Eupatoriochromene

J Chem Ecol. 1989 Jul;15(7):2073-87.

Eupatoriochromene and encecalin, plant growth regulators from yellow starthistle (Centaurea solstitialis L.).[Pubmed: 24272297]

METHODS AND RESULTS:
Two chromenes, Eupatoriochromene (1) and encecalin (2), have been isolated from yellow starthistle (Centaurea solstitialis L.). Both chromenes retard seed germination and reduce radicle and hypocotyl growth of weed and crop plant seedlings. In addition,1 increases adventitious root formation of mung bean cuttings.

J Chem Ecol. 1985 Jun;11(6):701-12.

Insecticidal chromenes from the volatile oil ofHemizonia fitchii.[Pubmed: 24310216]

Based on field observations of the effects of the resinous tarweedHemizonia fitchii A. Gray (Asteraceae) on mosquito populations in California, the volatile oil of this plant was investigated for insecticidal activity.
METHODS AND RESULTS:
Analysis of thé oil by TLC and capillary GC-MS showed the presence of five major constituentś which were identified as the monoterpenoid 1,8-cineole, and the chromenes encecalin, Eupatoriochromene (desmethylencecalin), 6-vinyl-7-methoxy-2,2-dimethylchromene, and desmethoxyencecalin. Trace amounts of several volatile fatty acids, alkanes,p-coumarate derivatives, additional chromene derivatives, and numerous mono- and sesquiterpenoids were also detected and identified by GC-MS. Fractionation of the oil by preparative TLC and column chromatography afforded the major chromenes, the identities of which were confirmed by NMR and IR spectral data.
CONCLUSIONS:
The chromenes exhibited weak to moderate toxicity againstCulex pipiens (house mosquito) larvae andOncopeltus fasciatus (large milkweed bug) nymphs. However, no antijuvenile hormone activity was observed for any of the compounds tested against these insect species.