Polyphenol contents, antioxidant properties, and anti-lipid peroxidation activity of different ripening myrtle fruit stages Myrtus communis L.

Abstract

This study quantified the total polyphenolic, flavonoid, and condensed tannin content and assessed the antioxidant activity (via DPPH and TBARS assays) of myrtle fruit ( Myrtus communis L.) across distinct ripening stages. The ripe stage exhibited the highest phytochemical concentrations: total polyphenols (96.61 mg GAE/g DM), flavonoids (11.02 mg CE/g DM), and condensed tannins (479.6 mg CE/g DM). It also demonstrated the strongest antioxidant activity, with the lowest IC₅₀ value in the DPPH assay (0.008 mg/mL) and the lowest EC₅₀ in the TBARS assay (4.26 μg/mL). LC-MS analysis revealed significant variations in individual polyphenols across maturation, identifying malvidin-3-glucoside as the predominant compound (0.726 × 10⁻³ to 27.3 × 10⁻³ M). Other quantified phenolics included ellagic acid, quercitrin, quercetin, isoquercetin, 1,5-dicaffeoylquinic acid, naringenin, and kaempferol. GC-MS profiling characterized fatty acid and volatile compositions. Fatty acids shifted from saturated dominance (palmitic acid, 72.67%) in early stages to polyunsaturated predominance (linoleic acid, 48.51%) at ripeness. Volatile terpenoid analysis identified α-pinene as the major constituent (23.52–25.23%), alongside eucalyptol, caranol, isopulegol, methyl-eugenol, caryophyllene, and humulene. The results comprehensively document the phytochemical evolution during myrtle fruit ripening, highlighting the ripe stage as the richest source of bioactive compounds with potent antioxidant capacity.