Table 2.

Flavonoids content in red and white onion extracts.

	Red onion	White onion
	RO-1	WO-1	WO-2
FLAVONOL
Quercetin 3,4-O-diglucoside	0.684 ± 0.001	7.846 ± 0.080	–
Isorhamnetin3,4-diglucoside	–	0.191 ± 0.001	–
Quercetin 3-O-glucoside	0.359 ± 0.001	0.413 ± 0.001	–
Quercetin 4-O-glucoside	10.546 ± 0.020	11.032 ± 0.010	1.478 ± 0.005
Isorhamnetin4-glucoside	0.500 ± 0.001	1.263 ± 0.008	–
Quercetin glycoside	1.44 ± 0.004	–	–
Quercetin aglycone	3.741 ± 0.050	–	–
Total flavonol	17.272	20.738	1.478
ANTHOCYANIN
Cyanidin 3-O-glucoside	1.162 ± 0.007	–	–

–, not detected; RO-1, red onion extract in methanol acidified with 2.5% acetic acid; WO-1, white onion extract in methanol; WO-2, white onion extract in methanol ammonium. All quercetin derivates were expressed as equivalents of quercetin 3-O-glucoside. All isorhamnetin derivates were expressed as isorhamnetin. All results were expressed as mg/100 mg of dry extract. In bold, the major compounds identified.