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Extensive agriculture application of rare earth elements (REEs) in Far East countries might cause spreading of these metals in aquatic and terrestrial ecosystems, thus inducing a growing concern about their environmental impact. In this work the effects of a mix of different REE nitrate (RE) and of lanthanum nitrate (LA) on catalase and antioxidant systems involved in the ascorbate-glutathione cycle were investigated in common duckweed Lemna minor L. The results indicated that L. minor shows an overall good tolerance to the presence of REEs in the media. Treatments at concentrations up to 5 mM RE and 5 mM LA did not cause either visible symptoms on plants or significant effects on reactive oxygen species (ROS) production, chlorophyll content, and lipid peroxidation. Toxic effects were observed after 5 days of exposition to 10 mM RE and 10 mM LA. A remarkable increase in glutathione content as well as in enzymatic antioxidants was observed before the appearance of the stress symptoms in treated plants. Duckweed plants pretreated with RE and LA were also exposed to chilling stress to verify whether antioxidants variations induced by RE and LA improve plant resistance to the chilling stress. In pretreated plants, a decrease in ascorbate and glutathione redox state and in chlorophyll content and an increase in lipid peroxidation and ROS production levels were observed. The use of antioxidant levels as a stress marker for monitoring REE toxicity in aquatic ecosystems by means of common duckweed is discussed.

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Artichoke by-products are rich in phenolic compounds although they represent a waste for the food industry. This paper examines the application of ultrasound-assisted extraction (UAE) for obtaining organic solvent-free extracts rich in nutraceuticals from artichoke scraps. Application of ultrasounds for 60 minutes on test samples, using water as a solvent, improved recovery of phenolic substances compared with untreated samples. Among the phenols detected by high performance liquid chromatography, 5-O-caffeoylquinic and 1,5-di-O-caffeoylquinic acids were identified. In vivo treatments of tobacco BY-2 cells with ultrasonic extracts consistently enhanced their antioxidant power, making the cells more resistant to heat stress. UAE applied to artichoke by-products, using water as a solvent, appears to be a powerful eco-friendly technique that can provide extracts rich in nutraceuticals and turn waste products into resources. The extracts could be advantageously utilized in the food industry to produce functional foods.