Chemical composition, antifungal and herbicidal effects of essential oil isolated from Chersodoma Argentina (Asteraceae).

Analysis of the hydrodistilled essential oil of the aerial parts of Chersodoma argentina Cabrera by GC-MS and NMR spectroscopy revealed that over 80% consisted of monoterpene hydrocarbons such as alpha-thujene, alpha-pinene and beta-pinene. Contact and headspace volatile exposure assays of the essential oil demonstrated antifungal activity against Sclerotinia sclerotiorum, Sclerotium rolfsii and Rhizoctonia solani with the contact assay showing greater activity than the headspace assay. Herbicidal activity was shown by reduced root growth of Allium porrum, Solanum lycopersicon and Sorghum halepense in both assays.

Flavonoids from Pterocaulon alopecuroides with antibacterial activity.

Three flavonoids, (2 R,3 R)-5,4'-dihydroxy-3'- O-methyl-7-(gamma,gamma-dimethylallyloxy)dihydroflavonol 1, (2 R,3 R)-5,7,4'-trihydroxy-3'- O-methyl-6-(alpha,alpha-dimethylallyl)dihydroflavonol 2, and (2 R,3 R)-5,7,4'-trihydroxy-6-(alpha,alpha-dimethylallyl)dihydroflavonol 3, together with three known flavonoids ( 4 - 6), were isolated from the aerial parts of PTEROCAULON ALOPECUROIDES. The structures of the compounds were determined by mass and by 1 D and 2 D NMR spectroscopy. Screening of the antibacterial activity of all six compounds was conducted by a disc diffusion test against BACILLUS CEREUS, BACILLUS SUBTILIS, SALMONELLA TYPHIMURIUM and PROTEUS MIRABILIS. The minimum inhibitory concentration (MIC) of the active compounds ( 2, 3, 4, 6) was determined by a microdilution assay. These compounds were active only against both Gram+ bacteria with MIC values < or = 200 microg/mL.