Variation in polyphenolics, bioactive compounds and nutrients in barley (Hordeum vulgare L.) after exposure to copper and copper oxide nanoparticles: Implications for use of nanofertilizers in agriculture.

Possible risks of nanofertilizer-mediated agriculture were assessed by studying the effects of copper and copper oxide nanoparticles (Cu NP and CuO NP) on barley (Hordeum vulgare L.) seedlings. Liquid chromatography coupled to mass spectrometry and gas chromatography coupled to mass spectrometry revealed qualitative and quantitative changes in the main phytochemicals. Cu NP and CuO NP caused depletion of several phenolic acids and flavonoids, which may reduce the antioxidant potential of foods derived from barley. An additional effect noted was a deficiency in some bioactive materials such as volatile organic compounds. In addition, an imbalance of essential mineral levels may alter biochemical and physiological functions in diets featuring barley. Effects on nutrients were complex. Some were nanoparticle-specific, some were common to both nanoparticles and some were associated with metallic copper becoming bioavailable. Alteration of nutritional quality, added to the accumulation of toxic cupric ions and hazards associated with the induction of oxidative stress raise some concerns about use of Cu and CuO based nanofertilizers.