High-performance liquid chromatography (HPLC) was used to quantify magnaldehyde B (6), magnaldehyde E (4) and 8',9'-dihydroxyhonokiol (7) simultaneously in the raw Chinese medicinal material honokiol. The separation was performed on a reversed-phase C18 column by using a gradient elution with mobile phases of water (A) and methanol (B). The mobile phase gradient was run from 40% B to 56.5% B in 55 min, 55-67 min from 56.5% to 51.5%, 67-80 min from 51.5% to 70%, 80-170 min at 70%. The elution was carried out at a flow rate of 1.0 mL/min at the column temperature of 35 оC with the UV detection wavelength at 256 nm. Magnaldehyde B, magnaldehyde E and 8',9'-dihydroxyhonokiol showed good linear relationships with peak areas in the range of 0.00864 to 0.07776 mg/mL, 0.01488 to 0.13392 mg/mL and 0.01568 to 0.10976 mg/mL, respectively. Their corresponding average recoveries were 100.30%, 99.63% and 98.29%, respectively. Our results showed that the established method is simple, rapid, and accurate with good reproducibility for evaluating the quality of raw Chinese medicinal material honokiol. Moreover, another five phenolic compounds, namely erythro-7-O-methylhonokitriol (1), threo-7-O-methylhonokitriol (2), 7-O-ethylhonokitriol (3), magnaldehyde C (5), honokiol (8), together with compounds 4, 6 and 7, were isolated and purified from the remaining substance in the process of preparing the raw material honokiol by silica gel column and semi-preparative HPLC. Their structures were characterized by 1D and 2D NMR spectroscopy. Among them, compounds 1 and 2 were reported to have common planar structures and their relative configurations were identified for the first time. Compounds 3 and 7 were not only obtained from the raw medicinal material for the first time but also novel compounds.
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