Dynamic variations in punicalagin and related metabolic substances in pomegranate fruit and leaves during development periods

Pomegranate (Punica granatum L.) is a functional fruit that is abundant in bioactive substances. Punicalagin is an abundant and important phenolic compound in pomegranate, but the variation patterns and linkage of punicalagin and related synthetic bioactive substances during development are unclear. In this study, the dynamic variations in punicalagin and related synthetic bioactive substances were investigated in different parts of pomegranate during development phases. Punicalagin and related synthetic substances in the pomegranate pericarp, juice, seeds, and leaves were determined by high-performance liquid chromatography. Results revealed that punicalagin, gallic acid, shikimic acid, and total phenol contents, as well as DPPH radical scavenging activity, decreased gradually in the fruit, whereas pentagalloylglucose and 3-dehydroshikimic acid contents increased gradually. Seven substances yielded different variation patterns in the leaves. Ellagic acid content initially decreased and then increased in the fruit and leaves. Pentagalloylglucose was mainly detected in the leaves, while shikimic acid, 3-dehydroshikimic acid, punicalagin, gallic acid, and ellagic acid were mainly found in the pericarp. The highest punicalagin concentration was 156.735 mg・/g in the TSH pericarp. Shikimic acid and 3-dehydroshikimic acid were closely related to gallic acid. Punicalagin was significantly positively correlated with gallic acid in the fruit, and significantly negatively correlated with pentagalloylglucose. Antioxidant activity and total phenol content were also closely correlated. Punicalagin and related substances presented different variation patterns in various pomegranate parts during development. Punicalagin was the most abundant phenolic compound in the pericarp, and this finding correlated significantly with gallic acid, ellagic acid, shikimic acid, 3-dehydroshikimic acid, and pentagalloylglucose in the fruit. The pomegranate pericarp contained abundant phenolic compounds and exhibited high antioxidant activity.