Phenylethanoid and iridoid glycosides from the Thai medicinal plant, Barleria strigosa

A phenylethanoid (4-hydroxyphenylethyl 4-O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranoside) and an iridoid (10-O-trans-coumaroyl-eranthemoside) were isolated from an entire Barleria strigosa plant together with verbascoside, isoverbascoside, decaffeoylverbascoside, (+)-lyoniresinol 3alpha-O-beta-D-glucoside, apigenin 7-O-alpha-L-rhamnosyl-(1-->6)-O-beta-D-glucoside, 7-O-acetyl-8-epi-loganic acid and (3R)-1-octen-3-ol-3-O-beta-D-xylosyl-(1-->6)-beta-D-glucoside. The structural elucidations were based on analyses of physical and spectroscopic data.     

A new iridoid glycoside from Veronica sibirica

A new iridoid glycoside,versibirioside（1）,and a known iridoid glycoside,verbaspinoside（2）,were isolated from the whole plant of Veronica sibirica L.Their structures were elucidated by spectroscopic methods,including 2D-NMR spectra.     

Phenylethanoid glycosides isolated from Paraboea paniculata

Phytochemical studies of the leaves and rhizomes of Paraboea pa niculata (Gesneriaceae) are reported for the first time. Three phenylethanoid glycosides were isolated and characterized as 3,4-dihydroxyphenethyl-(3"-O-beta-D-apiofuranosyl)-beta-D-glucopyranoside, calceoralarioside E, and acteoside. These isolates exhibited weak cytotoxic activity against the K-562 cell line with a 50% of cell killing rate of 40.18 microM, 27.05 microM, and 27.24 microM, respectively. In the DPPH free radical scavenging assay, their IC50 values were determined as 75.89 microM, 25.00 microM, and 26.04 microM, respectively.     

Aliphatic alcohol and iridoid glycosides from Asystasia intrusa

An aliphatic alcohol glycoside (asystoside) and an iridoid diglucoside (3'-O-beta-D-glucopyranosyl-catalpol) were isolated from the aerial part of Asystasia intrusa along with benzyl beta-D-glucopyranoside, zizybeoside I, (6S,9R)-roseoside, verbascoside, ehrenoside, 6beta-hydroxyantirrhide, angeloside, catalpol, ajugol, 6-deoxycatalpol, and scutellarioside II. The structural elucidations were based on analyses of physical and spectroscopic data.     

Efficient strategies for preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa

Efficient strategies for the preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa using preparative high-performance liquid chromatography combined with appropriate pretreatment technologies were developed. Four fractions (Fr.1-1, Fr.1-2, Fr.1-3, and Fr.2-1) were firstly isolated from the crude extract of Hedyotis diffusa by column chromatography with C18, resin, and silica gel materials, respectively. Then, corresponding separation strategies were developed according to the polarity and chemical constituents. High-polar compounds of Fr.1-1 were purified by hydrophilic reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography mode. The combination of C18 and phenyl columns realized the complementary separation of iridoid glycosides in Fr.1-2. Meanwhile, the improved selectivity caused by the change of organic solvent in the mobile phase was utilized to realize the purification of flavonoid glycosides in Fr.1-3 and Fr. 2-1. Finally, 27 compounds (purity > 95%) mainly involving nine iridoid glycosides and five flavonoid glycosides were obtained. A complete strategy was established for the separation of a complex sample with a wide polarity range, to jointly solve the problems of enrichment of target components and separation of structural analogs.     

Determination of phenylethanoid glycosides and iridoid glycosides from therapeutically used Plantago species by CE‐MEKC

CE methods are valuable tools for medicinal plant quality management, screening, and analysis. Therefore, the aim of the current study was to optimize and validate a CE‐MEKC method for simultaneous quantification of four chief bioactive metabolites from Plantago species. The two most important secondary metabolite groups were aimed to be separated. Different electrolyte and surfactant types were tested. Surfactant concentration, BGE pH, electrolyte concentration, and buffering capacity were optimized. The final BGE consisted of 15 mM sodium tetraborate, 20 mM TAPS, and 250 mM DOC at pH 8.50. Acceptable precision, good stability, and accuracy were achieved, with high resolution for phenylethanoid glycosides. Analytes were separated within 20 min. The method was shown to be suitable for the quantification of the iridoid glycosides aucubin and catalpol, and the phenylethanoid glycosides acteoside (verbascoside) and plantamajoside from water extracts of different samples. The method was shown to be applicable to leaf extracts of Plantago lanceolata, Plantago major, and Plantago asiatica, the main species with therapeutic applications, and a biotechnological product, plant tissue cultures (calli) of P. lanceolata. Baseline separation of the main constituents from minor peaks was achieved, regardless of the matrix type.     

Two new iridoid glycosides from the Tibetan folk medicine Swertia franchetiana

Two new iridoid glycosides designated as senburiside III (2) and senburiside IV (3), together with one known iridoid glycoside senburiside I (1) and three known secoiridoid glucosides swertiamarin (4), gentiopicroside (5) and sweroside (6), were isolated from the whole plant of Swertia franchetiana. The structures of the two new compounds were elucidated by spectroscopic methods.     

