Phytochemical and Analytical Characterization of Constituents from Fagopyrum esculentum

Abstract

Fagopyrum esculentum (buckwheat) is an annual herb that is commonly cultivated in Vietnam for ornamental and food purposes. Previous studies also indicated the medicinal potential of the plant due to its high content of bioactive compounds. However, every year, more than 300 ha of buckwheat cultivation has been discarded after flower festival in North Vietnam. The present study was conducted to clarify the main chemical constituents of F. esculentum aerial parts collected in Ha Giang, Vietnam. The investigation has led to the isolation and identification of nine compounds, specifically flavonoids (rutin, quercetin, quercetin 3-O-rhamnopyranoside, quercetin 3-O-galactopyranoside), lignan (isolariciresinol), phenylpropanoids linking with sucrose (lapathoside A, lapathoside D) and phytosterols (?-sitosterol, and daucosterol). An HPLC quantification method of the major component of F. esculentum leaves, rutin, was also developed. The optimized condition was performed on a Shimadzu LC-20D HPLC system; Shim-pack GIST C18 column (4.6 mm × 250 mm × 5 µm); eluting solvent system (0-20 min:16-26% acetonitrile in water containing 0.1% formic acid); injection volume 20 ?L; flow rate 1.2 mL/ min; column temperature 35°C; UV wavelength 254 nm. The method was also validated by various parameters, including linearity (R2= 0.9995), precision (6 samples; RSD= 1.58%), accuracy (recover rates from 94.4 to 103.9%), limit of detection (LOD= 0.049 ?g/mL), limit of quantification (LOQ= 0.147 ?g/mL). The analytical results showed that the content of rutin in leaf and flower samples were 1.794 ± 0.002% and 1.137 ± 0.002% , respectively.