title: Hydrophobic metabolites from Rhododendron formosanum and their allelopathic activities.
abstract: Eighteen components were isolated from the methanolic extract of leaves of Rhododendron formosanum Hemsl. (Ericaceae), an endemic species in Taiwan, and evaluated for their allelopathic properties. Of the isolated compounds, 3beta-friedelinol, 5,6beta-epoxy-5beta-stigmastan-3beta-ol, 5,6alpha-epoxy-5alpha-stigmastan-3beta-ol, lupeol and ursolic acid revealed inhibitory effects at 10(-4) M or above, whereas alpha-tocopherol, friedelin and beta-amyrin acetate exhibited stimulatory effects on the radicle growth of the test plants at the same concentration or above. However, squalene and alpha-amyrin showed either a stimulatory or inhibitory effect. The remaining four components, coumarin, beta-sitosterol, adian-5-en-3beta-ol and 3beta-acetoxyurs-12-en-28-al, were not significantly effective in the present bioassay, but have been reported as allelopathic agents elsewhere.
authors.affiliation: Research Center for Biodiversity and Graduate Institute of Ecology and Evolutionary Biology, China Medical University, Taichung 40402, Taiwan. choumasa@mail.cmu.edu.tw
authors.forename: Shen-Chieh
authors.initials: SC
authors.lastname: Chou
authors.forename: Vivek
authors.initials: V
authors.lastname: Krishna
authors.forename: Chang-Hung
authors.initials: CH
authors.lastname: Chou
mesh_terms: D001937:Brassica / Q000187:drug effects / Q000254:growth & development; D002850:Chromatography, Gel; D019906:Nuclear Magnetic Resonance, Biomolecular; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D029793:Rhododendron / Q000737:chemistry* / Q000378:metabolism; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D010936:Plant Extracts; D010937:Plant Growth Regulators; D014315:Triterpenes