ENGINEERING TOMATOES WITH INCREASED LEVELS OF THE ANTIOXIDANT METABOLITES G. GIOVINAZZO*, A. PARADISO**, I. NICOLETTI***, F. SPARVOLI****, L. DEGARA** *)ISPA-CNR, via Monteroni, 73100 Lecce, **)Dipartimento di Biologia e Patologia Vegetale, Via E. Orabona 4, I-70125 Bari, ***)IMC-CNR Area della Ricerca di Roma 1- Via Salaria Km 29,300 C.P.10, 00016 Monterotondo Staz., ****)IBBA-CNR, via Bassini 15, 20100 Milano. Antioxidants, trans-resveratrol, stilbene synthase, Lycopersicon esculentum Phenolics are a large family of secondary plant metabolites, with ideal structural chemistry for free radical scavenging activity. Antioxidant properties of polyphenols arise from their high reactivity as hydrogen or electron donors, and from the ability of the polyphenol-derived radical to stabilize and delocalize the unpaired electron and from their ability to chelate transition metal ions. Polyphenols as stilbenes are nutritional components of human diet synthesized in a limited number of plant, and are abundant in grape and wine. Among to the stilbenes group, trans-resveratrol has attracted much attention for the increasing body of epidemiological data suggests that high intake of this antioxidant molecule is correlated with a decreased risk for cancer and cardiovascular disease. Resveratrol is a product of a reaction catalysed by the enzyme stilbene synthase which is closely related to chalcone synthase, the first enzyme of the flavonoid pathway. Overexpression of a grape stilbene synthase cDNA in tomato (Lycopersicon esculentum L.) caused plants to accumulate new compounds identified as trans-resveratrol and their derivatives. This metabolite accumulation was possibly dependent upon a combination of sufficiently high levels of stilbene synthase and the availability of substrates. With the aim of verifing the metabolic impairment, the amount of chlorogenic acid and naringenin in both transgenic and wild type ripening fruits was compared and no dramatic variation in the profile synthesis of the two metabolites was noted. To our knowledge, no data are available about the assessment of the effects of the expression of the stilbene synthase gene on other antioxidant compounds present in tomato fruits. To establish whether the presence of a novel antioxidant molecule affected the redox regulation in transgenic tomato fruit cells, the effect of resveratrol synthesis on the naturally present antioxidant pool was analysed. In transgenic fruits which accumulate trans-resveratrol there is an increase in the levels of ascorbate and glutathione, the soluble antioxidants of primary metabolism, as well as in the total antioxidant activity. Conversely, the content of tocopherol and lycopene, which are membrane located antioxidants, is not affected. Consistent with the increased antioxidant properties, the lipid peroxidation was lower in trasformed than in wild type fruits.
Engineering tomatoes with increase levels of the antioxidant metabolites
G Giovinazzo;A Paradiso;I Nicoletti;F Sparvoli;
2004
Abstract
ENGINEERING TOMATOES WITH INCREASED LEVELS OF THE ANTIOXIDANT METABOLITES G. GIOVINAZZO*, A. PARADISO**, I. NICOLETTI***, F. SPARVOLI****, L. DEGARA** *)ISPA-CNR, via Monteroni, 73100 Lecce, **)Dipartimento di Biologia e Patologia Vegetale, Via E. Orabona 4, I-70125 Bari, ***)IMC-CNR Area della Ricerca di Roma 1- Via Salaria Km 29,300 C.P.10, 00016 Monterotondo Staz., ****)IBBA-CNR, via Bassini 15, 20100 Milano. Antioxidants, trans-resveratrol, stilbene synthase, Lycopersicon esculentum Phenolics are a large family of secondary plant metabolites, with ideal structural chemistry for free radical scavenging activity. Antioxidant properties of polyphenols arise from their high reactivity as hydrogen or electron donors, and from the ability of the polyphenol-derived radical to stabilize and delocalize the unpaired electron and from their ability to chelate transition metal ions. Polyphenols as stilbenes are nutritional components of human diet synthesized in a limited number of plant, and are abundant in grape and wine. Among to the stilbenes group, trans-resveratrol has attracted much attention for the increasing body of epidemiological data suggests that high intake of this antioxidant molecule is correlated with a decreased risk for cancer and cardiovascular disease. Resveratrol is a product of a reaction catalysed by the enzyme stilbene synthase which is closely related to chalcone synthase, the first enzyme of the flavonoid pathway. Overexpression of a grape stilbene synthase cDNA in tomato (Lycopersicon esculentum L.) caused plants to accumulate new compounds identified as trans-resveratrol and their derivatives. This metabolite accumulation was possibly dependent upon a combination of sufficiently high levels of stilbene synthase and the availability of substrates. With the aim of verifing the metabolic impairment, the amount of chlorogenic acid and naringenin in both transgenic and wild type ripening fruits was compared and no dramatic variation in the profile synthesis of the two metabolites was noted. To our knowledge, no data are available about the assessment of the effects of the expression of the stilbene synthase gene on other antioxidant compounds present in tomato fruits. To establish whether the presence of a novel antioxidant molecule affected the redox regulation in transgenic tomato fruit cells, the effect of resveratrol synthesis on the naturally present antioxidant pool was analysed. In transgenic fruits which accumulate trans-resveratrol there is an increase in the levels of ascorbate and glutathione, the soluble antioxidants of primary metabolism, as well as in the total antioxidant activity. Conversely, the content of tocopherol and lycopene, which are membrane located antioxidants, is not affected. Consistent with the increased antioxidant properties, the lipid peroxidation was lower in trasformed than in wild type fruits.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
