IRIDOIDS AND VERBASCOSIDES IN RETZIA

The nature of the iridoid glucosides and verbascosides in Retzia capen sis has been investigated. The known iridoids unedoside, stilbericosid e, thunbergioside and adoxosidic acid were isolated in addition to the partly characterized retzioside and three other new iridoids with an eight carbon aglucone. Two of these, namely holmioside and 5-deoxythun bergioside, have been fully characterized. The third new iridoid, 5-de oxyholmioside, was present in small quantities and only characterized by NMR. Three verbascosides were found, namely verbascoside, calceolar ioside E, and a compound which was tentatively identified as calceolar ioside E with an apiosyl residue attached to the 6-position of the glu copyranosyl moiety.