Phenol content and antioxidant activity of different young and adult plant parts of tobacco from Tunisia, dried at 40 and 70 ºC.

ABSTRACT

Different parts of tobacco plants were dried at 40 and 70 ºC. Some of them were also dried at room temperature. Dried plant material was extracted by sonication for obtaining hydro-alcoholic extracts (70%). Total phenol and total flavonoids were determined as well as antioxidant activities which were evaluated through different methods (capacity for scavenging DPPH, ABTS, superoxide and hydroxyl radicals; capacity for preventing lipid peroxidation using egg yolk as substrate; and reducing power). In young and adult plants, leaves generally had higher amounts of phenols (14.46-23.05 mg GAE g-1) than the remaining parts of the plant, independent on the temperature used. Generally, roots had lower amounts of phenols (1.56-4.63 mg GAE g-1). Leaves and flower had significantly higher concentrations of flavonoids (3.08-4.17 mg QE g-1 and 1.17-2.12 mg QE g-1, respectively) than the remaining parts. The antioxidant activity was generally higher in leaf extracts, although stalk ones had also a good capacity for scavenging hydroxyl radicals. Generally, young plants had the best capacity for scavenging DPPH and hydroxyl free radicals which may be related with the phenol content. Concerning drying temperatures, the results were not conclusive.