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PubMed2001

Iridoid biosynthesis in staphylinid rove beetles (Coleoptera: Staphylinidae, Philonthinae).

The biosynthesis of chrysomelidial and plagiodial was studied in the rove beetle subtribe Philonthina (Staphylinidae). Glandular homogenates were found to convert synthetic (2E,6E)-[trideuteromethyl-5,5-(2)H(5)]octa-2,6-diene-1,8-diol (10) into nor-chrysomelidial (14) and nor-plagiodial (13). The overall transformation requires; i) oxidation of the substrate at C(1) and C(8), ii) cyclization of the resulting dialdehyde to nor-plagiodial followed by iii) isomerization to give nor-chrysomelidial. The oxidase requires molecular oxygen as a cofactor and operates with removal of the pro-R hydrogen from C(1) and C(8) of synthetic (1R,8R,2E,6E)-[1,8-(2)H(2)]-2,6-dimethyl-octa-2,6-diene-1,8-diol (15), producing a dialdehyde along with H(2)O(2). Unlike enzymes from iridoid-producing leaf beetle larvae, the Philonthus enzyme is able to oxidize saturated substrates such as citronellol. Crude protein extracts prepared from Philonthus glands by ammonium sulfate precipitation, were found to produce hydrogen peroxide at a rate of 0.085+/-0.003 ng H(2)O(2) (ng protein)(-1) hr(-1) with nerol as an oxidase substrate. The cyclase operates with opposite stereochemistry to the enzyme(s) from Phaedon cochleariae and other herbivorous leaf beetles, specifically removing the C(5)-H(R) hydrogen atom from (4R,5S,2E,6E)-[4,5-(2)H(2)]-2-methyl-octa-2,6-diene-1,8-diol (17). These findings have enabled us to construct a detailed account of iridoid biosynthesis in rove beetles, which resembles the biosynthetic route in leaf beetle larvae, but exhibits distinct stereochemical differences.

Acyclic Monoterpenes↗

PubMed2001

Flavonol glycosides and novel iridoid glycoside from the leaves of Morinda citrifolia.

One new iridoid glycoside and five known flavonol glycosides have been isolated from the leaves of Morinda citrifolia. The new iridoid exists as an epimeric mixture in solution. Complete assignments of the proton and carbon chemical shifts for the individual epimers were accomplished on the basis of high-resolution 1D and 2D NMR data. Their antioxidative activities were measured. All of these compounds showed DPPH free radical scavenging activity at the concentration of 30 microM.

Antioxidants↗

PubMed2002

7-O-6'-O-malonylcachinesidic acid, a new macrocyclic iridoid ester of malonic acid from the Tunisian plant Ajuga pseudoiva.

A new iridoid glucoside, 7-O-6'-O-malonylcachinesidic acid (1), was isolated from the leaves of Ajuga pseudoiva and characterized as its triacetyl derivative (1a). Its structure was established by spectroscopic methods and showed an unusual feature, in which an alcoholic function of the iridoid moiety and the primary alcohol of a glucopyranose unit form a 13-membered heterocycle with malonic acid.

Chromatography, Thin Layer↗

PubMed1996

Pyridine monoterpene alkaloid formation from iridoid glycosides. A novel PMTA dimer from geniposide.

New pyridine monoterpene alkaloids (PMTAs) have been synthesized from the iridoid glycosides 8-epi-loganin, cornin, and antirrinoside by treatment with beta-glucosidase and aqueous NH4-OAc. The PMTA from antirrinoside contained an 8-alpha-OAc group from the opened 7,8-epoxide moiety. Treatment of genipin, the aglycone of geniposide, with HCl(g) and NH3(g) yielded the PMTA racemigerine, a known plant isolate, in which the C=C-CH2OH side chain was converted to C=C-CH3. Reaction of geniposide with beta-glucosidase and aqueous NH4OAc led to oligomeric alkaloids, but at high dilution a dimer was obtained whose structure was formally that of a Diels-Alder adduct between racemigerine and a dihydropyridine. These biomimetic semisyntheses were analyzed in terms of reaction mechanisms and the relative paucity of known plant PMTAs in comparison with the multitudinous occurrence of their presumed iridoid glycoside precursors.

Glycosides↗

PubMed1998

Gmelinosides A-L, twelve acylated iridoid glycosides from Gmelina arborea.

Besides the known iridoids 6-O-alpha-L-rhamnopyranosylcatalpol (1), 6-O-(3"-O-trans-feruloyl)-alpha-L-rhamnopyranosylcatalpol (14), 6-O-(2"-O-acetyl-3", 4"-O-di-trans-cinnamoyl)-alpha-L-rhamnopyranosylcatalpol (15) and the known phenylpropanoid glycosides verbascoside (acteoside) and martynoside, 12 new acylated iridoid glycosides named gmelinosides A-L (2-13) have been isolated from the leaves of Gmelina arborea. These compounds were structurally characterized using a variety of spectral methods.

