose, which are easily absorbed by the human body (9).
Also, the date seeds contain high percentage of carbohydrate (81.0-83.1%),
protein (5.17-5.56%), oil (10.19-12.67%), ash (1.12-1.15%) and oleic acid
Date fruits are listed in folk remedies for treatment of various infectious
diseases, atherosclerosis, diabetes, hypertension and cancer (7, 11, 12). There
are some reports of the enhancing effect of date fruit on haemagglutinating
antibody titers, plaque-forming cell counts in spleen, and macrophage migration
index as an index of cell-mediated immunity (7).
A common denominator in pathogenesis of most of the chronic diseases is the
involvement of oxidative stress, related to the production by all aerobic
organisms of reactive oxygen and nitrogen species, including free radicals
(13-18). In addition to having a role in intra and extra cellular signaling,
these reactive molecular species may initiate damaging biochemical reactions
(17-19). In response to such damages, a complex antioxidant defense has been
developed, and dietary antioxidants comprise an important role in this defense
Antioxidant activity is closely related to the phenolic content of plants (3).
Because synthetic antioxidants such as butylated hydroxytoluene or butylated
hydroxyanysol could promote cancer development in rats and the fact that
consumers are much interested in natural food additives, herbal phenolic
compounds and other natural antioxidants are extremely desirable (24, 25). Some
of these compounds were found in date seed oil: hydroxytyrosol, protocatechuic
acid, tyrosol, gallic acid, caffeic acid, p-coumaric acid and oleuropein (26).
In this paper the seed extracts of 14 native date varieties grown in Iran were
screened for their antioxidant activities and polyphenol contents.
The seeds of 14 varieties (Shahani, Khasuei, Sayer, Zahedi, Shekar, Shahabi,
Kabkab, Khenizi, Maktub, Kabkab dalaki 2, Shahabi 2, Majul, Goftar, Lasht), were
procured from a local farm in Bushehr, Iran, at the beginning of the 2006
harvest season. The shape, size and color of each variety were completely
different. Voucher specimens have been identified and deposited in the Herbarium
of the Agricultural Research and Natural Resource Center of Bushehr province,
Bushehr, Iran. They were dispatched by airplane to Tehran University of Medical
Sciences. Mature fruits of uniform size, free of physical damage and injury from
insects and fungal infection, were selected and used for all experiments. Upon
arrival at the laboratory, the samples (500 g portions) were packed in
polyethylene bags, sealed and stored at 2-8?C until analysis. The seeds were
washed to get rid of any adhering date flesh, and air-dried. Then, they were
further dried at about 50?C for 4 h. Date pits of each variety were separately
milled in a heavy-duty grinder to pass 1-2 mm screens and then preserved at
2-8?C until analysis.
About 0.02 g of powdered date seeds was shaked with 5 mL of solvent in a glass
tube at room temperature, two times for 30 min and then centrifuged. Water,
methanol:water (50:50, v/v), methanol, DMSO and water:methanol:acetone: formic
acid (20:40:40:0.1) (3) were used as the best solvents. The extraction was
carried out using five different solvents to compare the antioxidant activities
and the total phenolic contents of each extract.
Evaluation of antioxidant activity using FRAP method
The FRAP (ferric reducing antioxidant power assay) procedure described by Benzie
and Strain was followed (27). The principle of this method is the reduction of a
ferric-tripyridyl triazine complex to its colored ferrous form in the presence
of antioxidants. Briefly, the FRAP reagent contained 5 mL of 10 mmol/L solution
of TPTZ (2,4,6-tripyridyl-s-triazine) in 40 mmol/L HCL plus 5 mL of a 20 mmol/L
solution of FeCl3 and 50 mL of a 0.3 mol/L acetate buffer solution, pH 3.6 which
was prepared freshly and warmed at 37˚C. Aliquots of 50 μL extract were mixed
with 1.5 mL FRAP reagent and after incubation at 37˚C for 10 min, the absorbance
of the reaction mixture was measured at 593 nm. For construction of the
calibration curve, five concentrations of FeSO4, 7H2O (1000, 750, 500, 250, 125
?mol ∕ L) were used and the absorbance values were measured as for sample
solutions. The antioxidant activities were expressed as the concentration of
antioxidants having a ferric reducing ability equivalent to that of 1 mmol/L
Measurement of the total phenolic contents
Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent
as described by Velioglu et al. (28) with slight modifications. The prepared
extract (200 ?L) was mixed with 1.5 mL of Folin-Ciocaltue reagent (previously
diluted 10 fold with distilled water) and allowed to stand at 200?C for 5 min. A
1.5 mL sodium bicarbonate solution (60 g/L) was added to the mixture. After 90
min at 22?C, the absorbance was measured at 725 nm using a UV spectrophotometer
(Pharmacia Biotech). The total phenolics were quantified by the calibration
curve obtained from measuring the absorbance of a known concentration of gallic
acid (GA) standard (20-150 mg/Lit). The concentrations were expressed as
equivalent milligrams of gallic acid (GA) per 100 g dry plant.
