COMPARATIVE EVALUATION OF THE POLYPHENOLIC CONTENT AND THE RESULTING ANTIOXIDANT ACTIVITY OF SEVERAL COMMON ALLIUM SPECIES

Abstract

The Allium genus representatives are recognized as valuable nutrients, widely used in various national cuisines all over the World due to their specific taste. Besides, their evinced antioxidant properties, these species possess some pharmaceutic abilities. That is why these plants are the object of growing research interest. Thus, the present study provides data, regarding the polyphenolic compound contents, especially flavonoids, the resulting antioxidant activity and the functional groups of their molecules. The research activities included garlic, leek, shallot, red, white and yellow onions. These species were submitted to comparative analysis, by UV-Vis spectrophotometry, and Fourier Transform Infrared Spectroscopy (FT-IR). The former method was applied to four procedures on powder extracts for determination of to determine: (i) the total polyphenols and particularly (ii) flavonoids, followed by (iii) ferric reducing antioxidant power (FRAP) and (iv) free radical scavenging activity (also known as “DPPH-method”).
The analysis of the results showed that the yellow onion samples contained the highest amount of polyphenolic compounds, whereas the highest content of flavonoids was registered for the shallot. The results for antioxidant activities of the studied cultivars showed similar trends, completely coinciding with the data for the flavonoid contents. Hence, according to the obtained data, the antioxidant activity and flavonoid content decreased in the following order: shallot > yellow onion > red onion > white onion > leek > garlic.