Carbohydrate Sequence↗

PubMed1998

New iridoids from the medicinal plant Barleria prionitis with potent activity against respiratory syncytial virus.

Two new iridoid glycosides (1 and 2), together with the known compounds barlerin (3) and verbascoside (4), were isolated from Barleria prionitis. The new iridoid glycosides were determined to be 6-O-trans-p-coumaroyl-8-O-acetylshanzhiside methyl ester (1) and its cis isomer (2) by using spectroscopic, especially 2D NMR, data. A 3:1 mixture of 1 and 2 was shown to have potent in vitro activity against respiratory syncytial virus (EC50 2.46 microgram/mL, IC50 42.2 microgram/mL).

Antiviral Agents↗

PubMed1999

Iridoid glycosides of Leonurus persicus.

Two new iridoid glucosides, 6-O-acetylajugol (1) and 7, 8-epoxy-8-epi-loganic acid (2), together with five known iridoid glucosides, galiridoside (3), ajugoside (4), 10-deoxygeniposidic acid (5), 7-deoxy-8-epi-loganic acid (6), and 8-O-acetylharpagide (7), have been isolated from the aerial parts of Leonurus persicus. Leucosceptoside A (8), eugenyl beta-rutinoside (9), and kaempferol 3-O-glucoside (10) were also isolated. The structures of 1 and 2 were elucidated by extensive 1D- and 2D-NMR spectroscopy and molecular modeling. The structure of 3 was confirmed by single-crystal X-ray diffraction. Antimicrobial activity of compounds (1-10) was also evaluated against a panel of gram-positive and gram-negative bacteria and two strains of fungi.

Anti-Bacterial Agents↗

PubMed1999

Pikuroside: a novel iridoid from Picrorhiza kurroa.

A new iridoid, pikuroside (1), was isolated from the roots of Picrorhiza kurroa, together with three known iridoids, picroside I (2), picroside II (3), and 6-feruloyl catalpol (4). The structure of 1 was established by interpretation and full assignments of NMR spectral data. Pikuroside (1) had no antiinflammatory activity, although the crude extract and picroside II (3) demonstrated moderate activity.

Animals↗

PubMed1989

A mutagenic new iridoid in the water extract of catalpae fructus.

A mutagenic principle in the water extract from Catalpae Fructus (originated from Catalpa ovata G. DON) (Bignoniaceae) was isolated and characterized as a new iridoid named catalpin. The iridoid exhibited mutagenic activity towards Salmonella typhimurium strain TA100 in the presence and absence of rat liver homogenate (S9) mix in Ames' test.

Animals↗

PubMed1995

Cytochrome P-450 in plant/insect interactions: geraniol 10-hydroxylase and the biosynthesis of iridoid monoterpenoids.

The interactions between plant secondary metabolites (particularly monoterpenes) and insects are discussed. Such metabolites are likely to have influenced the evolution of cyt P450-linked detoxification systems in animals, through animal/plant coevolution. The biosynthesis of many classes of plant secondary metabolites involves cyt P450 enzymes. Of these, one of the best characterised is the geraniol/nerol 10-hydroxylase which catalyses a key step in the biosynthesis of the iridoid class of plant terpenes. It would appear that these monoterpenoids are synthesised (via cyt P450 hydroxylation) from different precursors in different plant species, namely geraniol, its isomer nerol, or the related monoterpenoid, citronellol. We show that cyt P450 from the plants Catharanthus roseus and Nepeta racemosa are capable of hydroxylating geraniol, nerol and citronellol, and thus do not impose precursor specificity on iridoid biosynthesis in plants.

Animals↗

PubMed2000

Iridoid glucosides from Caryopteris mongholica.

Two new iridoid glucosides, 8-acetyl-6'-O-(p-coumaroyl) harpagide and 6'-O-(p-coumaroyl) antirrinoside, were isolated from the Caryopteris mongholica, together with two known iridoid glucosides, 8-acetylharpagide and harpagide. Their structures were elucidated, mainly by interpretation of their spectroscopic data (UV, IR, MASS, 1H, 13C, 1H/1H-COSY, HMQC, HMBC and NOESY NMR) and chemical methods.

China↗

PubMed2002

Wound healing activity of acylated iridoid glycosides from Scrophularia nodosa.

