Copper Sulfate Elicitation Effect on Biomass Production, Phenolic Compounds Accumulation, and Antioxidant Activity of Morus nigra L. Stem Node Culture

Phenolic compounds are strong antioxidant and antibacterial agents with great pharmacological, medicinal, nutritional, and industrial value. The potential of <i>Morus nigra</i> in stem node culture was investigated for the production of phenolic compounds and their elicitation with CuSO₄. Individual phenolic compounds in the samples were identified and quantified by using HPLC-PDA and HPLC-MS methods, while the content of total phenolic compounds, the content of total flavonoids, and the antioxidant activity of methanolic extracts were evaluated spectrophotometrically. The highest fresh and dry weights were obtained in plantlets treated with 0.5 mM CuSO₄ for 42 days. The highest total phenolic content, total flavonoid content, and antioxidant activity of the extracts were determined in stem node cultures treated with 3 mM CuSO₄ for 42 days. Under the latter conditions, the predominant representatives of the caffeoylquinic acids, <i>p</i>-coumaric acid derivatives, kaempferol derivatives, and quercetin derivatives also achieved the highest content. The most abundant phenolic compound in all samples was the chlorogenic acid. The nodal culture of <i>M. nigra</i> elicited with CuSO₄ could potentially be used for the industrial production of phenolic compounds, especially caffeoylquinic acids. Moreover, considering the biochemical response to CuSO₄ treatment and the ability to tolerate and accumulate copper, the potential application of <i>M. nigra</i> in phytoremediation is also highlighted.