Phytochemistry Reviews (v.7, #2)

Foreword by Cristina García-Viguera; D. A. Moreno; A. Gil-Izquierdo; M. Carvajal (211-211).

Glucosinolates are sulphur compounds that are prevalent in Brassica genus. This includes crops cultivated as vegetables, spices and sources of oil. Since 1970s glucosinolates and their breakdown products, have been widely studied by their beneficial and prejudicial biological effects on human and animal nutrition. They have also been found to be partly responsible for the characteristic flavor of Brassica vegetables. In recent years, considerable attention has been paid to cancer prevention by means of natural products. The cancer-protective properties of Brassica intake are mediated through glucosinolates. Isothyocianate and indole products formed from glucosinolates may regulate cancer cell development by regulating target enzymes, controlling apoptosis and blocking the cell cycle. Nevertheless, variation in content of both glucosinolates and their bioactive hydrolysis products depends on both genetics and the environment, including crop management practices, harvest and storage, processing and meal preparation. Here, we review the significance of glucosinolates as source of bioactive isothiocyanates for human nutrition and health and the influence of environmental conditions and processing mechanisms on the content of glucosinolate concentration in Brassica vegetables. Currently, this area is only partially understood. Further research is needed to understand the mechanisms by which the environment and processing affect glucosinolates content of Brassica vegetables. This will allow us to know the genetic control of these variables, what will result in the development of high quality Brassica products with a health-promoting activity.
Keywords: Brassica ; Bioactive compounds; Chemoprevention; Isothiocyanates; Sulforaphane; Indole-3-carbinol; Seasonal variation; Thermal degradation

Tomato (Solanum lycopersicum) health components: from the seed to the consumer by Martine Dorais; David L. Ehret; Athanasios P. Papadopoulos (231-250).
It is widely accepted that a healthy diet is an important factor in preventing chronic diseases, and in improving energy balance and weight management. Studies have shown strong inverse correlations between tomato consumption and the risk of certain types of cancer, cardiovascular diseases and age-related macular degeneration. Because tomato is the second-most important vegetable in the world after potato, this horticultural crop constitutes an excellent source of health-promoting compounds due to the balanced mixture of minerals and antioxidants including vitamins C and E, lycopene, β-carotene, lutein and flavonoids such as quercetin. Improvement in phytonutrients in tomatoes can be achieved by cultivar selection, environmental factors, agronomic practices, stage of ripeness at harvest, and appropriate handling and conditioning all the way from the field to the consumer. The purpose of this paper is to review the recent literature of the main factors that can improve the nutritional quality of tomato and consequently their beneficial role in human diet. The importance of genotype selection and the optimization of environmental conditions (light, temperature, humidity, atmospheric CO2 and air pollutants) for high nutritional value is outlined first, followed by the optimization of agricultural practices (soil properties, water quality, mineral nutrition, salinity, grafting, pruning, growing systems, growth promoters, maturity, and mechanical and pest injuries). The review concludes by identifying several prospects for future research such as modelling and genetic engineering of the nutritional value of tomato.
Keywords: Antioxidants; Irrigation; Light; Mineral nutrition; Pigments; Phytonutrients; Salinity; Tomato; Temperature

Agricultural practices for enhanced human health by M. Carmen Martínez-Ballesta; Luis López-Pérez; Mercedes Hernández; Carmen López-Berenguer; Nieves Fernández-García; Micaela Carvajal (251-260).
Phytochemicals in vegetables are known to be responsible for protective effects against many human diseases, including cardiovascular diseases and different types of cancer. Environmental conditions and physiological factors may modify the amounts of these compounds present in vegetables and fruits, but also crop management strategies could increase the production of phytochemicals. Therefore, the effects of mineral nutrition, soil composition and water content on the production of phytochemicals have been considered in the development of different fertilisation strategies, efficient water management and techniques such as grafting. Finally, the contents of health-promoting compounds in vegetables and fruits depend both quantitatively and qualitatively on their genetic bases. Thus, conventional breeding and genetic modification have been developed as new methodologies to enhance the nutritional properties of plants.
Keywords: Crop management; Fertilisation; Grafting; Phytochemicals

Betalains in the era of global agri-food science, technology and nutritional health by Diego A. Moreno; Cristina García-Viguera; José I. Gil; Angel Gil-Izquierdo (261-280).
Natural pigments from plants are of growing interest as substitutes for synthetic dyes in the food and pharmaceutical industry and they increase their added value if they possess positive effects on health. These pigments can be added as such if they are in the legal authorized lists of additives or can be added as phytochemical-enriched plant extract achieving the original product, which has received it, the new nomenclature of functional food. In this way, we comprise on this review a wide point of view of a group of natural pigments known as betalains. From a chemical point of view, betalains are ammonium conjugates of betalamic acid with cyclo-DOPA (betacyanins, violet) and aminoacids or amines (betaxanthins, orange or yellow), which are compounds present in our diet. Besides and taking into account that one type of betalain, betanin is approved as food colorant (E-162) by the European Union and that enlarges the specific weight of these compounds in the diet, we have evolved an overview from the biosynthesis, technology and promoting production, industrial uses as pigments up to physiological and nutritional biovailability or biological and health-promoting properties of betalains for accessible information to industrials, researchers and consumers.
Keywords: Amaranthus ; Betalains; Betacyanins; Betaxanthins; Colouring agent; Opuntia ; Red beet

