Correlation Study of Biological Activity with Quercetin and Phenolics Content in Onion Extracts

Abstract

In this study it was shown that the fungistatic and antioxidant activities of onion extracts are related to the type of liquid used as the extractant and the technique of its preparation. A change in the antioxidant properties of white and red onion extracts was demonstrated with the change of the temperature of the pressurized hot water extraction process, which can be easily related to the changes accompanying the process of thermal processing of vegetables and fruits during cooking. Owing to the experimental and mathematical approaches concerning both the main and characteristic components of onions, i.e., quercetin and phenols, respectively, with the biological activity of the extracts, it was possible to demonstrate the significant share of these compounds in the antifungal and antioxidant properties of the extracts. Considering that the research was carried out, inter alia, on onion husks, demonstrating a very high potential of biological properties of this waste material from agricultural production, the research results presented in the paper should encourage the popularization of the use of this so far underestimated raw material for the production of various functional materials.

Comparison of the Antioxidant Properties of Extracts Obtained from Walnut Husks as well as the Influence of Juglone on Their Evaluation

“…Exhaustive Soxhlet extraction was performed according to [20] using a 1 g portion of ground husks using either methanol or ethyl acetate or acetone or chloroform as the extraction solvent (70 mL). Each sample was extracted for 3 h. The extract was then cooled.…”

“…Portions of 1 g of the material were immersed in methanol, ethyl acetate, acetone or chloroform (70 mL) [20]. The entire amount (tightly closed) was left for 72 h at room temperature.…”

Antioxidant Properties of Selected Flavonoids in Binary Mixtures—Considerations on Myricetin, Kaempferol and Quercetin

“…Plant extracts, especially those rich in polyphenolic compounds, are the source of natural antioxidants commonly used in the creation of functional foods. Myricetin, quercetin and kaempferol are representatives of one of their subgroups, i.e., flavonols, which, due to their high prevalence in the plant kingdom, are an important component of a healthy diet [ 8 , 9 , 10 , 11 ]. The structures of these compounds are shown in Figure 1 .…”

Phenolic Compounds from onion husk (Allium cepa L.): Mode of Extraction

“…The flavonoids include quercetin, which potentially protects against these diseases [1,4,8]. The source of quercetin is vegetable raw materials [9,10]. This compound is of particular interest to plant breeders, food technologists and nutritionists.…”