Three acylated iridoid glycosides (E)-6-O-(2", 4"-diacetyl-3" -O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scopolioside A) (1), (E)-6-O-(2"-acetyl-3", 4"-di-O,O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scrophuloside A(4)) (2) and (E)-6-O-(2",3"-diacetyl-4"-O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scrovalentinoside) (3) have been isolated from the dried seed pods of Scrophularia nodosa by HPLC. Their structures were determined by 1D and 2D NMR, UV/Vis and mass spectroscopy and by comparison with published data. All three compounds were shown in vitro to stimulate the growth of human dermal fibroblasts. The effect was negatively dose-dependent for 2 and 3 for which fibroblast growth stimulation was highest at 0.78 microg/mL but was not significantly different from the control at 100 microg/mL. The presence of these compounds in the mature seed pods may explain the ethnobotanical use of this plant in Europe for healing wounds.

Carbohydrate Sequence↗

PubMed2000

Iridoid glycosides from Lonicera quinquelocularis.

A new iridoid glycoside 6'-O-beta-apiofuranosylsweroside was isolated from the ethanolic extract of the roots of Lonicera quinquelocularis along with the known compounds loganin and sweroside.

Disaccharides↗

PubMed2004

Iridoids as allelochemicals and DNA polymerase inhibitors.

Growth inhibitory activities and nutritional indices of catalpol (1), 8-O-acetylharpagide (2), and harpagide (3) were determinated in larvae and adults of Tribolium castaneum, respectively. Compound 1 produced a series of allelochemical effects probably related with the DNA synthesis. This iridoid possessed the highest inhibitory activity against DNA polymerase. Molecular orbital calculations suggest that a pi-pi charge transfer recognition model could explain the action of iridioids toward nucleic acid synthesis.

Animals↗

PubMed2005

Synthesis and cytotoxicity of a novel iridoid glucoside derived from aucubin.

The novel iridoid glycoside 2 was prepared in six steps (15% overall yield) from natural aucubin (1) and fully characterized. Compound 2, which comprises the same conjugated cyclopentenone pharmacophore as known antitumor oxylipins and prostaglandins, displayed significant antiproliferative in vitro activity towards leukemia L1210 cells. The Michael addition of nucleophilic thiols to compound 2 occurred on a different position compared to classical delta7-prostaglandin A1 methyl ester. The resulting adducts 7a and 7b were fully characterized, and their MS fragmentation patterns were elucidated.

Animals↗

PubMed1996

An iridoid glucoside from dipsacus asperoides.

A new iridoid glucoside, loganic acid-6'-O-beta-D-glucoside, has been isolated from the defatted root of Dipsacus asperoides. Its structure has been elucidated by spectroscopic means as 1S-(1 alpha,4a alpha,6 alpha,7 alpha,7a alpha)-1-[(6-O-beta-D- glucopyranosyl-beta-D-glucopyranosyl)oxyl]1,4a,5,6,7,7a-hexahydro-6-hydr oxy-7- methyl-cyclopenta[c]pyran-4-carboxylic acid.

Carbohydrate Conformation↗

PubMed2006

Inhibition of the pro-inflammatory mediators' production and anti-inflammatory effect of the iridoid scrovalentinoside.

We have studied scrovalentinoside, an iridoid with anti-inflammatory properties isolated from Scrophularia auriculata ssp. pseudoauriculata, as an anti-inflammatory agent in different experimental models of delayed-type hypersensitivity. We found that scrovalentinoside reduced the edema induced by oxazolone at 0.5 mg/ear and sheep red blood cells at 10 mg/kg. The observed effect occurred during the last phase or inflammatory response; during the earlier phase or induction of the delayed-type hypersensitivity reaction, no significant activity was noted. Thus, scrovalentinoside reduced both the edema and cell infiltration in vivo and reduced lymphocyte proliferation in vitro, affecting the cycle principally during the first 48 h. Whereas cells stimulated with phytohemagglutinin changed from the G(0)/G(1) phase to the S and G(2)/M phases, when these same cells were treated with scrovalentinoside (100 microM), they remained in the G(0)/G(1) phase. Finally, scrovalentinoside inhibited the production of the pro-inflammatory mediators' TNF-alpha, IFN-gamma, IL-1beta, IL-2, IL-4, LTB(4), and NO, but had no effect on the production of the anti-inflammatory cytokine IL-10.

Animals↗

PubMed1998

The iridoid glucoside secologanin is derived from the novel triose phosphate/pyruvate pathway in a Catharanthus roseus cell culture.

Secologanin is the iridoid building block of the majority of the terpenoid indole alkaloids. In the biosynthesis of secologanin, mevalonate was considered to be the exclusive precursor of isopentenyl diphosphate. After [1-(13)C]glucose feeding to a cell culture of Catharanthus roseus, its incorporation into secologanin was studied by 13C NMR spectroscopy. The data showed that the novel triose phosphate/pyruvate and not the mevalonate pathway was the major route for the biosynthesis of secologanin.

Cells, Cultured↗