Abstract
Onions (Allium cepa) are consumed worldwide and represent an important source of dietary phytochemicals with proven antioxidant properties, such as phenolic acids, flavonoids, thiosulfinates, and anthocyanins. Epidemiological and experimental data suggest that regular consumption of onions is associated with a reduced risk of degenerative disorders. Therefore, it is of interest to investigate the biological properties of different varieties of onions. Here, we characterized for the first time a variety of onion, called Ramata di Montoro (coppery onion from Montoro), grown in a niche area in southern Italy, and compared its phenolic profile and antioxidant properties to a commercial ecotype of red onion, Tropea, also present in southern Italy. An analytical method based on high-performance liquid chromatography coupled with UV detection and mass spectrometry was used to separate and characterize the phenolic fraction (anthocyanins and flavonols) extracted from both coppery and red types. The main compounds detected in the two ecotypes were quercetin and quercetin glucosides, isorhamnetin glucosides, kaempferol glucoside, and, among anthocyanins, cyanidin glucosides. Tropea ecotype onion showed a higher content of flavonols (632.82 mg/kg fresh weight) than Montoro type onion (252.91 mg/kg fresh weight). Accordingly, the antioxidant activity of the former was 2.8-fold higher compared to the latter. More pronounced were the differences existing between the four anthocyanins detected in the two ecotypes, with those in the Tropea ecotype onion present at concentrations 20-230-fold higher than in the Montoro type onion. Both extracts reduced LDL oxidation about 6-fold and protected human erythrocytes from oxidative damage induced by HClO by about 40%. In addition, as a consequence of HClO treatment, glutathione concentration in erythrocytes was reduced about 50% and pretreatment with onion extracts induced a recovery of glutathione level by about 15-22%. Qualitative differences highlighted in the chemical composition of the two phenolic extracts, especially the total content of anthocyanins, which was 30-fold higher in Montoro type onion compared to Tropea ecotype, can be associated with the protective effects measured against oxidative damage induced in human erythrocytes.
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Claims 9
Claim · model-written summary
Both onion ecotypes contained named flavonols and anthocyanins.
- Taxon
- Allium cepa L.
Allium cepat0 - Outcome
- quercetin and quercetin glucosides, isorhamnetin glucosides, kaempferol glucosidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The main compounds detected in the two ecotypes were quercetin and quercetin glucosides, isorhamnetin glucosides, kaempferol glucoside, and, among anthocyanins, cyanidin glucosides”
t0“Allium cepa L.”
Claim · model-written summary
Tropea onion had higher flavonol content than Montoro onion.
- Taxon
- Allium cepa L.Allium cepat0
- Material
- Tropeae0
- Outcome
- content of flavonolse0
- Direction
- highere0
- Value
- 632.82 mg/kg fresh weighte0
- Qualifier
- 252.91 mg/kg fresh weighte0
- Comparator
- Montoro type onione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tropea ecotype onion showed a higher content of flavonols (632.82 mg/kg fresh weight) than Montoro type onion (252.91 mg/kg fresh weight)”
t0“Allium cepa L.”
Claim · model-written summary
Tropea antioxidant activity was 2.8 fold higher than Montoro.
- Taxon
- Allium cepa L.Allium cepat0
- Material
- Tropeae1
- Outcome
- antioxidant activitye0
- Direction
- highere0
- Value
- 2.8-folde0
- Comparator
- Montoro type onione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the antioxidant activity of the former was 2.8-fold higher compared to the latter”
e1“Tropea ecotype onion showed a higher content of flavonols (632.82 mg/kg fresh weight) than Montoro type onion (252.91 mg/kg fresh weight)”
t0“Allium cepa L.”
Claim · model-written summary
Four anthocyanins were 20 to 230 fold higher in Tropea than Montoro.
- Taxon
- Allium cepa L.Allium cepat0
- Material
- Tropea ecotype onione0
- Outcome
- anthocyaninse0
- Direction
- highere0
- Value
- 20-230-folde0
- Comparator
- Montoro type onione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“four anthocyanins detected in the two ecotypes, with those in the Tropea ecotype onion present at concentrations 20-230-fold higher than in the Montoro type onion”
t0“Allium cepa L.”
Claim · model-written summary
Both onion extracts reduced LDL oxidation about sixfold.
- Taxon
- Allium cepa L.Allium cepat0
- Treatment
- Both extractse0
- Outcome
- LDL oxidatione0
- Direction
- reducede0
- Value
- 6-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both extracts reduced LDL oxidation about 6-fold”
t0“Allium cepa L.”
Claim · model-written summary
Both extracts protected human erythrocytes from HClO damage by about 40%.
- Taxon
- Allium cepa L.Allium cepat0
- Treatment
- Both extractse1
- Outcome
- oxidative damage induced by HClOe0
- Direction
- protectede0
- Value
- about 40%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“protected human erythrocytes from oxidative damage induced by HClO by about 40%”
e1“Both extracts reduced LDL oxidation about 6-fold”
t0“Allium cepa L.”
Claim · model-written summary
HClO reduced erythrocyte glutathione about 50%.
- Taxon
- Allium cepa L.Allium cepat0
- Treatment
- HClO treatmente0
- Outcome
- glutathione concentration in erythrocytese0
- Direction
- reducede0
- Value
- about 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“as a consequence of HClO treatment, glutathione concentration in erythrocytes was reduced about 50%”
t0“Allium cepa L.”
Claim · model-written summary
Onion extracts restored erythrocyte glutathione by about 15 to 22%.
- Taxon
- Allium cepa L.Allium cepat0
- Treatment
- onion extractse0
- Outcome
- glutathione levele0
- Direction
- recoverye0
- Value
- about 15-22%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pretreatment with onion extracts induced a recovery of glutathione level by about 15-22%”
t0“Allium cepa L.”
Claim · model-written summary
The abstract also reports total anthocyanin content as 30 fold higher in Montoro than Tropea.
- Taxon
- Allium cepa L.Allium cepat0
- Material
- Montoro type onione0
- Outcome
- total content of anthocyaninse0
- Direction
- highere0
- Value
- 30-folde0
- Comparator
- Tropea ecotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total content of anthocyanins, which was 30-fold higher in Montoro type onion compared to Tropea ecotype”
t0“Allium cepa L.”
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See all 16 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.