The consumption of fruits and vegetables is accepted to be one of the strategies to reduce risk factors for these diseases. The aim of this study was to examine potential relationships between the antioxidant and the antiplatelet activities in green mature and fully ripe (red) tomatoes and of lycopene-rich byproducts of tomato paste processing such as pomace. The total phenol content of tomato components was the highest in peels, pulp, and in the mucilaginous myxotesta covering the tomato seeds with values
Among the nontransmissible chronic diseases (NCDS) cardiovascular diseases (CVDs) and cancer are associated with high mortality [
Epidemiological studies have shown that diets rich in fruits and vegetables may prevent from CVDs [
Pomace is a byproduct of industrial processing of tomatoes into paste and canned products. It mainly consists, of seeds and the peel [
Consequently, the present study aimed at the comprehensive characterization of the antioxidant and antiplatelet activities of different tissues, of fully and green ripe tomatoes including the pomace resulting from industrial tomato processing.
Cluster tomatoes, green ripe and fully mature (red) tomatoes were obtained from the Regional Supply Centre of Talca, Chile, and subsequently washed and manually separated into peels, pulp, and seeds, the latter being covered by mucilage formed by its myxotesta.
Pomace composed of seeds and peels arising from industrial tomato paste processing was obtained from “Tresmontes Luchetti” (Production plant Talca, Chile).
Sulfuric acid (p.a.), sodium hydroxide (p.a.), sodium carbonate (p.a.), sodium acetate (p.a.), 2,4,6-tripyridyl-s-triazine (p.a.), iron chloride (FeCl3), dimethyl sulfoxide (DMSO), acetylsalicylic acid, petroleum ether, methanol, ethanol, and acetone were obtained from Arquimed (Santiago, Chile), whereas lycopene, gallic acid, quercetin, catechin, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), butylated hydroxytoluene (BHT), 1,1-diphenyl-2-pycrylhydrazyl (DPPH), and Folin-Ciocalteu reagent were purchased from Sigma-Aldrich (St. Louis, MO, U.S.A). The agonists adenosine 5′-diphosphate bis (ADP), Thrombin receptor-activating peptide 6 (TRAP-6), and arachidonic acid were from Sigma-Aldrich (St. Louis, MO, U.S.A), while the collagen was obtained from Hormon-Chemie (Munich, Germany). Distilled water was used throughout.
Both, green and red peels of tomatoes were separately comminuted in a blender (Somela BL1500), and the mashed product was subsequently, mixed with methanol in a ratio of 1 g of peels to 1 mL of methanol. The mixture was sonicated (Elma Transsonic 700/H, Singen, Germany) for 5 min and then filtered through gauze twice. The filtrate was evaporated under
Small pieces of green and red tomatoe pulp, respectively, were comminuted in a blender, and the resulting mash was filtered twice through gauze. The liquid obtained was lyophilized and stored at −80°C until use.
The mucilaginous myxotesta covering the tomato seeds of green and red ripe tomatoes was mixed in a ratio of 1 g of seeds to 1 mL of distilled water. The suspension was sonicated for 5 min and then filtered twice through gauze. The resulting aqueous seed extract was subsequently lyophilized and stored at −80°C until use.
Wet pomace was dried in an oven at 60°C for two days and subsequently comminuted and dissolved in a proportion of 1 g of tomato pomace to 1 mL of distilled water. The suspension was sonicated for 5 min and then filtered twice through gauze. The obtained aqueous tomato pomace extract was then lyophilized and stored at −80°C until use.
