関: secoiridoid

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/19 16:20:50」(JST)

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Chemical structure of iridomyrmecin

Iridoids are a class of secondary metabolites found in a wide variety of plants and in some animals. They are monoterpenes biosynthesized from isoprene and they are often intermediates in the biosynthesis of alkaloids. Chemically, the iridoids usually consist of a cyclopentane ring fused to a six-membered oxygen heterocycle. The chemical structure is exemplified by iridomyrmecin, a defensive chemical produced by the Iridomyrmex genus, for which iridoids are named. Cleavage of a bond in the cyclopentane ring gives rise to a subclass known as secoiridoids, such as oleuropein and amarogentin. Iridoids are typically found in plants as glycosides, most often bound to glucose.

Occurrence[edit]

Iridoids are found in many medicinal plants and may be responsible for some of their pharmaceutical activities. Isolated and purified, iridoids exhibit a wide range of bioactivities including cardiovascular, antihepatotoxic, choleretic, hypoglycemic, analgesic, anti-inflammatory, antimutagenic, antispasmodic, antitumor, antiviral, immunomodulator, and purgative activities.^[1]^[2]

The iridoids are produced by plants primarily as a defense against herbivores or against infection by microorganisms. The Variable Checkerspot butterfly also uses iridoids obtained through its diet as a defense against avian predators.^[3] To humans and other mammals, iridoids are often characterized by a deterrent bitter taste.

Aucubin and catalpol are two of the most common iridoids in the plant kingdom. Iridoids are prevalent in the plant subclass Asteridae, such as Ericaceae, Loganiaceae, Gentianaceae, Rubiaceae, Verbenaceae, Lamiaceae, Oleaceae, Plantaginaceae, Scrophulariaceae, Valerianaceae, and Menyanthaceae.

Biosynthesis[edit]

The iridoid ring scaffold is synthesized, in plants, by the enzyme iridoid synthase.^[4] In contrast with other monoterpene cyclases , iridoid synthase uses 10-oxogeranial as a substrate. The enzyme uses a two-step mechanism, with an initial NADPH-dependent reduction step followed by a cyclization step that occurs through either a Diels-Alder reaction or an intramolecular Michael addition. ^[4]

References[edit]

^ Didna, B., Debnath, S., Harigaya, Y. "Naturally Occurring Iridoids. A Review, Part 1." Chem. Pharm. Bull. 55(2) 159-222 (2007).
^ Tundis R, Loizzo MR, Menichini F, Statti GA, Menichini F. Biological and pharmacological activities of iridoids: recent developments. Mini Rev Med Chem. 2008 Apr; 8(4):399-420.
^ Bowers, M. D. "Unpalatability as a Defense Strategy of Western Checkerspot Butterflies (Euphydryas Scudder, Nymphalidae)." Evolution 35.2 (1981): 367-75.
^ ^a ^b Geu-Flores, F.; Sherden, N. H.; Courdavault, V.; Burlat, V.; Glenn, W. S.; Wu, C.; Nims, E.; Cui, Y.; O'Connor, S. E. (2012). "An alternative route to cyclic terpenes by reductive cyclization in iridoid biosynthesis". Nature 492 (7427): 138–142. doi:10.1038/nature11692. PMID 23172143. edit

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English Journal

A sensitive liquid chromatographic-mass spectrometric method for simultaneous quantification of six iridoid glycosides from Zhi-zi-chi Decoction in rat plasma and its application to a pharmacokinetic study.

Qu K, Dai J, Zhao L, Lu Y, Li B, Zhao X, Hou P, Zhang Y, Bi K, Chen X.SourceThe Engineering Laboratory of National and Local Union of Quality Control for Traditional Chinese Medicine, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang 110016, China.
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A sensitive liquid chromatographic-mass spectrometric (LC-MS) method was developed and validated for simultaneous determination of geniposide, geniposidic acid, scandoside methyl ester, gardenoside, deacetyl asperulosidic acid methyl ester and genipin-1-β-gentiobioside after oral administration of
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Nyctanthes arbor-tristis Linn-A critical ethnopharmacological review.

Agrawal J, Pal A.SourceIn vivo testing facility, Molecular Bio-prospection Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow 226015, India.
Journal of ethnopharmacology.J Ethnopharmacol.2013 Apr 19;146(3):645-58. doi: 10.1016/j.jep.2013.01.024. Epub 2013 Jan 30.
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PMID 23376280

Neuroprotective activities of Catalpol against CaMKII-dependent apoptosis induced by LPS in PC12 cells.

Chen W, Li X, Jia LQ, Wang J, Zhang L, Hou D, Wang J, Ren L.SourceCenter of Teaching & Research, Liaoning University of Traditional Chinese Medicine, No.79, Chongshan Eastern Road, Huanggu District, Shenyang, 110847, PR of China.
British journal of pharmacology.Br J Pharmacol.2013 Apr 2. doi: 10.1111/bph.12200. [Epub ahead of print]
BACKGROUND AND PURPOSE: Neurodegenerative diseases present progressive neurological disorder induced by cell death or apoptosis. Catalpol, an iridoid glucoside separated from the root of Rehmannia glutinosa Libosch, exists broadly in many plant families. Despite the evidence shows that Catalpol perf
PMID 23550774

Japanese Journal

Isolation, Structural Elucidation, and Neuroprotective Effects of Iridoids from Valeriana jatamansi

XU Jing,LI Yushan,GUO Yuanqiang [他]
Bioscience, Biotechnology, and Biochemistry 76(7), 1401-1403, 2012-07
NAID 40019357830

2ND GENERATION PALLADIUM-CATALYZED CYCLOALKENYLATION IN IRIDOID SYNTHESIS : DIASTEREOSELECTIVE TOTAL SYNTHESIS OF ISOIRIDOMYRMECIN AND ISODIHYDRONEPETALACTONE (Dedicated to Dr. Albert Padwa on his 75th birthday)