ABSTRACT
Nonglycosidic Compounds) and Distribution of Iridoids ......................... 605 23.3 Physical and Chemical Properties.............................................................. 607 23.4 Isolation from Plant Material Combined with Preliminary Purification
and Fractionation of Extracts ..................................................................... 607 23.5 Thin Layer Chromatography ..................................................................... 610
23.5.1 Short Overview of Adsorbent and Solvent Systems Used in TLC Qualitative and Quantitative Analysis of Iridoids.......... 610
23.5.2 Detection Methods of Various Classes of Iridoid Compounds .. 610 23.5.3 Preparative TLC Including Forced-Flow Planar Techniques ..... 615
23.6 Conclusions................................................................................................ 617 References ............................................................................................................. 617
Based on biosynthetic origin, the classical term: iridoids refers to natural monoterpenoid compounds, being secondary plant metabolites with characteristic cyclopenta[c] pyranoid skeleton (Figure 23.1), also described as iridane (cis-2-oxabicyclo[4.3.0]- nonane). In practice, the term is used to cover the broader group of natural products which are considered to arise biogenetically from iridane. Ethymology of the name iridoids indicates that it derives from the volatile monoterpenes, called: irydodial and iridomyrmecin, being the components of the defensive secretion of Australian ants from Iridomyrmex genus [1-3]. The older name of iridoids was pseudoindicans as they were known to react with acids giving blue-colored derivatives [4].
