Brassinosterols (BS) are ubiquitous pluripotent growth regulator present in plants. They exist in isoforms of epi and homobrassinolides (HB). BS act as potent stimulators of root and shoot elongation, cell division, DNA and RNA polymerase activity, ethylene production and of stress tolerance to temperature, water scarcity and salinity in plants. It is also used to increase the yield of crop and to protect the plants against pesticides. Consumption of plant material as diet and used as growth regulator in animals, and application of BS in agriculture would increases its availability to the host tissues. In the present study, the effect of 28-HB, an isomer of brassinosterol on serum, liver and kidney marker enzymes, lipid peroxidation, tissue histology and the blood parameters of rat were investigated. The rats were given the compound by intradermal mode at the concentration of 75µg, 150µg and 300µg as single dose and the effects were observed after 4 hr to study the immediate response of the animal. The treatment of rats with 28-HB, caused different effects on the serum, liver and kidney parameters of this study. In conclusion, the present study showed that 28-HB affects the structure and function of rat tissues in a dose dependent manner.Keywords: Brassinosterols; homobrassinolides; 28-HB; lipid peroxidatio
