Twenty-nine samples were kindly supplied by different companies. Six samples of Rhamnus Frangula, five samples of Rhamnus purshiana, two samples of Rheum palmatum, one sample of Rheum raponticum, and 15 samples of Cassia angustifolia were analyzed. The samples were constituted by dried extract, bark, leaves, fruits, and vegetal material extracts. The list of the samples is summarized in Table 1
The reference standard compounds aloin A and B, aloe-emodin, emodin, cascaroside A, sennoside A and B, frangulin A and B, glucofrangulin A and B, rhein, physcion, chrysophanol, and rhein-8-glucoside were purchased from Extrasynthese. Danthron was purchased from PhytoLab. LC-MS–grade acetonitrile, formic acid, methanol, and ultrapure water were purchased from Merck Group.
The reference standard compounds aloin A and B, aloe-emodin, emodin, cascaroside A, sennoside A and B, frangulin A and B, glucofrangulin A and B, rhein, physcion, chrysophanol, and rhein-8-glucoside were purchased from Extrasynthese. Danthron was purchased from PhytoLab. LC-MS–grade acetonitrile, formic acid, methanol, and ultrapure water were purchased from Merck Group.