title: Determination of honokiol and magnolol by micro HPLC with electrochemical detection and its application to the distribution analysis in branches and leaves of Magnolia obovata.
abstract: A simple and sensitive method has been developed for determining honokiol and magnolol in fresh Magnolia obovata (M. obovata) by micro high-performance liquid chromatography with electrochemical detection (microHPLC-ECD). Chromatography was performed using a Capcell Pak C-18 UG 120 microbore octadecylsilica (ODS) column, methanol-water-phosphoric acid (65 : 35 : 0.5, v/v/v), as a mobile phase and applied potential at +0.8 V vs. Ag/AgCl. Peak heights were found linearly related to the amounts of honokiol and magnolol injected from 0.67 pg to 2.0 ng (r>0.999). The detection limits (S/N=3) were 0.13 pg, respectively. Honokiol and magnolol of 0.27 ng were detected with relative standard deviation (RSD) of 0.73 and 1.17% (n=5), respectively. Honokiol and magnolol in Magnolia Bark of the Japanese Pharmacopoeia were extracted with 70% methanol, diluted with a mobile phase, and injected into the microHPLC-ECD for determination. Recoveries of honokiol and magnolol in Magnolia Bark exceeded 98.7% with RSD, less than 0.93% (n=5). Determination of the distributions of honokiol and magnolol in bark, phloem, wood, leaf blades, and petioles of fresh M. obovata were made using weight samples of 40-238 mg. This method is useful to determine honokiol and magnolol in M. obovata, which is a candidate for crude magnolia bark for traditional Japanese herbal medicines.
authors.affiliation: Department of Analytical Chemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kotani
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kojima
authors.forename: Hideki
authors.initials: H
authors.lastname: Hakamata
authors.forename: Dongri
authors.initials: D
authors.lastname: Jin
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Kusu
mesh_terms: D001713:Biphenyl Compounds / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004563:Electrochemistry; D017705:Lignans / Q000032:analysis*; D031566:Magnolia / Q000737:chemistry*; D020835:Medicine, Kampo; D044085:Microfluidics; D035261:Plant Components, Aerial / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D001713:Biphenyl Compounds; D017705:Lignans; D010936:Plant Extracts; C005498:magnolol; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols