Biosynthesis significance of iridoids in chemosystematics

Abstract

Iridóides são substâncias monoterpenoídicas formadas em plantas por uma ciclização alternativa do pirofosfato de geranila. A estrutura química dessas substâncias é baseada no esqueleto ciclopentano-[C]-pirano, iridóides carbocíclicos, e a clivagem oxidativa da ligação 7,8 do anel ciclopentano fornece os chamados secoiridóides. Sob o aspecto biogenético, os iridóides são biossintetizados a partir do cátion iridodial e diversificam-se em 27 vias diferentes. Iridóides têm sido usados como marcadores quimiotaxonômicos para as superordens Corniflorae, Gentianiflorae, Loasiflorae e Lamiiflorae. O número e a natureza dos iridóides encontrados no Reino Vegetal são indicativos da complexidade das vias envolvidas na sua biossíntese. Em Quimiossistemática, os iridóides representam um marcador importante em classificação vegetal, filogenia e evolução.Iridoids represent a large group of monoterpenoid compounds that apparently seem to be formed in plants by an alternative cyclization of geranyl diphosphate. The structures of these compounds are based on a cyclopentan-[C]-pyran skeleton, carbocyclic iridoids, and oxidative cleavage at the 7,8-bond of the cyclopentane moiety affords the so called secoiridoids. On biogenetic grounds the iridoid formation may be considered to start from iridodial cation and follow diversification through 27 different routes. Iridoids have been used as chemical markers for the Corniflorae, Gentianiflorae, Loasiflorae and Lamiiflorae superorders. The number and nature of the iridoids occurring in plants are a measure of the complexity of the routes involved in their biosynthesis. In chemosystematics, the value of iridoid character shows important significance in plant classification, phylogeny and evolution

Glycogen Phosphorylase-a is a Common Target for Anti-Diabetic Effect of Iridoid and Secoiridoid Glycosides

“…Iridoids can consist of ten, nine, or rarely eight carbons in which C11 is more frequently missing than C10; aucubin has 10 carbons with the C11 carbon missing (Figure 2). The stereochemical configurations at C5 and C9 lead to cis fused rings, which are common to all iridoids containing carbocyclic-or seco-skeleton in non-rearranged form as discussed earlier (58). Aucubin has been reported to have a number of pharmacological activities namely, hepatoprotective, anti-oxidant and anti-diabetic effects.…”

Monoterpenoid Indole Alkaloid Biosynthesis

“…The biochemical specialisation of IPAP cells raises questions about their possible general involvement in the biosynthesis of iridoids, since they occur widely in plants and have been used as important chemical markers in studies on plant classification, phylogeny and evolution (Sampaio-Santosa and Kaplan, 2001). Snapdragon (Antirrhinum majus) contains two major iridoids, antirrhide and antirrhinoside (Guiso and Scarpati, 1969).…”

Biosynthesis of food constituents: Natural pigments. Part 2 - a review

“…Alternatively, geniposidic acid may be also formed from loganic acid and gardenoside may be produced from 7-deoxyloganic acid. Oxidation and dehydration of loganic acid leads to one of the minor gardenia pigments called geniposidic acid (Sampaio-Santos & Kaplan 2001;Collu et al 2001). …”