Isolation of Cinnamic Acid Derivatives from the Bulbs of Allium tripedale

Background: Allium genus with 750 species is the most diverse genus in the Amaryllidaceae family. Historically, Allium species have been used as medicinal plants, especially for prevention and treatment of cardiovascular diseases and considered as valuable sources of phytonutrients. Phytochemical investigation of Allium tripedale, locally called “Anashq,” which is an edible plant of the “Zagros” region (west of Iran) was conducted in the present study. Materials and Methods: Air-dried bulbs of the plant were extracted in a four-step extraction method with increasing polarity using hexane, chloroform, chloroform–methanol (9:1), and methanol. Chloroform-methanol (9:1) extract was fractionated by medium-pressure liquid chromatography on a RP-18 column using a linear gradient solvent system of H₂O to MeOH. Phenolic-rich fractions were subjected to the final isolation and purification of the constituents by reversed-phase high-performance liquid chromatography method. Structure elucidation of the compounds was performed through comprehensive methods including 1D-and 2D-NMR and mass spectroscopy. Results: Two cinnamic acid derivatives were isolated from the bulbs of A. tripedale; using spectroscopic methods, their chemical structures were determined as 6,7-dimethoxy N-trans-caffeoyltyramine (1) and N-trans-feruloyltyramine (2). Conclusion: Cinnamic acid derivatives are pharmacologically active phenolic compounds, which have been isolated from different Allium species. Isolation of these compounds from A. tripedale is reported for the first time in this study and could be used as a chemical basis for explanation of the plant biological and pharmacological activities.