Objective:The study aimed to evaluate the quality of commercial samples of Magnoliae Officinalis Cortex based on the contents of six active compounds. Method: An HPLC-DAD method was established to determine the contents of four polar constituents

magnoflorine

syringin

magnoloside A

magnoloside B. The HPLC separation was carried out on an Agilent Zorbax C18 column (4.6 mm×250 mm

5 μm) with a mixture solution of water-acetic acid (pH 3.0) and methanol as the mobile phase applied in a gradient elution at a flow rate of 1 mL · min-1. The wavelength was set at 265 nm for magnoflorine and syringin and 328 nm for the two magnolosides. The contents of magnolol and honokiol were determined using our previous method. Result: The average recovery of the four polar compounds ranged from 97.63% to 103.84% with RSDs less than 5.00%. The contents of honokiol/magnolol

magnolosides

magnoflorine

syringin in samples decreased in turn. The contents of polar compounds except syringin in the bark samples were higher than those in the decoction pieces (P<0.05). Contents of magnolol and honokiol in some samples didn't reach the requirement in Chinese Pharmacopoeia (2010 edition). Conclusion: The developed HPLC method is accurate and reliable. Generally speaking

the thick samples with good appearance possess higher contents of the active constituents than those thin and edge-damaged ones.