Flavonol glycosides from Anthyllis onobrychioides

A new flavonol glycoside, rhamnocitrin 3-O-β-D-galactopyranoside, has been isolated from aerial parts of Anthyllis onobrychioides, together with the known 3-O-β-D-galactopyranosides of quercetin, isorhamnetin and kaempferol.     

Anti-inflammatory secoiridoid glycosides from Gentianella azurea

A phytochemical investigation on crude extract of Gentianella azurea led to the isolation of ten new (1–10) and one known (11) secoiridoid glycosides. Their structures were unambiguously elucidated by analysis of 1D and 2D NMR. Compounds 2, 5 and 11 were found to inhibit nitric oxide (NO) production in RAW 264.7 macrophages with IC₅₀ values of 52.78 ± 8.61, 0.69 ± 0.23 and 5.18 ± 1.33, respectively, while indomethacin, the positive control, showed an IC₅₀ value of 1.25 ± 0.52 μM.     

Flavonol glycosides from Humata pectinata

A new flavonol glucoside, 8-methoxyquercetin 3-glucoside, and 8-methoxykaempferol 3-glucoside were characterized from the whole plant of Humata pectinata.     

Flavonol glycosides from Epimedium sagittatum

Two new flavonol glycosides were isolated from Epimedium sagittatum besides the known flavonol glycosides, icariin and icarisid I. On the basis of spectral analyses, the structures of the compounds were determined to be anhydroicaritin-3-O-α-rhamnoside and icaritin-3-O-α-rhamnoside.     

Flavonol glycosides from Asplenium bulbiferum

From aerial parts of the fern Asplenium bulbiferum, besides kaempferol 3,7-diglucoside and kaempferol 3-O-rhamnoside- 7-O-glucoside, the new glycoside kaempferol 3-O-β-glucoside-7-O-β-galactoside has been characterized.     

Flavonol glycosides from Cadaba glandulosa

A new flavonol triglycoside, rhamnocitrin-3-O-neohesperoside-4'-O-glucoside was isolated from the ethanol extract of Cadaba glandulosa together with two known diglycosides rhamnocitrin-3-O-neohesperoside and rhamnetin-3-neohesperoside. Characterization of the three compounds was achieved by various spectroscopic methods.     

Flavonol glycosides from Costus spicatus

Two flavonol diglycosides, tamarixetin 3-O-neohesperidoside, kaempferide 3-O-neohesperidoside and the known quercetin 3-O-neohesperidoside, together with six other known flavonoids were isolated from the leaves of Costus spicatus and their structures were elucidated by a combination of spectroscopic and chemical methods. The flavonol diglycosides were evaluated for inhibitory activity of nitric oxide production by activated macrophages (Fig. 1).     

Flavonol glycosides from Calotropis gigantea.

Besides isolation and characterization of isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucopyranoside and taraxasteryl acetate, a new flavonol trisaccharide was isolated from the aerial parts of Calotropis gigantea, and its structure was established as isorhamnetin-3-O-[2-O-beta-D-galactopyranosyl-6-O-alpha-L-rhamnopy ranosyl]- beta-D-glucopyranoside by a combination of fast atom bombardment mass spectroscopy, 1H and 13C NMR spectra and some chemical degradations.     

Flavonol glycosides from Monnina sylvatica.

A new kaempferol triglycoside and three known kaempferol glycosides, among them two apiosides, have been isolated from the aerial parts of Monnina sylvatica. The structures were established on the basis of acid and enzymatic hydrolysis and spectral data (UV, 1H and 13CNMR, NOE difference measurements, D/CI and FAB-MS) of the isolates and of some derivatives. The triglycoside kaempferol 3-O-beta-D-glucosyl-(1----2)-O-[alpha-L-rhamnosyl(1----6)]-beta-D- galactoside is a new natural product. The configuration of the apiosyl moiety in kaempferol 3-O-beta-D-apiosyl(1----2)-beta-D-galactoside and kaempferol 3-O-beta-D-apiosyl(1----2)-O-[alpha-L-rhamnosyl(1----6)]- beta-D-galactoside was established through NOE difference measurements on the peracetate.     

Flavonol and anthraquinone glycosides from Rhamnus formosana.

Two new flavonol triglycosides, and a new anthraquinone glycoside, have been isolated from the roots of Rhamnus formosana. These compounds have been characterized as rhamnazin 3-O-[alpha-L-rhamopyranosyl(1----4)-alpha-L-rhamnopyranosyl(1----6 )]-beta-D-galactopyranoside (rhamnazin 3-isorhamninoside), rhamnocitrin 3-O-isorhamninoside and 1,6,8-trihydroxy-3-methylanthraquinone 1-O-rhamnosyl(1----2)glucoside, respectively.     

Flavonol glycosides from Securidaca diversifolia

Twelve flavonol glycosides have been isolated from the leaves of Securidaca diversifolia. The separation of ten quercetin 3-glycosides and two kaempferol 3-glycosides was achieved by droplet counter-current chromatography (DCCC), preparative reversed-phase chromatography and gel chromatography. The structures were established on the basis of partial and total acid hydrolysis and spectral data (UV, ¹³C NMR, FAB, MS, D/CI MS). The four apiosides: quercetin 3-(2″-β-D-apiofuranosyl-β-D-glucopyranoside), 3-(2″-β-D-apiofuranosyl-β-D-galactoside), 3-(2″-β-D-apiofuranosyl-α-L-arabinopyranoside) and 3-(2″-β-D-apiofuranosyl-β-D-xylopyranoside) are new natural products. The structure of kaempferol 3-(2″-β-D-apiofuranosyl-β-D-glucopyranoside), previously isolated from Cicer arietinum, is confirmed.     

