Quantification and stability analysis of anthocyanins, chlorogenic acids and flavonoids in Roselle calyces

An HPLC method was developed for simultaneous analysis of anthocyanins, chlorogenic acids and flavonoids in Roselle calyces, i.e., delphinidin-3-O-sambubioside, cyanidin-3-O-sambubioside, 3-caffeoylquinic acid, 5-caffeoylquinic acid, 4-caffeoylquinic acid, rutin, myricetin, quercetin and kaempferol. The quantification method was validated using calibration curves and stability and recovery tests. The recoveries of the nine analytes in Roselle calyces were in the range of 90.6% to 116.0%. Extraction optimization showed that chlorogenic acids and anthocyanins in Roselle could be extracted with water, whereas flavonoids required an ethanol-water solution. Quantitative analysis of six Roselle samples of different origins showed that the total anthocyanin content ranged from 3.65 to 13.81 mg D3SE g^-1, and the total content of chlorogenic acids ranged from 4.52 to 6.32 mg g^-1, but the flavonoid contents were very low. Stability analysis revealed that Roselle anthocyanins were prone to decomposition under high temperature and alkaline conditions, while chlorogenic acids were more stable.