Vitamin B9 derivatives as carriers of bioactive cations for musculoskeletal regeneration applications: Synthesis, characterization and biological evaluation.

The development of new drugs for musculoskeletal regeneration purposes has attracted much attention in the last decades. In this work, we present three novel vitamin B9 (folic acid)-derivatives bearing divalent cations (ZnFO, MgFO and MnFO), providing their synthesis mechanism and physicochemical characterization. In addition, a strong emphasis has been placed on evaluating their biological properties (along with our previously reported SrFO) using human mesenchymal stem cells (hMSC). In all the cases, pure folate derivatives (MFOs) with a bidentate coordination mode between the metal and the folate anion, and a 1:1 stoichiometry, were obtained in high yields. A non-cytotoxic dose of all the MFOs (50 µg/mL) was demonstrated to modulate by their own the mRNA profiles towards osteogenic-like or fibrocartilaginous-like phenotypes in basal conditions. Moreover, ZnFO increased the alkaline phosphatase activity in basal conditions, while both ZnFO and MnFO increased the matrix mineralization degree in osteoinductive conditions. Thus, we have demonstrated the bioactivity of these novel compounds and the suitability to further studied them in vivo for musculoskeletal regeneration applications.