Analysis of precocenes in the essential oil of Ageratum spp. by reverse-phase high-performance liquid chromatography.

The chromenes precocene I (7-methoxy-2,2-dimethylchromene) and precocene II (6,7-methoxy-2,2-dimethylchromene) extracted from Ageratum houstonianum and A. conyzoides have been analysed by reverse-phase high-performance liquid chromatography. Separation was achieved using a C18 column eluted with a linear gradient of acetonitrile and water. Precocenes I and II in the essential oils were determined to be 270 +/- 23 and 482 +/- 34 mg/mL in A. houstonianum, and 687 +/- 21 and 20 +/- 2 mg/mL in A. conyzoides.