The Occurrence of Iridoid Glycosides in the Scrophulariaceae

Abstract

SUMMARY A study was made of the occurrence of iridoid glycosides (giving a colour reaction with anisidine) in the Scrophulariaceae. Aucuboside, catalpol and antirrhinoside were found in many species: in addition some hitherto unknown, presumably iridoid glycosides were found. Most tribes were homogeneous as to the types of glycosides present, while the subfamilies were not. On the basis of the prevailing glycosides the family can be segregated into the following groups: taxa devoid of glycosides (most Gratioleae, the Calceolarieae, most Digitaleae, Sphenandra, Sutera p.p., and Nemesia). taxa containing aucuboside and (or) catalpol (Verbasceae, Scrophularieae, Collinsieae Hemiphragmeae, Buchnereae, Veroniceae, Rhinantheae, Sutera p.p., Limosella, Mazus, Zaluzianskya, Angelonia, Diascia, Erinus, and Rehmannia). taxa containing antirrhinoside (Antirrhineae). the Selaginoideae with unidentified glysosides. The genera Leucocarpus, Halleria, and Alonsoa have aberrant, but presumably iridoid glycosides, and therefore do not fit in any of the groups mentioned.

Piecing together the “new” Plantaginaceae

“…Therefore, they were assumed to be part of Plantaginaceae, but our results agree with Oxelman et al (in press) who also showed that Lindernieae are well removed from this family. In support of this new finding, Lindernieae lack iridoids (Kooiman, 1970) and the kind of nuclear protein bodies (Bigazzi, 1993) that are typical for most Plantaginaceae. They also differ from most members of Plantaginaceae in their quadrangular stems (which may be found in some Gratioleae), glandular corolla trichomes (which are rare in the Angelonia clade), and alveolate endosperm (Fischer, 1992).…”

Untitled

“…The toxic terpenoid compounds commonly termed iridoid glycosides are widespread in both the Verbenaceae and the lower Lamiaceae as well as in the closely related Scrophulariaceae (Kooiman, 1970;Cantino, 1982), probably characterizing the common ancestor of these families (Cantino and Sanders, 1986). Iridoids dominate the secondary chemistries of both above-and belowground parts ofClerodendrum, Stachys, and Physostegia (Kooiman, 1970), as well as the extremely bitter Scutellaria.…”

“…However, this hypothesis is inconsistent with both the apparently equivalent ages ofthe two clades and the detailed match of several insect/plant vicariant distributions. Moreover, the apparently most toxic iridoids (catalpol and aucubin) are present in even the most p1esiomorphic plant taxa (Kooiman, 1970;Bowers, 1988), although future chemical work may reveal a stepwise transformation of plant toxins important to these beetles. Either model must account for the absence of the beetles from most species in the host clade by some plausible but untested mechanism such as geographic or chemical host "escape.…”

Hostplant Choice of Checkerspot Larvae: Euphydr Yas Chalcedona, E. Colon, and Hybrids (Lepidoptera: Nymphalidae)

“…(Scrophulariaceae). Both of these plant genera contain iridoid glycosides (Bowers, unpublished;Kooiman, 1970;Jensen, et al, 1974 (Kooiman, 1970;Jensen, et al, 1975;Bowers, unpublished).…”