Gas chromatographic method for the analysis of allelopathic natural products in rye (Secale cereale L.)

Accurate and reproducible methods for the analysis of plant allelochemicals are a requirement for the study of chemical interactions between plants. This paper describes a method for sample preparation and quantitative analysis of the allelopathic chemical content of rye (Secale cereale L.) using gas chromatography (GC). Sample preparation consists of extraction of freeze-dried rye vegetative tissue with aqueous ethanol followed by partitioning of the allelochemicals into ethyl acetate, evaporation, and derivatization using the trimethylsilylating reagent N-methyl-N-trimethylsilyltrifluoroacetamide. GC analysis of the silylated mixture was performed using flame ionization detection. This method permits analysis of all known rye allelopathic agents including 2,4-dihydroxy-1,4-benzoxazin-3-one, its corresponding glucoside, 2-benzoxazolinone, β-hydroxybutyric acid, and β-phenyllactic acid. Identities of all compounds were confirmed by GC/MS analysis.