Table 1.

The major constituents of Allium cepa.

Major compounds	Minor compounds	Reference.
Water		Nile and Park (2014)
Proteins		Nile and Park (2014), Ashwini and Sathishkumar (2014)
Carbohydrates	Inulin, fructooligosaccharides, isorhamnetin-4-glucoside, galactose, glucose and mannose	Nile and Park (2014)
Vegetal hormone Lectin	Glycoquinine	Corzo-Martínez et al. (2007)
Steroids	Catechol, protocatechnic acid, thiocyanate and thiopropiono aldehyde	Ashwini and Sathishkumar (2014), Nile and Park (2014), Benmalek et al. (2013)
Phytoestrogens	Coumestrol, zearalenol, isoflavones and humulone	Ashwini and Sathishkumar (2014), Nile and Park (2014), Benmalek et al. (2013)
Vitamins	A, B complex, C and E	Ashwini and Sathishkumar (2014), Nile and Park (2014), Benmalek et al. (2013)
Minerals	Selenium, phosphorus, iron, calcium and chromium	Nile and Park (2014), Ashwini and Sathishkumar (2014)
Flavonoids	Quercetin, apigenin, rutin, myricetin, kaempferol, catechin, resveratrol, epigallocatechol-3-gallate, luteolin and genistein Quercetin aglycone, quercetin diglucoside, quercetin 4-glucoside and isorhamnetin monoglycoside or kaempferol monoglycoside	Ashwini and Sathishkumar (2014); Lanzotti (2006), Benmalek et al. (2013), Corzo-Martínez et al. (2007), Yamamoto and Yasuoka (2010), Nile and Park (2014), Rhodes and Price (1996), Wiczkowski et al. (2008), Shi et al. (2016), Rodríguez Galdón et al. (2008), Ko et al. (2011), Rodrigues et al. (2017), Slimestad et al. (2007)
Organosulfuric compounds	Thiosulphinates, cepaenes, cysteine, S-methyl cysteine sulfoxide, diallyl disulphide, allyl methyl sulphide, allyl propyl disulphide, gamma-L-glutamyl-trans-S-1-propenyl-L-cysteine sulfoxide, S-propenyl cysteine sulfoxide, S-alk(en)yl cysteine sulfoxides, S-allyl cysteine sulfoxide	Ashwini and Sathishkumar (2014), Lanzotti (2006), Nile and Park (2014), Benmalek et al. (2013)
Allicin	Diallyl disulphide, diallyl trisulphide and ajoene	Ashwini and Sathishkumarn (2014), Lanzotti (2006), Nile and Park (2014), Corzo-Martínez et al. (2007), Benmalek et al. (2013)
Phenolic compounds	Phenolics, phenolic acids, anthocyanins and hydroxycinnamic acid	Lanzotti (2006), Nile and Park (2014)
Lipophilic antioxidants	Dialkyl disulphides, aglycones, anthocyanin, saponins and fistulosin (octadecyl 3-hydroxyindole)	Ashwini and Sathishkumar (2014), Lanzotti (2006), Takahashi and Shibamoto (2008), Benmalek et al. (2013), Ernst and Feldheim (2000), Corzo-Martínez et al. (2007), Dorsch et al. (1990), Yamamoto and Yasuoka (2010), Nile and Park (2014), Griffiths et al. (2002), Augusti (1996), Rhodes and Price (1996), Khaki et al. (2009), Kuhnau (1976), Arjmandi et al. (1996)