Resumo

RUEDA LORZA, Antoni; PELAEZ, Carlos Alberto; ROJAS, Mauricio  e  GIL, Andrés. Effect of copper and Paraquat^® on responses associated to oxidative stress in two related species of tomato. Rev Cubana Plant Med [online]. 2012, vol.17, n.3. ISSN 1028-4796.

Introduction: the antioxidant capacity in plants has aroused great interest due to their potential use in food for the prevention of oxidative stress-associated diseases. Objectives: to evaluate the effect of CuCl₂ and Paraquat^® induction on protoplasts and tomato seedlings belonging to Lycopersicon hirsutum Dunal and Lycopersicon esculentum Mill. species. Methods: the production of reactive oxygen species in protoplasts of tomato both species after exposure to CuCl₂ and Paraquat^® (1.1'-dimethyl-4.4'-bipiridyl dichloride) was evaluated by flow cytometry. Tomato seedlings were evaluated for total polyphenol content and free radical scavenging. Results: Paraquat^® induction showed a 17.4 fold increase in reactive oxygen species production for L. hirsutum protoplasts and a 12.4 fold for L. esculentum during early events with respect to their respective untreated controls. L. esculentum showed significant slopes for free radical scavenging and total polyphenol content: 1.81 galic acid eq per hour and 5.3 % DPPH discoloration per hour, respectively. In addition, in response to the two kinds of induction, positive slopes and a correlation between total polyphenol content and free radical scavenging were observed with copper induction (correlation close to 1 and highly significant), but not significant models during Paraquat^® induction. Conclusions: these results suggest that the biosynthesis of phenolic compounds and the correlation with the free radical scavenging are not necessarily related to antioxidant activity as a cellular defense mechanism.

Palavras-chave : Lycopersicon hirsutum; Lycopersicon esculentum; protoplasts; oxidative stress; polyphenols; antioxidant mechanism.

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