Effect of drying temperatures on phytochemical composition and antioxidant activity of rosa canina L. fruit extracts

This study investigated the phenolic composition, flavonoid profile, antioxidant capacity, and enzyme inhibitory activities of methanol extracts from fresh and dried (50 and 70°C) rosehip (Rosa canina) fruits. LC–MS/MS analysis identified quinic acid as the dominant compound among 53 phenolic compounds, with gallic acid, protocatechuic acid, tannic acid, ellagic acid, and various flavonoids (mikelianin, isoquercitrin, quercitrin, quercetin, astragalin, naringenin, luteolin, apigenin, amentoflavone, and acacetin) also detected. Drying initially increased quinic acid levels but decreased them at higher temperatures, whereas gallic acid, protocatechuic acid, and ellagic acid increased with increasing temperature. Total phenolic content was highest in fresh samples (65.05 mg GAE/g extract), decreasing to 43.60 mg GAE/g at 50°C and 33.79 mg GAE/g at 70°C. In contrast, total flavonoid content increased with drying temperature, reaching a maximum of 3.33 mg QE/g extract at 70°C. Antioxidant capacity measurements, including TPC, FRAP, CUPRAC, DPPH, and ABTS assays, decreased significantly with higher drying temperatures, with fresh samples showing the highest values. Enzyme inhibition assays revealed that acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities slightly increased with drying temperature, while tyrosinase inhibition was highest in fresh samples and decreased after drying. α-Amylase activity remained largely unchanged, whereas α-glucosidase inhibition varied depending on drying conditions. These findings indicate that the phenolic composition, antioxidant potential, and certain enzyme inhibitory activities of rosehip fruits are sensitive to drying temperature, with short-term drying at 50°C effectively preserving phenolic content and antioxidant capacity.