Flavonoid components and anti-photoaging activity of flower extracts from six Paeonia cultivars

Genus Paeonia is an important ornamental and medicinal crop. The flowers of Paeonia are rich in flavonoids, and flavonoids have excellent antioxidant and anti-inflammatory activities, which have the potential to slow down skin aging. In this study, flavonoids from whole flowers of six popular Paeonia cultivars were extracted using three different solvents. The composition and content of peony flowers flavonoids extracted with three solvents were determined by high performance liquid chromatography quadrupole time-of-flight mass spectrometry / mass spectrometry (HPLC-Q-TOF-MS/MS) and HPLC-diode array detection (DAD). A total of 26 flavonoids were isolated and identified, and 60 % ethanol showed the highest extraction efficiency. Not only flavonoids composition but also the content was significantly different in different peony flowers, among which 'Hei Tian E' had the most abundant composition (17 flavonoids) and the highest total content of flavonoids (57.75 mg/g DW by using 60 % ethanol). After that, the anti-skin photoaging effects of the 60 % ethanol extracts of the six Paeonia cultivars flowers were evaluated by UVR-Fulkutis and UVA-Fibroblasts photoaging models. Under exposure to UV radiation, some Paeonia flowers' extracts can prevent the decrease of skin surface thickness and reduce the loss of Collagen IV and VII. In addition, the production and accumulation of ROS, MMP-1 and MMP-3 in fibroblasts were inhibited, indicating the attenuation of skin photoaging by the extracts. Among the six samples tested, 'Hei Tian E' whole flower extract (BH-HT) had the best comprehensive effect. Finally, the correlations between components and anti-photoaging efficacy were analyzed. We speculate that the anti-photoaging effect was significantly related to its richness in quercetin 3-O-di-glucoside, quercetin 3-O-glucoside, isorhamnetin 3-O-galloyl arabinoside, cyanidin 3,5-di-O-glucoside, cyanidin 3-O-glucoside, and peonidin 3-O-glucoside. In general, the results show that Paeonia flowers have potential for development of anti-photoaging herbal essence products.