Structural profile of soluble and bound phenolic compounds in teff (Eragrostis tef) reveals abundance of distinctly different flavones in white and brown varieties

Reliable data on polyphenol in teff, an increasingly important food crop, is currently lacking. This study investigated the structural and quantitative profile of soluble and bound polyphenols in white and brown teff grown in Ethiopia and USA using LC-tandem quadrupole mass spectrometry. Thirty-four phenolic compounds (32 newly identified in teff), mostly flavones and phenolic acid derivatives, were characterized. Unusually high levels of flavones were present in both white (1398-2049 μg/g), and brown (1720-1847 μg/g) teff soluble fractions. Interestingly, white teff exclusively contained apigenin derivatives, whereas brown teff contained mainly luteolin derivatives, mostly di-C-linked-glycosides. Additionally, non-extractable procyanidins (condensed tannins) were detected in brown teff only. Phenolic acids (600-728 μg/g) were mostly present in bound fractions, dominated by ferulic acid. Polyphenol profiles of Ethiopian and USA grown grains were similar. The high levels of the relatively rare flavones in teff may have important implications in chronic disease prevention.