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PubMed2000

Iridoid glycosides from Gmelina philippensis.

Six new iridoids, 6-O-alpha-L-(2"-O-, 3"-O-, 4"-O-tribenzoyl)rhamnopyranosylcatalpol, 6-O-alpha-L-(2"-O-, 3"-O-dibenzoyl, 4"-O-cis-p-coumaroyl)rhamnopyranosylcatalpol, 6-O-alpha-L-(2"-O-, 3"-O-dibenzoyl, 4"-O-trans-p-coumaroyl)rhamnopyranosylcatalpol, 6-O-alpha-L-(2"-O-benzoyl, 3"-O-trans-p-coumaroyl)rhamnopyranosylcatalpol, 6-O-alpha-L-(2"-O-, 3"-O-dibenzoyl)rhamnopyranosylcatalpol, and gmephiloside as well as five known monoacyl and diacyl rhamnopyranosylcatalpol derivatives were isolated from the aerial parts of Gmelina philippensis. Their structures were established by spectroscopic means. Additionally, the known iridoids catalpol, geniposidic acid, gardoside, and 8-epi-loganic acid were identified and quantified by GC and GC-MS. The taxonomic significance of rhamnopyranosylcatalpol derivatives and iridoid acids as chemical characters is discussed.

Carbohydrate Sequence↗

PubMed2002

Effects of phenylpropanoid and iridoid glycosides on free radical-induced impairment of endothelium-dependent relaxation in rat aortic rings.

The protective effect of phenylpropanoid glycosides, forsythoside B and alyssonoside, and the iridoid glycoside lamiide, isolated from the aerial parts of Phlomis pungens var. pungens, against free radical-induced impairment of endothelium-dependent relaxation in isolated rat aorta was investigated. Aortic rings were exposed to free radicals by the electrolysis of the physiological bathing solution. Free radical-induced inhibition of the endothelium-dependent relaxation in response to acetylcholine was countered by incubation of the aortic rings before electrolysis with the aqueous extract (200 microg/ml), phenylpropanoid fraction (100 microg/ml) and iridoid fraction (150 microg/ml) of P. pungens var. pungens. Major components of the phenylpropanoid fraction forsythoside B and alyssonoside also prevented the inhibition of the acetylcholine response, at 10(-4) M concentration. However, the major component of iridoid fraction lamiide was found ineffective at the same concentration. The protective activity of phenylpropanoid glycosides against the free radical-induced impairment of endothelium-dependent relaxation may be related to their free radical scavenging property.

Animals↗

PubMed2001

Resolution of an iridoid synthon, gastrolactol, by means of dynamic acetylation and lipase-catalyzed alcoholysis.

A short synthetic route to asymmetric iridoids was developed. The three key steps were an intramolecular [4 + 2] cycloaddition reaction of an enamine derivative of 8-oxocitral (2), a dynamic acetylation, and an enzymatic resolution of the gastrolactyl acetates 5a and 5b, iridoids with three stereocenters. Some regio- and stereoselective heterogeneous catalytic hydrogenations of double bonds in iridoid aglucones were discussed.

Acetylation↗

PubMed2001

Iridoids from Rothmannia macrophylla.

A new iridoid glucoside with an ether linkage between C-3 and C-10 and a novel nonglycosidic iridoid with an ether linkage between C-3 and C-6 and a lactonic linkage at C-1, named macrophylloside (1) and macrophyllide (2), respectively, were isolated from the leaves of Rothmannia macrophylla, along with six known iridoids. Their structures were established by NMR and MS spectroscopies.

Ethers↗

PubMed2000

Effects of some iridoids from plant origin on arachidonic acid metabolism in cellular systems.

Seven iridoid glycosides isolated from different extracts of Scrophularia scorodonia L., namely bartsioside, aucubin, harpagide, harpagoside, 8-acetylharpagide, scorodioside and scropolioside B, had been evaluated for their in vitro anti-inflammatory activity in cellular systems generating COX and LOX metabolites. Structure-activity relationships obtained from in vitro screening results were discussed. Most compounds assayed did not exhibit any significant effect on PGE2- and LTC4-release from calcium ionophore-stimulated mouse peritoneal macrophages. In the LTC4-assay, only aucubin showed a significant effect, with an IC50 value of 72 microM. Harpagoside and harpagide also inhibited release of LTC4, but neither effect reached statistical significance. The release of PGE2 by mouse peritoneal macrophages stimulated with calcium ionophore was inhibited by harpagoside and 8-acetylharpagide, but this effect is not statistically significant. However, most iridoids assayed showed a significant effect on TXB2-release from calcium ionophorestimulated human platelets, with inhibition percentages slightly lower than the reference drug ibuprofen. Only harpagide, scorodioside and scropolioside B had no significant effect on TXB2-release. Our results indicate that selective inhibition of the TX-synthase enzyme may be the primary target of action of most of these iridoids, and one of the mechanisms through which they exert their anti-inflammatory effects.

Animals↗

PubMed1991

Iridoid Glucosides from Penstemon nitidus.