Bioactivity of secoiridoid glycosides from Centaurium erythraea.

As part of our on-going search for bioactive compounds from Scottish plants, two secoiridoid glycosides, swertiamarin and sweroside, have been isolated from the aerial parts of Centaurium erythraea Rafn (Family: Gentianaceae) by reversed-phase preparative HPLC coupled with a photo-diode-array detector. The structures of these compounds were elucidated unambiguously by UV, FABMS and extensive 1D and 2D NMR spectroscopic analyses and also by comparing experimental data with literature data. Antibacterial, free radical scavenging activities and general toxicity of these glycosides have been assessed. Both compounds inhibited the growth of Bacillus cereus, Bacillus subtilis, Citrobacter freundii and Escherichia coli. While swertiamarin was also active against Proteus mirabilis and Serratia marcescens, sweroside inhibited the growth of Staphylococcus epidermidis. Swertiamarin and sweroside exhibited significant general toxicity in brine shrimp lethality bioassay and the LD50 values were 8.0 microg/ml and 34 microg/ml, respectively, whereas that of the positive control podophyllotoxin, a well known cytotoxic lignan, was 2.79 microg/ml. Chemotaxonomic implications of these compounds in the family Gentianaceae have also been discussed briefly.     

Phenylpropanoid and iridoid glycosides from Pedicularis spicata.

One new phenylpropanoid glycoside, pedicularioside H, and five known glycosides, gardoside methyl ester, shanzhiside methyl ester, 5-deoxypulchelloside I, verbascoside and pedicularioside A, were isolated from whole plants of Pedicularis spicata. On the basis of the spectral data, chemical evidence and comparison with authentic samples, pedicularioside H was determined to be 1'-O-beta-D-(3-methoxy-4-hydroxy-beta-phenyl)-ethyl-4'-O-feruloyl- beta-D- apiosyl(1----3')-alpha-L-rhamnosyl-(1----6')-glucopyranoside .     

Flavonol glycosides from Pteridium aquilinum

Two new flavonol glycosides from aerial parts of Pteridium aquilinum were identified as quercetin 3-O-β-laminaribioside and isorhamnetin 3-o-β-laminaribioside by chemical and spectroscopic methods.     

Phenylethanoid and secoiridoid glycosides from the leaves of Ligustrum purpurascens

A new phenylethanoid glycoside (2) and a new secoiridoid glycoside (16) were isolated from the leaves of Ligustrum purpurascens together with fourteen known compounds (1 and 3–15). The structures of the new compounds were determined by spectroscopic analyses (UV, IR, HR-ESI-MS, 1D, and 2D NMR). The absolute configuration of 16 was further determined by CD analysis. All phenylethanoid glycosides were prepared and their up-regulation of IFN-γ production in mouse splenic lymphocytes was evaluated. Compounds 1, 5, 6, 10, 11, 13 and 15 exhibited potent stimulatory effect on IFN-γ secretion.     

Flavonol glycosides from Chenopodium foliosum Asch

Three new flavonol glycosides, namely 6-methoxykaempferol-3-O-β-gentiobioside, gomphrenol-3-O-β-gentiobioside and gomphrenol-3-O-α-l-rhamnopyranosyl-(1 → 2)[β-d-glucopyranosyl-(1 → 6)]-β-d-glucopyranoside as well as the known patuletin-3-O-β-gentiobioside and spinacetin-3-O-β-gentiobioside were isolated from the aerial parts of Chenopodium foliosum Asch. The structures of the compounds were determined by means of spectroscopic methods (1D and 2D NMR, UV, IR, and HRMS). DPPH free radical scavenging activity of the new compounds was low or lacking.     

Flavonol glycosides from the stems of Trigonella foenum-graecum

Two kaempferol glycosides [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside and kaempferol 3-O-beta-D-glucosyl(1-->2)-(6"-O-acetyl)-beta-D-galactoside 7-O-beta-D-glucoside] as well as the quercetin glycoside [quercetin 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside] were isolated from the stems of Trigonella foenum-graecum L. (Leguminosae) along with a known kaempferol glycoside, lilyn [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside]. Their structures were established by analysis of chemical and spectral evidence.     

Flavonol glycosides in Brassica and Sinapis

The 7-glucosides and 3,7-diglucosides of kaempferol and isorhamnetin were identified in leaves and flowers of Sinapis arvensis. Additionally, the 3-sophoroside-7-glucosides of kaempferol, quercetin and isorhamnetin were found in leaves of S. arvensis and Brassica oleracea. Two dimensional surveys of leaf extracts of 27 species and cultivars of Brassica and Sinapis showed that the same pattern occurred in most species. B. tournefortii and S. flexuosa were exceptional in having flavonol 3-monosides and 3-diglycosides instead. The results suggest that it is the glycosidic patterns, rather than the distribution of the flavonol aglycones, which are likely to be of taxonomic value for distinguishing groups of species or genera within the Cruciferae.