ECDYSTEROIDS FROM PENSTEMON VENUSTUS

For the first time ecdysteroids have been found in the genus Penstemon . In addition to the known ecdysteroids taxisterone, 20-hydroxyecdyson e, makisterone A and C, the new ecdysteroid venustone has been isolate d from the roots of Penstemon venustus. This ecdysteroid was shown to be 22-O-[(3R)-3-hydroxybutanoyl]-20-hydroxyecdysone. The structure has been determined primarily on the basis of NMR spectroscopy. The assig nments of the NMR signals were performed by means of H-1-H-1 COSY - 45 degrees and H-1 - C-13 COSY experiments.