title: Structure elucidation of degradation products of Z-ligustilide by UPLC-QTOF-MS and NMR spectroscopy.
abstract: Z-Ligustilide, a major phthalide isolated from a widely used traditional Chinese medicine Ligusticum chuanxiong, possesses various pharmacological activities including neuroprotective, anti-inflammatory, antiproliferative and vasorelaxing effects. However, it is unstable and inclined to degrade in natural conditions, which limits its study and application greatly. In this study, degradation behavior of Z-ligustilide and its degradation products stored at room temperature under direct sunlight were investigated and structure elucidated by HPLC-UV, UPLC-QTOF-MS and NMR. Z-ligustilide degradation and total five degradation products were generated and detected. Two degradation products were unequivocally identified as senkyunolide I and senkyunolide H by comparison with reference compounds. Another two degradation products were further isolated by semi-preparative HPLC and structure elucidated as (E)-6, 7-trans-dihydroxyligustilide and (Z)-6, 7-epoxyligustilide by 1H and 13C NMR, respectively. The degradation pathways of Z-ligustilide were finally proposed. Oxidation, hydrolysis and isomerization are the major degradation reactions.
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy ofScience, Dalian 116023, China.
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Zuo
authors.forename: Meng-Chun
authors.initials: MC
authors.lastname: Cheng
authors.forename: Rong-Jie
authors.initials: RJ
authors.lastname: Zhuo
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Xiao
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000378:metabolism; D001572:Benzofurans / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006868:Hydrolysis; D030004:Ligusticum / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001572:Benzofurans; C584604:senkyunolide H; C576743:senkyunolide I; C027820:ligustilide; D015107:4-Butyrolactone