Novel bisphosphonates with antiresorptive effect in bone mineralization and osteoclastogenesis

Bisphosphonates such as zoledronic, alendronic and risedronic acids are a class of drugs clinically used to prevent bone density loss and osteoporosis. Novel P-C-P bisphosphonates were synthesized for targeting human farnesyl pyrophosphate synthase (hFPPS) and human geranylgeranyl pyrophosphate synthase (hGGPPS), key enzymes of the mevalonate pathway, and capable of anti-proliferative action on a number of cell lines (PC3, MG63, MC3T3, RAW 264.7, J774A.1, bone marrow cells and their co-colture with PC3) involved in bone homeostasis, bone formation and death. Among sixteen compounds, [1-hydroxy-2-(pyrimidin-2-ylamino)ethane-1,1-diyl]bis(phosphonic acid) (10) was effective in reducing PC3 and RAW 264.7 cell number in crystal-violet and cell-dehydrogenase activity assays at 100 μM concentration. 10 reduced differentiated osteoclasts number similarly with zoledronic acid in osteoclastogenesis assay. At nanomolar concentrations, 10 was more effective than zoledronic acid in inducing mineralization in MC3T3 and murine bone marrow cells. Further, 10 significantly inhibited the activity of hFPPS showing an IC50 of 0.31 μM and a remarkable hydroxyapatite binding of 90%. Docking calculations were performed identifying putative interactions between some representative novel bisphosphonates and both hFPPS and hGGPPS. Then, 10 was found to behave similarly or even better than zoledronic acid as a anti-resorptive agent.