Metabolomics-based screening and chemically identifying abundant stachydrine as quality characteristic of rare Leucosceptrum canum Smith honey

Leucosceptrum canum Smith honey (LcSH) is a rare and high-value monofloral honey. However, it is difficult to evaluate the authenticity of LcSH since there is little knowledge of its chemical composition. In the present research, we compared LcSH to other common honeys using a metabolomics strategy and screened a molecular feature with a mass of 143.0948 Da that was unique to LcSH. According to HR-MS and NMR spectroscopy, it was identified as stachydrine, which is well known to have a variety of pharmacological activities. The result was confirmed against a reference standard. A UHPLC-MS/MS method was developed to determine its concentration in honey samples. Stachydrine was abundant in LcSH compared to other honeys, ranging from 0.35 mg/g to 0.68 mg/g. Levels of stachydrine were measured 18 months after the initial sampling and did not show significant statistical differences (p < 0.01), suggesting it is chemically stable in LcSH. This study indicates that stachydrine is a useful characteristic component to evaluate and control LcSH authenticity.