Volume 5 Special Issue 2 2011
Antioxidant Properties of Crops III

ISBN 978-4-903313-86-3

Guest Editors

Ana Jiménez

Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Spain
www.cebas.csic.es/dep_ingles/estres/grupo_estres.html

Cristina García-Viguera

Department of Food Science and Technology, CEBAS-CSIC, Spain
www.cebas.csic.es/dep_ingles/aliment/group_quality.html

CONTENTS AND ABSTRACTS

Brígida R. Pinho, Patrícia Valentão (Portugal), Federico Ferreres (Spain), Jorge M. A. Oliveira, Paula B. Andrade (Portugal) Antioxidants in Natural Matrices: The Case of Phenolics (pp 1-11)

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Invited Review: Small quantities of reactive species of oxygen and nitrogen are produced in physiological processes occurring in all organisms. However, when they are formed in excess or when the antioxidant defence system is depleted, homeostasis is disrupted favouring pro-oxidants. Loss of oxidative status has been linked to several diseases. Thus, antioxidants compounds may assist the prevention and therapeutics of diseases in which oxidative phenomena are involved, e.g. cancer, chronic inflammatory disease, cardiovascular disorders and aging. There are several synthetic compounds with antioxidant properties, although their use has been restricted due to their toxicity. So, there is a growing interest on the search of natural compounds with antioxidant potential, which may exhibit improved tolerability. Natural matrices have proven antioxidant activity, which is due to their chemical composition. These matrices present a wide range of low molecular weight phytochemicals, like alkaloids, carotenoids and organic acids, which constitute the basis of their antioxidant capacity. Phenolic compounds are among those with more interest, because they are largely distributed in nature and can exert their antioxidant activity at several levels. As different natural matrices have distinct compounds contents, with several structures, they offer different protective mechanisms. In this chapter we describe different vegetable matrices, like Catharanthus roseus, Passiflora edulis, Rumex induratus and insect-plant system considerations, involving Pieris brassicae. All refered matrices display antioxidant activity, with special attention being given to their phenolic compounds. Because no single method is able to provide exact information about antioxidant potential, some methods currently used to assess this capacity will be referred.

Fabiola Domínguez, Hermelinda Salgado-Ceballos, Eva González-Trujano, Sergio Torres-Castillo, Sandra Orozco-Suarez (Mexico) Therapeutic Effects of Natural Antioxidants on Neurodegenerative Disease (pp 12-21)

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Invited Review: The free radical theory of aging hypothesizes that oxygen-derived free radicals are responsible for age-related damage at the cellular and tissue levels. In a normal situation, a balanced equilibrium exists among oxidants, antioxidants and biomolecules. Excess generation of free radicals may overwhelm natural cellular antioxidant defenses, leading to oxidation and further contributing to cellular functional impairment. The identification of free radical reactions as promoters of the neurodegenerative process implies that interventions aimed at limiting or inhibiting them should be able to reduce the rate of formation of degenerative changes with a consequent reduction in the aging rate and disease pathogenesis. Although the human diet is the main source of antioxidants, medicinal plants have received increasing attention in this context. Because antioxidant therapy is vital for the elimination of free radicals and ROS prevent the propagation of tissue damage and neuronal degeneration in the face of oxidative stress, diverse compounds and a broad variety of chemical structures have been investigated as therapeutic agents for acute central nervous system lesions. Indeed, there are currently many research groups working on this theme with the objective of discovering more potent and effective compounds. Here, we provide an overview of the current knowledge of the use of several medicinal plants as antioxidant agents to reduce the cellular damage produced by neurodegenerative diseases, focusing on basic and clinical evidence.

Emma Cantos-Villar, Pilar Zafrilla, Juana Mulero (Spain) Antioxidant Activity of Wine Polyphenols for Alzheimer Prevention (pp 22-32)

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Invited Review: Increasing evidence demonstrates that oxidative stress causes damage to cell function with aging and is involved in a number of age related disorders including atherosclerosis, arthritis, and neurodegenerative disorders. Cellular changes show that oxidative stress is an event that precedes the appearance of the hallmark pathologies of the disease, neurofibrillary tangles and senile plaques. Although excessive consumption of ethanol in alcoholic beverages causes multi-organ damage, moderate consumption, particularly of red wine, is protective against all-cause mortality. There is currently much interest in phytochemicals as bioactive compounds of wine. Wine intake is associated with a lower incidence of AD (Alzheimer disease) since wine is enriched in antioxidant compounds with potential neuroprotective activities. The findings that red wine presented more health-promotion activity than beer or spirits caused research attention to focus on phenolic compounds. Several studies have been undertaken to differentiate the effects of phenolic and other non-alcohol components of wine from those due to alcohol. From polyphenolics resveratrol and flavanols can be underlined. Resveratrol is a potential therapeutic agent to amilorate age-related neurodegenerative disorders. Catechins, the most abundant phenolics in wine, could influence on the development of AD. This manuscript summarizes recent studies on the possible mechanisms of action, potential therapeutic uses, and bioavailability of the nonalcoholic constituents of wine.

