Phenolic content and antioxidant activity of parts of Passiflora edulis as a function of plant developmental stage

Abstract

ABSTRACT Passiflora edulis Sims var. flavicarpa O. Deg. (Yellow-passion fruit) is the native plant species most used by juice industries in Brazil while its leaf extracts are widely employed in folk medicine. This study evaluated the phenolic content of leaves, roots, fruit shells and pulp of plants of P. edulis in juvenile, flowering and fruiting stages. The extent of scavenging and/or degradation of reactive nitrogen and oxygen species by plant extracts was also investigated. Leaves were the organs that most accumulated phenolics/flavonoids, regardless of plant developmental stage. Leaf extracts efficiently scavenged DPPH by up to 67 % while root and fruit shell extracts effectively captured up to 80 % O2 -. Maximum activity of catalase (51.6 mmol H2O2 min-1 mg prot-1) and ascorbate peroxidase (2.2 mmol ascorbate min-1 mg prot-1) was recorded in leaf extracts from plants in the fruiting stage. Superoxide dismutase activity reached its highest levels (37.5 U min-1 mg prot-1, on average) in plant leaves of both juvenile and fruiting plants. Overall, these results suggest that, for therapeutic purposes, parts of P. edulis should be harvested when plants are in the fruiting stage due to the excellent antioxidant properties of their extracts and their accumulation of phenolic compounds.

Keywords

• antioxidant enzymes
• DPPH
• flavonoids
• passion fruit
• secondary metabolism
• superoxide anion