Iridoid glycosides from Gmelina arborea

Three iridoid glycosides 6-O-(3'-O-benzoyl)-alpha-l-rhamnopyranosylcatalpol (1a), 6-O-(3'-O-trans-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (2a) and 6-O-(3'-O-cis-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (3a) were isolated from aerial parts of Gmelina arborea and structures were elucidated by spectral analysis. Additionally a known iridoid 6-O-(3', 4'-O-dibenzoyl)-alpha-l-rhamnopyranosylcatalpol (4) was also isolated and identified.     

Anti-inflammatory iridoid glycosides from fruits of Cornus officinalis

Three undescribed iridoid glycosides, cyc(7β-O-6′)-morroniside (1), 6′-methyl succinate-7β-O-methylmorroniside (2), and 7β-O-methyl phenyllactate morroniside (3) were isolated from 50% ethanol extract of Cornus officinalis fruits. The structures of the isolated compounds were determined by HRESIMS, ¹D NMR, ²D NMR, UV and IR spectroscopic methods. Compounds 1-3 exhibited moderate anti-inflammatory activities in vivo in a CuSO₄-induced zebrafish inflammation model (when evaluated at 50 μM).     

New iridoid glycosides from the fruits of Forsythia suspensa and their hepatoprotective activities

A novel iridoid glycoside trimer named forsydoitriside A (1) and five new iridoid glycosides (2–6) were isolated from the fruits of Forsythia suspensa together with two known compounds (7, 8). These new structures were elucidated by comprehensive spectroscopic data and the comparison of experimental and calculated electronic circular dichroism spectra. Compounds 1–8 were all assayed on acetaminophen-induced HepG2 cell damage. The results exhibited that compounds 2, 3, 5 and 6 possessed strong hepatoprotective activities against the damage in HepG2 cell.     

Antioxidant efficacy of iridoid and phenylethanoid glycosides from the medicinal plant Teucrium chamaedris in cell-free systems

Twelve glycosides, seven iridoids and five phenylethanoids, have been isolated from leaf and root methanolic extracts of Wall Germander (Teucrium chamaedrys), a Mediterranean species historically used as a medicinal plant. Among them, three iridoid and one phenylethanoid glycosides have been isolated and characterized for the first time. All of the structures have been elucidated on the basis of their spectral data, especially 1D and 2D NMR experiments.The antioxidative properties of pure metabolites, as well as of crude organic extracts of the plant, have been analyzed on the basis of their DPPH radical scavenging capability. The antioxidant capacity in cell-free systems of the isolated metabolites was carried out by measuring their capabilities to inhibit the synthesis of thiobarbituric acid reactive species in assay media using as oxidable substrates a vegetable fat and the pentose sugar 2-deoxyribose and to prevent oxidative damage of the hydrosoluble bovine serum albumin (BSA) protein. Phenylethanoid glycosides resulted efficacious DPPH radical, while iridoid glycosides prevent massively the 2-deoxyribose and BSA oxidations in assay media.     

New tetraacetylated iridoid glycosides from Sambucus ebulus L. leaves

Two new minor “Valeriana type” iridoid glycosides (1) and (2) along with 3 known flavonol glycosides [quercetin-3-O-β-glucopyranosyl-7-O-α-rhamnopyranoside (3), quercetin-3-O-β-glucopyranoside (4) and isorhamnetin-3-O-β-glucopyranoside (5)] were isolated from Sambucus ebulus L. leaves. Their structures were unambiguously elucidated by means of 1D- and 2D-NMR, and UPLC-TOF MS. Compound 2 is a rare representative of iridoid diglycosides, containing uncommon ribohexo-3-ulopyranosyl sugar moiety.     

Acylated pregnane glycosides from Caralluma russeliana

The chloroform extract of the aerial parts of Caralluma russeliana yielded four acylated pregnane glycosides, namely russeliosides E-H, three were found now. The structures of the compounds were elucidated using MS, 1H NMR, 13C NMR, 1H-1H COSY, HMQC, NOESY and HMBC experiments.     

Acylated flavonoid and phenylethanoid glycosides from Marrubium velutinum

From the aerial parts of Marrubium velutinum, one acylated flavonoid glycoside, chrysoeriol 7-O-(3",6"-di-O-E-p-coumaroyl)-beta-D-glucopyranoside, and two tetrasaccharidic phenylethanoid glycosides, velutinosides I-II, have been isolated together with ten known flavonoids and seven known phenylethanoid glycosides. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses.     

Acylated flavonol glycosides from leaves of Planchonia grandis

Three acylated flavonol glycosides have been identified from leaves of Planchonia grandis Ridley. They possess kaempferol as aglycone and two triglycosidic chains substituting hydroxyl groups at the 3- and 7-positions. The first glycosidic unit of each chain is esterified by a cis or trans p-coumaric acid. Structural elucidation was achieved by means of UV, NMR and mass spectrometry.     

