Changes in phenolic content, phenylalanine ammonia-lyase (PAL) activity, and antioxidant capacity of two buckwheat sprouts in relation to germination

Total phenol, total flavonoid, rutin and quercetin contents as well as antioxidant activity in ethanol extracts of common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tararicum Gaertn) sprouts were determined, and the phenylalanine ammonia-lyase (PAL) activity in the sprouts were estimated. Total flavonoid content and rutin in the sprouts of both buckwheat species gradually increased and reached the maximum levels on days 7 and 9 of germination, respectively; total phenol and free phenylalanine content also had the same trend. However, quercetin in tartary buckwheat decreased from day 5 and became undetectable on day 7, similar to that observed in common buckwheat sprouts beyond the germinating period. An obvious positive linear relationship (r2 = 0.9792, P < 0.01) was found between PAL activity and flavonoid accumulation. The phenolic extracts of the sprouts of both buckwheat species exhibited strong antioxidant activity. This study suggests that buckwheat sprouts are a good health-promoting food source.