Phytotoxicity of imidazolium ionic liquids

Ionske tekućine su skupina organskih soli s temperaturom tališta nižom od 100 °C. Zbog jedinstvenih svojstava poput neznatne hlapljivosti, nezapaljivosti i dobre stabilnosti te posebice mogućnosti reciklacije i višestruke uporabe intenzivno se proučavaju kao zelena zamjena za tradicionalna organska otapala sveprisutna u industriji. No, prije primjene ionskih tekućina u industrijskom mjerilu potrebno istražiti njihovu toksičnost i mogućnost biorazgradnje. Stoga je u ovom radu ispitan utjecaj dvije 1-butil-3-metilimidazolijeve ionske tekućine s acetatnim i tetrafluoroboratnim anionom na klijanje i rast ječma (Hordeum vulgare). Rezultati istraživanja pokazali su da odabrane ionske tekućine imaju toksičan učinak na rani rast i razvoj klijanaca ječma, pri čemu toksičnost raste s povećanjem koncentracije ionskih tekućine. Fitotoksično djelovanje ionskih tekućina očituje se u smanjenju količine klorofila te povećanju količine malondialdehida kao pokazatelja lipidne peroksidacije i količine H2O2. Nadalje, uočena je povećana aktivnost antioksidativnih enzima superoksiddismutaze, nespecifičnih peroksidaza, katalaze i askorbat-peroksidaze te povećani sadržaj neproteinskih tiola što upućuje da sudjeluju u obrani od oksidativnog stresa uzrokovanog ionskim tekućinama, dok antioksidativni sustav klijanaca nakon izlaganja većim masenim koncentracijama ionskih tekućina ne može učinkovito ukloniti kisikove reaktivne čestice koji uzrokuje lipidnu peroksidaciju i oštećenja fotosintetskog sustava.Ionic liquids are organic salts that are in liquid state at temperatures below 100° C. Due to their features such as very low vapour pressure, non-flammability, great dissolving power for a wide range of compounds, their thermal, chemical and electrochemical stability, as well as recycle potential, ionic liquids are extensively studied as a green alternative to traditional organic solvents. However, prior to their use on industrial scale it is crucial to proactively characterize their biodegradation potential and toxicity. Therefore, in this study the impact of two imidazolium ionic liquids (1-butyl-3-methylimidazolium acetate and 1- butyl-3-methylimidazolium tetrafluoroborate) on the germination and growth of barley (Hordeum vulgare) is investigated. The results showed that the selected ionic liquids possess inhibitory effect on the early growth and development of barley, while the inhibitory effect depends on the ionic liquids concentration. Toxic effects of ionic liquids are reflected in reduced amounts of chlorophyll, as well as in increased amount of malondialdehyde (indicator of lipid peroxidation) and H2O2. Furthermore, increased activity of antioxidant enzymes (superoxide dismutase, nonspecific peroxidase, catalase and ascorbate peroxidase) and increased content of non-protein thiols was observed, which indicates their participation in the plant defence mechanism against oxidative stress caused by ionic liquids. However, when seedlings were exposed to higher concentrations of ionic liquids antioxidant system couldn’t effectively remove reactive oxidative particles, leading to lipid peroxidation and damage to the photosynthetic system