Pedro Mena, Amadeo Gironés-Vilaplana, Diego A. Moreno, Cristina García-Viguera (Spain) Pomegranate Fruit for Health Promotion: Myths and Realities (pp 33-42)

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Invited Review: The role of pomegranate on folk medicine has been largely established and in recent years a notable increase of scientific support has occurred. However, what is real? Evidence suggests that phenolic phytochemicals of pomegranate fruit, mainly anthocyanins and ellagitannins, could exert multiple therapeutic properties on health management as playing an essential role in oxidative stress balance, preventing important cardiovascular diseases, and fighting as chemoprotective agent against several kinds of cancer. In addition, pomegranate antioxidant bioactives also could possess a role as neuroprotectors in some neurological disorders just as broad antimicrobial activities among other beneficial implications. Regarding promising prospects of pomegranate phenolics, this review summarizes the available scientific information related to health promotion features of pomegranate-derived products and underlines the influence of multiple constituents on the observed biological actions, pointing out pomegranate juice as an interesting source to obtain health benefits.

Pilar Soengas, Tamara Sotelo, Pablo Velasco, Maria Elena Cartea (Spain) Antioxidant Properties of Brassica Vegetables (pp 43-55)

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Invited Review: Brassica vegetables include some economically interesting crops such as cabbage, broccoli, cauliflower, Brussels sprouts, kale and turnip, which are consumed all over the world. A high intake of Brassica vegetables reduces the risk of age-related chronic illness such as cardiovascular health and other degenerative diseases and reduces the risk of several types of cancer, thanks in part to the antioxidant properties of different compounds. Compared to other vegetables, Brassica vegetables have higher antioxidant potential which makes them very interesting crops from the consumer’s point of view. This review focuses on the composition and antioxidant capacity of both lipid- and water-soluble extracts of Brassica vegetables. Here, we will provide an overview of the role of phenolic compounds, vitamins and carotenoids present in Brassica vegetable crops in relation to antioxidant properties and human health. Both climatic conditions and agronomic practices influence the phytochemical content of the plant. The effects of genotype and plant organ on the stability of bioactive components and antioxidant activity are discussed, as well as post-harvest storage, processing and different cooking methods. Furthermore, we summarize in this review the current knowledge on the role of the antioxidant compounds present in Brassica vegetables in relation to human health. As conclusion, Brassica vegetables contain bioactive substances with a potential for reducing the physiological as well as oxidative stress and this could explain the suggested cancer preventive effect of these plants as well as their protective role on other major diseases.

José M. Palma, Ana Jiménez, Francisco J. Corpas, Rosa M. Mateos, M. Carmen Martí, Francisca Sevilla, Luis A. del Río (Spain) Role of Ascorbate on the Fruit Physiology of Pepper (Capsicum annuum L.) (pp 56-61)

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ABSTRACT

Invited Mini-Review: Ascorbate (vitamin C) is essential for cell metabolism, and its supply to the human diet derives basically from the consumption of fruits and vegetables. Several biosynthetic pathways of ascorbate have been reported in plants, the major physiological one being the so-called Smirnoff-Wheeler pathway. Ascorbate is a powerful antioxidant in plants, although it also plays an important role in hormone synthesis, cell signalling, gene expression, cell division and growth, and programmed cell death. Based on this multiplicity of functions, nowadays it is considered that ascorbate works as a redox buffer in the plant cell. Bell pepper (Capsicum annuum L.) is the second most consumed vegetable worldwide, and its fruit is one of the richest sources of vitamin C. In our laboratory, we have analysed a number of enzymatic and non-enzymatic antioxidants in fruits from different pepper cultivars under distinct developmental and environmental conditions. Unlike the majority of parameters determined, total ascorbate levels underwent few changes during the fruit ripening process. Likewise, under certain stress situations, provoked by environmental variations, total ascorbate remained practically invariable, and only the ascorbate/dehydroascorbate ratio was modified. Therefore, ascorbate seems to play a relevant role in the physiology of pepper fruit, possibly functioning as a regulator of processes which imply important metabolic alterations, thus contributing to the stability of fruits, a typical feature of peppers which commonly display a long life-span after harvest.