Acylated quercetagetin glycosides with antioxidant activity from Tagetes maxima

The fractionation of a methanolic extract of Tagetes maxima guided for antioxidant activity resulted in the isolation of three acylated quercetagetin glycosides, quercetagetin-7-O-(6-O-caffeoyl-beta-D-glucopyranoside), quercetagetin-7-O-(6-O-p-coumaroyl-beta-D-glucopyranoside) and quercetagetin-7-O-(6-O-galloyl-beta-D-glucopyranoside), as well as four known flavonoid glycosides. The structural elucidation was accomplished by spectroscopic methods (ESI-MS/MS and NMR). The antioxidant activity of fractions and isolated compounds was determined by checking the scavenging activity against three different radicals: 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH*), hydroxyl (*OH), and superoxide (O2*-). The three isolated compounds exhibited a high radical scavenging activity in comparison with reference compounds.     

Phenolic and iridoid glycosides from Strychnos axillaris

Five phenolic glycosides 1-5 and an iridoid glucoside 6 were isolated, together with 22 known compounds, from the dried barks and woods of Strychnosaxillaris. Their structures were determined by application of spectroscopic (NMR, MS) and chemical methodologies.     

Flavonol and iridoid glycosides of Ajuga remota aerial parts

Six flavonol glycosides characterised as myricetin 3-O-alpha-rhamnosyl-(1'-->2')-alpha-rhamnoside-3'-O-alpha-rhamnoside, 5'-O-methylmyricetin 3-O-[alpha-rhamnosyl (1'-->2')][alpha-rhamnosyl (1'-->4')]-beta -glucoside-3'-O-beta-glucoside, 5'-O-methylmyricetin 3-O-alpha-rhamnosyl (1'-->2')-alpha-rhamnoside 3'-O-beta-galactoside, kaemferol 3-O-rutinoside-7-O-rutinoside, myricetin 3-O-rutinoside-3'-O-alpha-rhamnoside, myricetin 3-O-beta-glucosyl (1'-->2')-beta-glucoside-4'-O-beta-glucoside together with two iridoid glycosides identified as 6,8-diacetylharpagide and 6,8-diacetylharpagide-1-O-beta-(3',4'-di-O-acetylglucoside) have been isolated from extract of Ajuga remota aerial parts. Also isolated from the same extract were known compounds; kaempferol 3-O-alpha-rhamnoside, quercetin 3-O-beta-glucoside, quercetin 3-O-rutinoside, 8-acetylharpagide, ajugarin I and ajugarin II.     

Acylated flavonoids and phenol glycosides from Veronica thymoides subsp. pseudocinerea

A new acylated flavone glucoside, 3'-hydroxyscutellarein 7-O-(6'-O-protocatechuoyl)-beta-glucopyranoside (1), and a new phenol glucoside, 3,5-dihydroxyphenethyl alcohol 3-O-beta-glucopyranoside (6) were isolated from Veronica thymoides subsp. pseudocinerea together with seven known flavone, phenol and lignan glycosides; 3'-hydroxyscutellarein 7-O-(6'-O-trans-feruloyl)-beta-glucopyranoside (2), 3'-hydroxy, 6-O-methylscutellarein 7-O-beta-glucopyranoside (3), luteolin 7-O-beta-glucopyranoside (4), isoscutellarein 7-O-(6'-O-acetyl)-beta-allopyranosyl (1' --> 2')-beta-glucopyranoside (5), 3,4-dihydroxyphenethyl alcohol 8-O-beta-glucopyranoside (7), benzyl alcohol 7-O-beta-xylopyranosyl (1" --> 2')-beta-glucopyranoside (8), and (+)-syringaresinol 4'-O-beta-glucopyranoside (9). Compounds 2, 3 and 7-9 were reported for the first time in the genus Veronica. The structures of the isolates were determined by means of spectroscopic (UV, IR, 1D and 2D NMR, HR ESI-MS) methods. Isolated compounds (1-7) exhibited potent radical scavenging activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.     

Iridoid glycosides from the stems of Pithecoctenium crucigerum (Bignoniaceae)

Sixteen crude extracts from six Panamanian plants of the family Bignoniaceae were submitted to rapid TLC tests against DPPH and acetylcholinesterase. Pithecoctenium crucigerum (L.) A.H. Gentry, which showed interesting activity against DPPH, has been studied. The chemical investigation of the methanol extract from the stems afforded the iridoid glycoside theviridoside and three derivatives (6'-O-cyclopropanoyltheviridoside, 10-O-hydroxybenzoyltheviridoside and 10-O-vanilloyltheviridoside), along with five known phenylethanoid glycosides (verbascoside, isoverbascoside, forsythoside B, jionoside D and leucosceptoside B). These last compounds were all active against DPPH. The structures were determined by means of spectrometric and chemical methods, including 1D and 2D NMR experiments and MS analysis.     

