A New Trihydroxylated Fatty Acid and Phytoecdysteroids from Rhizomes of Trillium govanianum

摘要

A crude hydro-methanolic extract of Trillium govanianum ex D. Don ( Melanthiaceae, Trilliaceae ) rhizomes and its subsequent solvents soluble fractions were tested against different fungal strains i.e. Trichophyton rubrum ATCC 40051 , Aspergillus niger ATCC 16888, Candida albicans ATCC 18804, Microsporum canis ATCC 32903 and Fusarium lini ATCC 16888. The hydro-methanolic extract showed significant activity against T. rubrum and M. canis with 80 and 75% inhibitions respectively. Among the fractions, chloroform soluble fraction showed 90% inhibition, with minimum inhibitory concentration (MIC) of 10μg/mL against T. rubrum followed by ethyl acetate, butanol and n -hexane fractions. The bio-activity guided isolation of chloroform soluble fraction leads to a new trihydroxylated fatty acid, named govanic acid ( 1 ) along with two known phytoecdysteroids i.e. 20-hydroxyecdysone ( 2 ) and 5, 20-dihydroxyecdysone ( 3 ). The structures of isolated compounds were elucidated through 1D, 2D-NMR spectroscopic data analysis. All compounds ( 1 - 3 ) in T. govanianum are reported herein for the first time. Compound 1 showed significant activity against T. rubrum with 70% inhibition and MIC value of 5 μg/mL, but lack of activity against the other test strains.