The values were reported as mean ? SD. One-way ANOVA and Tukey post-hoc
multicomparison tests were used for the analyses.
Results and Discussion
To compare the effects of the extraction methods on antioxidant activities and
total phenolic contents in 14 varieties of date seed, five different solvents
were used (Table 1, 2). All the extracts had considerable antioxidant activities
from the equivalent of 13.13 mmol of FeII/100 g dry plant in seeds of the Lasht
variety to 37.42 mmol of FeII/100 g dry plant in Zahedi variety (Figure1). All
the extracts contained considerable phenolic contents from the equivalent of
1260 mg GA/100 g dry plant in seeds of the Shahabi variety to 3541 mg GA/100 g
dry plant in Zahedi variety (Figure 2).
In previous investigations of Phoenix dactylifera L., Arecacea varieties,
evaluation of the antioxidant activity and the presence of polyphenol compounds
were reported (29). Antioxidant activities of different extracts of the edible
portion of date fruit according to the β-carotene bleaching method ranged from
9.28% to 75.96%. The activity of petroleum ether seed extract was 8.19% and the
total phenolic content was found to be 1416 mg of GA/100 g dry weight (29). In
two different researches, antioxidant effects of the edible portion of
hydro-alcoholic extracts of Kabkab and Zahedi varieties were reported as 11.7
and 19.1 (30), and 1510 and 1400 ?mol FeII/100 g dry plant (3). Also their total
phenol contents were reported as 3250 and 4370 (30), and 200, 170 (3) mg GA/100
g dry plant. It seems that this variation was related to different method of
In another study, the flavonoid glycoside and procyanidin compositions of date
were investigated and 19 flavonoid glycosides of luteolin, quercetin and
apigenin were also identified (8). Besbes et al had investigated the quality and
oxidative stability of the date seed oils from two date palm cultivators, Deglet
Nour and Allig, during storage. Total phenolic contents were reported by them to
be for them about 220-520 vg/g oil respectively and the results showed that the
date seed oil could be easily stored (31).
In this research, the antioxidant activities and phenolic contents of 14 date
seed varieties were determined representing 37.42 mmol FeII/100 g dry plant as
the highest activity, and 3658 mg GA/100 g dry plant as the highest phenolic
content in date samples compared to the previous works (29).
Significant differences (P < 0.001) existed among different solvents used, with
some exception (Figures 1 and 2). Extraction by DMSO gave the highest
antioxidant activity and total phenolic content, whereas water and
methanol:water (50:50, v/v) resulted in the lowest values. The results showed
that most of the potent antioxidant and phenolic compounds in the seeds of 14
date varieties were soluble in DMSO.
Although there was a relationship between the presence of high amounts of
phenolic compounds, and the antioxidant effect of 14 varieties of date seeds in
(R2 = 0.791), there are some reports on the role of other compounds in this
activity. The oleic acid contents, as a major antioxidant component of the date
seeds varies from 41.1 to 58.8%, suggests that the seeds of date could be used
as a source of oleic acid (4, 32).
Date seeds have previously been examined for extractable high value-added
components for incorporation into functional foods (33). The results showed that
date seeds contained large quantities of fiber, and possibly resistant starch,
which may have potential health benefits.
Also in some other studies, the antioxidant effects of
Phoenix dactylifera L.
seeds were investigated. However, different methods were used for the studies,
thus the results are not directly comparable.
As mentioned before, Phoenix dactylifera L., seeds could easily be conserved and
used in cosmetics, pharmaceuticals and food products. Therefore, the potency of
these extracts could provide a chemical basis for some of the health benefits
claimed for Phoenix dactylifera L. seeds in folk medicine. Further studies are
necessary to assess the potential of their components as effective natural
This research has been supported by a grant from Tehran University of Medical
Sciences and health services. We are also grateful to Mr. Hossien Jamalifar for
his technical helps.
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