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African Journal of Biotechnology Vol. 9(32), pp. 5173-5176, 9 August, 2010
Available online at http://www.academicjournals.org/AJB
ISSN 1684–5315 ©2010 Academic Journals
Full Length Research Paper
Evaluation of total phenolics, anthocyanins and
antioxidant capacity in purple tomatillo (Physalis
ixocarpa) genotypes
Daniel González-Mendoza1* Onecimo Grimaldo-Juárez1, Roberto Soto-Ortiz, Fernando
Escoboza-Garcia1 and José Francisco Santiguillo Hernández2
1Instituto de Ciencias Agrícolas -Universidad Autónoma de Baja California, Carretera Delta S/N, Ejido Nuevo León
21705, Baja California México.
2Centro Regional Occidente, Universidad Autónoma Chapingo, Chapingo, México.
Accepted 16 July, 2010
Purple tomatillo genotypes were evaluated for their total anthocyanin, phenolic and antioxidant
capacity. The result showed that ICTS-UDG-9-224 and ICTS-UDG-9-32 had the highest amount of total
phenolic compounds 10.08 and 9.6 mg GAE/g fresh weight in genotypes, respectively, followed by
ICTS-UDG-1-1 and ICTS-UDG-2-2 (5.5 and 5.3 mg GAE/g fresh weight), respectively. The highest content
of anthocyanins was found in the genotypes ICTS-UDG-9-32 (6.94 mg of pelargonidin 3-glucoside
equivalents/g of fresh weight). In contrast, the genotypes ICTS-UDG-9-224 showed lowest values of
antocyanins content. On the other hand, for total antioxidant capacity, the 2,2-diphenyl-1-picrylhydrazyl
(DPPH) methods showed that genotypes, ICTS-UDG-2-2 and ICTS-UDG-1-1 had the highest antioxidant
capacity (approximately 80%) followed by genotypes ICTS-UDG-9-32 (55%) and ICTS-UDG-9-224 (28%),
respectively. These results provide useful and important information for researchers in order to
increase the antioxidant capacity and functional value of purple tomatillo for the food and nutraceutical
industries.
Key word: Antocyanins, purple tomatillos, bioactive compounds, antioxidant capacity.
INTRODUCCION
The production of reactive oxygen species in organisms
can have a role in cell communication processes and
defense mechanisms. However, excessive production
and accumulation of these products can cause a series of
biochemical reactions that can generate various dis-
orders on the cells. For example, may oxidize nucleic
acid, proteins, lipids or DNA and can initiate a variety of
disease processes such as cancer, neurodegenerative
disorders, cardiovascular disease and arteriosclerosis
(Migliore and Coppedé, 2009). The alternatives to reduce
*Corresponding author. E-mail: daniasaf@gmail.com Tel: +52
686 5230079. Fax: +52 686 5230217.
Abbreviations: DPPH, 2,2-Diphenyl-1-picrylhydrazyl; UV,
ultraviolet; GAE, gallic acid equivalent; RSA, radical
scavenging.
the presence of reactive oxygen species in higher
organisms have suggested the consumption of fruits rich
in bioactive compounds such as anthocyanins (Salinas-
Moreno et al., 2009).
Anthocyanins are plant secondary metabolites, res-
ponsible for most of the red, blue and purple pigmen-
tation found in flowers, fruits and leaves (Harborne and
Williams, 2000). They are involved in plant resistance
against ultraviolet (UV) light and in animal attraction for
pollination and seed dissemination (Archetti, 2000;
Manetas, 2006). The major sources of anthocyanins in
edible plants include the families Vitaceae (grape) and
Rosaceae (blackberry, apple, peach, etc.). Other plant
families which contain anthocyanin pigments are
Solanaceae (tomato and eggplant) and Cruciferae (red
cabbage) (Lohachoompol et al., 2004). Among the plants
of the Solanaceae family, are the peel tomato (Tomatillo)
whose fruits, especially green color, are consumed in
different regions of Mexico, USA and Central America
5174 Afr. J. Biotechnol.
(Mulato-Brito and Peña-Lomeli, 2007). In contrast,
consumption of the fruit, purple tomatillo, is limited mainly
to the western region of Mexico (Santiaguillo et al., 1994).
Therefore, information on the functional properties of this
fruit would be helpful in increasing the awareness of the
consumers regarding the level of beneficial phyto-
chemicals present in this nutritious vegetable.
Thus, the current study was undertaken to determine
the content of bioactive compounds such as phenolic
compounds, anthocyanins and antioxidant activity present
in the fruit pericarp of purple tomatillo.
MATERIALS AND METHODS
Collection of fruits from plant materials
Fresh fruits of four selected purple tomatillo (Physalys ixocarpa)
genotypes from different regions of Jalisco, Mexico were collected
in June 2009 from a cultivated green house at the Institute of
Agronomy Sciences of the Autonomous University of Baja, Cali-
fornia (UABC). Immediately after harvesting, fruits were frozen and
stored at -20°C until analysis.
Sample preparation
A ground freeze-dried sample of 300 mg of each genotypes were
weighted and phenols and anthocyanins were extracted with 3 ml
80% aqueous solution of HCl-methanol (1%) at 4°C and then
homogenates were centrifuged at 3000 rpm for 10 min; super-
natants were subjected to further analysis.
Quantitative determination of total phenolic content
The total phenolic content of the crude acidified methanol extract
was determined by using a modified Folin-Ciocalteu method with
gallic acid (Sigma Chemical Co.) as a standard. Folin Ciocalteu
reagent (600 µl, Fluka) was added for methanolic extract solution
(120 µl), then 1 N aqueous sodium carbonate solution (360 µl) was
added and the tube was vortexed and then incubated for 40 min.