Acylated peonidin glycosides from duskish mutant flowers of Ipomoea nil

Five acylated peonidin glycosides were isolated from the pale gray-purple flowers of a duskish mutant in the Japanese morning glory (Ipomoea nil or Pharbitis nil) as major pigments, along with a known anthocyanin, Heavenly Blue Anthocyanin (HBA). Three of these were based on peonidin 3-sophoroside and two on peonidin 3-sophoroside-5-glucoside as their deacylanthocyanins; both deacylanthocyanins were acylated with caffeic acid and/or glucosylcaffeic acids. By spectroscopic and chemical methods, the structures of the former three pigments were determined to be 3-O-[2-O-(6-O-(trans-caffeoyl)-beta-D-glucopyranosyl)-beta-D-glucopyranoside], 3-O-[2-O-(6-O-(3-O-(beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranosyl)-6-O-(4-O-(6-O-(3-O-(beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranosyl)-trans-caffeoyl)-beta-glucopyranoside], and 3-O-[2-O-(6-O-(trans-caffeoyl)-beta-D-glucopyranosyl)-6-O-(4-O-(6-O-(3-O-(beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranoside] of peonidin. The structures of the latter two pigments were also confirmed as 3-O-[2-O-(6-O-(trans-caffeoyl)-beta-D-glucopyranosyl)-beta-D-glucopyranoside]-5-O-beta-D-glucopyranoside, and 3-O-[2-O-(6-O-(trans-caffeoyl)-beta-D-glucopyranosyl)-6-O-(4-O-(6-O-(3-O-(beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranoside]-5-O-beta-D-glucopyranoside of peonidin. The mutation affecting glycosylation and acylation in anthocyanin biosynthesis of Japanese morning glory was discussed.     

Iridoid and phenylethanoid glycosides from Heterophragma sulfureum

An unusual iridoid diglycoside (specioside 6′-O-α-d-galactopyranoside) and a new phenylethanoid triglycoside (heterophragmoside) were isolated from the leaves and branches of Heterophragma sulfureum together with specioside, verminoside, 6-trans-feruloylcatapol, stereospermoside, (−)-lyoniresinol 3α-O-β-d-glucopyranoside, (+)-lyoniresinol 3α-O-β-d-glucopyranoside, (−)-5′-methoxyisolariciresinol 3α-O-β-d-glucopyranoside, (+)-5′-methoxyisolariciresinol 3α-O-β-d-glucopyranoside, and dehydroconiferyl 4-O-β-d-glucopyranoside. The structural elucidations were based on analyses of chemical and spectroscopic data.     

Acylated iridoid glucosides from Veronica anagallis-aquatica

Three new (1-3) and four known iridoid glucosides (4-7) as well as a known phenylethanoid glycoside (8) were isolated from the aerial parts of Veronica anagallis-aquatica and their structures were determined as 6'-O-benzoyl-8-epiloganic acid named aquaticoside A (1), 6'-O-p-hydroxybenzoyl-8-epiloganic acid named aquaticoside B (2), 6'-O-benzoyl-gardoside named aquaticoside C (3), veronicoside (4), catalposide (5), verproside (6), verminoside (7) and martynoside (8) on the basis of 1D and 2D NMR spectral analysis.     

Steryl glycosides and acylated steryl glycosides ofPinus sylvestris L. sapwood and heartwood

Summary The amounts of steryl glycosides (SG) and acylated steryl glycosides (ASG) were investigated in the sapwood, transition zone, inner heartwood and outer heartwood ofPinus sylvestris L. Only traces of both sterol derivates were present and their amounts decreased slightly towards the heartwood. The amount of SG decreased nearly to zero in the inner heartwood but the amount of ASG in the inner heartwood increased slightly. The suitability of enzymatic methods in SG and ASG hydrolysis, and sterol and glucose quantitative determinations, is discussed.     

Three acylated flavone glycosides from Sideritis ozturkii Aytac & Aksoy

From the aerial parts of Sideritis ozturkii, three new flavonoids, chrysoeriol 7-O-[2'-O-caffeoyl-O-acetyl-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside], chrysoeriol 7-O[2'-O-caffeoyl-beta-D-glucopyranosyl-(1 -->2)-beta-D-glucopyranoside] and chrysoeriol 7-O[2'-O-p-coumaroyl-6'-beta-O-acetyl-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside] named as ozturkosides A, B and C, respectively, were isolated, along with three known phenylethanoid glycosides, verbascoside, leucoseptoside A, martynoside and five known diterpenoids, 7-epicandicandiol, linearol, sidol, sideroxol, epoxyisolinearol. The structures were elucidated mainly by spectroscopic methods.