Preparative HPLC for Purification of Four Isomeric Bioactive Saponins from the Seeds of Aesculus chinensis

Four isomeric bioactive saponin compounds named escin Ia, isoescin Ia, escin Ib, and isoescin Ib were successfully isolated and purified from the crude extract of the seeds of a traditional chinese medicinal plant Aesculus chinensis Bge (Hippocastanaceae) by preparatory high performance liquid chromatography (Pre‐HPLC). The gradient mobile phase solvent system composed of methanol–water–acetic acid was employed. An efficient large scale preparatory method was developed based on the stability investigation of escin Ia for the first time. A total amount of 5.2 g escin Ia, 2.8 g isoescin Ia, 3.8 g escin Ib, and 1.6 g isoescin Ib, separately, over 99% purity was obtained from 50 g of total saponins. The preparatory purification of four isomeric saponins by Pre‐HPLC was completed in 120 min in a one step separation.