Flavonoid analysis of buckwheat sprouts

Area of Science:

• * Phytochemistry
• * Plant Biochemistry

Background:

• * Common buckwheat sprouts are known to contain various flavonoids like orientin, isoorientin, vitexin, isovitexin, rutin, and quercetrin.
• * Tartary buckwheat sprouts predominantly contain rutin, with other flavonoids present in trace amounts or undetectable.

Purpose of the Study:

• * To comprehensively evaluate the flavonoid profiles of common and tartary buckwheat sprouts.
• * To identify and characterize previously unreported flavonoids in buckwheat sprouts.

Main Methods:

• * High-performance liquid chromatography (HPLC) for simultaneous separation and detection of flavonoids.
• * Novel HPLC elution gradient method for improved separation of rutin and unidentified compounds.
• * HPLC-Electrospray Ionization-Mass Spectrometry/Mass Spectrometry (HPLC-ESI-MS/MS) for flavonoid identification.
• * Nuclear Magnetic Resonance (NMR) spectroscopy for structural elucidation of the new compound.

Main Results:

• * Six flavonoids were identified in buckwheat sprouts, including a newly discovered compound.
• * The novel flavonoid was identified as quercetin-3-O-robinobioside (epimer of rutin) with [M+H](+) = 611.17.
• * Tartary buckwheat sprouts showed rutin as the main flavonoid, with other flavonoids in trace amounts or absent.
• * Quercetin-3-O-robinobioside was not detected in tartary buckwheat sprouts.

Conclusions:

• * A novel flavonoid, quercetin-3-O-robinobioside, has been identified and structurally characterized in common buckwheat sprouts.
• * Significant differences exist in the flavonoid composition between common and tartary buckwheat sprouts.
• * The advanced HPLC method developed allows for better separation and identification of buckwheat flavonoids.