Anthocyanins: from plant to health by Sonia de Pascual-Teresa; Maria Teresa Sanchez-Ballesta (281-299).
Anthocyanins are a group of natural occurring pigments responsible for the red-blue colour of many fruits and vegetables. Anthocyanins are of interest for two reasons because they cannot only be used in the technological field as natural colorants but also have important implications in the field of human health. Numerous studies indicate the potential effect that this family of flavonoids may have in reducing the incidence of cardiovascular disease, cancer, hyperlipidemias and other chronic diseases through the intake of anthocyanin-rich foods. This review examines existing literature in this area: from plant content and distribution to health implications, including the effect of agronomic and genetic modifications on the anthocyanin content of plants as well as other biotechnological factors and food processing. The bioavailability, metabolism, bioactivity, and epidemiology of anthocyanins will also be reviewed.
Keywords: Bioavailability; Biological activity; Food processing and storage; Postharvest treatments

Bioavailability of phenolic acids by Sophie Lafay; Angel Gil-Izquierdo (301-311).
Two large classes of phenolic acids were comprised in this review: benzoic acid derivatives and cinnamic acid derivatives. They have been found to be very extended in fruits and vegetables at different concentrations. For example, hydroxycinnamic acids concentration was higher than that found for hydroxybenzoic acids. Concerning their consumption, hydroxycinnamic acids provide larger contributions to the total polyphenol intake than benzoic acid derivatives or flavonoids. This phenolic acid intake is led by the coffee intake since it has very rich concentrations in hydroxycinnamic acids. Moreover, several experimental and epidemiological studies report the protection of phenolic acids against various degenerative diseases. However, despite all these interesting attributions and even if phenolic acids are the main polyphenols consumed, their bioavailability has not received as attention as that flavonoids. This concept is an essential step to understand the health-promoting properties of phenolic acids and to serve as tool to design in vivo and in vitro experiments to know their biological properties. Therefore, a compilation of bioavailability data of phenolic acids have been presented here paying attention to the two types of phenolic acid bioavailability, direct and indirect derived from the direct phenolic acid and flavonoid consumption, respectively. Then, a new relevant concept which may be named as total bioavailability of phenolic acids includes the direct absorption and metabolism of phenolic acids from food consumption and phenolic acids bioavailability as a result of the cleavage on the main skeleton ring of flavonoids by the gut microflora.
Keywords: Phenolic acid; Polyphenol; Nutrition; Bioavailability; Absorption; Metabolism; Health

Phenolic phytochemicals and bone by Véronique Habauzit; Marie-Noëlle Horcajada (313-344).
Concerning the prevention of osteoporosis, recognized as a major public health problem, nutrition may appear as an alternative strategy for optimizing health skeleton. The importance of adequate calcium and vitamin D intakes for bone health is now well documented. But, in addition to essential macro- and micronutrients, human diet contains a complex array of non-nutrient natural bioactive molecules, namely the phytochemicals that may act and protect bone. Among phytochemicals, emphasis has been so far placed upon polyphenols. Indeed, subsequent epidemiological studies have suggested associations between long-term consumption of diets rich in polyphenols and protection against chronic diseases. With respect to human health, flavonoids are the most extensively studied polyphenols. These compounds may be partly responsible for some of the positive links found between fruit and vegetables intake and higher bone mineral density in adults and children. However, no long-term intervention studies in humans have investigated the effect of specific phenolic phytochemicals on the prevention of bone loss in postmenopausal women, except for phytoestrogens (soy isoflavones, lignans). Besides, in animal models of postmenopausal osteoporosis, consumption of some dietary flavonoids has been shown to prevent ovariectomy-induced bone loss. Finally, few in vitro experiments with bone cells have reported cellular and molecular mechanisms of phytochemicals involved in bone metabolism. To date, investigations providing some evidence of a positive impact of some phytochemicals on bone metabolism are accumulating but further studies, notably clinical trials, are needed to explore the various bioactivities offered by such compounds. Anyway, it can be postulated that increased consumption of plant-derived foods, especially fruit and vegetables, may be positive in the prevention of osteoporosis.
Keywords: Bone metabolism; Flavonoids; Osteoporosis; Phenolics; Phytonutrients

Effect of domestic processing on bioactive compounds by Alejandro Ruiz-Rodriguez; Francisco R. Marín; Aurelio Ocaña; Cristina Soler-Rivas (345-384).
Nowadays, most of the consumed foods are rarely ready for direct consumption. Food can be purchased at the local supermarket as fresh raw product such as meat, fruit, fish etc. or as manufactured product after an industrial processing (canned meat, dried fish, packed fruit etc.). But later on, both food types are usually submitted to culinary treatments which will transform the selected food into a cooked dish ready to eat. Domestic methods of food processing have been developed over the centuries to make the final product more attractive in flavour, appearance, taste and consistency. But, until the last centuries, none of the gourmets realize that at the same time, the cooking process was making their foods more digestible, microbiologically safer and more or less nutritive depending on the selected cooking technology. Besides consumer preferences, the selected cooking method is an important factor affecting not only the food chemical composition, but also the intake of bioactive compounds under normal dietary conditions. Therefore, in this work, the different culinary treatments and domestic cooking methods will be compared to define the optimal process to reduce the degradation of biologically active metabolites present in foods commonly consumed as an elaborated dish. Compounds such as carotenoids, glucosinolates, flavonoids and other phenolic compounds, ω-3 fatty acids, tocopherols, phytosterols, etc. have been pointed as bioactive compounds beneficial for human health. Apparently, they are able to prevent cardiovascular diseases (CVD), tumour formation, hiper-cholesterolemia in blood and other deleterious disorders. An adequate domestic practice might help to increase in taking of those functional molecules enhancing their functionality and reducing the risk of chronic diseases.
Keywords: Culinary methods; Domestic practices; Nutraceuticals; Functional food