Contribution of the Glucosinolate Fraction to the Overall Antioxidant Potential, Cytoprotection against Oxidative Insult and Antimicrobial Activity of Eruca sativa Mill. Leaves Extract

BACKGROUND: Eruca sativa Mill. (Brassicaceae) is commonly utilized as an ingredient in salads and also as a folk remedy to treat various diseases. OBJECTIVE: The objective of this study was to establish the contribution of the glucosinolate (GLS) fraction to the overall antioxidant, cytoprotection against oxidative insult and antimicrobial properties of the hydro-alcoholic extract of E. sativa leaves from Sicily (Italy), characterized phytochemically. MATERIALS AND METHODS: The antioxidant activity was evaluated by different in vitro systems. The cytoprotective effect against hydrogen peroxide (H(2)O(2))-induced oxidative stress was tested in human peripheral blood mononuclear cells (PBMCs). The antimicrobial potential against bacteria and fungi was assayed by standard methods. RESULTS: E. sativa extract exhibited both radical scavenging (50% inhibitory concentration [IC(50)] 1.04 ± 0.04 mg/mL) and ferrous ions-chelating activity (IC(50) 0.327 ± 0.0032 mg/mL) and mild reducing power; the GLS fraction showed chelating ability only (IC(50) 0.225 ± 0.009 mg/mL). In the experimental model of H(2)O(2)-induced oxidative stress in human PBMCs, a significant cytoprotective effect and a suppression of reactive oxygen species production by both extract and GLS fraction were observed (P < 0.001). E. sativa extract displayed moderate antimicrobial activity against Gram-positive bacteria, and Staphylococcus aureus was the most sensitive strain (minimum inhibitory concentration 0.125 mg/mL), whereas the GLS fraction was not active. CONCLUSION: GLSs are not involved in the primary antioxidant activity of E. sativa leaf extract but they are, almost in part, responsible for its ferrous ion-chelating properties. Iron-chelating compounds in E. sativa extract may protect cells under conditions of oxidative stress, and GLSs might play a chief role in this effect. SUMMARY: Eruca sativa Mill. leaf extract exhibited antioxidant activity in different in vitro systems, whereas the glucosinolate (GLS) fraction showed Fe(2+)-chelating ability only A significant cytoprotective effect and a suppression of intracellular reactive oxygen species production by both extract and GLS fraction were observed in human peripheral blood mononuclear cells. E. sativa extract displayed moderate antimicrobial activity against Gram-positive bacteria, whereas the GLS fraction was not active. [Image: see text] Abbreviations used: GLS: Glucosinolate; H(2)O(2): Hydrogen peroxide; PBMCs: Peripheral blood mononuclear cells; IC(50): 50% inhibitory concentration; MIC: Minimum inhibitory concentration.