Valorization of Colombian Gulupa (Passiflora edulis f. edulis Sims) Peel as a Bioactive Agro-Industrial By-product: Antioxidant Activity and Cytotoxic Assessment

Abstract

Passiflora edulis f. edulis Sims (gulupa) has gained international relevance as one of Colombia’s main export fruits. However, its peel, an abundant but underutilized agro-industrial by-product, remains poorly characterized despite its potential as a source of bio-based compounds. This study evaluated the bioactive composition, antioxidant activity, and cytotoxic profile of gulupa peel extract obtained from a single commercial batch, following an initial solvent screening using water, acidified water, ethanol, and acidified ethanol, with analyses performed on independent biological replicates, aimed at supporting its valorization within bioeconomy and circular economy frameworks. The extract exhibited high contents of total polyphenols (2970 mg gallic acid eq/100 g dry weight (d.w.) and flavonoids (595 mg catechin eq/100 g d.w.). Antioxidant activity assessed by ABTS, DPPH, FRAP, and ORAC assays revealed outstanding radical-scavenging capacity, with ORAC presenting the highest value (43,200 µmol Trolox eq/100 g d.w.). Strong positive correlations were observed between polyphenol content and antioxidant activity, particularly with DPPH (r = 0.952). Cytotoxicity assays conducted on CHO-K1 cells (10-200 µg/mL) showed cell viabilities above 72% (neutral red uptake) and 84% (MTT reduction), confirming a low cytotoxic profile. Overall, these findings position gulupa peel as a promising bio-based resource rich in antioxidant compounds.