Cristina Ortega-Villasante, Juan Sobrino-Plata, Ramón O. Carpena-Ruiz (Spain), Nathalie Verbruggen (Belgium), Carolina Escobar, Luis E. Hernández (Spain) Oxidative Stress Induced by Cadmium in Transgenic Nicotiana tabacum Over-expressing a Plastidial Mn-Superoxide Dismutase (pp 62-67)

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ABSTRACT

Original Research Paper: Nicotiana tabacum transgenic plants overexpressing manganese (Mn) superoxide dismutase (SOD) targeted to plastids were studied upon 12.5 mM cadmium (Cd) application. No differences in tolerance were observed in comparison to wild type plants. Seed germination inhibition, seedling growth, and plant biomass were measured at different developmental stages. Cd analysis revealed the usual distribution of Cd between roots and shoots, 10-times higher in roots. Lipid peroxidation level, a characteristic parameter of oxidative stress, indicated that little protection was gained by overexpressing MnSOD. However, chlorophyll concentration was not affected upon Cd treatment in 35S:MnSOD transgenic plants, suggesting that a possible protection localised at the chloroplast could indeed occur. Three antioxidant enzymes sensitive to metal stress were also analysed after in gel activity staining: SOD, ascorbate peroxidase (APX) and glutathione reductase (GR). As expected, MnSOD activity was remarkably higher in transgenic N. tabacum plants. Interestingly, Cu/ZnSOD activity decreased upon exposure of plants to 12.5 mM Cd. GR and APX activities augmented in metal-treated plants. In particular, APX activity was slightly higher in MnSOD over-expressing plants, which was possibly related with an enhanced generation of H₂O₂ through higher SOD activity.

Rogelio Ramírez-Serrano, Juan A. Larrinaga-Mayoral, Bernardo Murillo-Amador, Norma Y. Hernández-Saavedra (Mexico), Hideyasu Fujiyama (Japan), Ana Jiménez (Spain) Antioxidant System Response in Hot Pepper Fruits (Capsicum annuum L.) under Saline Stress Conditions during Cold Storage (pp 68-74)

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Original Research Paper: A pot experiment was carried out with hot pepper (Capsicum spp. cv. ‘Caballero’) to investigate the antioxidant system response in fruits of this species under moderate saline conditions (12.5 and 25 mM NaCl) for 60 days and stored in the immature stage at 4°C for 90 days. After different storage periods, we counted the number of fruits and measured their length, diameter, and fresh weight, as well as superoxide dismutase (SOD) and catalase (CAT) activities, lipid peroxidation, ascorbic acid content, protein oxidation, chlorophyll a and b content, and carotenoids (violaxanthin, zeaxanthin, and β-carotene). The results showed no statistical changes in the number of fruits or in their morphological characteristics in the different treatments. However, the other parameters that were measured showed significant differences between salt treatments, storage periods, and interaction between both factors. The results suggested the involvement of the different SOD isoenzymes in the ripening process of fruits from the salt-treated plants. The 12.5 mM NaCl treatment was beneficial for the fruits, which presented higher levels of ascorbate (100 mg L^-1) than control fruits and for the long storage at 4°C where fruits showed lower oxidative stress parameters.

Ramesh Joshi, Bhanwar Lal Jat, Anshul Sharma, Vinod Joshi, Nitu Bohra (India), Dilip Nandwani (USA) In Vitro Determination of Antioxidant Activity of Murraya koenigii (L.) Spreng. (pp 75-77)

