Synthesis of new indole-based bisphosphonates and evaluation of their chelating ability in PE/CA-PJ15 cells

Bisphosphonates are the most important class of antiresorptive agents used against osteoclast-mediated bone loss, and, more recently, in oncology. These compounds have high affinity for calcium ions (Ca(2+)) and therefore target bone mineral, where they appear to be internalized selectively by bone-resorbing osteoclasts and inhibit osteoclast function. They are extensively used in healthcare, however they are affected by severe side effects; pharmacological properties of bisphosphonates depend on their molecular structure, which is frequently the cause of poor intestinal adsorption and low distribution. In this work we synthesized six novel bisphosphonate compounds having a variably substituted indole moiety to evaluate their extra- and intracellular calcium chelating ability in PE/CA-PJ15 cells. Preliminary in silico and in vitro ADME studies were also performed and the results suggested that the indole moiety plays an important role in cell permeability and metabolism properties.