Ethanol Crude extract of Cosicinium fenestratum stems (Gaertre) Coleb (Menispermaceae) exhibited inhibiting activity against seven plant pathogenic fungi and one antagonistic fungus when they were tested using the dilution method. Ethanolic crude extract of C. fenestratum stems was then fractionated by column chromatography using six organic solvents, and subsequent antimicrobial activity evaluation revealed that

only the fraction eluted with methanol exhibited inhibitory activity against the tested phytopathogenic fungi. Further re-fractionation resulted in 60 subfractions eluted with 60 solvent combination systems of increased polarity, that were also evaluated for their antimicrobial effect, being the subfractions eluted with mixture of acetone: chloroform and chloroform: methanol identified as the most active against tested plant pathogenic fungi. The chromatographic profile of the active subfractions revealed a common metabolite, which was isolated by PTLC (Preparative Thin Layer Chromatography) and identified as berberine through NMR (Nuclear Magnetic Resonance) analysis. Berberine displayed relevant antimicrobial activity against several of the tested plant pathogenic fungi being identified as the main active constitutuent from the active subfractions.