Polyphenols tomatoes

Chalcones and dihydrochalcones have been reported in a restricted number of foods (Robards and others 1999 Tomas-Barbcran and Clifford 2000). Chalconaringenin occurs in tomato skin, but the acid extraction conditions of the usual polyphenol analyses convert the chalcone to the corresponding flavanone (naringenin) in the tomato. The most common dihydrochalcones found in foods are phloretin glucoside (phloridzin) and phloretin xylogalactoside, which are characteristic of apples (see Table 2.2) and derived products such as apple juice, cider, and pomace (Robards and others 1999 Tomas-Barbcran and Clifford 2000). 

Li L, Steffens JC. 2002. Overexpression of polyphenol oxidase in transgenic tomato plants results in enhanced bacterial disease resistance. Planta 215 239-247. 

We will discuss selected current knowledge on the use of plant enzymes as bases of insect resistance the review is not comprehensive. Particular attention will be given to induced de novo synthesis of proteinase inhibitors in the tomato plant Lvcop-ersicon esculentum, and on the simultaneous use of plant polyphenol oxidases as a means of conferring resistance to insect pests. 

Polyphenol Oxidases. Plant trichomes and their exudates confer resistance to a variety of insects (54-56). In solanaceous plants, such as the tomato and potato, trichomes contain polyphenol oxidases and catecholic phenolics (e.g., caffeic and chlorogenic acids), which contribute to resistance to a variety of insect pests. In the potato plant, the polyphenol oxidases and phenolics are separated in different trichomes. When insects, such as aphids or leaf hoppers, walk across the surface of the plant they break the two types of trichomes. Trichomal fluids are liberated and, upon mixing, polymerize as a result of polyphenol oxidase activity on catechols, forming an often lethal adhesive trap for the insects (52,58) In tomato plants, the polyphenol oxidase and chlorogenic acid are separated by intracellular compartments, but upon breakage of trichomes by insects, polymerization and physical entrapment occurs (54). 

The tomato plant contains a number of enzymes that we have already discussed and that may be important mediators of resistance to insects (e.g., polyphenol oxidases, peroxidases, lipoxygenases, ureases, chitinases, phenylalanine and tyrosine ammonia lyases, en-dopolygalacturonases). We discuss here the potential interaction of these enzymes. 

Figure 3. Diagram of Multicomponent Defenses in the Tomato Plant. PHE - phenylalanine TYR - tyrosine POD - peroxidase PPO - polyphenol oxidase PAL - phenylalanine ammonia lyase TAL — tyrosine ammonia lyase.

Table V. The Effect of Tomato Plant Foliar Polyphenol Oxidase Activity on Proteinase Inhibitors in Snodoptera exigua...

Vallverdu-Queralt, A. Jauregui, O. Medina-Remon, A. Andres-Lacueva, C. Lamuela-Raventos, R.M. 2010. Improved characterization of tomato polyphenols using liquid chromatography/electrospray ionization linear ion trap quadrupole Orbitrap mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry. Rapid Comm. Mass Spectrom. 24 2986-2992. 

Even people who have been taking blood pressure-lowering drugs will benefit from this natural choice. And individuals who are determined to get their blood pressure down without drugs will benefit enormously. Tomato extract, which is rich in the antioxidant polyphenols lycopene, phytoene, and phytofluene, has been shown to reduce blood pressure for treated but not completely controlled hypertensive individuals, as well as for never-treated men and women in the category of prehypertension. Two studies have been done at the University of the Negev in Beer Sheva, Israel, by Dr. Esther Paran and her colleagues. 

Typical of many members of the botanical plant family Solanaceae, which also includes the tomato, eggplant, and pepper, goji is phytochemically rich, characterized by having both major classes of pigments—carotenoids and polyphenols, identified in laboratory research as having antidisease mechanisms. Goji appears to be one of the richest plant sources of the carotenoid zeaxanthin (closely related in chemical structure to the... 

Enzymes other than peroxidase and catalase have been used less frequently to monitor adequacy of heat treatment. Some enzymes that have been used include polyphenol oxidase for off-color development in fruits, polygalacturonase for loss of consistency in tomatoes, potatoes and eggplants and lipoxygenase and lipase for... 

Wang, S., DeGroff, V. L., and Clinton, S. K. 2003. Tomato and soy polyphenols rednce insulin-like growth factor-I-stimnlated rat prostate cancer cell proliferation and apop-totic resistance in vitro via inhibition of intracellnlar signaling pathways involving tyrosine kinase. J. Nutr. 133 2367-76. 

CONSTABEL, C.P., BERGEY, D.R., RYAN, C.A., Polyphenol oxidase as a component of the inducible defense response of tomato against herbivores, in Phytochemical Diversity and Redundancy in Ecological Interactions (J.T. Romeo, J.A. Saunders, P. Barbosa, eds.). Plenum Press, New York. 1996, pp. 231-252... 

Chapter 12 summarizes the role of dietary phytochemicals, especially those from fruits, herbs, and spices, in the prevention of cardiovascular disease. Chapter 13 is devoted to the effects and mecharusms of action of resveratrol, a polyphenolic phytoalexin that has received considerable publicity. The same is tine of lycopene, the topic of Chapter 14, which occurs in especially high levels in fresh and processed tomatoes. Consideration is given in Chapter 15 to the effects of oltipraz on phase 1 and 2 xenobiotic-metabolizing enzymes this draws together nutritional, clinical, and pharmacological investigation and provides some pointers for the future. These are elaborated upon in Chapter 16, which addresses research directions, challenges, and opportunities. 

These enzymes (e.g., lipoxygenases, polyphenol oxidases, peroxidases) also occur in the tomato plant and are locally and/or systemically inducible, as a result of infection by pathogens (49,53,55,58-62). It should follow that they are also inducible by insect-feeding damage such as that inflicted by H. zea or S. exigua. and amplify the antinutritive defense. 

Polyphenol Oxidase. Peroxidase, and Lipoxygenase in Resistance. Polyphenol oxidase in conjunction with chlorogenic acid as a substrate has the potential to reduce the ability of larval H. zea and S. exigua to utilize dietary protein. For example, alkylation of casein in artificial diet (at 1.0% wwt) by PPO (from mushroom or tomato plant) and chlorogenic acid, at levels commensurate with that found in tomato foliage, inhibits the growth of both larval species by up to 70% (Table 1). Rutin is a very poor substrate for mushroom tyrosinase and tomato PPO (79 unpubl data), and hence,... 

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