Royal jelly acid (10-Hydroxy-trans-2-decenoic acid, 10H2DA) is the principal lipid component in royal jelly which is the food for queen and larvae honeybees. It is involved in several treatment processes of autoimmune and inflammatory diseases, including inhibition of lipopolysaccharide (LPS)- and interferon (IFN)-γ-stimulated macrophage responses, inhibition of T-cell proliferation and anti-rheumatoid activity.