The queen bee acid (10-hydroxy-2-decenoic acid) or 10-HDA is a bio-active compound found in royal jelly. ; Royal jelly acid is being investigated for its pharmacological activities. Reports indicate that it promotes neurogenesis of neural stem/progenitor cells (cells capable of differentiating into neurons, astrocytes, or oligodendrocytes) in vitro and could provide an effective method to treat and prevent neurological disorders. In addition, royal jelly acid has been reported to have anti-tumor, anti-biotic, immunomodulatory, estrogenic, neurogenic, and innate immune response modulating activities.