Validation study on the geometric isomers from bulbs of Allium fistulosum and their conversion

Abstract

To discover new standard for the standardization of bulbs of Allium fistulosum (Chongbaek, Korean herbal name), twelve compounds (1–12) were isolated. Among them, a new HPLC/UV analysis method by selecting the five cinnamic acid amides (5–9) and two decursidate isomers (10 and 11), was fully validated. The developed analysis method showed sufficient reproducibility (< 2.58%) and accuracy (96.00–106.72%). Moreover, among compounds 5–11, only trans-isomers were verified from all four Chongbaek samples which produced in different regions, and this finding implied that the cis-forms were not originally nature compounds, thus, it led us to verify the conversion processes. The four trans-standard solutions and extracts of Chongbaek were converted to the cis- derivatives after 96 h of UV (254 nm) light exposure as 78.74% (6), 82.29% (8), and 63.99% (11) in solution and 82.38% (6), 62.91% (8), and 61.64% (11) in extracts. A verified analysis method using new indicators was developed for quality control of Chongbaek, as well as their stability control under UV light exposure. These results might be important for the industrial use of Chongbaek.