Ellagitannins from Pomegranate Flower with Whitening and Anti‐skin Photoaging Effect

A new depside glucoside rosarugoside E (1), together with four known compounds punicalagin (2), corilagin (3), granatin B (4) and ellagic acid (5) were isolated from the ethanol extract of pomegranate (Punica granatum L.) flower. Their structures were identified based on careful analysis of various spectral data including UV, IR, HR‐ESI‐MS, 1D and 2D NMR. The whitening and anti‐aging effects of all compounds were evaluated based on the levels of protein and gene. The result displayed that all compounds exhibited inhibitory activity for tyrosinase at maximum safe concentration, except for compound 2. Compound 3 and 5 exhibited significant inhibitory activity for tyrosinase, indicating their whitening efficacy. The anti‐aging activity evaluation assay showed that all compounds could downregulate expression of MMP1 gene, decreased expression of MMP1, and increased the content of COL1 at the maximum safe concentration compared with negative control (UVA irradiation treatment).