Iridoid glucosides from Penstemon secundiflorus and P-grandiflorus: Revised structure of 10-hydroxy-8-epihastatoside

Thorough large scale investigations of Penstemon secundiflorus ssp. lavendu lus and of P. grandiflorus resulted in the isolation of the new iridoid glu cosides 5, 6 beta-dihydroxyadoxoside. The structure of 10-hydroxyepihastato side has been revised to 10-hydroxyhastatoside: using a chemical correlatio n. Also, the known iridoids (5 alpha H)-6-epidihydrocornin, cornin, hastato side, 8-epihastatoside, beta-dihydrohastatoside, penstemoside, (5 alpha H)- 10-hydroxy-6-epidihydrocornin, 10-hydroxycornin and catalpol were isolated. (C) 1998 Elsevier Science Ltd. All rights reserved.