DISTRIBUTION OF IRIDOIDS IN DIFFERENT POPULATIONS OF PHYSOSTEGIA-VIRGINIANA AND SOME REMARKS ON IRIDOIDS FROM AVICENNIA-OFFICINALIS AND SCROPHULARIA-NINGPOENSIS

Two subspecies of Physostegia virginiana from seven different origins were investigated for iridoid glycosides. The plant material included the authentic sources of 'deoxyloganic acid', isolated in 1970 by one of the authors. This substance has now been identified as a 2.6:1 mixt ure of 7-deoxy-8-epiloganic acid and 10-deoxygeniposidic acid. Additio nally, we isolated 14 known compounds and three new iridoids: stegiosi de I from P. virginiana ssp. virginiana (origin Freiburg) and stegiosi des II and III from P. virginiana ssp. paemorsa (origin Chicago). The distribution of 16 out of 20 iridoids, previously reported or now isol ated from P. virginiana, was determined in all populations. The iridoi d patterns were significantly different between the two subspecies. Th e differences within ssp. virginiana were substantially smaller. The s tructure of 'avicennioside', previously isolated from Avicennia offici nalis, is revised to linarioside. Ningpogenin, previously isolated fro m Scrophularia ningpoensis, is identical to a compound obtained by par tial synthesis from aucubin.