Plenary Poster 29th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2019

Development of potent fatty acid analogues for inhibition of osteoclastogenesis (#91)

Jian-ming Lin 1 , Ivo Dimitrov 2 , William A Denny 2 , Jillian Cornish 1
  1. Department of Medicine, University of Auckland, Auckland, New Zealand
  2. Auckland Cancer Society Research Centre, School of Medical Sciences, University of Auckland, Auckland, New Zealand

This study reports the production of fatty acid analogues for osteoporosis treatment and methods to solubilize them.  We have earlier reported that long-chain saturated fatty acids (palmitic and stearic acids) are inhibitory to osteoclastogenesis.  However, their effect is modest likely due to rapid metabolism.  In addition, high doses of saturated fatty acids could lead to detrimental health outcomes.  This has prompted us to develop fatty acid analogues with higher potency by the introduction of a triazole group in the carbon chain.  We have previously synthesized a molecule with significantly higher potency as tested in osteoclastogenesis assays in mouse bone marrow and RAW264.7 cell cultures.  Following this strategy, we now report on a modified tetrazole analogue, which displays about 10-fold higher activity in inhibiting osteoclast than the natural fatty acids.  This inhibition is not due to non-specific toxic effect as the molecule increased bone marrow cell and primary osteoblast viability.  Further investigation found that the modified tetrazole also inhibited the expression of osteoclast regulating and marker genes, NFAT-c1, DC-STAMP, cathepsin K and TRAP.  This tetrazole has low solubility in aqueous solutions; thus we formulated it as an inclusion complex with (2-hydroxypropyl)-β-cyclodextrin (β-CD), which has hydrophobic cavity and hydrophilic surface.  The complex of the modified tetrazole/β-CD is aqueously soluble and its activity is comparable to that when the molecule dissolved in an organic solvent.  This allowed us to test the molecule in an in vivo model for the skeletal action.  This study shows that chemical modification on the backbone of natural fatty acids is a pathway to develop more potent molecules and β-CD is a suitable solubilizing agent for such compounds.