THE TITLE COMPOUND [SYSTEMATIC NAME: 3,8-dihydr-oxy-3-(hydroxy-meth-yl)-9-methyl-6-methyl-enedeca-hydro-azuleno[4,5-b]furan-2(3H)-one], C(15)H(22)O(5), is a sesquiterpene lactone showing the typical tricyclic guaianolide skeleton which has been isolated, together with other related metabolites, from the plant Centaurea musimomum. The present study confirms the mol-ecular structure, assigned by ...

Phytochemical studies on the ethanolic extract of the aerial parts of Centaurea scoparia led to the isolation of two new flavonoids, 3',4'-dihydroxy-(3'',4''-dihydro-3''-hydroxy-4''-acetoxy)-2'',2''-dimethylpyrano-(5'',6'':7,8)-flavone-3-O- β -D-glucopyranoside (1) and 3,3',4'-trihydroxy-(3'',4''-dihydro-3'',4''-dihydroxy)-2'',2''-dimethylpyrano-(5'',6'':7,8)-flavone (2), along with eight known...

Biological control of Canada thistle using Puccinia punctiformis has been largely unsuccessful in part due to a low incidence of systemically infected shoots and heterogeneous distribution of teliospores in the soil. The present study investigated the feasibility of strategic mowing to improve incidence of systemically infected shoots, and enhance intraand/or inter-season disease development in...

Competition is generally regarded as an important force in organizing the structure of vegetation, and evidence from several experimental studies of species mixtures suggests that larger mature plant size elicits a competitive advantage. However, these findings are at odds with the fact that large and small plant species generally coexist, and relatively smaller species are more common in virtu...

The antitumor activity of extracts of Centaurea ainetensis (C. ainetensis), a plant endemic to Lebanon, was investigated in human colon carcinoma cells. At concentrations that were non-cytotoxic to normal human intestinal epithelial cells, the crude extract inhibited the proliferation of a host of colon-derived cancer cells. The crude extract effect was then investigated in HCT-116 (p53+/+) cel...

Giles C. Thelen, Jorge M. Vivanco, Beth Newingham, William Good, Harsh P. Bais, Peter Landres, Anthony Caesar and Ragan M. Callaway* Abstract Exotic invasive plants are often subjected to attack from imported insects as a method of biological control. A fundamental, but rarely explicitly tested, assumption of biological control is that damaged plants are less fit and compete poorly. In contrast...

The biological control program for diffuse knapweed, Centaurea diffusa Lamarck, a Eurasian plant that has invaded large areas of grasslands in western North America, has gone on for over 35 years. This program involved the release of 12 biological control agents of which four are numerous and widely distributed; two species of Tephritid flies, Urophora affinis and Urophora quadrifasciata, the r...

Janzen-Connell effects are negative effects on the survival of a plant's progeny at high conspecific densities or close to its conspecifics. Although the role of Janzen-Connell effects on the maintenance of plant diversity was frequently studied, only few studies targeted Janzen-Connell effects via postdispersal seed predation in temperate grassland systems. We examined effects of conspecific d...