Influence of Deep Eutectic Solvents (DESs) on Antioxidant and Antimicrobial Activity of Seed Extracts of Selected Citrus Species
Lamija Kolarević
Faculty of Pharmacy, University of Tuzla, Urfeta Vejzagića 8, 75 000 Tuzla, Bosnia and Herzegovina.
Emir Horozić *
Faculty of Technology, University of Tuzla, Urfeta Vejzagića 8, 75 000 Tuzla, Bosnia and Herzegovina.
Zahida Ademović
Faculty of Technology, University of Tuzla, Urfeta Vejzagića 8, 75 000 Tuzla, Bosnia and Herzegovina.
Broza Šarić- Kundalić
Faculty of Pharmacy, University of Tuzla, Urfeta Vejzagića 8, 75 000 Tuzla, Bosnia and Herzegovina.
Darja Husejnagić
Faculty of Natural Sciences, University of Tuzla, Urfeta Vejzagića 4, 75 000 Tuzla, Bosnia and Herzegovina.
*Author to whom correspondence should be addressed.
Abstract
Deep eutectic solvents (DESs), as an alternative to ionic liquids, have greener credentials than ionic liquids and have attracted increasing attention in many applications. Choline chloride-based DESs in combination with different hydrogen bond donors (organic acid, sugars and urea), showed a high extraction efficiency. The aim of this study was to examine the possible effects of choline chloride-based eutectic solvents on the antioxidant and antimicrobial activity of lemon and mandarin orange seed extracts. Lactic acid, glucose, urea and water were used to prepare choline chloride-based Natural Deep Eutectic Solvents (NADESs). Ferric-Reducing Antioxidant Power (FRAP) Assay and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) method were used to determine antioxidant activity. Antibacterial activity was investigated by diffusion method on reference bacterial strains E. coli, E. faecalis, S. aureus, B. subtilis and L. monocytogenes. The analysis revealed a significant reduction potential of the eutectic solvent based on lactic acid as well as significant antioxidant activity of lemon and mandarin seed extracts. In general, mandarin extracts showed better antioxidant capacity. In vitro antibacterial activity assays showed a complete absence of bacterial growth inhibition of the extracts. However, eutectic solvents with lactic acid have shown a significant antimicrobial effect.
Keywords: Seeds, lemon, mandarin orange, bioactivity, in vitro study.