An HPLC-DAD method for simultaneous quantitative determination of four active hydrophilic compounds in Magnoliae officinalis cortex

Magnoliae officinalis cortex (MOC), derived from Magnolia officinalis and its variation M. officinalis var. biloba, is an important traditional Chinese medicine. In our previous work, 11 hydrophilic ingredients of MOC were isolated and structurally elucidated and four, namely syringin (SG), magnoloside A (MA), magnoloside B (MB) and magnoflorine (MF), showed bioactive effects. Herein, we describe an HPLC-DAD method for the simultaneous quantitative determination of MA, MB, MF and SG in MOC for the first time. The chromatographic separation of samples was performed on an Agilent Zorbax SB-C18 column (250 × 4.6 mm i.d., 5 µm) by gradient elution with water-acetic acid (pH 3.0) and methanol at a flow rate of 1.0 mL/min. The wavelengths were set at 265 nm for MF and SG, and 328 nm for MA and MB. The average recovery of the four compounds was from 97.63 to 103.84%. Nearly 100 MOC samples harvested from eight habitats were analyzed in which the contents of the tested compound varied in the range of 0.016-0.350% (MF), 0.010-0.337% (SG), 0.017-3.009% (MB) and 0.077-2.529% (MA). The analysis also indicated that MOC contains a significant amount of phenylethanoid glycosides. This was an unexpected finding because previously lignan was considered to be the main component of MOC.