Introduction Investigation of non-traditional sources of bioactive substances is one of the current directions of biotechnology development in many countries worldwide. Cyanobacteria Spirulina platensis is widely explored and used in recent decades as a source of valuable biologically active substances [1, 2]. An important role in neutralizing the harmful effects of oxidative stress have the enzime superoxiddismutase (SOD), that it is present, also, in the biomass of cyanobacteria Spirulina platensis [3]. The aim of this investigation presents a study of possibility of utilization of some coordination compounds of V(IV) and Co(III) as regulators of the content of bioactive substances with antioxidant properties in the biomass of cyanobacteria Spirulina platensis. Material and methods Object of study is a strain of cyanobacteria Spirulina platensis CNM-CB-02, stored at the National Collection of Nonpathogenic Microorganisms of the Institute of Microbiology and Biotechnology, Academy of Sciences of Moldova. As stimulators of growth processes of cyanobacteria Spirulina platensis and accumulation of bioactive substances with antioxidant properties in the biomass coordination compounds of V(IV) and Co(II) with different ligands of organic nature: [(VO)2(2PyTCH)]SO4·4H2O; [(VO)2(2PyCH)]SO4·4H2O; [(VO)2(2PyFx)] SO4·4H2O; L4 - [Co(L-H)En]·3H2O; Na[Co(DH)2(NO2)2] have been used. Results and discussions The analysis of obtained results has demonstrated that phycobiliproteins content is increased by 45-74% compared to the reference sample in the case of utilization of compounds of V(IV). The administration of the coordinative compound of Co (III) - [Co(L-H)En] 3H2O in the concentration of 20mg/l has recorded a maximum increase of phycobiliproteins contents ( by 160% compared to the reference sample). Beta-carotene contents in the biomass of spirulina cultivated in the presence of complexes [(VO)2(2PyTCH)]SO4•4 H2O and [(VO)2(2PyCH)]SO4•4H2O reaches the values of 29 and 25mg%, respectively, at optimal concentration of compounds of 25 mg/l. The determination of activity of superoxiddismutase (SOD) in obtained extracts from spirulina biomass allowed to establish a positive effect of coordination compounds of Co (III) on the activity of this enzyme. It was demonstrated that all tested compounds contribute to increased synthesis of lipids in biomass with a maximum of about 45-47% increase of their content compared to the reference sample in the case of utilization of coordination compounds of Co(III) - [Co(L-H) En]·3H2O and Na[Co(DH)2(NO2)2] in the optimal concentration of 20 and 15mg/l, respectively. Conclusions The present study reveals that obtained biomass of cyanobacteria Spirulina platensis with high content of bioactive substances with antioxidant properties (superoxiddismutase, phycobiliproteins, carotenoids, lipids) can be used for the elaboration of medical remedies for prophylaxis and treatment of diseases, caused by the negative effect of oxidative stress on live organisms and, also, for the elaboration of cosmetic preparations for the prevention of premature skin aging, protection against solar radiation and treatment of skin diseases.