Seeds were recovered from pomace by sieving to obtain aqueous and petroleum ether extracts. In the first case, a portion of seeds was extracted and dissolved at a ratio of 1 g of seeds to 1 mL of distilled water, and then the mixture was sonicated for 5 min and filtered twice through gauze. The filtrate was lyophilized and stored at −80°C until use. For the petroleum ether extract, tomato pomace seeds were macerated after the addition of the solvent, and the suspension was sonicated for 5 min and then filtered twice through gauze. The filtrate was concentrated
To characterize the chemical composition of the pulp of green and red tomatoes, tomato pomace, and seed mucilage, the water content (%) was determined by drying in a convection oven at 60°C, the protein content was measured using the Kjeldahl method, and fat content was determined using the Soxhlet method. Ash content was obtained by drying the samples in a muffle furnace at 550°C for two hours. Crude fiber was determined by the acid sequence method using 1.25% H2SO4 and 1.25% NaOH for acid and alkaline hydrolysis, respectively. Carbohydrate content was calculated as the difference between the total and the contents of all other ingredients [
Extraction and quantitative determinations of lycopene were conducted according to Fish et al. (2002) [
Quantification of lycopene for pulp of green and red tomato absorbance of the hexane extract was monitored at 503 nm using a Unicam Helios Gamma spectrometer (Thermo Spectronic, Helios Gamma, Cambridge, UK). Calibration curves of lycopene standard
Determination of total phenolic contents was performed using Folin-Ciocalteu reagent as adapted from Velioglu et al. (1998) [
The scavenging activity of the extracts was estimated using DPPH as the free radical model according to the method adapted from Molyneux [
Determinations were conducted according to Benzie and Strain [
Venous blood samples were taken from two volunteers, (healthy university students), who previously signed informed consent, in 3.2% citrate tubes (9 : 1 v/v) by phlebotomy with vacuum tube system (Becton Dickinson Vacutainer Systems, Franklin Lakes, NJ, USA). The protocol was authorized by the ethic committee of the Universidad de Talca in accordance with the Declaration of Helsinki (approved by the 18th World Medical Assembly in Helsinki, Finland, in 1964). The samples were gently homogenized by 5-fold inversion and allowed to stand for 5 minutes. Then, they were centrifuged (DCS-16 Centrifugal Presvac RV) at 240 g for 10 minutes, and 1 mL of platelet-rich plasma (PRP) was taken from each tube for platelet count (in triplicate) in an hematologic counter (Bayer Advia 60 Hematology System, Tarrytown, NY, USA). The original tubes were centrifuged at 650 g for 10 minutes to obtain the platelet-depleted plasma (PDP). Finally, the PRP was adjusted to
Mean ± standard errors of mean (S.E.M) were determined using SPSS version 17.0. The data were statistically analyzed by Student's
Table
Approximate chemical composition.
Moisture (%) | Protein (%) | Fat (%) | Ash (%) | Carbohydrate (%) | Crude fiber (%) | |
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Red tomato pulp |
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Green tomato pulp |
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Tomato pomace |
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Seeds of tomato pomace |
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Values are presented as mean ± S.E.M (
The levels of lycopene in the pulps strongly depended on the ripening degree of the green and red tomatoes. Thus, red-colored pulp of fully mature tomatoes had a more than 40 times higher lycopene content (
The phenolic contents deceased in the following order: peels > pulp > seeds with total contents of
Total phenolic contents from green and fully ripe tomato fruits and pomace from industrial tomato processing. Values are presented as mean ± S.E.M (
In contrast, levels of phenols in the pomace were lower than those of the green and red tomatoes. Aqueous extracts of pomace yielded higher polyphenol contents (
Generally, overall antioxidant activities were greater in all concentrations for peels and pulp followed by the seed mucilage of fully mature tomatoes. In contrast, the green tomato pulp represented the highest antioxidant activity.
When comparing different ripeness stages, the differences in their antioxidant potential were significant. At a concentration of 1000
Antioxidant activity in extracts from green and fully ripe tomato fruits and pomace from industrial tomato processing. Values are presented as mean ± S.E.M (
At the highest test concentration (1000
The reducing ability was higher in extracts of red tomato than in those of green tomatoes, the latter being superior to pomace extracts. In red tomatoes, peels had higher FRAP values (
The results of platelet aggregation induced by the agonists ADP, collagen, TRAP-6, and arachidonic acid, respectively, with added extracts from green and fully mature tomatoes are presented in Table
Antiplatelet activity in extracts from green and fully ripe tomato fruits.
