Increased healthy properties of tomato fruit synthesising different amount of stilbenes.

Tomato tissues were transformed with a grape cDNA encoding the enzyme stilbene synthase transcriptionally regulated by TomLoxB, a tomato fruit specific promoter. The modified plants LoxS, accumulated new products, absent in the wild-type plants. These were identified as trans-resveratrol and trans-piceid. The accumulation of these metabolites was monitored in the fruit and in particular in the skin and the flesh of the mature fruit. The quantitative analyses carried out on LoxS plants were compared with those of tomato line constitutively expressing the grape cDNA (35SS). LoxS plants showed 20 times lower accumulation of the trans-resveratrol than 35SS line. In order to estimate the effects of the new biosynthetic pathways, chlorogenic acid, naringenin, and flavonols were quantified. The results obtained showed an increase in the synthesis of chlorogenic acid, naringenin and kaempferol in transgenic fruit. The total antioxidant capability and ascorbate content increased proportionally to the resveratrol synthesised. These results could explain the higher capability of transgenic fruits to inhibit the phorbole ester induced cyclooxygenase-2 enzyme, in monocyte-macrophage cultures.