The Study of Senkyunolide I Degradation Products by Ultra-High Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

Abstract

Ligusticum chuanxiongHort. (Umbelliferae) has been prescribed widely to treat cardiovascular diseases in China for centuries. Senkyunolide I is a major bioactive component inL. chuanxiongthat shows pharmacological activity against migraines and oxidative damage. Here, we identified the degradation products of senkyunolide I under different conditions (temperature, light alkaline) by ultra-high-performance liquid chromatography–quadrupole time-of-flight–tandem mass spectrometry (UPLC-QTOF-MS) analyses. Senkyunolide I was separated on an ACQUITY UPLC HSS T3 C18 (100 mm × 2.1 mm i.d., 1.8 μm) column using a binary eluent under gradient conditions. Analytes were detected by ESI/QTOF–MS/MS in positive ion mode to obtain MS and MS/MS spectra together with extracted molecular weights. Upon comparison with reference data, we concluded that senkyunolide I undergoes a ring-opening reaction under alkaline conditions (pH >10.0), and dual-key addition or hydration on 3,4-unsaturated bonds and branched terminal hydroxyl groups under high-temperature and aerobic conditions. With auxiliary application1H-NMR, we determined that partial isomerization of senkyunolide I takes place under bright light. In the method detailed here, the advantages of separation and identification of a complex system of small and medium-sized molecules was exploited using UPLC–QTOF–MS, not only to avoid complicated separation and purification, but also to isolate and identify trace amounts of degradation products that were previously difficult to identify.