Metabolic profiling, free-radical scavenging and tyrosinase inhibitory activities of Lemna minor whole plants cultivated in various concentrations of proline and sucrose

► L. minor plants were cultivated in various concentrations of proline and sucrose. ► Metabolic profiling of the plants was performed using GC–MS. ► Antioxidative and tyrosinase inhibitory activities were investigated in the plants. ► Total phenolics and cinnamic acid contents contributed to the activities. Metabolic profiling of Lemna minor whole plants cultivated in proline and sucrose at various concentrations was performed using gas chromatography–mass spectrometry coupled with multivariate statistical analysis. In total, 46 compounds including alkaloids, amino acids, fatty acids, organic acids, phenolics, phytosterols, purines, and sugars were assigned, and the relative levels of these metabolites were compared in the L. minor whole plant samples. Free-radical scavenging and tyrosinase inhibitory activities were also investigated in L. minor whole plants cultivated in proline and sucrose at various concentrations. The whole plants cultivated in 3% sucrose and 0.5 mM proline for 42 days exhibited the highest antioxidative and tyrosinase inhibitory activities, and biomass accumulation. Total phenolic content and cinnamic acid content were also highest under those conditions, which might have contributed to the free-radical scavenging and tyrosinase inhibitory activities. There were strong correlations between free-radical scavenging activity and total phenolic content, and between tyrosinase inhibition activity and cinnamic acid content in L. minor whole plants cultivated under various conditions.