In relation to flavonols, quercetin and isorhamnetin
were detected. The concentration of isorhamnetin (from
3.1 to 11.8 mg/kg DW) was higher than quercetin concentration
(up to 4.5 mg/kg DW) in spinach samples. In
previous studies, the concentration of quercetin fluctuated
from not detected (Cao et al. 2010) to 766 mg/kg DW
(Nuutila et al. 2002), whereas isorhamnetin was not
detected previously (Cao et al. 2010). Regarding
isoflavones, glycitein was the only detected compound,
and its concentration ranged from 2.2 to 5.4 mg/kg DW.
Up to our knowledge, this is the first study that detects
the presence of isoflavones in spinach.