Iridoid Derivatives Research Articles

Two new simple iridoids from the ant-plant Myrmecodia tuberosa and their antimicrobial effects

Six iridoid derivatives (1–6), including two new compounds myrmecodoides A and B (1 and 2), were isolated from the ant-plant Myrmecodia tuberosa. Their structures were determined on the basis of spectroscopic data (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, NOESY and HR-ESI-MS) and by comparison with the literature values. Among isolates, 3 and 4 exhibit weak antibacterial effect against Staphylococcus aureus subsp. aureus with MIC value of 100.0 μg/mL.

Identification of Triterpenes from the Leaves of Jacaranda puberula

The Bignoniaceae family of flowering plants is made up of approximately 100–125 genera and 860 species, and plants belonging to this family are especially common in the tropical regions of South America. Flowering plants belonging to this particular family contain a wide variety of chemical constituents, including naphthoquinones (lapachol type), iridoid glycosides, alkaloids, flavones, triterpenes, polyphenols, and tannins. Although the genus Jacaranda contains 49 distinguished species, only 13 of these species have been reported in the scientific literature, with reports focusing primarily on the application of these plants in ethnobotanical medicine or their phytochemical evaluation [1]. Only six species from the Jacaranda genus have been subjected to phytochemical investigation [1]. Although Jacaranda puberula was recent reported to contain polyphenol compounds such as verbascoside and cis-caffeoyl aldehyde [2], our general knowledge and understanding of the phytochemical properties of the plants belonging to this genus is poor. Phytochemical investigation of plants belonging to this genus, however, has revealed that they contain a variety of different compounds, including triterpenes (e.g., -sitosterol, lupenone, betulinic acid, ursolic acid, corosolic acid, oleanolic acid, and jacoumaric acid), quinones (e.g., jacaranone and hydroquinone), flavonoids (e.g., luteolin, quercetin, apigenin, and isoquercitrin), fatty acids (e.g., triacontanoic acid and 8Z,10E,12Z-octadocatrienoic acid), acetosides (e.g., E-acetoside, Z-acetoside, and isoacetoside), and a novel phenylethanoid dimer known asjacraninoside A [1]. Herein, we report for the first time the identification of several pentacyclic triterpenes, including ursolic acid (1), oleanolic acid (2), corosolic acid (3), and maslinic acid (4) from Jacaranda puberula. Furthermore, the work described in this study represents the first reported account of maslinic acid (4) being identified in a species belonging to this genus. We therefore believe that the results of this study will improve our overall understanding of the phytochemical properties of plants belonging to the Jacaranda genus, which are interesting from both biological and chemical perspectives. The identification of triterpenes in the current study is particularly interesting in view of their contribution to the biological properties of species belonging to the Bignoniaceae family. Phytochemical analysis of J. puberula confirmed that this species belonged to Tecomeaea species of the Bignoniaceae family of flowering plants. In accordance with the evolution of species belonging to this family, significant quantities of secondary metabolites derived from acetate-mevalonate were detected in J. puberula, including iridoid glycosides and pentacyclic triterpene derivatives. Tecomeaea, which is the second most studied species belonging to this family, has been found to contain a wide variety of different terpene-based compounds. Taken together, these features are considered by many to indicate the general high level of evolutionary advancement in flowering plants [3].

Mild and chemoselective lactone ring-opening with (TMS)ONa. Mechanistic studies and application to sweroside derivatives.

Mild and chemoselective opening of lactones with sodium trimethylsilanolate in high yields and aprotic solvents is described. Kinetic studies demonstrate that the B(Ac)2 mechanistic pathway is followed. Nucleophilic attack of silanolate onto the carbonyl of the lactone moiety is the rate-determining step. NaOH present as an impurity accelerates the reaction. The method was further applied to the base-sensitive and stable lactones derived from highly functionalized iridoid derivatives.

A systematic review of the wound-healing effects of monoterpenes and iridoid derivatives.

The search for more effective and lower cost therapeutic approaches for wound healing remains a challenge for modern medicine. In the search for new therapeutic options, plants and their metabolites are a great source of novel biomolecules. Among their constituents, the monoterpenes represent 90% of essential oils, and have a variety of structures with several activities such as antimicrobial, anti-inflammatory, antioxidant and wound healing. Based on that, and also due to the lack of reviews concerning the wound-healing activity of monoterpenes, we performed this systematic review—which provides an overview of their characteristics and mechanisms of action. In this search, the terms “terpenes”, “monoterpenes”, “wound healing” and “wound closure techniques” were used to retrieve articles published in LILACS, PUBMED and EMBASE until May 2013. Seven papers were found concerning the potential wound healing effect of five compouds (three monoterpenes and two iridoid derivatives) in preclinical studies. Among the products used for wound care, the films were the most studied pharmaceutical form. Monoterpenes are a class of compounds of great diversity of biological activities and therapeutic potential. The data reviewed here suggest that monoterpenes, although poorly studied in this context, are promising compounds for the treatment of chronic wound conditions.

