Metal coordination complexes with different ligands attract particular attention by their ability to model biosynthetic processes in living cells, even being applied in very low concentrations. As xenobiotics for living organisms, these compounds can generate oxidative stress of varying intensity, which is most often associated with an initial increase in antioxidant activity of cells. In this way, transition metal complexes can serve as modulators for directed synthesis of bioactive compounds with antioxidant properties in the objects of biotechnological interest. As inductors of the accumulation of bioactive principles with antioxidant effect in Nostoc linckia biomass, two different classes of iron coordination compounds were used – iron(III) complex compounds with amino acids and iron(III) complexes with Schiff bases as ligands. The selection of these two classes was based on the attempt to compare the response reactions of nostoc culture to the action of compounds with a different degree of toxicity. Both types of compounds contain iron – a metal with multiple valence states, one of the main metal elements responsible in living systems for triggering oxidation and free radical formation reactions. Ligands presented by amino acids are friendly elements to cellular environments, capable of mitigating the negative effects of metal, while ligands presented by Schiff bases, on the contrary, due to their high toxic potential, can amplify the negative effects of metal. Thus, iron(III) complexes with the amino acid ligands (alanine and glycine) did not generate a state of oxidative stress and, therefore, did not intensify the processes of accumulation of components with antioxidant effects in nostoc biomass. Unlike other phycological cultures, which quickly responded to these actions, nostoc turned out to be rather inert. Four iron(III) coordination compounds with Schiff base ligands were added to nutrient medium on the first day of cultivation cycle in various concentrations (each compound in five different concentrations from 1 to 20 mg/L), in order to induce an oxidative stress in exposed cyanobacterium Nostoc linckia. Cyanobacterial culture responded by modifying the synthesis of protective factors, including phycobiliproteins that act as free-radical scavengers or chain breaking antioxidants.  In the case of [Fe(H2L2)(H2O)2](NO3)3·5H2O, the highest content of phycobiliproteins was registered under the concentration of 20 mg/L (250% C). We can assume that high phycobiliprotein content under the maximum concentration of compound was a reaction of antioxidant protection and an increase of photosynthesis and productivity of Nostoc linckia. In the case of other three compounds, stimulatory effect on phycobiliprotein synthesis depends on the applied dose and concentration of 20 mg/L was determined as one with moderate intensity. The antioxidant activity determined the existence of a dependent correlation between phycobiliprotein content and ABTS assay values shown by the aqueous extracts from experimental biomass of Nostoc linckia. Hence, it is possible to alter the antioxidant activity of Nostoc biomass by applying low concentrations of chemical stimuli. In fact, when stress factor becomes critical as the primary response reaction, some strains of cyanobacteria, including Nostoc linckia, have developed avoidance as a first line of defense mechanisms. This includes migration in the surface layers of nutrient medium under laboratory conditions or synthesis of extracellular polysaccharides that can act as natural metal chelators. Moreover, the exopolysaccharides can reduce the metal mainly through chemical functional groups and store it in the form of nanoparticles. This provides much insight for understanding the mechanisms responsible for metal ion transport and maintaining homeostatic levels.