Antioxidant and anti-inflammatory properties of tomato fruit synthesising stilbenes.

Resveratrol, a plant phenolic compound, is found in grapes and red wine, but is not widely distributed in other common food sources. The pathway for resveratrol biosynthesis is well characterized. Metabolic engineering of this compound has been achieved in tomato plants (Lycopersicon esculentum Mill.) in order to improve their nutritional value. Tomato plants synthesizing resveratrol were obtained via the heterologous expression of a grape (Vitis vinifera L.) cDNA encoding for the enzyme stilbene synthase (StSy), under the control of the fruit-specific promoter TomLoxB or the constitutive CaMV 35S promoter. The resulting 35S plants accumulate resveratrol in all the tissues, but in the highest amount in the fruits. While, as expected, LoxS transgenic plants only accumulate it in the fruits, in particular in the skin of the mature fruits. Quantitative analyses carried out on LoxS fruits were compared with those of 35S tomato lines. The LoxS fruits contained levels of trans -resveratrol that were 20-fold lower than those reported for the 35S line. The total antioxidant capability, ascorbate and gluthatione contents were also evaluated. A significant increase in all these antioxidant paramenters was found in the LoxS and 35S lines. These results could explain the higher capability that extract from transgenic fruits have to counteract the pro-inflammatory effects of phorbol ester in monocyte- macrophages via the inhibition of induced cyclo-oxygenase-2 enzyme.