Brassinosteroids brs are a class of polyhydroxysteroids that have been recognized as a sixth class of plant hormones and may have utility as an anticancer drug for endocrineresponsive cancers to induce apoptosis and inhibit growth. Biochemistry and molecular biology of plant hormones, volume 33. Brassinosteroids, the sixth class of phytohormones. Pdf brassinosteroids occurence and chemical structures. Brassinolide, the first brassinosteroid isolated and shown to have biological activity. Initial research into plant hormones identified five major classes. Developing a model of plant hormone interactions ncbi. Look up phytohormone in wiktionary, the free dictionary. Plant hormones also known as phytohormones are signal molecules, produced within plants. Lack of the plant hormone auxin can cause abnormal growth right. Although the other plant hormones have been studied for a much longer period, there has not been similar development. This group of plant steroids includes more than 70 compounds that show structural similarities to insect, animal and human steroid hormones. Plants possess the ability to biosynthesize a large variety of steroids, but it was not until 1979 that a hormonal function was demonstrated in plants. Due to brs growth regulator activity, this class of phytohormones is.