Effect of Annona muricata aqueous leaf extract on reactive oxygen and nitrogen species

Annona muricata extracts are used in traditional medicine due to their significant biological effects. Verification and elucidation of their mechanisms is beneficial in terms of the usefulness of these extracts in everyday life or in the context of disease treatment or prevention.

The effectiveness of the extract was assessed from dried A. muricata leaves available for direct consumption. It is targeted against reactive oxygen and nitrogen species such as superoxide (O2•-), hydroxyl (•OH), nitric oxide (NO) radicals, and peroxynitrite anion (ONO2-) at concentrations of 5, 10, 25, 50, 100 μg.ml-1.

No significant inhibitory activity was measured against O2·- at the assessed concentrations of the extract. Conversely, substantial antioxidant properties were found towards ·OH. Moreover, very efficient uptake was recorded at low concentrations of the extract, 5 μg.ml-1 (53.91%) and 10 μg.ml-1 (45.3%). The antioxidant effect decreased with increasing concentration. By indirect determination of NO oxidation derivatives it was found that, as the extract concentration increased, the nitrite concentration decreased. In contrast, even at low concentrations, the extract causes an increase in the peroxynitrite concentration.

The results themselves show that the effects of A. muricata leaf extract are mainly mediated by the activity against •OH, as well as the consequences of increased ONO2- formation.