Anti-osteoclastogenic activity of Crocus sativus petal extract: turning saffron waste into a valuable resource against bone disruption.

The dried stigmas of Crocus sativus (Iridaceae) are traditionally processed to produce saffron, a spice widely used as a food coloring and flavoring agent, but also important in pharmaceutics and textile dye producing industries. The labor-intensive by-hand harvesting and the use of only a small amount of each flower make saffron to be the most expensive spice in the world. Crocus sp. petals are by-products of saffron production and represent an interesting raw material for the preparation of extracts intended for health protection in a perspective of a circular economy. In the present study, ethanolic extract from C. sativus petals (C. sativus petal extract, CsPE) was tested on macrophages by in vitro models of inflammation and osteoclastogenesis. The extract was found to be endowed with anti-inflammatory activity, significantly reducing nitric oxide production and IL-6 release by RAW 264.7 murine cells. Moreover, CsPE demonstrated an anti-osteoclastogenic effect, as revealed by complete inhibition of TRAP-positive osteoclast formation, and decreased expression of key osteoclast-related genes. This study, enlightening macrophages as cell target of bioactive extract from C. sativus petals, suggests that the petal by-product of saffron processing can usefully be part of a circular economy network aimed at producing an extract potentially preventing bone disruption.