From the leaves of PENSTEMON NITIDUS Dougl. (smooth blue beardtongue) besides the known iridoid glucosides cornin (syn. verbenalin), hastatoside and beta-dihydrohastatoside the new compound 10-hydroxycornin has been isolated. The structures of all compounds were established by spectroscopic means (FD-MS, (1)H-, (13)C-, 2D-NMR, and NOE). This is the first report of cornin and analogous 6-keto iridoids in scrophulariaceous plants. Up to now iridoid glucosides like these have only been found in plants belonging to the Cornaceae and its allies and to the Lamiaceae-Verbenaceae complex.

Journal Article↗

PubMed1990

Recent developments in the isolation and structure elucidation of naturally occurring iridoid compounds.

Naturally occurring iridoid compounds are widely distributed in sympetalous plants and they serve as important taxonomic markers. In this survey their classification is given from the biosynthetic point of view. The recent literature concerning isolation and structure elucidation is reviewed, data on chromatography and spectroscopy, new types of iridoids and secoiridoids as well as new sugar moieties as constituents of iridoid glycosides are presented.

Journal Article↗

PubMed2005

Iridoid glycosides isolated from Oldenlandia diffusa inhibit LDL-oxidation.

An iridoid glycoside, oldenlandoside III (5) was isolated from the n-butanol fraction of methanol extracts of the aerial parts of Oldenlandia diffusa Roxb. along with six others previously characterized iridoid glycosides; geniposidic acid (1), scandoside (2), feretoside (3), 10-omicron-benzoylscandoside methyl ester (4), asperulosidic acid (6) and deacetylasperulosidic acid (7). Compounds 1, 2, and 7 inhibited LDL-oxidation, and showed 63.3+/-2.0, 62.2+/-1.6, and 63.8+/-1.5% inhibition, respectively, at a concentration of 20 microg/mL.

Glucosides↗

PubMed1993

Karsoside and scropolioside D, two new iridoid glycosides from Scrophularia ilwensis.

Two new iridoid glycosides, karsoside [1] and scropolioside D [2], were isolated from the aerial parts of Scrophularia ilwensis. Their structures were elucidated on the basis of chemical and spectral data as 6'-O-(beta-D-xylopyranosyl)-methylcatalpol and 6-O-[(2",4"-di-O-acetyl-3"-O-trans-cinnamoyl)-alpha-L-rhamnopyranosyl]- catalpol, respectively. Additionally, four known iridoids (aucubin, harpagide, 8-O-acetylharpagide, and ajugol), a phenylpropanoid glycoside (angoroside C), and two flavonoids (quercetin-3-O-rutinoside and kaempferol-3-O-rutinoside) were isolated and identified.

Acetylation↗

PubMed1998

A new iridoid from Scrophularia auriculata ssp. pseudoauriculata.

A new iridoid glycoside, scrovalentinoside (1), was isolated from the MeOH extract of the aerial parts of Scrophularia auriculata L. ssp. pseudoauriculata. The structure of the new compound 1 was elucidated as 6-O-(2", 3"-di-O-acetyl-4"-O-p-methoxy-cinnamoyl)-alpha-L-rhamnopyranosyl catalpol by spectroscopic methods. The known iridoid glycoside, scropolioside A; two saponins, verbascosaponin A and verbascosaponin; and the phenylethanoid glycoside, verbascoside, were also isolated.

Glycosides↗

PubMed1999

Verbaspinoside, a new iridoid glycoside from Verbascum spinosum.

A new iridoid glycoside, verbaspinoside (1), was isolated from the aerial parts of Verbascum spinosum. Its structure was elucidated on the basis of chemical and spectral data as 6-O-[(2' '-O-trans-cinnamoyl)-alpha-L-rhamnopyranosyl]-catalpol. Additionally, three known iridoids (aucubin, catalpol, and ajugol) and three phenylpropanoid glycosides [acteoside, angoroside A (2), and angoroside C (3)] were isolated and identified.

Carbohydrate Conformation↗

PubMed2004

Patterns of iridoid glycoside production and induction in Plantago lanceolata and the importance of plant age.

Induction of allelochemicals is one way that plants efficiently deploy defenses against herbivory. In two separate experiments we investigated the time course of this inductive response and the importance of the timing of herbivory for Plantago lanceolata (Plantaginaceae). We found a localized induced response of catalpol and the ratio of catalpol to total iridoid glycosides in damaged leaves that was evident at d 6 after caterpillars of the specialist Junonia coenia were put onto the plants. On the whole plant level, we detected small, but significant changes in the iridoid glycoside metabolism of P. lanceolata on several different days following herbivory. We also found considerable change in the amounts of allelochemicals produced during P. lanceolata's ontogeny. This ontogenetic effect might help to explain some of the reasons why induction may be difficult to detect in P. lanceolata. We also investigated the importance of the timing of herbivory on P. lanceolata's inductive response, but neither herbivory after 5 wk of growth nor after 6 or 7 wk of growth induced an increase in aucubin or catalpol.

Glucosides↗

PubMed2005

A new iridoid diglycoside from Clerodendrum chinense.