Synthesis of novel anticancer iridoid derivatives and their cell cycle arrest and caspase dependent apoptosis

Nyctanthes arbortristis Linn (Oleaceae) is widely distributed in sub-Himalayan regions and southwards to Godavari, India commonly known as Harsingar and Night Jasmine. In continuation of our drug discovery programme on Indian medicinal plants, we isolated arbortristoside-A (1) and 7-O-trans-cinnamoyl 6β-hydroxyloganin (2) from the seeds of N. Arbortristis, which exhibited moderate in vitro anticancer activity. Chemical transformation of 2 led to significant improvement in the activity in derivative 8 and 15 against HepG2 (human hepatocellular carcinoma), MCF-7 (breast adenocarcinoma) cell lines. The compounds 8 and 15 were also capable of cell cycle arrest and caspase dependent apoptosis in HepG2 cell lines. These iridoid derivatives hold promise for developing safer alternatives to the marketed drugs.

Enantioselective Rauhut-Currier-Type Cyclizations via Dienamine Activation: Scope and Mechanism

This Feature Article describes our mechanistic studies in organocatalytic Rauhut–Currier-type reactions and some applications in target-oriented synthesis. The developed approach involves the cyclization of two tethered Michael acceptors via dienamine intermediates and leads to highly functionalized cycloalkenes. The utility of these intermediates is further demonstrated by the synthesis of biologically important targets, such as optically active iridoid derivatives. 1 Introduction 2 Organocatalytic Cyclization of Tethered α,β-Unsaturated Carbonyl Compounds; Synthesis of Cyclopentene Derivatives 2.1 Mechanistic Proposal 2.1.1 ESI-HRMS Measurements 2.1.2 NMR Experiments 2.1.3 Complementary Reactivity 2.2 Synthetic Applications 3 Organocatalytic Cyclization of Tethered α,β-Unsaturated Carbonyl Compounds; Synthesis of Cyclohexene Derivatives 4 Conclusions

A Chemical–Biological Study Reveals C9-type Iridoids as Novel Heat Shock Protein 90 (Hsp90) Inhibitors

The potential of heat shock protein 90 (Hsp90) as a therapeutic target for numerous diseases has made the identification and optimization of novel Hsp90 inhibitors an emerging therapeutic strategy. A surface plasmon resonance (SPR) approach was adopted to screen some iridoids for their Hsp90 α binding capability. Twenty-four iridoid derivatives, including 13 new natural compounds, were isolated from the leaves of Tabebuia argentea and petioles of Catalpa bignonioides. Their structures were elucidated by NMR, electrospray ionization mass spectrometry, and chemical methods. By means of a panel of chemical and biological approaches, four iridoids were demonstrated to bind Hsp90 α. In particular, the dimeric iridoid argenteoside A was shown to efficiently inhibit the chaperone in biochemical and cellular assays. Our results disclose C9-type iridoids as a novel class of Hsp90 inhibitors.

The chemical constituents from the roots of Gentiana crassicaulis and their inhibitory effects on inflammatory mediators NO and TNF-α

Graphical abstractElectronic Supplementary MaterialSupplementary material is available for this article at 10.1007/s13659-012-0067-3 and is accessible for authorized users.

Allergy-Preventive Effects of Chlorogenic Acid and Iridoid Derivatives from Flower Buds of Lonicera japonica

Allergy-preventive activity of flower buds of Lonicera japonica THUNB. was found in the 35% EtOH extract (LJ) using an in vivo assay, The assay system uses monitoring of a decrease in blood flow (BF) in the tail vein of mice subjected to sensitization with hen-egg white lysozyme (HEL). Bioassay-guided fractionation of the 35% EtOH extract led to isolation of chlorogenic acid (1) and three known iridoid derivatives, loganin (2), secoxyloganin (3) and sweroside (4), all of which inhibited the BF decrease. This suggested that the flower buds of L. japonica and compounds isolated from them have allergy-preventive properties. The structure-activity relationship of iridoid derivatives, morroniside (5), geniposide (6), asperuloside (7), aucubin (8) and catalpol (9), were also tested using the same bioassay method. Compounds 2-5 and 9 having the sp(3) atom at C-8 showed an allergy-preventive effect, while compounds 6, 7 and 8 having a double bond at C-7, C-8 did not.

