Rice lamina joint test

A Modified Method of the Rice Lamina Joint Test for Brassinosteroids... 

We are able to readily search for naturally occurring brassinosteroid using rice-lamina joint test [LJT] (1) as the bioassay method and GC/MS as the microanalytical method, which was established by Ikekawa and his co-workers as a microanalytical method for BS (2). Plant material was extracted three times in methanol or 80% methanol-H20. After the extract was evaporated under reduced pressure, the resulting aqueous residue was extracted with EtOAc at pH3 and the EtOAc fraction was partitioned with Na2C03-NaHC03 buffer at pH 10 to get neutral substances. 

Typhasterol. Typhasterol and Teasterone are the first tri-hydroxy 6-ketone sterols (2-deoxy-castasterones and its 3-epimer) isolated that show biological activity in the rice lamina joint bending test despite the lack of a hydroxyl group at C-2. Typhasterol was isolated from cattail (Typha latifolia L) pollen (29), and both teasterone and typhasterol were present at 60 and 15 ng respectively per kg fr. wt. of leaves and were isolated from the less polar active fraction obtained from tea leaves (30). The biological activity of these two ketones as tested in the rice test, is about one tenth that of brassinolide (30). Typhasterol has recently been synthesized (31), but its biological activity was not tested. 

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