A blue color appeared and the absorbance was measured at 725
nm with a Beckman DU-50 spectrophotometer. All measurements
were made in triplicates and the results expressed as milligrams of
gallic acid equivalent (GAE) per g of fresh weight.
Anthocyanin extraction and determination
The extracts were freshly prepared from frozen fruit and did not
undergo extensive processing or significant browning; a pH differential
method for determination anthocyanin content was considered
unnecessary. Therefore, the total anthocianin of the acidified
methanol extract from 10 selected purple tomatillo (P. ixocarpa)
genotypes was measured at 535 nm using a Beckman DU-50
spectrophotometer. All measurements were made in triplicates and
the results expressed as milligrams of pelargonidin 3-glucoside
equivalents per gram of fresh weight.
Determination of DPPH scavenging activity
A methanolic solution (60 µl) of sample extract was added to 1200
µl (0.025 g L-1) of DPPH solution. The mixture was shaken
vigorously and allowed to stand at room temperature for 30 min.
The absorbance was measured at 517 nm by a spectrophotometer
using methanol as a blank. Lower absorbance of the reaction mixture
indicates higher free radical scavenging activity. The percentage of
2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging (RSA) was
calculated using the equation:
Initial absorbance - Final absorbance
%DPPH RSA = x 100
Initial absorbance
Statistical analysis
Data were analyzed with analyses of variance (ANOVA), and mean
of comparison test (Tukey’s = 0.05) was performed (Statistical
Package version 5.5, Statsoft, USA). Significant differences were
accepted if p < 0.05 and data was expressed as mean ± standard
error.
RESULTS AND DISCUSSION
The phenolic compounds (one of the most important
antioxidant plant components) are widely investigated on
plants and fruits (Djeridane et al., 2006). These com-
pounds might interfere in several of the steps that lead to
the development of malignant tumors, inactivating
carcinogens, inhibiting the expression of mutant genes
and the activity of enzymes involved in the activation of
procarcinogens and activating enzymatic systems involved
in the detoxification of xenobiotics. In the present study,
significant variations were observed in the content of total
phenolic compounds from different genotypes of selected
purple tomatillo genotypes (Figure 1). The maximum
values of total phenolic compounds per geno-types were
10.08, 8.34 and 7.31 mg GAE/g fresh weight in
genotypes ICTS-UDG-9-224, ICTS-UDG-9-32 and ICTS-
UDG-13-52, respectively. While minimum values were
recorded from ICTS-UDG-1-1 and ICTS-UDG-2-2 (5.5
and 5.3 mg GAE/g fresh weight, respectively).
On the other hand, the presence of anthocyanins in
plant-derived food is very important because their intake
in the human diet is associated with protection against
coronary heart disease and an improvement in sight. In
this study, our results showed that anthocyanin content in
purple tomatillo genotypes were slightly different (Figure
2).
The highest content of anthocyanins was found in the
genotypes ICTS-UDG-9-32 (6.94 mg of pelargonidin 3-
glucoside equivalents / g of fresh weight). In contrast, the
genotypes ICTS-UDG-2-2 and ICTS-UDG-1-1 did not
show significant difference in antocyanins content. On the
other hand, the genotypes ICTS-UDG-9-224 showed the
lowest values of antocyanins content (Figure 2). To the
best of our knowledge, there are no reports on total phenolic
and anthocyanin content from purple tomatillo genotypes,
thus preventing a direct comparison. How-ever, our
findings are in accordance with those reported on black
Soybean Cikuray variety (Astadi et al., 2009) and
strawberry (Tulipani et al., 2008). In this sense, we found
González-Mendoza et al 5175
Figure 1. Total soluble compounds phenolics of four different genotypes of purple tomatillo. Means ± standard error; n = 3.
Figure 2. Values of total anthocyanin of four different genotypes of purple tomatillo. Means ± standard error; n = 3.
similar values on phenolic and anthocyanin content. On the
other hand, for total antioxidant capacity, the DPPH
methods showed that genotypes, ICTS-UDG-2-2 and
ICTS-UDG-1-1 had the highest antioxidant capa-city
(90% approximately) followed by genotypes ICTS-UDG-
9-32 (55%) and ICTS-UDG-9-224 (28%), respectively
(Figure 3). Similar values have been observed in different
plants such as roselle of Hibiscus sabdariffa (Galicia-
Flores et al., 2008) and Camellia sinensis Linn (Khalaf et
al., 2008). Finally, these results provide useful and
important information for researchers in order to increase
the antioxidant capacity and functional value of purple
5176 Afr. J. Biotechnol.
% inhibition of DFFH radical
Figure 3. Antioxidant capacity of four different genotypes of purple tomatillo. Means ± standard error. n = 3.
tomatillo for the food and nutraceutical industries.
Conclusion
In the present study, selected purple tomatillo (P.
ixocarpa) genotypes appear to be good and safe source
of antioxidants. The fruits of this plant could be used for
direct consumption as salads or as extracts to increase
the nutritional value of different foods and diets. Future
studies include identification of the remaining antioxidant
constituents in the semi purified aqueous fractions and
study of the anticancer effects of these aqueous extracts.
ACKNOWLEDGEMENTS
We thank Ph.D. José Sánchez Martínez for excellent
technical assistance and Red de Tomate de Cascara for
helping us obtain the seeds used in the studyand
Programa de Mejoramiento del Profesorado (PROMEP)
convocatoria 2008, incorporacion de Nuevos Profesores
de Tiempo Completo.
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