Mass spectrometry studies of iridoid aglycone derivatives

Mass spectrometry studies of iridoid aglycone derivatives

Asymmetric Synthesis of Iridoid Derivatives Using Resolved 2‐Phenylindoline as a Chiral Auxiliary

AbstractAn asymmetric synthetic route to cis,cis‐nepetalactol (component of the sex pheromone for the hop aphid, Phorodon humuli) is presented. 2‐Phenylindoline was resolved to provide a chiral auxiliary for the cycloaddition of oxocitral. The resolution was made by chromatographic separation of the diastereomers of the urea derivative made from 2‐phenylindoline and with (R)‐(+)‐α‐methylbenzyl isocyanate, followed by reductive cleavage of the isolated diasteromers using diborane. The cycloaddition of oxocitral using (S)‐2‐phenylindoline yielded an enantiopure product after chromatography. Hydrolysis of the cycloaddition adduct yielded gastrolactol (3). As gastrolactol is a versatile synthon for the synthesis of iridoids, the overall procedure provides a general asymmetric route to elaborated iridoids. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

New iridoid derivatives from table olives cv Throuba Thassos and olive mill waste waters

Through a phytochemical screening of ten commercially available types of Greek table olives, a variety of naturally black dry salted olives cv. Throuba Thassos was found to be comparatively a very rich source of polyphenols and iridoid derivatives. Subsequent extensive phytochemical study of the methanolic extract led to the isolation of 16 natural products identified by NMR and MS spectroscopy. Among them, a macrocyclic analogue of oleuropein, named Fraxamoside B (1) and 2-[5-eth-(E)-ylidene-2-oxo-tetrahydro-pyranyl-4] acrylic acid methyl ester (oleone) (2) are new natural products [1]. Cornoside, 4-O glycoside of hydroxytyrosol and oleuropein along with (5-ethylidene-2-oxo-tetrahydro-pyranyl-4) acetic acid (lactone), 2-(5 -ethylidene-2-oxo-tetrahydro-pyranyl-4) acetic acid methyl ester (3), 3-methoxy tyrosol, are products that have not been reported in edible olives [2]. The known compounds hydroxytyrosol, tyrosol, glycoside of tyrosol, 11-oleoside methylester, ligstroside, catechol, oleanolic and maslinic acid were also isolated. Compounds 2 and 3 were also isolated from olive mill waste water (OMWW) treated with XAD resins [3]. From the same source one more compound named oleolactone (4) was for the first time isolated as a natural product.

Naturally Occurring Iridoids. A Review. Part 1.

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Naturally Occurring Iridoids. A Review, Part 1

A compilation of new naturally occurring iridoid glycosides, iridoid aglycones, iridoid derivatives and bis-iridoids reported during 1994-2005 is provided with available physical and spectral data: mp, [alpha]D, UV, IR, 1H- and 13C-NMR as well as natural source with family and references. 418 compounds with 202 references are cited.

Stereoselective Synthesis of 2,2‐Bis(C‐Branched‐Chain)glucopyranosid‐3‐ulose via an Autoxidation—Michael Addition Reaction.

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Stereoselective synthesis of 2,2-bis(C-branched-chain)glucopyranosid-3-ulose via an autoxidation-Michael addition reaction.

2,2-Bis(C-branched-chain)glucopyranosid-3-uloses, designed for the preparation of biologically active natural product iridoid derivatives, are synthesized selectively by the new reaction of butenolide-containing sugar with active methylene compounds, and the new reaction is clarified as autoxidation followed by Michael addition of carbanion.

Anticomplementary activity of the constituents of Eucommia ulmoides bark

A study was made on the anticomplementary activity of the lignoid and iridoid derivatives isolated from the bark of Eucommia ulmoides as well as the enzymatic hydrolysis products of the isolated iridoid glucosides.

Iridoide—XII : Bestimmung der relativen konfiguration und konformation isomerer iridoidglycoside mit hilfe der 1H-, 13C-NMR- und massenspektroskopie

Zusammenfassung Determination of the configuration at C-1and C-1' of iridoid glycosides as well as at C-1 of other iridoid derivatives by 1 H-, 13 C-NMR- andmass-spectroscopy. Discussion of the conformation of iridoids.

Iridoid glucosides in Griselinia, Aralidium and Toricellia

From three of five investigated species of Griselinia a new iridoid glucoside, griselinoside, was isolated. It was found to be present also in foliage of Aralidium pinnatifidum and Toricellia angulata, accompanied in the former by aralidioside another novel iridoid glucoside. The structures and absolute configurations of the two iridoids were elucidated by NMR spectroscopy and chemical conversions. From G. littoralis and T. angulata the glucosides magnolioside and syringoside respectively were isolated. 13C NMR spectra are given for thirteen iridoid derivatives.