Compatible solutes content, enzymatic and non-enzymatic antioxidant activities of fennel (Foeniculum vulgare L.) in response to Zn-induced oxidative damage

The purpose of this study was to evaluate for the first time the growth, nutrient element, soluble sugar and proline contents as well as the enzymatic and non enzymatic antioxidative systems in roots and aerial part of Foeniculum vulgare after treatments with 0, 2 and 4 mM ZnSO4 for 21 days. Zn treatment caused a significant decrease of fresh and dry weight of F. vulgare, followed by a reduction in the amount of total chlorophyll and cationic nutrients, and an increase in malondialdehyde as well as H2O2, soluble sugar and proline contents. Concomitantly, the increasing Zn concentration resulted in the stimulation of superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase activities. The non-enzymatic antioxidant assay showed that extracts exhibited the ability to scavenge the DPPH radical. Results suggest the key role of the coordinated antioxidant enzymes, non-enzymatic antioxidants and some compatible solutes, notably proline, activated by this species to withstand Zn toxicity.