Recent Advances in Iridoid Chemistry: Biosynthesis and Chemical Synthesis

Abstract

Iridoids are a large family of monoterpenoids found in traditional medicinal plants and show significant effects for the human species. In addition to their wide range of biological activities, such as neuroprotective and antitumor activities, the cis-fused bicyclic ring systems of iridoids are still attractive as synthetic targets to apply novel synthetic methodologies. Accordingly, recent progress regarding the biosynthesis and chemical synthesis of iridoids is covered in this minireview. Identification of new enzymes for the iridoid biosynthesis in Catharanthus roseus and ingenious synthetic strategies for the construction of the iridoid skeleton are described.

The isolation of water-soluble natural products – challenges, strategies and perspectives

“…643,644 Glycosylated terpenoids other than iridoids have also been isolated, but the large majority is mono-glycosylated, a structural feature that does not guarantee complete solubility in H 2 O. 640–646 Water-soluble iridoids have been isolated by various approaches, including 201 from the leaves of Premna japonica , 647 as well as picrorhizaoside A ( 202 ) from the rhizomes of Picrorhiza kurroa . 648 Known water-soluble glycosylated iridoids have been isolated using HPCCC, 649 HSCCC 650 and CPC.…”

“…Hydrophilic terpenoids other than saponins are not commonly isolated, with iridoid glycosides being the better-known group, among which secologanin (200) is the archetypical member of this class. [640][641][642] Iridoids are frequently glycosylated, [640][641][642][643][644] several of which display an array of potent biological activities. 643,644 Glycosylated terpenoids other than iridoids have also been isolated, but the large majority is mono-glycosylated, a structural feature that does not guarantee complete solubility in H 2 O.…”

“…643,644 Glycosylated terpenoids other than iridoids have also been isolated, but the large majority is mono-glycosylated, a structural feature that does not guarantee complete solubility in H 2 O. [640][641][642][643][644][645][646] Water-soluble iridoids have been isolated by various approaches, including 201 from the leaves of Premna This journal is © The Royal Society of Chemistry 2022…”

Potential Roles of Iridoid Glycosides and Their Underlying Mechanisms against Diverse Cancer Growth and Metastasis: Do They Have an Inhibitory Effect on Cancer Progression?

“…Iridoids are glycosides found in various plants, and they reportedly bind to glucose [ 5 ]. They have the general form of cyclopentopyran, and a molecular structure related to iridodial ( Figure 1 A) [ 6 , 7 ]. Iridoids are structurally classified into iridoid glycosides and non-glycosidic iridoids according to the presence or absence of intramolecular glycosidic bonds; additionally, iridoid glycosides can be further subdivided into carbocyclic iridoids and secoiridoids [ 8 ].…”

Cell-Free Total Biosynthesis of Plant Terpene Natural Products Using an Orthogonal Cofactor Regeneration System

“…Initial efforts to recapitulate nepetalactol production using cell-free biosynthesis were prompted by the expensive cost from commercial vendors, the low titers observed in microbial hosts, − and difficulties in implementing synthetic routes. − Reported syntheses suffer from low yields and enantioselectivities, or rely on the costly synthon (−)-citronellol as an enantiopure starting material. − To perform cell-free biosynthesis, geraniol 1 was selected as the starting material because of its high abundance as an essential oil and low cost. Since the plant homologues of G8H are membrane-bound and not suitable for in vitro biocatalysis, a functionally equivalent, soluble bacterial P450 was used.…”