Analysis of Phenolic Content and Its Antioxidant and Anti-inflammatory Activities During the Fermentation Process of Rosa rugosa ‘Dianhong’

Objective: The aim of this study was to analyze the changes of phenolic content, antioxidant and anti-inflammatory activities of fermented Rosa rugosa ‘Dianhong’, the most frequently used rose in Dali Bai ethnic group area. Methods: Medicinal and edible rose varieties were confirmed by investigation using ethnobotanical methods. The object of the study was to imitate the traditional rose sugar fermentation process. Antioxidant activity of fermented Rosa rugosa ‘Dianhong’ (FDR) with different sugar content and time were evaluated using DPPH and ABTS⁺ methods. Lipopolysaccharide-induced RAW 264.7 cell model (NO inhibition rate) was established to evaluate the anti-inflammatory activity of the extracts. The correlations between phenolic content and antioxidant and anti-inflammatory activities were performed. Results: Among seven rose species loccally used as medicinal and food homologous plants, the frequency value (f) of R. rugosa ‘Dianhong’ was highest. During the fermentation process of R. rugosa ‘Dianhong’ fermented by Saccharomyces rouxii, the phenolic content (total flavonoids, total phenols), DPPH and ABTS⁺ free radical scavenging rates and NO inhibition rates of FDR-2 (35% brown sugar, 65% petals) and FDR-3 (25% brown sugar, 75% petals) showed an increasing trend at first and then decreasing trend. All indicators of FDR-2 and FDR-3 reached the highest value at 7 d of fermentation, i.e. the phenolic content, the DPPH and ABTS⁺ free radical scavenging rates and NO inhibition rates significantly increased (P<0.05) compared to samples before fermentation. However, FDR-1 (50% brown sugar, 50% petals) presented decreasing the contents of phenolic (total flavonoids, total phenols), and declining rates of DPPH and ABTS⁺ free radical scavenging capacity, as well as NO inhibition after fermentation. Besides, in this study correlation analysis showed that the phenolic content of fermented R. rugosa ‘Dianhong’ extracts presented positive correlation (P<0.05), significantly with activities of antioxidant and anti-inflammatory. Conclusion: With the highest phenolic content of fermented extracts, the strongest capacity of antioxidant and anti-inflammatory carried out in this study for seven days’ fermentation is when the brown sugar ratio with R. rugosa ‘Dianhong’ petal is 25%~35%.