Assessment of the complex formation process in the “Lanthanum(III) chloride – ascorbic acid” system

The synthesis of a coordination compound of lanthanum(III) with L‑ascorbic acid was performed under mild conditions (ice bath, pH 7). The composition and structure of the complex were confirmed by elemental analysis, IR and UV‑Vis spectroscopy; the metal‑to‑ligand ratio was found to be 1:1. The instability constant of the compound was determined by spectrophotometry. Virtual screening using the PASS Online and ProTox resources was performed to forecast the biological activity and toxicological effects of free ascorbic acid and its lanthanum(III) complex. The complexation transforms the pharmacological profile. As a result, an antioxidant activity decreases and inhibition of NADPH oxidase, ubiquinol‑cytochrome C reductase and osmotic diuretic action occur. The toxicological profile of the complex is characterized by metabolic acidosis, hyperglycemia, and nephrotoxicity in the absence of cardiotoxicity, mutagenicity, and carcinogenicity. However, the forecast in terms of hepatotoxicity requires experimental verification. Therefore, further study of rare‑earth ascorbates as compounds with potential biological activity is promising one.