Iridoids secoiridoids

Dinda B, Chowdhury DR, Mohanta BC. Naturally Occurring Iridoids, Secoiridoids and Their Bioactivity. Tkn Update Review, Part 3. Chemical Pharmaceuhcal Bulletin 2009 57(8) 765-796. 

G. depressa D. Don generally distributed in Nepal at an altitude of 3,000- 3,500 m. From the aerial part of this species mixed iridoid-secoiridoid glucoside, depresteroside (74), iridoid glucoside such as depressoside (75), 3"-glucosyl depresteroside (76) and depressin (77) have been isolated [114-116]. 

Sylvestrosides. The S. are iridoid/ secoiridoid glu-cosides in which the two molecules are joined by an ester bond. Loganin is the alcohol component and a secologanic acid derivative (see secoiridoids) is the acid component. S. II is the acetyl derivative of S. 1, while in S. Ill the glucose unit at the loganin part is missing. 

Dinda B, Roy Chowdhury D, Mohanta BC (2009) Naturally occurring iridoids secoiridoids and their bioactivity. An updated review part 3. Chem Pharm Bull 57 765-796... 

Dinda B, Debnath S, Banik R. Naturally Occurring Iridoids and Secoiridoids. An Update review, Part 4. Qiemical Pharmaceutical Bulletin 2011 59(7) 803-833. 

In most natural iridoids and secoiridoids, there is an additional oxygenation (hydroxy) at C-1, which is generally involved in the glycoside formation. 

It is also extremely common amongst natural iridoids and secoiridoids, to have a double bond between C-3 and C-4, and a carboxylation at C-11. Changes in functionalities at various other carbons in iridoid and secoiridoid skeletons are also found in nature, as shown below. 

Iridoid and secoiridoid glycosides with modified functionalities... 

Cyclopentanes, Iridoids.—A very useful review of the biosynthesis of the known sweroside-, morroniside-, and oleuropein-type secoiridoid glucosides, together with the biosynthesis of alkaloidal glucosides which can be regarded as secoiridoid... 

Thirty-three known iridoid and secoiridoid glucosides have been analysed by gas chromatography of their trimethylsilyl derivatives. G.c.-m.s. analysis of several representative compounds e.g. 4-CO2H, 4-C02Me, 4-unsubstituted) demonstrated the feasibility of iridoid-containing plant extract analysis and resulted in the identification of secologanoside 11-methyl ester (99 R = H, X = CH2) from Lonicera morrowii the sixth paper in a series of chemotaxonomic studies on iridoids illustrates the need for accurate analysis of minor components. ... 

Iridoids are derivatives of monoterpenes and occur usually, but not invariably, as glycosides.100,101 Structurally, they are cyclopentano [r] pyran monoterpenoids and they provide a biogenetical and chemotaxonomical link between terpenes and alkaloids. The cleavage of the cyclopentane ring of iridoids produces secoiridoids.10... 

Additional examples as representative of approaches used for the HPLC separation are shown for iridoids in Table 3 and for secoiridoids in Table 4. 

Finally, since many natural product compounds have been investigated with various chromatographic modes and detection techniques, a selection of examples has been summarized in this chapter. This information has been compiled in the form of tables for well-researched classes of secondary metabolites selected from the major subgroups of isoprenoids (mono-, sesqui-, di-, and triterpenes iridoids and secoiridoids carotenoids saponins and ecdysteroids), of phenolics (coumarins, flavonoids, and isoflavonoids), and of alkaloids. 

Several new secoiridoid glucosides711-714 and a bis-diglucoside composed of linked iridoid and seco-iridoid units715 have been isolated and characterized. Of numerous other reports on these compounds, a selection is noteworthy in recording new compounds,716-734 ascertaining or correcting structures of known com-... 

G. In Vitro Conversion of Iridoids and Secoiridoids to Monoterpene Alkaloids... 

Cyclopentanes, Iridoids.— The taxonomic significance of iridoids in Tubiflorae sensu and the occurrence of secoiridoids in the Gentianaceae have been reviewed. Some papers of related synthetic interest have been discussed... 

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