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Research Note: Murraya koenigii (Linn.) Spreng, locally known as “curry patta” or “mitha neem” (curry leaf tree) belonging to the Rutaceae family, is commonly used as raw material for traditional medicinal formulation in India. Its aromatic leaves contain essential oil and it is used as a condiment. The fresh leaves of M. koenigii have been reported to possess anti-microbial, mosquitocidal, topo-isomerase inhibition and antioxidant properties. The present paper aims to undertake a comparative study of the antioxidant potential of extracts of plant parts and fruits/seeds in different stages of biological development and ripeness. Eight different plant materials were tested to determine antioxidant activity, including roots, leaf, un-ripened (green colored) fruit and its seed, half ripened fruit and its seed, ripened fruit, and its seed. Stable 1,1-diphenyl-2-picryl hydrazyl (DPPH) was used for in vitro determination of free radical scavenging activity of the extracts. The ripened fruit exhibited highest phenol (16.4 mg.g^-1) and flavonoid (2.8 mg.g^-1) contents (fresh weight basis) and lowest activity in half-ripened fruit. The antioxidant activity of fruit extracts changed with their biological development and ripeness. This investigation is the first report on the comparative in vitro analysis of antioxidant potential of extracts of leaves, roots, fruits and seeds of M. koenigii.

Karuna Mulleegadoo, Asha Dookun-Saumtally (Mauritius) Leaf Roll Disc: An Explant Source for in Vitro Propagation and Genetic Transformation of Sugarcane (pp 78-82)

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Original Research Paper: The use of leaf roll discs for in vitro propagation and genetic transformation of sugarcane was investigated. For in vitro propagation, three varieties namely, M 3035/66, S 17 and R 570 were used, and the number of shoots produced from leaf roll discs was compared to that of apical buds. No shoots were regenerated from apical buds of variety S 17 following a culture period of 24 weeks, as they were all either contaminated or oxidized. With M 3035/66 and R 570, only few shoots were obtained. On the other hand, using leaf roll discs, contamination and oxidation were minimal resulting in more than 70% of the cultured explants forming shoots. Prolific shoot regeneration occurred in all three varieties with a total of 400 and 280 shoot clumps produced in varieties M 3035/66 and S 17 respectively, and 250 clumps in R 570. For genetic transformation, leaf roll discs of varieties M 292/70 and M 3035/66, pre-cultured for 10 days on callus induction medium, were bombarded with plasmid pAHC25 containing the gus and bar genes using the Bio-Rad PDS-1000/He Particle Delivery System. After selection on bialaphos, 66 and 24 plants of M 3035/66 and M 292/70 were respectively regenerated and transferred to the glasshouse. Fifty-eight well-established plants of M 3035/66 and 17 of M 292/70 were sprayed with 0.1% herbicide Basta^® four weeks later. Two plants of the latter variety were highly resistant to the herbicide whilst one displayed moderate tolerance. Upon analysis by PCR, all three plants were found to contain the bar gene. For M 3035/66, seven plants with a functional bar gene were obtained. Gene integration was confirmed by Southern blot analysis.

Kasem Z. Ahmed, Mohamed K. A. Aly, Shadia K. Ahmed (Egypt), Jaime A. Teixeira da Silva (Japan), Hossam M. Kamel (Egypt) Establishment of Embryogenic Cell Suspension Culture and Plant Regeneration of Egyptian Cumin (Cuminum cyminum L.) (pp 83-90)

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Original Research Paper: Embryogenic cell suspension (ECS) cultures were established from hypocotyl segments-derived embryogenic calli of Egyptian cumin (Cuminum cyminum L. cv. 'Balady'), the sole popular commercial variety of cumin in Egypt. After culture for 2-4 months on B5 solid callus induction medium supplemented with 0.88 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) plus 0.86 mg/l kinetin (Kin), meristematic globules and yellow, friable ECS were induced from the explants of seedling hypocotyls. ECS were initiated from these embryogenic calli in the same liquid B5 callus induction medium. After selection of small aggregates and single cell cultures at 15-day intervals for 2 months, homogeneous and yellow ECSs, composed of single cells, small cell aggregates were established. Based upon the growth dynamic of ECS, the entire old medium was replaced weekly by an equal volume of fresh medium. Plating of ECS (1-12 months old) on 3 different solid B5 media (B5_Z, B5_K and B5_ZK) resulted in the induction and development of approximately six, two and six compact, organized calli/ml of ECS, respectively. Variation in callus induction ability was influenced by the time elapsed after subcultures and the medium used. Plated cells responded best 5 days after subculture; 11 calli/ml ECS were obtained while 8.2 shoots/ml ECS regenerated on B5_ZK medium containing 0.065 mg/l Zeatin + 0.021 mg/l Kin. A total of 230 plants were obtained, ~75% of which were survived under ex-vitro conditions, flowered and produced normal seeds. Chromosome number of suspension cells ranged from 12-28 chromosomes, and the majority of cells (51%) had a normal (14) chromosome number, which was also observed in 63% of tested root tip cells of regenerated plants.