Two new iridoid glycosides from the root barks of Sambucus williamsii Hance

Two new iridoid glycosides, named williamsoside C (1) and williamsoside D (2) were isolated from the root barks of Sambucus williamsii Hance. Their structures were established on the basis of extensive spectroscopic analysis (1D, 2D NMR and HRESIMS) and chemical studies as α-D-glucopyranosyl (1→2)-β-D-fructofuranosyl (4→6)-β-morroniside (1) and 7β-O-ethyl morroniside-(6'-O-7')-β-morroniside (2), respectively.     

Two new iridoid glycosides from the root barks of Sambucus williamsii Hance

Chemical investigation of the ethanol extract of the root barks of Sambucus williamsii Hance collected in the Heilongjiang province of China resulted in the isolation of two new iridoid glycosides, williamsoside A (1) and williamsoside B (2). Their structures were elucidated on the basis of extensive spectroscopic analysis (1D, 2D-NMR and HRESIMS) and chemical studies. Iridoid glycosides have for a long time been considered as characteristic ingredients of S. williamsii. However, the presence of iridoid glycosides with apiofuranosyl moieties in S. williamsii is reported for the first time in this study.     

New phenylethanoid glycosides from Veronica pectinata var. glandulosa and their free radical scavenging activities

A known phenylethanoid glycoside, ehrenoside (1), was isolated together with three new phenylethanoid glycosides, verpectoside A (2), B (3) and C (4) from the aerial parts of Veronica pectinata var. glandulosa. On the basis of spectral analysis (UV, FAB-MS, 1H-, 13C- and 2D-NMR), compounds 2-4 were determined to be 2-(3,4-dihydroxyphenyl)ethyl-O-alpha-L-arabinopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->3)]-(4-O-trans-feruloyl)-beta-D-glucopyranoside, 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-glucopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->3)]-(4-O-trans-caffeoyl)-beta-D-glucopyranoside and 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-glucopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->3)]-(4-O-trans-feruloyl)-beta-D-glucopyranoside, respectively. Isolated phenylethanoid glycosides exhibited potent radical scavenging activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.     

Allobetonicoside and 6-O-Acetylmioporoside: Two new iridoid glycosides from Betonica officinalis L.

A new allose-containing iridoid diglycoside, allobetonicoside ( 1 ), and a new acyl iridoid glucoside, 6-O-acetylmioporoside ( 2 ) have been isolated from the aerial parts of Betonica officinalis L. in addition to two known iridoid glucosides, acetylharpagide ( 3 ) and reptoside ( 4 ). Their structures have been determined by spectroscopic methods as well as by means of chemical evidence.     

Diterpene lactones and iridoid glycosides of plants of the genusLagochilus

The structure of the diterpenoid lagohirsin, found not only in the plant Lagochilus hirsutissimus but also inL. setulosus andL. olgae, has been confirmed by independent synthesis. In L. hirsutissimus new mono- and diacetyllagohirsins have been found together with lagohirsin itself. Iridoid glycosides — harpagide and its 8-O acetate — have been found for the first time in plants of the genus Lagochilus.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 33–37, January–February, 1994.     

Extraction of iridoid glycosides and their determination by micellar electrokinetic capillary chromatography

Several methods for the extraction of two iridoid glycosides, catalpol and aucubin, from the plant matrix (Veronica longifolia leaves) were compared. Pressurized hot water extraction and hot water extraction were the most efficient isolation techniques for both. Pressurized liquid extraction and maceration with various organic solvents were also tested. Relative to the amounts extracted with hot water, ethanol extracted only 22% of catalpol and 25% of aucubin and pressurized hot water extracted 83% of catalpol and 92% of aucubin. The lowest relative standard deviations, 22% for catalpol and 8% for aucubin, were achieved with hot water extraction (13 repetitions), and the highest relative standard deviations, 76% for catalpol and 73% for aucubin, with pressurized liquid extraction (five repetitions). A fast capillary electrophoretic method was developed for the quantitative determination of catalpol and aucubin.     

The occurrence of iridoid glycosides in Cymbalaria spp. in Italy

The occurrence of iridoid glycosides in a number of Cymbalaria spp. collected in Italy is shown and chemosystematic implications are discussed.     

A syringic acid derivative and two iridoid glycosides from the roots of Stachys geobombycis and their antioxidant properties

A new derivative of syringic acid, stageobester A (1) and two iridoid glycosides which including a new one, stageoboside A (2), were isolated from the roots of Stachys geobombycis. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR and MS spectra. In addition, all the isolates were tested for their antioxidant capacity. Compounds 1 and 2 showed moderate antioxidant activities against DPPH radical, with IC₅₀ values of 113.33 ± 1.53 and 40.33 ± 2.08 mg/L, respectively.     

Iridoid glucosides from Veronica hederifolia

A new iridoid glucoside, urphoside A, and six known iridoid glucosides, pikuroside, aucubin, veronicoside, catalposide, amphicoside, and verminoside, were isolated from Veronica hederifolia together with a known megastigmane glucoside, 3-hydroxy-5,6-epoxy-beta-ionol-9-O-beta-D-glucopyranoside, and a hexitol, dulcitol. The structures of the isolated compounds were established by the extensive 1D- and 2D-NMR spectroscopy.