Probing the degradation mechanism of forsythiaside A and simultaneous determination of three forsythiasides in Forsythia preparations by a single marker.

Forsythiaside A is the major component of Forsythia suspensa. This study investigated the degradation mechanism of forsythiaside A. Eight degraded components including forsythiaside I, forsythiaside H, forsythiaside E, caffeic acid, suspensaside A, β-hydroxy forsythiaside I, β-hydroxy forsythiaside H, and β-hydroxy forsythiaside A were identified by using ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry. Then, the quantitative analysis of multi-components by a single-marker was performed with ultra-high performance liquid chromatography to simultaneously determine forsythiaside A, forsythiaside H, and forsythiaside I in Forsythia suspensa preparations. The result showed good linear relationships within 2.871-287.1, 0.231-23.1, and 0.983-98.3 μg/mL (r > 0.9998), with average recoveries of 97.7, 95.7, and 95.8% and relative standard deviations of 1.4, 2.4, and 1.8%, respectively. Using forsythiaside A as an internal reference, the relative retention values of forsythiaside H and forsythiaside I to forsythiaside A were calculated to be 0.89 and 0.61, respectively, and the relative correction factors were 0.816 and 0.799, respectively. The method for quantitative analysis of multi-components by a single-marker was applied to evaluate the overall quality of forsythia preparations. There was no significant difference in the measurement results of the method developed and the method of external standard.