Correlation between epicarp spots and the overall quality of Forsythiae Fructus

Forsythiae Fructus (FF, Lianqiao in Chinese) is the dried fruit of Forsythia suspensa (Thunb.) Vahl. As one of the commonly used bulk medicinal materials, FF has been used as a heat-clearing and detoxifying traditional Chinese medicine for the treatment of infectious diseases. Epicarp spots are inherent traits of the FF. Previous reports have suggested that it might be related to the quality of FF, while the accurate correlation between them remains ambiguous. In this study, 32 groups of FF were selected from the same batch, and the information of epicarp spots was converted into spot area index (SAI). Then, the overall quality of FF was evaluated by principal component analysis (PCA) based on the content of 21 major bioactive ingredients. Subsequently, the Pearson correlation analysis was conducted to explore the correlation between SAI and the overall quality of FF. Ingredients related to SAI were identified. The results indicated that a significant negative correlation was shown between the SAI and the overall quality of FF. Six bioactive ingredients, including forsythoside B, p-coumaric acid, galuteolin, hesperidin, baicalin and kaempferol, were negatively correlated with SAI. This research will provide scientific information on the relationship between epicarp spots and the overall quality of FF and facilitate the general quality assessment of FF in a rapid and convenient way.