Brassinosteroids are polyhydroxylated compounds related to the structure of 5a-cholestane, a chemical structure similar to many androgenic compounds. The chemical class of brassinosteroids share similar actions of mammalians steroids, but act in plants mostly via genetically mediated factors.
One of the main sources of brassinosteroids is in pollens in order to induce growth. They act in micromolar concentrations, which helps to explain a past yield of 10mg from 230kg pollen. Brassinosteroids can be synthesized in laboratory settings.
In does of 20-60mg/kg bodyweight, a brassinosteroid found in mustard (28-Homobrassinolide, or 28-HB) was able to stimulate protein synthesis and concomitantly inhibit breakdown of muscle while increasing strength. The mode of adminstration was oral consumption via Akt phosphorylation, and the results were somewhat confounded with increases in food intake, although the magnitude of which is not causative of the differences seen in lean mass. No binding to the Androgen Receptor (AR) was noted, and no changes in serum testosterone noted.