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

OBJECTIVE: Annona muricata ex- tracts are used in traditional medicine due to their significant biological effects. Verification and eluci- dation 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.MATERIALS AND METHODS: The effectiveness of the extract was assessed from dried A. muricata leaves available for direct consumption. It is target- ed against reactive oxygen and nitrogen species such as superoxide (O2 center dot-), hydroxyl (center dot OH), nitric ox- ide (NO) radicals, and peroxynitrite anion (ONO2-) at concentrations of 5, 10, 25, 50, 100 mu g.ml-1.RESULTS: No significant inhibitory activity was measured against O2middot- at the assessed concentra- tions of the extract. Conversely, substantial antioxi- dant properties were found towards middotOH. Moreover, very efficient uptake was recorded at low concen- trations of the extract, 5 mu g.ml-1 (53.91%) and 10 mu g.ml-1 (45.3%). The antioxidant effect decreased with increasing concentration. By indirect determi- nation 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. CONCLUSIONS: The results themselves show that the effects of A. muricata leaf extract are mainly mediated by the activity against center dot OH, as well as the consequences of increased ONO2-formation.