Antioxidant activity and metal content: a study on <i>Dictamnus albus</i>

Dictamnus albus is a perennial plant of warm, dry, and sunny habitats that have been traditionally used as a medicinal plant since ancient times. Our study focused on examining the phenolic compound content, antioxidant capacity, and concentrations of Fe, Cu, Zn, Mn, and Ni in the leaves of D. albus. The concentration of phenolic compounds in the leaves of D. albus was 5.40±0.09 mg GAE/gDW. The leaf ethanol extract of D. albus exhibited significant antioxidant activity, as demonstrated by its ability to scavenge DPPH radicals, with an IC50 value of 38.20±0.46 μg/mL. The ethanol extract showed a slightly lower capacity to scavenge H2O2, with an IC50 value of 912±40 μg/mL. For the first time, we demonstrated that D. albus extract has a significant capacity to scavenge hydroxyl radicals (•OH). After adding D. albus extract, the residual •OH radicals percentage was 39%, compared to 13% when using a 2 mM Trolox standard. In addition, the ethanol extract of D. albus showed the ability to reduce Fe3+ and Cu2+, indicating the extract's ability to inhibit oxidative processes. Furthermore, D. albus extract can chelate Fe and thus prevent the Fenton reaction. The metal content in the leaves of D. albus was as follows: Fe 44.16±0.685 mg/kg, Cu 6.06±0.253 mg/kg, Zn 21.64±0.571 mg/kg, Mn 22.01±0.413 mg/kg, and Ni 1.21±0.112 mg/kg. Our results showed that the ethanol extract of D. albus has significant antioxidant capacity, that the concentrations of Fe, Cu, Zn, Mn, and Ni were below permissible doses for medicinal plants, and that the extract can contribute to the daily intake of these essential elements. These findings suggest that D. albus extract could be used in the therapy of diseases associated with oxidative stress.