Chapter 6 A General Description of Apocynaceae Iridoids Chromatography

Iridoids are considered atypical monoterpenoid compounds, based on a methylcyclopentan[C]-pyran skeleton, often fused to a six-membered oxygen ring consisting of ten, nine or in rare cases, eight carbon atoms (Figure 1a) [1, 2]. More than 2500 iridoid compounds have been described in nature, with structural differences related mainly to the degree and type of substitution in the cyclopentane ring skeleton [3]. Iridoids can be found in nature as secoiri‐ doids (Figure 1b), a large group characterized by cleavage of the 7,8-bond on the cyclopentane ring, glycosides, mainly 1-O-glucosides, and nor-iridoids, originating from oxidative decar‐ boxylation on C10 or C11 (Figure 1) [3, 4]. A General Description of Apocynaceae Iridoids Chromatography