Three new compounds from the flower branch of Gastrodia elata Blume and anti-microbial activity.

Three new compounds (1-3), including novel tetra- p -cresol substituted cyclopenta[ a ]naphthalene derivatives, named gastrodinol (1), 2-(4'-hydroxybenzoyl)-3-hydroxyethyl indole (2), 2-(4'-hydroxybenzoyl)-3-(4''-hydroxybenzyl)indole (3) were isolated from the flower branch of G. elata , along with five known compounds (4-8). Among them, compound 1 exhibited the most anti-microbial activity against Streptococcus agalactiae , with the minimum inhibitory concentration of 1 μg ml -1 . This study demonstrated that the novel gastrodinol 1 found in the flower branch of G. elata may be responsible for the anti-microbial effect. It will lead to the development of new antibiotics, and how to utilize the TCM ''Tianma'' better.