A new iridoid diglucoside, 5-O-beta-glucopyranosyl-harpagide, has been isolated from the aerial part of Clerodendrum chinense together with three known iridoid glucosides and six known cyclohexylethanoids. Their structures have been determined by analyses of spectroscopic data.

Clerodendrum↗

PubMed2005

Iridoids as DNA topoisomerase I poisons.

The discovery of new topoisomerase I inhibitors is necessary since most of the antitumor drugs are targeted against type II and only a very few can specifically affect type I. Topoisomerase poisons generate toxic DNA damage by stabilization of the covalent DNA-topoisomerase cleavage complex and some have therapeutic efficacy in human cancer. Two iridoids, aucubin and geniposide, have shown antitumoral activities, but their activity against topoisomerase enzymes has not been tested. Here it was found that both compounds are able to stabilize covalent attachments of the topoisomerase I subunits to DNA at sites of DNA strand breaks, generating cleavage complexes intermediates so being active as poisons of topoisomerase I, but not topoisomerase II. This result points to DNA damage induced by topoisomerase I poisoning as one of the possible mechanisms by which these two iridoids have shown antitumoral activity, increasing interest in their possible use in cancer chemoprevention and therapy.

Camptothecin↗

PubMed2006

beta-Glucosidase catalyzing specific hydrolysis of an iridoid beta-glucoside from Plumeria obtusa.

An iridoid beta-glucoside, namely plumieride coumarate glucoside, was isolated from the Plumeria obtusa (white frangipani) flower. A beta-glucosidase, purified to homogeneity from P. obtusa, could hydrolyze plumieride coumarate glucoside to its corresponding 13-O-coumarylplumieride. Plumeria beta-glucosidase is a monomeric glycoprotein with a molecular weight of 60.6 kDa and an isoelectric point of 4.90. The purified beta-glucosidase had an optimum pH of 5.5 for p-nitrophenol (pNP)-beta-D-glucoside and for its natural substrate. The Km values for pNP-beta-D-glucoside and Plumeria beta-glucoside were 5.04+/-0.36 mM and 1.02+/-0.06 mM, respectively. The enzyme had higher hydrolytic activity towards pNP-beta-D-fucoside than pNP-beta-D-glucoside. No activity was found for other pNP-glycosides. Interestingly, the enzyme showed a high specificity for the glucosyl group attached to the C-7' position of the coumaryl moiety of plumieride coumarate glucoside. The enzyme showed poor hydrolysis of 4-methylumbelliferyl-beta-glucoside and esculin, and did not hydrolyze alkyl-beta-glucosides, glucobioses, cyanogenic-beta-glucosides, steroid beta-glucosides, nor other iridoid beta-glucosides. In conclusion, the Plumeria beta-glucosidase shows high specificity for its natural substrate, plumieride coumarate glucoside.

Apocynaceae↗

PubMed2003

Scropolioside-D2 and harpagoside-B: two new iridoid glycosides from Scrophularia deserti and their antidiabetic and antiinflammatory activity.

Five iridoid glycosides, including the two new compounds scropolioside-D(2) (1) and harpagoside-B (2), were isolated from the aerial parts of Scrophularia deserti DEL (Scrophulariaceae). Their structures were elucidated on the basis of spectral data to be 6-O-[2",4"-di-O-acetyl-3"-O-trans-cinnamoyl)-alpha-L-rhamnopyranosyl]-8 alpha-hydroxymethyl-1 alpha,5 beta,6 alpha,7 alpha,9 beta-pentahydro-7(8)-epoxy-2-oxaind-3-ene-1-O-beta-D-glucopyranoside-6'-O-acetate (1) and 5-O-beta-hydroxy-8-O-beta-trans-cinnamoyl-8 alpha-methyl-1,6,7,9-tetrahydro-2-oxaind-3-ene-1-O-beta-D-glucopyranoside (2), respectively. In addition, three more iridoid glycosides, scropolioside-D (3), koelzioside (4), and 8-O-acetyl-harpagide (5), were also isolated and characterized from this source. The biological activity and the structure activity relationship of the compounds were also studied, and scropolioside-D (3) and harpagoside-B (2) were found to possess significant antidiabetic and antiinflammatory activity, respectively.

Animals↗

PubMedDate not supplied

Iridoids and phenylethanoids of Verbena bipinnatifida nutt.

Iridoids and phenylethanoids were separated from Verbena bipinnatifida Nutt. (Verbenaceae). The compounds identified are pulchelloside I and II--iridoids and martynoside, verbascoside-phenylethanoids. The structures of all the compounds isolated were elucidated by classical and spectroscopic methods.

Chromatography, High Pressure Liquid↗

PubMed1993

[HPLC determination of iridoids in Cape jasmine Frvit (Zhizi)].

Four iridoid constituents: geniposide, gardenoside, geniposidic acid and genipin-1-beta-gentiobioside, have been separated by using an ODS (7 microns) column with gradient elution. The iridoid contents of the crude drug were quantified by peak height ratio. Thirty-one specimens from various sources were analyzed.

Drugs, Chinese Herbal↗