Maximum aggregation (%) | Slope | Area under | Lag time (s) | |
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ADP | ||||
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Red tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Green tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Negative control |
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Collagen | ||||
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Red tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Green tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Negative control |
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TRAP-6 | ||||
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Red tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Green tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Negative control |
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Arachidonic acid | ||||
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Red tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Green tomato | ||||
Peels |
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Pulp |
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Seed mucilage |
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Negative control |
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Values are presented as mean ± S.E.M (
Inhibition of platelet aggregation induced by collagen compared to negative control was in the following order
Extracts from the pulp and seed myxotesta of red ripe tomatoes displayed a net lag time of
Each of the pomace extracts exerted a potent inhibition of platelet aggregation induced by ADP, collagen, TRAP-6 and arachidonic acid, respectively (Table
Antiplatelet activity in extracts from pomace.
Maximum aggregation (%) | Slope | Area under | Lag time (s) | |
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ADP | ||||
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Pomace |
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Aqueous seeds |
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PE seeds |
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Negative control |
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Collagen | ||||
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Pomace |
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Aqueous seeds |
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PE seeds |
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Negative control |
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TRAP-6 | ||||
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Pomace |
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Aqueous seeds |
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PE seeds |
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Negative control |
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Arachidonic acid | ||||
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Pomace |
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Aqueous seeds |
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PE seeds |
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Negative control |
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Values are presented as mean ± S.E.M (
Epidemiological studies have provided evidence of a protective role of healthy diets in the prevention of CVDs and cancer [
Although pomace is a byproduct of industrial tomato processing, it presents high amount of crude fiber and protein [
The total phenolic content was higher in the red than in the green ripe tomatoes, which has been described by Ilahy et al. [
The antioxidant activities as determined by the DPPH and FRAP assays were higher in red tomato followed by green tomato and tomato pomace. Although the mechanisms of action of DPPH and FRAP are different, that is, scavenging of DPPH cationic radicals in the DPPH assay and reduction of ferric ion in the FRAP assay, respectively, the results of these two assays were significantly correlated for red tomato (
The levels of total phenols showed a strong correlation with antioxidant activity as determined by the DPPH (
It was observed that red tomatoes exert
Extracts prepared from the mucilaginous myxotesta of the tomato seeds exerted the greatest antiplatelet activity induced by ADP independent of the ripening stages (green and red ripe tomato). Among the tissues of the red and green tomato, the mucilage (myxotesta) covering the mature seeds exerted the maximum antiplatelet activity, which is in agreement with previous findings of Dutta-Roy et al. [
In food industry, pomace is obtained as a byproduct from processing tomatoes into fluid and pasty products such as tomato juice, sauce, and paste constituting a major environmental problem. It represents approximately 2% of the total weight of tomatoes processed in the agro-industry containing about 44% seeds and 56% of peels [
Despite tomato processing under heat exposure, the active principles exerting antiplatelet activity are obviously well retained, since all the extracts were active independent of the agonist used. This may be due to the presence of lipids and
The antioxidant activity was found to be dependent on the ripening degree of the tomato fruits, in contrast to the antiplatelet activity, which was also observed for extracts prepared from tomato pomace. Based on the present results, both extracts from seed mucilage and pomace may be used as functional ingredients adding antioxidant and antiplatelet activities to processed foods which may be supportive in the primary prevention of NCD.
The authors report no conflict of interests.
This work was funded by the CONICYT REGIONAL/GORE MAULE/CEAP/R09I2001, Programa de Investigación de Excelencia Interdisciplinaria en Envejecimiento Saludable (PIEI-ES) and supported by grant No. 1130216 (I.P., M.G., R.M., M.A., J.C.) from Fondecyt, Chile.