Phenolic acid content and radical scavenging activity of extracts from medlar (Mespilus germanica L.) fruit at different stages of ripening

The medlar fruit (Mespilus germanica L.) has been gaining commercial importance in recent years, attracting research on its chemical composition. In this study, we have investigated how the degree of ripeness affects the concentrations and proportions of phenolic acids. The DPPH scavenging activity and the total phenolic content (TPC) were determined. Five stages of fruit maturity were studied and eight phenolic acids (protocatechuic, 4-hydroxybenzoic, syringic, 3-hydroxybenzoic, caffeic, salicylic, 4-coumaric and sinapic) were determined by HPLC–MS. The concentrations of phenolic acids mostly decreased as the fruit ripening progressed, except for insoluble ester-bound phenolics, which increased at the early stages of maturity and decreased only during the ripe to over-ripe stage of maturity. The DPPH scavenging activity also decreased during fruit maturation, suggesting a decrease of natural antioxidants in fruit. A strong correlation between TPC and antioxidant capacity measured by the DPPH method was found. The data presented demonstrates the influence of ripening on the phenolic acid content and antioxidant properties of medlar fruit.