Evaluation and comparison of bioactive substances in selected species of the genus Allium

Abstract

Allium is a genus of some 650 species belonging to the family Liliaceae. However only a few of these are important as food plants, notably garlic (Allium sativum L.), onion (Allium cepa L.), leek (Allium porrum L.) and wild garlic (Allium ursinum L.). They contain many health beneficial substances, such as sulphur compounds, vitamins (vitamin C), mineral substances (Fe, Mg, Ca, P), polyphenols (especielly quercetin) and substances antioxidant activity and fiber. In this work we evaluated the content of bioactive substances, especially the content of total polyphenols and antioxidant activity in several species (red onion, yellow onion, white onion, garlic, leek, wild garlic) of the genus Allium. Samples of plant material were collected at full maturity stages from Zohor (Slovak Republic). Zohor is an area without negative influences and emission sources. Samples of fresh species of the genus Allium were homogenized and prepared as an extract: 25 g cut plants material (red onion, yellow onion, white onion, garlic, leek, wild garlic) extracted with 50 mL of 80% ethanol for sixteen hours. These extracts were used for analyzes. The content of total polyphenols was determined using the Folin-Ciocalteu reagent (FCR). The absorbance was measured at 765 nm of wavelength versus blank. Antioxidant activity was measured using DPPH˙ (2,2-difenyl-1-picrylhydrazyl) at 515.6 nm in the spectrophotometer. In the present experiment it was found that total polyphenols content in samples ranged from 83.59 mg.kg-1 to 758.63 mg.kg-1 and values of antioxidant activity were in the range from 7.19% to 53.55%. 

Keywords

• polyphenols
• antioxidant activity
• Allium
• species
• variety