HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY COUPLED WITH FLUORESCENCE DETECTION FOR SIMULTANEOUS DETERMINATION OF HONOKIOL AND MAGNOLOL IN HANGE-KOBOKU-TO DRIED EXTRACT GRANULES

Honokiol and magnolol in Magnoliae Cortex, one of five medical herbal ingredients of Hange-koboku-to dried extract granules, have pharmacological activities, including decreasing anxiety and improving sleep. Here, we present a method employing aqueous extraction, followed by high-performance liquid chromatography with fluorescence detection, for the simultaneous determination of honokiol and magnolol in Hange-koboku-to dried extract granules. Excitation and emission wavelengths were set at 304 nm and 340 nm, respectively, for honokiol detection until 9 min, then the emission wavelength was shifted at 405 nm for magnolol detection. The regression equations for honokiol and magnolol in standard aqueous solutions showed good linearity in the range of 0.05-1 mu g/mL with lower limits of detection (signal-to-noise ratio of 3) of 0.0047 and 0.0061 mu g/mL, respectively. The coefficients of variation were less than 5.6%. It was found that Hange-koboku-to dried extract granules (1.00 g) contains honokiol (3.30 +/- 0.21 mg; range, 3.08 to 3.63 mg) and magnolol (5.40 +/- 0.37 mg; range, 4.80 to 5.80 mg) (mean +/- S.D., n = 5). Recovery tests were satisfactory (90.7-104.8%).