Identification of p -Coumaric Acid and Ethyl p -Coumarate as the Main Phenolic Components of Hemp ( Cannabis sativa L.) Roots.

Hemp ( Cannabis sativa L.) contains a variety of secondary metabolites, including cannabinoids, such as psychoactive (-)- trans -Δ⁹-tetrahydrocannabinol. The present study was conducted to identify the major phenolic components contained in hemp root, which has been relatively under-researched compared to other parts of hemp. The aqueous ethanol extract of hemp roots was fractionated into methylene chloride (MC), ethyl acetate (EA), and water (WT) fractions, and high-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis was performed. The main ultraviolet (UV)-absorbing phenolic compound contained in the EA fraction was identified as p -coumaric acid by comparing the retention time and UV absorption spectrum with a standard. Silica gel column chromatography was performed to isolate a hydrophobic derivative of p -coumaric acid contained in the MC fraction. Nuclear magnetic resonance (NMR) analysis identified the isolated compound as ethyl p -coumarate. For comparative purposes, ethyl p -coumarate was also chemically synthesized by the esterification reaction of p -coumaric acid. The content of p -coumaric acid and ethyl p -coumarate in the total extract of hemp root was estimated to be 2.61 mg g -1 and 6.47 mg g -1 , respectively, by HPLC-DAD analysis. These values correspond to 84 mg Kg -1 dry root and 216 mg Kg - 1 dry root, respectively. In conclusion, this study identified p -coumaric acid and ethyl p -coumarate as the main phenolic compounds contained in the hemp roots.